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Bibliography on: Wolbachia

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ESP: PubMed Auto Bibliography 27 Nov 2020 at 01:57 Created: 


WIKIPEDIA: Wolbachia is a genus of bacteria which "infects" (usually as intracellular symbionts) arthropod species, including a high proportion of insects, as well as some nematodes. It is one of the world's most common parasitic microbes and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host species cannot reproduce, or even survive, without Wolbachia infection. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70 percent of all insect species are estimated to be potential hosts. Wolbachia also harbor a temperate bacteriophage called WO. Comparative sequence analyses of bacteriophage WO offer some of the most compelling examples of large-scale horizontal gene transfer between Wolbachia coinfections in the same host. It is the first bacteriophage implicated in frequent lateral transfer between the genomes of bacterial endosymbionts. Gene transfer by bacteriophages could drive significant evolutionary change in the genomes of intracellular bacteria that were previously considered highly stable or prone to loss of genes overtime. Outside of insects, Wolbachia infects a variety of isopod species, spiders, mites, and many species of filarial nematodes (a type of parasitic worm), including those causing onchocerciasis ("River Blindness") and elephantiasis in humans as well as heartworms in dogs. Not only are these disease-causing filarial worms infected with Wolbachia, but Wolbachia seem to play an inordinate role in these diseases. A large part of the pathogenicity of filarial nematodes is due to host immune response toward their Wolbachia. Elimination of Wolbachia from filarial nematodes generally results in either death or sterility of the nematode.

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Citations The Papers (from PubMed®)


RevDate: 2020-11-26

Momtaz AZ, Ahumada Sabagh AD, Gonzalez Amortegui JG, et al (2020)

A Role for Maternal Factors in Suppressing Cytoplasmic Incompatibility.

Frontiers in microbiology, 11:576844.

Wolbachia are maternally transmitted bacterial endosymbionts, carried by approximately half of all insect species. Wolbachia prevalence in nature stems from manipulation of host reproduction to favor the success of infected females. The best known reproductive modification induced by Wolbachia is referred to as sperm-egg Cytoplasmic Incompatibility (CI). In CI, the sperm of Wolbachia-infected males cause embryonic lethality, attributed to paternal chromatin segregation defects during early mitotic divisions. Remarkably, the embryos of Wolbachia-infected females "rescue" CI lethality, yielding egg hatch rates equivalent to uninfected female crosses. Several models have been discussed as the basis for Rescue, and functional evidence indicates a major contribution by Wolbachia CI factors. A role for host contributions to Rescue remains largely untested. In this study, we used a chemical feeding approach to test for CI suppression capabilities by Drosophila simulans. We found that uninfected females exhibited significantly higher CI egg hatch rates in response to seven chemical treatments that affect DNA integrity, cell cycle control, and protein turnover. Three of these treatments suppressed CI induced by endogenous wRi Wolbachia, as well as an ectopic wMel Wolbachia infection. The results implicate DNA integrity as a focal aspect of CI suppression for different Wolbachia strains. The framework presented here, applied to diverse CI models, will further enrich our understanding of host reproductive manipulation by insect endosymbionts.

RevDate: 2020-11-23

Amala M, Richard M, Saritha P, et al (2020)

Molecular evolution, binding site interpretation and functional divergence of aspartate semialdehyde dehydrogenase.

Journal of biomolecular structure & dynamics [Epub ahead of print].

Aspartate Semialdehyde Dehydrogenase (ASDH) is an important enzyme essential for the viability of pathogenic microorganisms. ASDH is mainly involved in amino acid and cell wall biosynthesis of microorganisms, hence it is considered to be a promising target for drug design. This enzyme depicts similar mechanistic function in all microorganisms; although, the kinetic efficiency of an enzyme differs according to their active site residual composition. Therefore, understanding the residual variation and kinetic efficiency of the enzyme would pave new insights in structure-based drug discovery and a novel drug molecule against ASDH. Here, ASDH from Wolbachia endosymbiont of Brugia malayi is used as a prime enzyme to execute evolutionary studies. The phylogenetic analysis was opted to classify 400 sequences of ASDH enzymes based on their structure and electrostatic surfaces. Analysis resulted in 37 monophyletic clades of diverse pathogenic and non-pathogenic organisms. The representative structures of 37 ASDHs from different clades were further deciphered to structural homologues. These enzymes exhibited presence of more positively charged surfaces than negatively charged surfaces in the active site pocket which restrains evolutionary significance. Docking studies of NADP+ with 37 enzymes reveals that site-specific residual variation in the active site pocket modulates the binding affinity (ranges of -13 to -9 kcal/mol). Type-I and Type-II divergence studies show, no significant functional divergence among ASDH, but residual changes were found among the enzyme that modulates the biochemical characteristics and catalytic efficiency. The present study not only explores residual alteration and catalytic variability, it also aids in the design of species-specific inhibitors. Communicated by Ramaswamy H. Sarma.

RevDate: 2020-11-20

Cormier A, Chebbi MA, Giraud I, et al (2020)

Comparative genomics of strictly vertically transmitted, feminizing microsporidia endosymbionts of amphipod crustaceans.

Genome biology and evolution pii:5995313 [Epub ahead of print].

Microsporidia are obligate intracellular eukaryotic parasites of vertebrates and invertebrates. Microsporidia are usually pathogenic and undergo horizontal transmission or a mix of horizontal and vertical transmission. However, cases of non-pathogenic microsporidia, strictly vertically transmitted from mother to offspring, have been reported in amphipod crustaceans. Some of them further evolved the ability to feminize their non-transmitting male hosts into transmitting females. However, our understanding of the evolution of feminization in microsporidia is hindered by a lack of genomic resources. We report the sequencing and analysis of three strictly vertically-transmitted microsporidia species for which feminization induction has been demonstrated (Nosema granulosis) or is strongly suspected (Dictyocoela muelleri and Dictyocoela roeselum), along with a draft genome assembly of their host Gammarus roeselii. Contrary to horizontally transmitted microsporidia that form environmental spores that can be purified, feminizing microsporidia cannot be easily isolated from their host cells. Therefore, we co-sequenced symbiont and host genomic DNA and devised a computational strategy to obtain genome assemblies for the different partners. Genomic comparison with feminizing Wolbachia bacterial endosymbionts of isopod crustaceans indicated independent evolution of feminization in microsporidia and Wolbachia at the molecular genetic level. Feminization thus represents a remarkable evolutionary convergence of eukaryotic and prokaryotic microorganisms. Furthermore, a comparative genomics analysis of microsporidia allowed us to identify several candidate genes for feminization, involving functions such as DNA binding and membrane fusion. The genomic resources we generated contribute to establish G. roeselii and its microsporidia symbionts as a new model to study the evolution of symbiont-mediated feminization.

RevDate: 2020-11-17

Tongkrajang N, Ruenchit P, Tananchai C, et al (2020)

Molecular identification of native Wolbachia pipientis in Anopheles minimus in a low-malaria transmission area of Umphang Valley along the Thailand-Myanmar border.

Parasites & vectors, 13(1):579 pii:10.1186/s13071-020-04459-7.

BACKGROUND: Wolbachia, obligate intracellular bacteria, infect the majority of arthropods, including many mosquito species of medical importance. Some Wolbachia strains interfere with the development of Plasmodium parasites in female Anopheles, a major vector of malaria. The use of Wolbachia as a means to block malaria transmission is an emerging vector control strategy in highly endemic areas. Hence, identification of native Wolbachia strains in areas where malaria transmission is low may uncover a particular Wolbachia strain capable of Plasmodium interference. This study aims to identify native Wolbachia strains in female Anopheles spp. that are predominant in a low-malaria transmission area in mainland Southeast Asia.

METHODS: Following a 2-year survey of malaria vectors in Umphang Valley of Tak Province, Thailand, DNA extracts of female An. minimus, An. peditaeniatus, and An. maculatus were subjected to amplification of the conserved region of the 16S rRNA-encoding gene. The DNA sequences of the amplicons were phylogenetically compared with those of known Wolbachia strains.

RESULTS: Among three Anopheles spp., amplification was detected in only the DNA samples from An. minimus. The DNA sequencing of amplicons revealed 100% similarity to Wolbachia pipientis, confirming the specificity of amplification. The Wolbachia-positive An. minimus samples were devoid of Plasmodium 18S rRNA amplification. The phylogenetic trees indicate a close relationship with Wolbachia strains in subgroup B.

CONCLUSION: To the best of our knowledge, the data presented herein provide the first molecular evidence of a Wolbachia strain in An. minimus, hereinafter named wAnmi, in a low-malaria transmission area in the Umphang Valley of western Thailand. Further biological characterization is required to examine its potential for malaria transmission control in the field.

RevDate: 2020-11-16

Chao LL, Castillo CT, CM Shih (2020)

Molecular detection and genetic identification of Wolbachia endosymbiont in Rhipicephalus sanguineus (Acari: Ixodidae) ticks of Taiwan.

Experimental & applied acarology pii:10.1007/s10493-020-00574-3 [Epub ahead of print].

The genetic identity of Wolbachia endosymbiont in Rhipicephalus sanguineus ticks was determined for the first time in Taiwan. In total 1004 Rh. sanguineus ticks were examined for Wolbachia by polymerase chain reaction assay targeting the Wolbachia surface protein (wsp) gene. The prevalence of Wolbachia infection was detected in nymphs, females, and males with an infection rate of 55.8, 39.8, and 44%, respectively. The phylogenetic relationships were analyzed by comparing the sequences of wsp gene obtained from 60 strains of Wolbachia representing 11 strains of supergroup A and 10 strains of supergroup B. In general, seven major clades of supergroup A and six major clades of supergroup B can be easily distinguished by neighbour-joining analysis and were congruent by maximum likelihood method. All these Wolbachia strains of Taiwan were genetically affiliated to supergroups A and B with high sequence similarity of 98.3-100% and 98.6-100%, respectively. Intra- and inter-group analysis based on the genetic distance (GD) values indicated a lower level (GD < 0.017) within the group A strains of Taiwan compared with the group B (GD > 0.576) of other Wolbachia strains, as well as a lower level (GD < 0.062) within the group B strains of Taiwan compared with the group A (GD > 0.246) of other Wolbachia strains. Our results provide the first genetic identification of Wolbachia endosymbiont in Rh. sanguineus ticks collected from Taiwan, and detection of Wolbachia in male and nymphal ticks may imply the possible mechanism of transstadial transmission in Rh. sanguineus ticks.

RevDate: 2020-11-16

Salgueiro J, Pimper LE, Segura DF, et al (2020)

Gut Bacteriome Analysis of Anastrepha fraterculus sp. 1 During the Early Steps of Laboratory Colonization.

Frontiers in microbiology, 11:570960.

Microbial communities associated to insect species are involved in essential biological functions such as host nutrition, reproduction and survivability. Main factors have been described as modulators of gut bacterial community, such as diet, habit, developmental stage and taxonomy of the host. The present work focuses on the complex changes that gut microbial communities go through when wild insects are introduced to artificial rearing conditions. Specifically, we analyzed the effect of the laboratory colonization on the richness and diversity of the gut bacteriome hosted by the fruit fly pest Anastrepha fraterculus sp. 1. Bacterial profiles were studied by amplicon sequencing of the 16S rRNA V3-V4 hypervariable region in gut samples of males and females, in teneral (1-day-old, unfed) and post-teneral (15-day-old, fed) flies. A total of 3,147,665 sequence reads were obtained and 32 bacterial operational taxonomic units (OTUs) were identified. Proteobacteria was the most abundant phylum (93.3% of the total reads) and, Wolbachia and Enterobacter were the most represented taxa at the genus level (29.9% and 27.7%, respectively, of the total read counts). Wild and laboratory flies showed highly significant differences in the relative abundances of bacteria. The analysis of the core bacteriome showed the presence of five OTUs in all samples grouped by origin, while nine and five OTUs were exclusively detected in laboratory and wild flies, respectively. Irrespective of fly origin or sex, a dominant presence of Wolbachia was observed in teneral flies, whereas Enterobacter was highly abundant in post-teneral individuals. We evidenced significant differences in bacterial richness and diversity among generations under laboratory colonization (F0, F1, F3 and F6) and compared to laboratory and wild flies, displaying also differential patterns between teneral and post-teneral flies. Laboratory and wild A. fraterculus sp. 1 harbor different gut bacterial communities. Laboratory colonization has an important effect on the microbiota, most likely associated to the combined effects of insect physiology and environmental conditions (e.g., diet and colony management).

RevDate: 2020-11-13

Wang YF, He K, Guo W, et al (2020)

[Genes associated with Wolbachia-induced cytoplasmic incompatibility in natural populations of Culex pipiens pallens: a preliminary study].

Zhongguo xue xi chong bing fang zhi za zhi = Chinese journal of schistosomiasis control, 32(5):517-521.

OBJECTIVE: To investigate the genes involved in Wolbachia-induced cytoplasmic incompatibility among three natural populations of Culex pipiens pallens in eastern China, so as to provide insights into the development of preventive and control measures for mosquito-borne diseases based on Wolbachia.

METHODS: The cytoplasmic incompatibility was tested among three natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province and Tangkou of Shandong Province using reciprocal crosses. Wolbachia infection was detected in C. pipiens pallens using a PCR assay, and the expression of Wolbachia wsp and WD0513 genes was quantified using a fluorescent quantitative real-time PCR (qPCR) assay.

RESULTS: Bidirectional compatibility was found between the natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province (t = 0.57 and 0.15, both P values > 0.05), while bidirectional incompatibility was seen between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Wuxi of Jiangsu Province (t = 63.81 and 43.51, both P values < 0.01), and between the natural populations of C. pipiens pallens collected from Nanjing of Jiangsu Province and Tangkou of Shandong Province (t = 39.62 and 43.12, both P values < 0.01). Wolbachia wsp gene was amplified in all three natural populations of C. pipiens pallens, and qPCR assay detected no significant difference in the Wolbachia wsp gene expression among the three natural populations of C. pipiens pallens (F = 2.15, P > 0.05). In addition, there was no significant difference in the WD0513 gene expression between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Nanjing of Jiangsu Province (q = 8.42, P < 0.05) or between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Wuxi of Jiangsu Province (q = 7.84, P < 0.05); however, there was a significant difference detected in the WD0513 gene expression between the natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province (q = 0.40, P > 0.05).

CONCLUSIONS: Different Wolbachia numbers are detected in natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province and Tangkou of Shandong Province, and WD0513 gene may be involved in the Wolbachia-induced cytoplasmic incompatibility among three natural populations of C. pipiens pallens.

RevDate: 2020-11-12

Arias-Giraldo LM, Muñoz M, Hernández C, et al (2020)

Species-dependent variation of the gut bacterial communities across Trypanosoma cruzi insect vectors.

PloS one, 15(11):e0240916 pii:PONE-D-20-09096.

Triatomines (Hemiptera: Reduviidae) are the insect vectors of Trypanosoma cruzi, the causative agent of Chagas disease. The gut bacterial communities affect the development of T. cruzi inside the vector, making the characterization of its composition important in the understanding of infection development. We collected 54 triatomine bugs corresponding to four genera in different departments of Colombia. DNA extraction and PCR were performed to evaluate T. cruzi presence and to determine the discrete typing unit (DTU) of the parasite. PCR products of the bacterial 16S rRNA gene were pooled and sequenced. Resulting reads were denoised and QIIME 2 was used for the identification of amplicon sequence variants (ASVs). Diversity (alpha and beta diversity) and richness analyses, Circos plots, and principal component analysis (PCA) were also performed. The overall T. cruzi infection frequency was 75.9%, with TcI being the predominant DTU. Approximately 500,000 sequences were analyzed and 27 bacterial phyla were identified. The most abundant phyla were Proteobacteria (33.9%), Actinobacteria (32.4%), Firmicutes (19.6%), and Bacteroidetes (7.6%), which together accounted for over 90% of the gut communities identified in this study. Genera were identified for these main bacterial phyla, revealing the presence of important bacteria such as Rhodococcus, Serratia, and Wolbachia. The composition of bacterial phyla in the gut of the insects was significantly different between triatomine species, whereas no significant difference was seen between the state of T. cruzi infection. We suggest further investigation with the evaluation of additional variables and a larger sample size. To our knowledge, this study is the first characterization of the gut bacterial structure of the main triatomine genera in Colombia.

RevDate: 2020-11-12

Masson F, B Lemaitre (2020)

Growing Ungrowable Bacteria: Overview and Perspectives on Insect Symbiont Culturability.

Microbiology and molecular biology reviews : MMBR, 84(4):.

SUMMARYInsects are often involved in endosymbiosis, that is, the housing of symbiotic microbes within their tissues or within their cells. Endosymbionts are a major driving force in insects' evolution, because they dramatically affect their host physiology and allow them to adapt to new niches, for example, by complementing their diet or by protecting them against pathogens. Endosymbiotic bacteria are, however, fastidious and therefore difficult to manipulate outside of their hosts, especially intracellular species. The coevolution between hosts and endosymbionts leads to alterations in the genomes of endosymbionts, limiting their ability to cope with changing environments. Consequently, few insect endosymbionts are culturable in vitro and genetically tractable, making functional genetics studies impracticable on most endosymbiotic bacteria. However, recently, major progress has been made in manipulating several intracellular endosymbiont species in vitro, leading to astonishing discoveries on their physiology and the way they interact with their host. This review establishes a comprehensive picture of the in vitro tractability of insect endosymbiotic bacteria and addresses the reason why most species are not culturable. By compiling and discussing the latest developments in the design of custom media and genetic manipulation protocols, it aims at providing new leads to expand the range of tractable endosymbionts and foster genetic research on these models.

RevDate: 2020-11-10

Onah IE, S Sumner (2020)

DNA barcodes and new primers for nature's pest controllers: the social wasps.

Genome [Epub ahead of print].

Globally, biodiversity is declining as a result of anthropogenic pressures, and this could lead to extinction of some species before they are discovered. The loss of insect taxa is of prime concern, given recent reports of significant declines in the populations of many taxa across the globe. Efforts to document biodiversity have met with several challenges, amongst which are the difficulties in using morphological features to discriminate species, especially in insects. DNA barcoding is a rapid and reliable method for species identification and discovery, but choosing appropriate primers to amplify the barcode region without coamplifying contaminants remains a key challenge. We developed and tested a set of primers for PCR amplification of the DNA barcode region of the COI gene in polistine wasps. We tested their efficacy in 36 species of vespid wasps, and the solitary wasp Zethus miniatus Saussure. Samples were obtained from Africa, Americas, Asia and Europe. The polistine-specific primers successfully amplified the barcode region for all polistines tested, without amplifying any Wolbachia present; they also worked with many species from the other Vespidae wasp subfamilies. The new primers are valuable for the discovery and accurate documentation of polistine wasps in the four continents.

RevDate: 2020-11-10

Torres R, Hernandez E, Flores V, et al (2020)

Wolbachia in mosquitoes from the Central Valley of California, USA.

Parasites & vectors, 13(1):558 pii:10.1186/s13071-020-04429-z.

BACKGROUND: Wolbachia bacteria are widely distributed throughout terrestrial arthropod species. These bacteria can manipulate reproduction and influence the vector competence of their hosts. Recently, Wolbachia have been integrated into vector control programmes for mosquito management. A number of supergroups and strains exist for Wolbachia, and they have yet to be characterized for many mosquito species. In this study, we examined Wolbachia prevalence and their phylogenetic relationship to other Wolbachia, using mosquitoes collected in Merced County in the Central Valley of California.

METHODS: Adult mosquitoes were collected from 85 sites in Merced County, California in 2017 and 2018. Traditional and quantitative PCR were used to investigate the presence or absence and the density of Wolbachia, using Wolbachia-specific 16S rRNA and Wolbachia-surface protein (wsp) genes. The supergroup of Wolbachia was determined, and Multilocus Sequence Typing (MLST) by sequencing five housekeeping genes (coxA, gatB, ftsZ, hcpA and fbpA) was also used to determine Wolbachia supergroup as well as strain.

RESULTS: Over 7100 mosquitoes of 12 species were collected: Aedes melanimon, Ae. nigromaculis, Ae. vexans, Ae. aegypti, Culex pipiens, Cx. stigmatosoma, Cx. tarsalis, Anopheles franciscanus, An. freeborni, An. punctipennis, Culiseta incidens and Cs. inornata. Eight showed evidence of Wolbachia. To our knowledge, this study is the first to report detection of Wolbachia in five of these species (Ae. melanimon, Cx. stigmatosoma, Cx. tarsalis, Cs. incidens and Cs. inornata). Culex pipiens and Cx. stigmatosoma had a high frequency and density of Wolbachia infection, which grouped into supergroup B; Cs. inornata clustered with supergroup A. MLST comparisons identified Cx. pipiens and Cx. stigmatosoma as wPip strain type 9 supergroup B. Six species had moderate to low (< 14%) frequencies of Wolbachia. Four species were negative, Ae. nigromaculis, An. franciscanus, An. freeborni and Ae. aegypti.

CONCLUSIONS: New records of Wolbachia detection were found in mosquitoes from Merced County, California. Culex stigmatosoma and Cs. inornata were new records for Wolbachia supergroup B and A, respectively. Other species with Wolbachia occurred with low frequency and low density. Detection of Wolbachia in mosquitoes can be used to inform potential vector control applications. Future study of Wolbachia within Cx. stigmatosoma and Cs. inornata in California and through the range of these species could further explore Wolbachia infection in these two species.

RevDate: 2020-11-07

Varotto-Boccazzi I, Epis S, Arnoldi I, et al (2020)

Boosting immunity to treat parasitic infections: Asaia bacteria expressing a protein from Wolbachia determine M1 macrophage activation and killing of Leishmania protozoans.

Pharmacological research pii:S1043-6618(20)31596-6 [Epub ahead of print].

Leishmaniases are severe vector-borne diseases affecting humans and animals, caused by Leishmania protozoans. Over 350 million people and millions of dogs are at risk of infection. Immune polarization plays a major role in determining the outcome of Leishmania infections: hosts displaying M1-polarized macrophages are protected, while those biased on the M2 side acquire a chronic infection that could develop into a potentially deadly disease. The identification of the factors involved in M1 polarization is essential for the design of therapeutic and prophylactic interventions, including vaccines. Infection by the filarial nematode Dirofilaria immitis could be one of the factors that interfere with leishmaniasis in dogs. Indeed, filarial nematodes induce a partial skew of the immune response towards M1, likely caused by their bacterial endosymbionts, Wolbachia. Here we have examined the potential of AsaiaWSP, a bacterium engineered for the expression of the Wolbachia surface protein (WSP), as an inductor of M1 macrophage activation and Leishmania killing. Macrophages stimulated with AsaiaWSP displayed a strong leishmanicidal activity, comparable to that determined by the choice-drug amphotericin B. Additionally, AsaiaWSP determined the expression of markers of classical macrophage activation, including M1 cytokines, ROS and NO, and an increase in phagocytosis activity. Asaia not expressing WSP also induced macrophage activation, although at a lower extent compared to AsaiaWSP. In summary, the results of the present study confirm the immunostimulating properties of WSP highlighting a potential therapeutic efficacy against Leishmania parasites. Furthermore, Asaia was designed as a delivery system for WSP, thus developing a novel type of immunomodulating agent, worthy of being investigated for immuno-prophylaxis and -therapy of leishmaniases and other diseases that could be subverted by M1 macrophage activation.

RevDate: 2020-11-09

Pagendam DE, Trewin BJ, Snoad N, et al (2020)

Modelling the Wolbachia incompatible insect technique: strategies for effective mosquito population elimination.

BMC biology, 18(1):161 pii:10.1186/s12915-020-00887-0.

BACKGROUND: The Wolbachia incompatible insect technique (IIT) shows promise as a method for eliminating populations of invasive mosquitoes such as Aedes aegypti (Linnaeus) (Diptera: Culicidae) and reducing the incidence of vector-borne diseases such as dengue, chikungunya and Zika. Successful implementation of this biological control strategy relies on high-fidelity separation of male from female insects in mass production systems for inundative release into landscapes. Processes for sex-separating mosquitoes are typically error-prone and laborious, and IIT programmes run the risk of releasing Wolbachia-infected females and replacing wild mosquito populations.

RESULTS: We introduce a simple Markov population process model for studying mosquito populations subjected to a Wolbachia-IIT programme which exhibit an unstable equilibrium threshold. The model is used to study, in silico, scenarios that are likely to yield a successful elimination result. Our results suggest that elimination is best achieved by releasing males at rates that adapt to the ever-decreasing wild population, thus reducing the risk of releasing Wolbachia-infected females while reducing costs.

CONCLUSIONS: While very high-fidelity sex separation is required to avoid establishment, release programmes tend to be robust to the release of a small number of Wolbachia-infected females. These findings will inform and enhance the next generation of Wolbachia-IIT population control strategies that are already showing great promise in field trials.

RevDate: 2020-11-04

Mugerwa H, Wang HL, Sseruwagi P, et al (2020)

Whole-genome single nucleotide polymorphism and mating compatibility studies reveal the presence of distinct species in sub-Saharan Africa Bemisia tabaci whiteflies.

Insect science [Epub ahead of print].

In sub-Saharan Africa cassava growing areas, two members of the Bemisia tabaci species complex termed sub-Saharan Africa 1 (SSA1) and SSA2 have been reported as the prevalent whiteflies associated with the spread of viruses that cause cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) pandemics. At the peak of CMD pandemic in the late 1990s, SSA2 was the prevalent whitefly, although its numbers have diminished over the last two decades with the resurgence of SSA1 whiteflies. Three SSA1 subgroups (SG1 to SG3) are the predominant whiteflies in East Africa and vary in distribution and biological properties. Mating compatibility between SSA1 subgroups and SSA2 whiteflies was reported as the possible driver for the resurgence of SSA1 whiteflies. In this study, a combination of both phylogenomic methods and reciprocal crossing experiments were applied to determine species status of SSA1 subgroups and SSA2 whitefly populations. Phylogenomic analyses conducted with 26 548 205 bp whole genome single nucleotide polymorphisms (SNPs) and the full mitogenomes clustered SSA1 subgroups together and separate from SSA2 species. Mating incompatibility between SSA1 subgroups and SSA2 further demonstrated their distinctiveness from each other. Phylogenomic analyses conducted with SNPs and mitogenomes also revealed different genetic relationships among SSA1 subgroups. The former clustered SSA1-SG1 and SSA1-SG2 together but separate from SSA1-SG3, while the latter clustered SSA1-SG2 and SSA1-SG3 together but separate from SSA1-SG1. Mating compatibility was observed between SSA1-SG1 and SSA1-SG2, while incompatibility occurred between SSA1-SG1 and SSA1-SG3, and SSA1-SG2 and SSA1-SG3. Mating results among SSA1 subgroups were coherent with phylogenomics results based on SNPs but not the full mitogenomes. Furthermore, this study revealed that the secondary endosymbiont - Wolbachia did not mediate reproductive success in the crossing assays carried out. Overall, using genome wide SNPs together with reciprocal crossings assays, this study established accurate genetic relationships among cassava-colonizing populations, illustrating that SSA1 and SSA2 are distinct species while at least two species occur within SSA1 species. This article is protected by copyright. All rights reserved.

RevDate: 2020-11-04

Diarra AZ, Kone AK, Niare DS, et al (2020)

Molecular Detection of Microorganisms Associated with Small Mammals and Their Ectoparasites in Mali.

The American journal of tropical medicine and hygiene [Epub ahead of print].

Small mammals are the natural reservoirs for many zoonotic pathogens. Using molecular tools, we assessed the prevalence of bacteria and protozoans in small mammals and their ectoparasites in Faladjè, Bougouni, and Bamoko, Mali. A total of 130 small mammals belonging to 10 different species were captured, of which 74 (56.9%) were infested by ectoparasites, including Laelaps echidnina, Xenopsylla cheopis, Amblyomma variegatum, Rhipicephalus sanguineus sensu lato, and Haemaphysalis spp. nymphs. DNA of Bartonella was found in 14/75 (18.7%), 6/48 (12.5%), and 3/7 (42.8%) small mammals from Faladjè, Bougouni, and Bamako, respectively. In Faladjè, Bartonella DNA was detected in 31/68 (45.6%) of L. echidnina and 14/22 (63.6%) of X. cheopis. In Bougouni, it was found in 2/26 (7.7%) of L. echidnina and 10/42 (23.8%) of X. cheopis. The sequences of Bartonella obtained from small mammals were close to those of Bartonella mastomydis, Bartonella elizabethae, and uncultured Bartonella spp. In Faladjè, Coxiella burnetii DNA was detected in 64.4% (29/45) of Haemaphysalis spp. ticks, 4.5% (2/44) of Mastomys erythroleucus, 12.5% (1/8) of Praomys daltoni, and 1.5% (1/68) of L. echidnina. We found DNA of Wolbachia in X. cheopis from Faladjè and DNA of Rickettsia africae and Ehrlichia ruminantium in Am. variegatum from Bougouni. The results of our study show that several small mammal species harbor and may serve as potential reservoirs of Bartonella spp., likely to play a major role in the maintenance, circulation, and potential transmission of bacteria in Mali. The pathogenicity of these bacteria for humans or animals remains to be demonstrated.

RevDate: 2020-11-04

DeVries ZC, Santangelo RG, Booth W, et al (2020)

Reproductive compatibility among populations and host-associated lineages of the common bed bug (Cimex lectularius L.).

Ecology and evolution, 10(20):11090-11099 pii:ECE36738.

As populations differentiate across geographic or host-association barriers, interpopulation fertility is often a measure of the extent of incipient speciation. The bed bug, Cimex lectularius L., was recently found to form two host-associated lineages within Europe: one found with humans (human-associated, HA) and the other found with bats (bat-associated, BA). No unequivocal evidence of contemporary gene flow between these lineages has been found; however, it is unclear whether this is due to an inability to produce viable "hybrid" offspring. To address this question and determine the extent of compatibility between host-associated lineages, we set up mating crosses among populations of bed bugs based on both their host association (human-HA vs. bat-BA) and geographic origin (North America vs. Europe). Within-population fecundity was significantly higher for all HA populations (>1.7 eggs/day) than for BA populations (<1 egg/day). However, all within-population crosses, regardless of host association, had >92% egg hatch rates. Contrary to previous reports, in all interlineage crosses, successful matings occurred, fertile eggs were oviposited, and the F1 "hybrid" generation was found to be reproductively viable. In addition, we evaluated interpopulation genetic variation in Wolbachia among host-associated lineages. We did not find any clear patterns related to host association, nor did we observe a homogenization of Wolbachia lineages across populations that might explain a breakdown of reproductive incompatibility. These results indicate that while the HA and BA populations of C. lectularius represent genetically differentiated host-associated lineages, possibly undergoing sympatric speciation, this is in its incipient stage as they remain reproductively compatible. Other behavioral, physiological, and/or ecological factors likely maintain host-associated differentiation.

RevDate: 2020-11-03

Laidoudi Y, Levasseur A, Medkour H, et al (2020)

An Earliest Endosymbiont, Wolbachia massiliensis sp. nov., Strain PL13 from the Bed Bug (Cimex hemipterus), Type Strain of a New Supergroup T.

International journal of molecular sciences, 21(21): pii:ijms21218064.

The symbiotic Wolbachia are the most sophisticated mutualistic bacterium among all insect-associated microbiota. Wolbachia-insect relationship fluctuates from the simple facultative/parasitic to an obligate nutritional-mutualistic association as it was the case of the bedbug-Wolbachia from Cimexlectularius. Understanding this association may help in the control of associated arthropods. Genomic data have proven to be reliable tools in resolving some aspects of these symbiotic associations. Although, Wolbachia appear to be fastidious or uncultivated bacteria which strongly limited their study. Here we proposed Drosophila S2 cell line for the isolation and culture model to study Wolbachia strains. We therefore isolated and characterized a novel Wolbachia strain associated with the bedbug Cimexhemipterus, designated as wChem strain PL13, and proposed Wolbachiamassiliensis sp. nov. strain wChem-PL13 a type strain of this new species from new supergroup T. Phylogenetically, T-supergroup was close to F and S-supergroups from insects and D-supergroup from filarial nematodes. We determined the 1,291,339-bp genome of wChem-PL13, which was the smallest insect-associated Wolbachia genomes. Overall, the wChem genome shared 50% of protein coding genes with the other insect-associated facultative Wolbachia strains. These findings highlight the diversity of Wolbachia genotypes as well as the Wolbachia-host relationship among Cimicinae subfamily. The wChem provides folate and riboflavin vitamins on which the host depends, while the bacteria had a limited translation mechanism suggesting its strong dependence to its hosts. However, the clear-cut distinction between mutualism and parasitism of the wChem in C. hemipterus cannot be yet ruled out.

RevDate: 2020-11-02

Savić S, Stosic MZ, Marcic D, et al (2020)

Seroepidemiological Study of Canine and Human Dirofilariasis in the Endemic Region of Northern Serbia.

Frontiers in veterinary science, 7:571.

Dirofilariasis is a vector-borne zoonotic disease caused mainly by Dirofilaria immitis and Dirofilaria repens that affect dogs and humans all over the world. Serbia is considered an endemic country to both forms of dirofilariasis, although most of the population is concentrated in the north of the country. The aims of this study were to show the prevalence of D. immitis and D. repens in dogs and the seroprevalence in humans compared to previous studies in Northern Serbia. In total, 346 dog sera samples and 265 human samples were analyzed. Dog blood samples were analyzed using the modified Knott's method to check whether there were Dirofilaria spp. microfilariae and serum samples were checked by a commercial D. immitis antigen test. Human serum samples were analyzed with a non-commercial ELISA for detection of specific anti-D. immitis, anti-D. repens, and anti-Wolbachia IgG antibodies, and confirmed by western blotting. The overall prevalence for Dirofilaria spp. in dogs was 29.19%. The overall prevalence for D. immitis was 26.30%. The percentages of D. immitis and D. repens microfilaremia in dogs were 25.72 and 1.45%, respectively, while D. immitis./D. repens microfilaremia co-infections were also 1.45%. The overall seroprevalence for Dirofilaria spp. in humans was 3.77%. The overall seroprevalence for D. immitis was 1.51, 1.13% for D. repens, and for D. immitis/D. repens co-infections was 1.13%. The results indicate that D. immitis and D. repens are present in dogs and humans in the province of Vojvodina, in the northern part of Serbia. It is most likely associated with the presence of many rivers, the climate, and presence of mosquitoes in the area, so there could be a real public health risk.

RevDate: 2020-11-02

Dacey DP, FJJ Chain (2020)

The Challenges of Microbial Control of Mosquito-Borne Diseases Due to the Gut Microbiome.

Frontiers in genetics, 11:504354.

Mosquitoes are one of the deadliest animals on earth because of their ability to transmit a wide range of human pathogens. Traditional mosquito control methods use chemical insecticides, but with dwindling long-term effectiveness and negative effects on the environment, microbial forms of control have become common alternatives. The insecticide Bacillus thuringiensis subspecies israelensis (Bti) is the most popular of these alternatives, although it can also have direct effects on lowering environmental biodiversity and indirect effects on food-web relationships in the ecosystems where it is deployed. In addition, microbial control agents that impede pathogen development or transmission from mosquito to human are under investigation, including Wolbachia and Asaia, but unexpected interactions with mosquito gut bacteria can hinder their effectiveness. Improved characterization of mosquito gut bacterial communities is needed to determine the taxa that interfere with microbial controls and their effectiveness in wild populations. This mini-review briefly discusses relationships between mosquito gut bacteria and microbial forms of control, and the challenges in ensuring their success.

RevDate: 2020-10-31

Sanaei E, Charlat S, J Engelstädter (2020)

Wolbachia host shifts: routes, mechanisms, constraints and evolutionary consequences.

Biological reviews of the Cambridge Philosophical Society [Epub ahead of print].

Wolbachia is one of the most abundant endosymbionts on earth, with a wide distribution especially in arthropods. Effective maternal transmission and the induction of various phenotypes in their hosts are two key features of this bacterium. Here, we review our current understanding of another central aspect of Wolbachia's success: their ability to switch from one host species to another. We build on the proposal that Wolbachia host shifts occur in four main steps: (i) physical transfer to a new species; (ii) proliferation within that host; (iii) successful maternal transmission; and (iv) spread within the host species. Host shift can fail at each of these steps, and the likelihood of ultimate success is influenced by many factors. Some stem from traits of Wolbachia (different strains have different abilities for host switching), others on host features such as genetic resemblance (e.g. host shifting is likely to be easier between closely related species), ecological connections (the donor and recipient host need to interact), or the resident microbiota. Host shifts have enabled Wolbachia to reach its enormous current incidence and global distribution among arthropods in an epidemiological process shaped by loss and acquisition events across host species. The ability of Wolbachia to transfer between species also forms the basis of ongoing endeavours to control pests and disease vectors, following artificial introduction into uninfected hosts such as mosquitoes. Throughout, we emphasise the many knowledge gaps in our understanding of Wolbachia host shifts, and question the effectiveness of current methodology to detect these events. We conclude by discussing an apparent paradox: how can Wolbachia maintain its ability to undergo host shifts given that its biology seems dominated by vertical transmission?

RevDate: 2020-10-30

Tzuri N, Caspi-Fluger A, Betelman K, et al (2020)

Horizontal Transmission of Microbial Symbionts Within a Guild of Fly Parasitoids.

Microbial ecology pii:10.1007/s00248-020-01618-2 [Epub ahead of print].

Many insects harbor facultative microbial symbionts which affect the ecology of their hosts in diverse ways. Most symbionts are transmitted vertically with high fidelity, whereas horizontal transmission occurs rarely. Parasitoid larvae feed on a single host and are in close physical contact with it, providing an ecological opportunity for symbionts' horizontal transmission, but there is little empirical evidence documenting this. Here we studied horizontal transmission of three bacterial symbionts-Rickettsia, Sodalis, and Wolbachia-between three fly pupal ectoparasitoid species: Spalangia cameroni, S. endius, and Muscidifurax raptor. Muscidifurax raptor readily parasitized and successfully developed on the Spalangia spp., while the inverse did not happen. The two Spalangia spp. attacked each other and conspecifics in very low rates. Symbiont horizontal transmissions followed by stable vertical transmission in the recipient species were achieved, in low percentages, only between conspecifics: Wolbachia from infected to uninfected M. raptor, Rickettsia in S. endius, and Sodalis in S. cameroni. Low frequency of horizontal transmissions occurred in the interspecific combinations, but none of them persisted in the recipient species beyond F4, at most. Our study is one of few to demonstrate symbionts' horizontal transmission between hosts within the same trophic level and guild and highlights the rarity of such events.

RevDate: 2020-10-30

Chakraborty A, Ashraf MZ, Modlinger R, et al (2020)

Unravelling the gut bacteriome of Ips (Coleoptera: Curculionidae: Scolytinae): identifying core bacterial assemblage and their ecological relevance.

Scientific reports, 10(1):18572 pii:10.1038/s41598-020-75203-5.

Bark beetles often serve as forest damaging agents, causing landscape-level mortality. Understanding the biology and ecology of beetles are important for both, gathering knowledge about important forest insects and forest protection. Knowledge about the bark beetle gut-associated bacteria is one of the crucial yet surprisingly neglected areas of research with European tree-killing bark beetles. Hence, in this study, we survey the gut bacteriome from five Ips and one non-Ips bark beetles from Scolytinae. Results reveal 69 core bacterial genera among five Ips beetles that may perform conserved functions within the bark beetle holobiont. The most abundant bacterial genera from different bark beetle gut include Erwinia, Sodalis, Serratia, Tyzzerella, Raoultella, Rahnella, Wolbachia, Spiroplasma, Vibrio, and Pseudoxanthomonas. Notable differences in gut-associated bacterial community richness and diversity among the beetle species are observed. Furthermore, the impact of sampling location on the overall bark beetle gut bacterial community assemblage is also documented, which warrants further investigations. Nevertheless, our data expanded the current knowledge about core gut bacterial communities in Ips bark beetles and their putative function such as cellulose degradation, nitrogen fixation, detoxification of defensive plant compounds, and inhibition of pathogens, which could serve as a basis for further metatranscriptomics and metaproteomics investigations.

RevDate: 2020-10-30

Allman MJ, Fraser JE, Ritchie SA, et al (2020)

Wolbachia's Deleterious Impact on Aedes aegypti Egg Development: The Potential Role of Nutritional Parasitism.

Insects, 11(11): pii:insects11110735.

The artificial introduction of the endosymbiotic bacterium, Wolbachia pipientis, into Aedes (Ae.) aegypti mosquitoes reduces the ability of mosquitoes to transmit human pathogenic viruses and is now being developed as a biocontrol tool. Successful introgression of Wolbachia-carrying Ae. aegypti into native mosquito populations at field sites in Australia, Indonesia and Malaysia has been associated with reduced disease prevalence in the treated community. In separate field programs, Wolbachia is also being used as a mosquito population suppression tool, where the release of male only Wolbachia-infected Ae. aegypti prevents the native mosquito population from producing viable eggs, subsequently suppressing the wild population. While these technologies show great promise, they require mass rearing of mosquitoes for implementation on a scale that has not previously been done. In addition, Wolbachia induces some negative fitness effects on Ae. aegypti. While these fitness effects differ depending on the Wolbachia strain present, one of the most consistent and significant impacts is the shortened longevity and viability of eggs. This review examines the body of evidence behind Wolbachia's negative effect on eggs, assesses nutritional parasitism as a key cause and considers how these impacts could be overcome to achieve efficient large-scale rearing of these mosquitoes.

RevDate: 2020-10-27

Prigot-Maurice C, Cerqueira de Araujo A, Camille N, et al (2020)

Immune priming depends on age, sex and Wolbachia in the interaction between Armadillidium vulgare and Salmonella.

Journal of evolutionary biology [Epub ahead of print].

The protection conferred by a first infection upon a second pathogenic exposure (i.e immune priming) is an emergent research topic in the field of invertebrate immunity. Immune priming has been demonstrated in various species, but little is known about the intrinsic factors that may influence this immune process. In this study, we tested whether age, gender and the symbiotic bacterium Wolbachia affect the protection resulting from immune priming in A. vulgare against S. enterica. We firstly primed young and old, symbiotic and asymbiotic males and females, either with a non-lethal low dose of S. enterica, LB broth or without injection (control). Seven days post-injection, we performed a LD50 injection of S. enterica in all individuals and we monitored their survival rates. We demonstrated that survival capacities depend on these three factors: young and old asymbiotic individuals (males and females) expressed immune priming (S. enterica-primed individuals survived better than LB-primed and non-primed), with a general decline in the strength of protection in old females, but not in old males, compared to young. When Wolbachia is present, the immune priming protection was observed in old, but not in young symbiotic individuals, even if the Wolbachia load on entire individuals is equivalent regardless to age. Our overall results showed that the immune priming protection in A. vulgare depends on individuals' states, highlighting the need to consider these factors both in mechanistical and evolutionary studies focusing on invertebrate's immunity.

RevDate: 2020-10-26

Costa GB, Smithyman R, O'Neill SL, et al (2020)

How to engage communities on a large scale? Lessons from World Mosquito Program in Rio de Janeiro, Brazil.

Gates open research, 4:109.

One of the pillars of the World Health Organization's (WHO) Global Vector Control Response 2017-2030 strategy is the engagement of communities. Among the priority activities, defined by 2022 by the WHO, is the development of plans for the effective engagement and mobilisation of communities in vector control. Novel technologies for arboviruses control are being developed, such as the Wolbachia method, implemented by the World Mosquito Program (WMP). Here we discuss and analyse the framework for community engagement implemented by the WMP in Brazil, during the large-scale deployment of the method in the municipalities of Niterói and Rio de Janeiro, Brazil. Our experience indicates that the community engagement work for arboviruses control should be understood as an opportunity for local development. It is necessary, based on an integrated analysis of the territory, to understand that the actions for arboviruses control could be a catalyst for the necessary socioenvironmental, cultural and public health changes. Furthermore, it is essential to understand that community engagement goes beyond informing or asking for population consent, but it constitutes a possibility for dialogue and exchange between the various stakeholders present in the territories, to build on cooperation for mosquito-borne disease control.

RevDate: 2020-10-25

Sandri TL, Kreidenweiss A, Cavallo S, et al (2020)

Molecular epidemiology of Mansonella species in Gabon.

The Journal of infectious diseases pii:5939539 [Epub ahead of print].

Mansonella perstans, a filarial nematode, infects large populations in Africa and Latin America. Recently, a potential new species Mansonella sp. "DEUX" was reported. Carriage of endosymbiotic Wolbachia opens treatment options for Mansonella infections. Within a cross-sectional study, we assessed the prevalence of filarial infections in 834 Gabonese individuals and the presence of the endosymbiont Wolbachia. Almost half of the participants (400/834, 48%) were infected with filarial nematodes, with Mansonella sp. "DEUX" being the most frequent (295/400, 74%), followed by Loa loa (273/400, 68%), and M. perstans (82/400, 21%). Being adult/elderly, male, and living in rural areas was associated with a higher risk of infection. Wolbachia carriage was confirmed in M. perstans and Mansonella sp. "DEUX". In silico analysis revealed that Mansonella sp. "DEUX" is not detected with currently published M. perstans specific assays. Mansonella infections are highly prevalent in Gabon and might have been underreported, likely also beyond Gabon.

RevDate: 2020-10-23

Knerer G, Currie CSM, SC Brailsford (2020)

The economic impact and cost-effectiveness of combined vector-control and dengue vaccination strategies in Thailand: results from a dynamic transmission model.

PLoS neglected tropical diseases, 14(10):e0008805 pii:PNTD-D-18-00776 [Epub ahead of print].

BACKGROUND AND AIMS: Dengue fever is a major public health problem in tropical/subtropical regions. Prior economic analyses have predominantly evaluated either vaccination or vector-control programmes in isolation and do not really consider the incremental benefits and cost-effectiveness of mixed strategies and combination control. We estimated the cost-effectiveness of single and combined approaches in Thailand.

METHODS: The impacts of different control interventions were analysed using a previously published mathematical model of dengue epidemiology and control incorporating seasonality, age structure, consecutive infection, cross protection, immune enhancement and combined vector-host transmission. An economic model was applied to simulation results to estimate the cost-effectiveness of 4 interventions and their various combinations (6 strategies): i) routine vaccination of 1-year olds; ii) chemical vector control strategies targeting adult and larval stages separately; iii) environmental management/ public health education and awareness [EM/ PHEA]). Payer and societal perspectives were considered. The health burden of dengue fever was assessed using disability-adjusted life-years (DALYs) lost. Costs and effects were assessed for 10 years. Costs were discounted at 3% annually and updated to 2013 United States Dollars. Incremental cost-effectiveness analysis was carried out after strategies were rank-ordered by cost, with results presented in a table of incremental analysis. Sensitivity and scenario analyses were undertaken; and the impact and cost-effectiveness of Wolbachia was evaluated in exploratory scenario analyses.

RESULTS: From the payer and societal perspectives, 2 combination strategies were considered optimal, as all other control strategies were dominated. Vaccination plus adulticide plus EM/ PHEA was deemed cost-effective according to multiple cost-effectiveness criteria. From the societal perspective, incremental differences vs. adulticide and EM/ PHEA resulted in costs of $157.6 million and DALYs lost of 12,599, giving an expected ICER of $12,508 per DALY averted. Exploratory scenario analyses showed Wolbachia to be highly cost-effective ($343 per DALY averted) vs. other single control measures.

CONCLUSIONS: Our model shows that individual interventions can be cost-effective, but that important epidemiological reductions and economic impacts are demonstrated when interventions are combined as part of an integrated approach to combating dengue fever. Exploratory scenario analyses demonstrated the potential epidemiological and cost-effective impact of Wolbachia when deployed at scale on a nationwide basis. Our findings were robust in the face of sensitivity analyses.

RevDate: 2020-10-21

Huang B, Yang Q, Hoffmann AA, et al (2020)

Wolbachia Genome Stability and mtDNA Variants in Aedes aegypti Field Populations Eight Years after Release.

iScience, 23(10):101572 pii:S2589-0042(20)30764-1.

A dengue suppression strategy based on release of Aedes aegypti mosquitoes infected with the bacterium Wolbachia pipientis is being trialed in many countries. Wolbachia inhibits replication and transmission of dengue viruses. Questions remain regarding the long-term stability of virus-suppressive effects. We sequenced the Wolbachia genome and analyzed Ae. aegypti mitochondrial DNA markers isolated from mosquitoes sampled 2-8 years after releases in the greater Cairns region, Australia. Few changes were detected when Wolbachia genomes of field mosquitoes were compared with Wolbachia genomes of mosquitoes obtained soon after initial releases. Mitochondrial variants associated with the initial Wolbachia release stock are now the only variants found in release sites, highlighting maternal leakage as a possible explanation for rare Wolbachia-negative mosquitoes and not migration from non-release areas. There is no evidence of changes in the Wolbachia genome that indicate selection against its viral-suppressive effects or other phenotypes attributable to infection with the bacterium.

RevDate: 2020-10-21

Duplouy A, Pranter R, Warren-Gash H, et al (2020)

Towards unravelling Wolbachia global exchange: a contribution from the Bicyclus and Mylothris butterflies in the Afrotropics.

BMC microbiology, 20(1):319 pii:10.1186/s12866-020-02011-2.

BACKGROUND: Phylogenetically closely related strains of maternally inherited endosymbiotic bacteria are often found in phylogenetically divergent, and geographically distant insect host species. The interspecies transfer of the symbiont Wolbachia has been thought to have occurred repeatedly, facilitating its observed global pandemic. Few ecological interactions have been proposed as potential routes for the horizontal transfer of Wolbachia within natural insect communities. These routes are however likely to act only at the local scale, but how they may support the global distribution of some Wolbachia strains remains unclear.

RESULTS: Here, we characterize the Wolbachia diversity in butterflies from the tropical forest regions of central Africa to discuss transfer at both local and global scales. We show that numerous species from both the Mylothris (family Pieridae) and Bicyclus (family Nymphalidae) butterfly genera are infected with similar Wolbachia strains, despite only minor interclade contacts across the life cycles of the species within their partially overlapping ecological niches. The phylogenetic distance and differences in resource use between these genera rule out the role of ancestry, hybridization, and shared host-plants in the interspecies transfer of the symbiont. Furthermore, we could not identify any shared ecological factors to explain the presence of the strains in other arthropod species from other habitats, or even ecoregions.

CONCLUSION: Only the systematic surveys of the Wolbachia strains from entire species communities may offer the material currently lacking for understanding how Wolbachia may transfer between highly different and unrelated hosts, as well as across environmental scales.

RevDate: 2020-10-19

Wangkeeree J, Suwanchaisri K, Roddee J, et al (2020)

Effect of Wolbachia infection states on the life history and reproductive traits of the leafhopper Yamatotettix flavovittatus Matsumura.

Journal of invertebrate pathology pii:S0022-2011(20)30196-8 [Epub ahead of print].

Wolbachia is a maternally inherited bacterium of insects that can affect host reproduction and fitness. We examined the effect of Wolbachia infection on the life history and reproductive traits of the leafhopper Yamatotettix flavovittatus, which is a vector of the phytoplasma that causes white leaf disease in sugarcane. This investigation was performed using Wolbachia-infected and uninfected leafhopper lineages. Results revealed that Wolbachia infection did not significantly affect the survival of nymphal stages, male longevity, and sex ratio. However, Wolbachia-infected lineages had prolonged immature development periods and female longevity. In intrapopulation crosses, Wolbachia infection had no significant effects on occupation success, number of eggs laid, and female offspring, but the effect on egg-hatching varied. In interpopulation crosses, Wolbachia infection had no significant effect on occupation success and female offspring, but it did affect the number of eggs laid and egg-hatching rates. Assortative pairings regarding infection status resulted in normal egg deposition and hatching, whereas disassortative pairings resulted in lower egg deposition and no hatching. Wolbachia was thus shown to be highly vertically transmitted (>98% of the tested individuals). Our findings provide additional data on the interactions between Wolbachia in insect hosts. This evidence of perfect maternal transmission and strong reproductive incompatibility highlights the importance of further studies on the use of Wolbachia as a biological control agent for the leafhopper vector.

RevDate: 2020-10-19

Can-Vargas X, Barboza N, Fuchs EJ, et al (2020)

Spatial Distribution of Whitefly Species (Hemiptera: Aleyrodidae) and Identification of Secondary Bacterial Endosymbionts in Tomato Fields in Costa Rica.

Journal of economic entomology pii:5930138 [Epub ahead of print].

In Costa Rica, tomato (Solanum lycopersicum Linnaeus) Linnaeus (Solanales: Solanaceae) is one of the crops most severely affected by the whiteflies (Hemiptera: Aleyrodidae) Trialeurodes vaporariorum (Westwood) and the Bemisia tabaci (Gennadius) species complex. The objective of this study was to monitor the spatial distribution and diversity of these species and to detect the presence of secondary bacterial endosymbionts in individuals collected in areas of intensive tomato production. In total, 628 whitefly individuals were identified to the species level using restriction analysis (PCR-RFLP) of a fragment of the mitochondrial cytochrome C oxidase I gene (mtCOI). Trialeurodes vaporariorum was the predominant species, followed by B. tabaci Mediterranean (MED). Bemisia tabaci New World (NW) and B. tabaci Middle East-Asia Minor 1 (MEAM1) were present in lower numbers. The mtCOI fragment was sequenced for 89 individuals and a single haplotype was found for each whitefly species. Using molecular markers, the 628 individuals were analyzed for the presence of four endosymbionts. Arsenophonus Gherna et al. (Enterobacterales: Morganellaceae) was most frequently associated with T. vaporariorum, whereas Wolbachia Hertig (Rickettsiales: Anaplasmataceae) and Rickettsia da Rocha-Lima (Rickettsiales: Rickettsiaceae) were associated with B. tabaci MED. This study confirmed that B. tabaci NW has not been completely displaced by the invasive species B. tabaci MED and B. tabaci MEAM1 present in the country. An association was found between whitefly species present in tomato and certain secondary endosymbionts, elevation was the most likely environmental factor to affect their frequency.

RevDate: 2020-10-19

Verspoor RL, Price TAR, N Wedell (2020)

Selfish genetic elements and male fertility.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 375(1813):20200067.

Selfish genetic elements (SGEs) are diverse and near ubiquitous in Eukaryotes and can be potent drivers of evolution. Here, we discuss SGEs that specifically act on sperm to gain a transmission advantage to the next generation. The diverse SGEs that affect sperm often impose costs on carrier males, including damaging ejaculates, skewing offspring sex ratios and in particular reducing sperm-competitive success of SGE-carrying males. How males and females tolerate and mitigate against these costs is a dynamic and expanding area of research. The intense intra-genomic conflict that these selfish elements generate could also have implications for male fertility and spermatogenesis more widely. This article is part of the theme issue 'Fifty years of sperm competition'.

RevDate: 2020-10-18

Xu S, Jiang L, Qiao G, et al (2020)

Diversity of bacterial symbionts associated with Myzus persicae (Sulzer) (Hemiptera: Aphididae: Aphidinae) revealed by 16S rRNA Illumina sequencing.

Microbial ecology pii:10.1007/s00248-020-01622-6 [Epub ahead of print].

Aphids are known to be associated with a variety of symbiotic bacteria. To improve our knowledge of the bacterial diversity of polyphagous aphids, in the present study, we investigated the microbiota of the cosmopolitan agricultural pest Myzus persicae (Sulzer). Ninety-two aphid samples collected from different host plants in various regions of China were examined using high-throughput amplicon sequencing. We comprehensively characterized the symbiont diversity of M. persicae and assessed the variations in aphid-associated symbiont communities. We detected a higher diversity of symbionts than has been previously observed. M. persicae hosted the primary endosymbiont Buchnera aphidicola and seven secondary symbionts, among which Wolbachia was the most prevalent and Rickettsia, Arsenophonus, and Spiroplasma were reported for the first time. Ordination analyses and statistical tests revealed that the symbiont flora associated with M. persicae did not change with respect to host plant or geography, which may be due to frequent migrations between different aphid populations. These findings will advance our knowledge of the microbiota of polyphagous insects and will enrich our understanding of assembly of host-microbiome systems.

RevDate: 2020-10-19

Scholz M, Albanese D, Tuohy K, et al (2020)

Large scale genome reconstructions illuminate Wolbachia evolution.

Nature communications, 11(1):5235 pii:10.1038/s41467-020-19016-0.

Wolbachia is an iconic example of a successful intracellular bacterium. Despite its importance as a manipulator of invertebrate biology, its evolutionary dynamics have been poorly studied from a genomic viewpoint. To expand the number of Wolbachia genomes, we screen over 30,000 publicly available shotgun DNA sequencing samples from 500 hosts. By assembling over 1000 Wolbachia genomes, we provide a substantial increase in host representation. Our phylogenies based on both core-genome and gene content provide a robust reference for future studies, support new strains in model organisms, and reveal recent horizontal transfers amongst distantly related hosts. We find various instances of gene function gains and losses in different super-groups and in cytoplasmic incompatibility inducing strains. Our Wolbachia-host co-phylogenies indicate that horizontal transmission is widespread at the host intraspecific level and that there is no support for a general Wolbachia-mitochondrial synchronous divergence.

RevDate: 2020-10-19

Pan X, Wang X, F Zhang (2020)

New Insights into Cockroach Control: Using Functional Diversity of Blattella germanica Symbionts.

Insects, 11(10): pii:insects11100696.

Insects have close symbiotic relationships with several microbes, which extends the limited metabolic networks of most insects. Using symbiotic microorganisms for the biological control of pests and insect-borne diseases has become a promising direction. Blattella germanica (L.) (Blattaria: Blattidae) is a public health pest worldwide, which is difficult to control because of its strong reproductive ability, adaptability, and resistance to insecticides. In this paper, the diverse biological functions (nutrition, reproductive regulation, insecticide resistance, defense, and behavior) of symbionts were reviewed, and new biological control strategies on the basis of insect-symbiont interaction were proposed. We highlight new directions in B. germanica control, such as suppressing cockroach population using Wolbachia or paratransgenes, and combining fungal insecticides with synergistic agents to enhance insecticidal efficacy.

RevDate: 2020-10-15

Lee CC, Lin CY, Tseng SP, et al (2020)

Ongoing Coevolution of Wolbachia and a Widespread Invasive Ant, Anoplolepis gracilipes.

Microorganisms, 8(10): pii:microorganisms8101569.

While Wolbachia are commonly found among arthropods, intraspecific infection rates can vary substantially across the geographic populations. Here we report nearly 100% prevalence of Wolbachia in the global populations of the yellow crazy ant, Anoplolepis gracilipes. To understand coevolutionary history between Wolbachia and A. gracilipes, we identified single nucleotide polymorphisms (SNPs) in Wolbachia from the ant across 12 geographical regions and compared the phylogeny of SNP-based Wolbachia to patterns of the ant's mitochondrial DNA (mtDNA) variation. Our results revealed a strong concordance between phylogenies of Wolbachia and host mtDNA, providing immediate evidence of co-divergence. Among eight identified SNP loci separating the genetic clusters of Wolbachia, seven loci are located in potential protein-coding genes, three of which being non-synonymous SNPs that may influence gene functions. We found a Wolbachia hypothetical protein gene with signature of positive selection. These findings jointly allow us to characterize Wolbachia-ant coevolution and also raise a question about mechanism(s) underlying maintenance of high prevalence of Wolbachia during the colonization of this invasive ant.

RevDate: 2020-10-14

Montoya-Alonso JA, Morchón R, Matos JI, et al (2020)

Dirofilaria immitis Could Be a Risk Factor for the Development of Allergic Diseases in Humans.

Animals : an open access journal from MDPI, 10(10): pii:ani10101847.

The Canary Islands are hyperendemic for canine heartworm and the risk of zoonotic infection is high. Additionally, there is evidence of development of allergies due to nematode infections in animals and humans. Since the population of the Canary Islands presents high prevalence of allergic comorbidities, and previous studies have shown a possible relationship between allergies and seropositivity to heartworm, the aim was to evaluate whether exposure to heartworm may contribute to the development of allergies in the human population. First, an epidemiological study was conducted on 248 owners of dogs with/without heartworm infection in the Canary Islands. Secondly, a serological analysis of the presence of total IgE and specific IgE against heartworm was conducted in 66 samples of inhabitants of the Canary Islands. The survey showed that allergic owners had heartworm-positive dogs more frequently (p < 0.01). Of the analyzed human samples, 43.9% were seropositive to heartworm and Wolbachia. Total IgE concentrations were increased in 34.5% seropositive samples and 8.1% seronegative samples. Specific IgE against heartworm was only found in human seropositive samples (17.2%). Contact with heartworm may be a risk factor for the development of allergic diseases, although further studies to elucidate the relationship between heartworm and allergies should be carried out.

RevDate: 2020-10-13

Carneiro Dutra HL, Deehan MA, H Frydman (2020)

Wolbachia and Sirtuin-4 interaction is associated with alterations in host glucose metabolism and bacterial titer.

PLoS pathogens, 16(10):e1008996 pii:PPATHOGENS-D-20-00817 [Epub ahead of print].

Wolbachia is an intracellular bacterial symbiont of arthropods notorious for inducing many reproductive manipulations that foster its dissemination. Wolbachia affects many aspects of host biology, including metabolism, longevity and physiology, being described as a nutrient provisioning or metabolic parasite, depending on the host-microbe association. Sirtuins (SIRTs) are a family of NAD+-dependent post-translational regulatory enzymes known to affect many of the same processes altered by Wolbachia, including aging and metabolism, among others. Despite a clear overlap in control of host-derived pathways and physiology, no work has demonstrated a link between these two regulators. We used genetically tractable Drosophila melanogaster to explore the role of sirtuins in shaping signaling pathways in the context of a host-symbiont model. By using transcriptional profiling and metabolic assays in the context of genetic knockouts/over-expressions, we examined the effect of several Wolbachia strains on host sirtuin expression across distinct tissues and timepoints. We also quantified the downstream effects of the sirtuin x Wolbachia interaction on host glucose metabolism, and in turn, how it impacted Wolbachia titer. Our results indicate that the presence of Wolbachia is associated with (1) reduced sirt-4 expression in a strain-specific manner, and (2) alterations in host glutamate dehydrogenase expression and ATP levels, key components of glucose metabolism. We detected high glucose levels in Wolbachia-infected flies, which further increased when sirt-4 was over-expressed. However, under sirt-4 knockout, flies displayed a hypoglycemic state not rescued to normal levels in the presence of Wolbachia. Finally, whole body sirt-4 over-expression resulted in reduced Wolbachia ovarian titer. Our results expand knowledge of Wolbachia-host associations in the context of a yet unexplored class of host post-translational regulatory enzymes with implications for conserved host signaling pathways and bacterial titer, factors known to impact host biology and the symbiont's ability to spread through populations.

RevDate: 2020-10-09

Gong JT, Li Y, Li TP, et al (2020)

Stable Introduction of Plant-Virus-Inhibiting Wolbachia into Planthoppers for Rice Protection.

Current biology : CB pii:S0960-9822(20)31364-6 [Epub ahead of print].

Progress has been made in developing the maternally inherited endosymbiotic bacterium Wolbachia as a tool for protecting humans from mosquito-borne diseases. In contrast, Wolbachia-based approaches have not yet been developed for the protection of plants from insect pests and their associated diseases, with a major challenge being the establishment of artificial Wolbachia infections expressing desired characteristics in the hemipterans that transmit the majority of plant viruses. Here, we report stable introduction of Wolbachia into the brown planthopper, Nilaparvata lugens, the most destructive rice pest that annually destroys millions of hectares of staple crops. The Wolbachia strain wStri from the small brown planthopper, Laodelphax striatellus, was transferred to this new host, where it showed high levels of cytoplasmic incompatibility, enabling rapid invasion of laboratory populations. Furthermore, wStri inhibited infection and transmission of Rice ragged stunt virus and mitigated virus-induced symptoms in rice plants, opening up the development of Wolbachia-based strategies against major agricultural pests and their transmitted pathogens. VIDEO ABSTRACT.

RevDate: 2020-10-09

Puerta-Guardo H, Contreras-Perera Y, Perez-Carrillo S, et al (2020)

Wolbachia in Native Populations of Aedes albopictus (Diptera: Culicidae) From Yucatan Peninsula, Mexico.

Journal of insect science (Online), 20(5):.

This study reports the results of a molecular screening for Wolbachia (Wb) infection in Aedes albopictus (Skuse) populations recently established in the Yucatan Peninsula, Mexico. To do so, collections of free-flying adults with BG traps and emerged adults from eggs after ovitrap field collections were performed in three suburban localities of the city of Merida, Yucatan. Overall, local populations of Ae. albopictus present a natural Wb infection rate of ~40% (18 of 45). Wb infection was detected in both field-collected adults (76.5%, 13 of 17) and eggs reared (17.8%, 5 of 28) and in 37.9% (11/29) of females and 43.7% (7/16) of male Ae. albopictus mosquitoes. An initial screening for Wolbachia strain typing showed that native Ae. albopictus were naturally coinfected with both wAlbA and wAlbB strains. The knowledge of the prevalence and diversity of Wolbachia strains in local populations of Aedes mosquitoes is part of the baseline information required for current and future Wolbachia-based vector control approaches to be conducted in Mexico.

RevDate: 2020-10-09

Ogunlade ST, Adekunle AI, Meehan MT, et al (2020)

Modeling the potential of wAu-Wolbachia strain invasion in mosquitoes to control Aedes-borne arboviral infections.

Scientific reports, 10(1):16812 pii:10.1038/s41598-020-73819-1.

Arboviral infections such as dengue, Zika and chikungunya are fast spreading diseases that pose significant health problems globally. In order to control these infections, an intracellular bacterium called Wolbachia has been introduced into wild-type mosquito populations in the hopes of replacing the vector transmitting agent, Aedes aegypti with one that is incapable of transmission. In this study, we developed a Wolbachia transmission model for the novel wAu strain which possesses several favourable traits (e.g., enhanced viral blockage and maintenance at higher temperature) but not cyctoplasmic incompatibility (CI)-when a Wolbachia-infected male mosquito mates with an uninfected female mosquito, producing no viable offspring. This model describes the competitive dynamics between wAu-Wolbachia-infected and uninfected mosquitoes and the role of imperfect maternal transmission. By analysing the system via computing the basic reproduction number(s) and stability properties, the potential of the wAu strain as a viable strategy to control arboviral infections is established. The results of this work show that enhanced maintenance of Wolbachia infection at higher temperatures can overcome the lack of CI induction to support wAu-Wolbachia infected mosquito invasion. This study will support future arboviral control programs, that rely on the introduction of new Wolbachia variants.

RevDate: 2020-10-09

Nguyen AHL, Tiawsirisup S, M Kaewthamasorn (2020)

Molecular detection and genetic characterization of Anaplasma marginale and Anaplasma platys-like (Rickettsiales: Anaplasmataceae) in water buffalo from eight provinces of Thailand.

BMC veterinary research, 16(1):380 pii:10.1186/s12917-020-02585-z.

BACKGROUND: Anaplasmosis, an animal disease caused by rickettsial bacteria in the genus Anaplasma, is of considerable economic importance in livestock animals in many countries worldwide. The objectives of this study were to determine the identity, prevalence, and geographic distribution of Ehrlichia and Anaplasma in naturally infected water buffalo in Thailand using PCR amplification and sequencing of the 16S ribosomal RNA and heat shock protein groEL genes. A total of 456 buffalo blood samples from Thailand were investigated. Species identification and genetic differentiation of intra-population and inter-population with the global isolates were conducted based on nucleotide sequences. Interplay between the infection and host factors was also assessed.

RESULTS: Overall, 41% of water buffalo were found to be infected with rickettsial organisms in the family Anaplasmataceae, but Ehrlichia spp., Neorickettsia spp., and Wolbachia spp. were not found in any of the sequenced samples in this study. Female buffalo were more frequently infected with bacteria in the family Anaplasmataceae than males [71 out of 176 females (40.3%) versus 11 out of 47 males (23.4%)]. The Odds Ratio value indicated that the risk of infection for female buffalo was 2.2-fold higher than that for males (p < 0.05). We detected three haplotypes of A. marginale 16S rRNA gene and they were placed in a clade that was closely related to the A. marginale in buffalo in China; and cattle in Thailand, Uganda, and China. Homology searching of groEL sequences against the GenBank™ database using the BLASTn algorithm revealed that the obtained sequences had a high percentage similarity (98.36-99.62%) to A. platys sequences. The groEL sequences of three A. platys-like isolates were clustered in the same clade as the A. platys from the tick Rhipicephalus microplus in China.

CONCLUSIONS: Our data showed that the apparently healthy buffalo were naturally infected by bacteria in the family Anaplasmataceae at a relatively high prevalence. We also report the finding of A. platys-like infections in water buffalo in Thailand for the first time. Water buffalo serving as the reservoir host of anaplasmosis is of concern for managing the disease control and prevention in ruminants.

RevDate: 2020-10-08

Bakovic V, Schebeck M, Stauffer C, et al (2020)

Wolbachia-Mitochondrial DNA Associations in Transitional Populations of Rhagoletis cerasi.

Insects, 11(10): pii:insects11100675.

The endosymbiont Wolbachia can manipulate arthropod host reproduction by inducing cytoplasmic incompatibility (CI), which results in embryonic mortality when infected males mate with uninfected females. A CI-driven invasion of Wolbachia can result in a selective sweep of associated mitochondrial haplotype. The co-inheritance of Wolbachia and host mitochondrial DNA can therefore provide significant information on the dynamics of an ongoing Wolbachia invasion. Therefore, transition zones (i.e., regions where a Wolbachia strain is currently spreading from infected to uninfected populations) represent an ideal area to investigate the relationship between Wolbachia and host mitochondrial haplotype. Here, we studied Wolbachia-mitochondrial haplotype associations in the European cherry fruit fly, Rhagoletis cerasi, in two transition zones in the Czech Republic and Hungary, where the CI-inducing strain wCer2 is currently spreading. The wCer2-infection status of 881 individuals was compared with the two known R. cerasi mitochondrial haplotypes, HT1 and HT2. In accordance with previous studies, wCer2-uninfected individuals were associated with HT1, and wCer2-infected individuals were mainly associated with HT2. We found misassociations only within the transition zones, where HT2 flies were wCer2-uninfected, suggesting the occurrence of imperfect maternal transmission. We did not find any HT1 flies that were wCer2-infected, suggesting that Wolbachia was not acquired horizontally. Our study provides new insights into the dynamics of the early phase of a Wolbachia invasion.

RevDate: 2020-10-07

Hague MTJ, Caldwell CN, BS Cooper (2020)

Pervasive Effects of Wolbachia on Host Temperature Preference.

mBio, 11(5):.

Heritable symbionts can modify a range of ecologically important host traits, including behavior. About half of all insect species are infected with maternally transmitted Wolbachia, a bacterial endosymbiont known to alter host reproduction, nutrient acquisition, and virus susceptibility. Here, we broadly test the hypothesis that Wolbachia modifies host behavior by assessing the effects of eight different Wolbachia strains on the temperature preference of six Drosophila melanogaster subgroup species. Four of the seven host genotypes infected with A-group Wolbachia strains (wRi in Drosophila simulans, wHa in D. simulans, wSh in Drosophila sechellia, and wTei in Drosophila teissieri) prefer significantly cooler temperatures relative to uninfected genotypes. Contrastingly, when infected with divergent B-group wMau, Drosophila mauritiana prefers a warmer temperature. For most strains, changes to host temperature preference do not alter Wolbachia titer. However, males infected with wSh and wTei tend to experience an increase in titer when shifted to a cooler temperature for 24 h, suggesting that Wolbachia-induced changes to host behavior may promote bacterial replication. Our results indicate that Wolbachia modifications to host temperature preference are likely widespread, which has important implications for insect thermoregulation and physiology. Understanding the fitness consequences of these Wolbachia effects is crucial for predicting evolutionary outcomes of host-symbiont interactions, including how Wolbachia spreads to become common.IMPORTANCE Microbes infect a diversity of species, influencing the performance and fitness of their hosts. Maternally transmitted Wolbachia bacteria infect most insects and other arthropods, making these bacteria some of the most common endosymbionts in nature. Despite their global prevalence, it remains mostly unknown how Wolbachia influence host physiology and behavior to proliferate. We demonstrate pervasive effects of Wolbachia on Drosophila temperature preference. Most hosts infected with A-group Wolbachia prefer cooler temperatures, whereas the one host species infected with divergent B-group Wolbachia prefers warmer temperatures, relative to uninfected genotypes. Changes to host temperature preference generally do not alter Wolbachia abundance in host tissues, but for some A-group strains, adult males have increased Wolbachia titer when shifted to a cooler temperature. This suggests that Wolbachia-induced changes to host behavior may promote bacterial replication. Our results help elucidate the impact of endosymbionts on their hosts amid the global Wolbachia pandemic.

RevDate: 2020-10-07

Lemon A, Bordenstein SR, SR Bordenstein (2020)

Discover the Microbes Within! The Wolbachia Project: Citizen Science and Student-Based Discoveries for 15 Years and Counting.

Genetics, 216(2):263-268.

The Elizabeth W. Jones Award for Excellence in Education recognizes an individual who has had a significant impact on genetics education at any education level. Seth R. Bordenstein, Ph.D., Centennial Professor of Biological Sciences at Vanderbilt University and Founding Director of the Vanderbilt Microbiome Initiative, is the 2020 recipient in recognition of his cofounding, developing, and expanding Discover the Microbes Within! The Wolbachia Project.

RevDate: 2020-10-06

Hoffmann A (2020)


Current biology : CB, 30(19):R1113-R1114.

Ary Hoffman introduces Wolbachia.

RevDate: 2020-10-05

Moussa A, Passera A, Sanna F, et al (2020)

Bacterial microbiota associated with insect vectors of grapevine Bois noir disease in relation to phytoplasma infection.

FEMS microbiology ecology pii:5917978 [Epub ahead of print].

Bois noir is a grapevine disease causing severe yield loss in vineyards worldwide. It is associated with 'Candidatus Phytoplasma solani', a phloem-limited bacterium transmitted by polyphagous insects. Due to its complex epidemiology, it is difficult to organize effective containment measures. This study aimed to describe the bacterial microbiota associated with 'Candidatus Phytoplasma solani' infected and non-infected insect hosts and vectors to investigate if phytoplasma presence can shape the microbiota. Alpha-diversity analysis showed a low microbiota diversity in these insects, in which few genera were highly abundant. Beta-diversity analysis revealed that the xylem- and phloem-feeding behavior influences the microbiota structure. Moreover, it highlighted that phytoplasma infection is associated with a restructuring of microbiota exclusively in Deltocephalinae insect vectors. Obtained data showed that 'Candidatus Phytoplasma solani' may have adverse effects on the endosymbionts Sulcia and Wolbachia, suggesting a possible fitness modification in the insects. The phytoplasma-antagonistic Dyella was not found in any of the examined insect species. The results indicate an interesting perspective regarding the microbial signatures associated with xylem- and phloem-feeding insects, and determinants that could be relevant to establish whether an insect species can be a vector or not, opening up new avenues for developing microbial resource management-based approaches.

RevDate: 2020-10-02

Mathers TC, Mugford ST, Hogenhout SA, et al (2020)

Genome Sequence of the Banana Aphid, Pentalonia nigronervosa Coquerel (Hemiptera: Aphididae) and Its Symbionts.

G3 (Bethesda, Md.) pii:g3.120.401358 [Epub ahead of print].

The banana aphid, Pentalonia nigronervosa Coquerel (Hemiptera: Aphididae), is a major pest of cultivated bananas (Musa spp., order Zingiberales), primarily due to its role as a vector of Banana bunchy top virus (BBTV), the most severe viral disease of banana worldwide. Here, we generated a highly complete genome assembly of P.nigronervosa using a single PCR-free Illumina sequencing library. Using the same sequence data, we also generated complete genome assemblies of the P.nigronervosa symbiotic bacteria Buchneraaphidicola and Wolbachia To improve our initial assembly of P.nigronervosa we developed a k-mer based deduplication pipeline to remove genomic scaffolds derived from the assembly of haplotigs (allelic variants assembled as separate scaffolds). To demonstrate the usefulness of this pipeline, we applied it to the recently generated assembly of the aphid Myzus cerasi, reducing the duplication of conserved BUSCO genes by 25%. Phylogenomic analysis of P.nigronervosa, our improved M. cerasi assembly, and seven previously published aphid genomes, spanning three aphid tribes and two subfamilies, reveals that P.nigronervosa falls within the tribe Macrosiphini, but is an outgroup to other Macrosiphini sequenced so far. As such, the genomic resources reported here will be useful for understanding both the evolution of Macrosphini and for the study of P.nigronervosa. Furthermore, our approach using low cost, high-quality, Illumina short-reads to generate complete genome assemblies of understudied aphid species will help to fill in genomic black spots in the diverse aphid tree of life.

RevDate: 2020-10-01

Izraeli Y, Lalzar M, Netanel N, et al (2020)

Wolbachia influence on the fitness of Anagyrus vladimiri (Hymenoptera: Encyrtidae), a bio-control agent of mealybugs.

Pest management science [Epub ahead of print].

BACKGROUND: Like numerous other animals, biocontrol agents (BCAs) of arthropod pests carry various microorganisms that may have diverse effects on the biology of their eukaryote hosts. We postulated that it is possible to improve the efficacy of BCAs by manipulating the composition of their associated microbiota. The parasitoid wasp Anagyrus vladimiri (Hymenoptera: Encyrtidae) from a mass-rearing facility was chosen for testing this hypothesis.

RESULTS: High-throughput sequencing analysis indicated that fungal abundance in A. vladimiri was low and variable, whereas the bacterial community was dominated by the endosymbiont Wolbachia. Wolbachia was fixed in the mass-rearing population, whereas in field-collected A. vladimiri Wolbachia's prevalence was only ~20%. Identification of Wolbachia strains from the two populations by Multi Locus Sequence Typing, revealed two closely related but unique strains. A series of bioassays with the mass-rearing Wolbachia-fixed (W+) and a derived antibiotic-treated Wolbachia-free (W-) lines revealed that: a) Wolbachia does not induce reproductive manipulations; b) W- females have higher fecundity when reared individually, but not when reared with conspecifics; c) W+ females outcompete W- when they share hosts for oviposition; d) longevity and developmental time were similar in both lines.

CONCLUSIONS: The findings suggest that W+ A. vladimiri have no clear fitness benefit under mass-rearing conditions and may be disadvantageous under lab-controlled conditions. In a broader view, the results suggest that augmentative biological control can benefit from manipulation of the microbiome of natural enemies. This article is protected by copyright. All rights reserved.

RevDate: 2020-09-25

Shropshire JD, Leigh B, SR Bordenstein (2020)

Symbiont-mediated cytoplasmic incompatibility: what have we learned in 50 years?.

eLife, 9: pii:61989.

Cytoplasmic incompatibility (CI) is the most common symbiont-induced reproductive manipulation. Specifically, symbiont-induced sperm modifications cause catastrophic mitotic defects in the fertilized embryo and ensuing lethality in crosses between symbiotic males and either aposymbiotic females or females harboring a different symbiont strain. However, if the female carries the same symbiont strain, then embryos develop properly, thereby imparting a relative fitness benefit to symbiont-transmitting mothers. Thus, CI drives maternally-transmitted bacteria to high frequencies in arthropods worldwide. In the past two decades, CI experienced a boom in interest due to its (i) deployment in worldwide efforts to curb mosquito-borne diseases, (ii) causation by bacteriophage genes, cifA and cifB, that modify sexual reproduction, and (iii) important impacts on arthropod speciation. This review serves as a gateway to experimental, conceptual, and quantitative themes of CI and outlines significant gaps in understanding CI's mechanism that are ripe for investigation from diverse subdisciplines in the life sciences.

RevDate: 2020-09-24

Price TAR, Windbichler N, Unckless RL, et al (2020)

Resistance to natural and synthetic gene drive systems.

Journal of evolutionary biology [Epub ahead of print].

Scientists are rapidly developing synthetic gene drive elements intended for release into natural populations. These are intended to control or eradicate disease vectors and pests, or to spread useful traits through wild populations for disease control or conservation purposes. However, a crucial problem for gene drives is the evolution of resistance against them, preventing their spread. Understanding the mechanisms by which populations might evolve resistance is essential for engineering effective gene drive systems. This review summarizes our current knowledge of drive resistance in both natural and synthetic gene drives. We explore how insights from naturally occurring and synthetic drive systems can be integrated to improve the design of gene drives, better predict the outcome of releases and understand genomic conflict in general.

RevDate: 2020-09-23

Guo Y, Khan J, Zheng XY, et al (2020)

Wolbachia increase germ cell mitosis to enhance the fecundity of Laodelphax striatellus.

Insect biochemistry and molecular biology pii:S0965-1748(20)30160-0 [Epub ahead of print].

Wolbachia are intracellular bacteria that infect a wide range of invertebrates and have evolved various strategies to alter host reproduction for their own survival and dissemination. In small brown planthopper Laodelphax striatellus, Wolbachia-infected females lay more eggs than uninfected females. Our previous study has shown that Wolbachia are abundant in ovarian cells of L. striatellus and change the number of apoptotic nurse cells in a caspase-dependent manner to provide nutrition for oogenesis. The cellular and molecular bases of the Wolbachia-mediated alterations in L. striatellus oogenesis remain largely unknown. Here, we investigated whether germ cell mitosis, which has been implicated in determination of egg production rates, influences the interaction between fecundity and Wolbachia in L. striatellus. We used an anti-phospho-histone 3 (pH3) antibody to label and visualize mitotic cells. Microscopic observations indicated that the Wolbachia strain wStri increased the number of ovarioles that contained mitotic germ cells. The increased fecundity of Wolbachia-infected females was a result of mitosis of germ cells; the frequency of germ cell mitosis was much higher in infected females than in uninfected females. In addition, mitosis inhibition by Cdc20, CDK1, and CycB messenger RNA interference in Wolbachia-infected L. striatellus markedly decreased egg numbers. Live Wolbachia recolonization enhanced the egg production of uninfected L. striatellus by directly affecting mitosis regulators. Together, these data suggest that wStri might increase germ cell mitosis to enhance the fecundity of L. striatellus in a mitosis-regulating manner. Our findings establish a link between Wolbachia-induced mitosis and Wolbachia-mediated egg production effects.

RevDate: 2020-09-19

Koh C, Islam MN, Ye YH, et al (2020)

Dengue virus dominates lipid metabolism modulations in Wolbachia-coinfected Aedes aegypti.

Communications biology, 3(1):518 pii:10.1038/s42003-020-01254-z.

Competition between viruses and Wolbachia for host lipids is a proposed mechanism of Wolbachia-mediated virus blocking in insects. Yet, the metabolomic interaction between virus and symbiont within the mosquito has not been clearly defined. We compare the lipid profiles of Aedes aegypti mosquitoes bearing mono- or dual-infections of the Wolbachia wMel strain and dengue virus serotype 3 (DENV3). We found metabolic signatures of infection-induced intracellular events but little evidence to support direct competition between Wolbachia and virus for host lipids. Lipid profiles of dual-infected mosquitoes resemble those of DENV3 mono-infected mosquitoes, suggesting virus-driven modulation dominates over that of Wolbachia. Interestingly, knockdown of key metabolic enzymes suggests cardiolipins are host factors for DENV3 and Wolbachia replication. These findings define the Wolbachia-DENV3 metabolic interaction as indirectly antagonistic, rather than directly competitive, and reveal new research avenues with respect to mosquito × virus interactions at the molecular level.

RevDate: 2020-09-18

Xia X, Peng CW, Cui JR, et al (2020)

Wolbachia affects reproduction in the spider mite Tetranychus truncatus (Acari: Tetranychidae) by regulating chorion protein S38-like and Rop.

Insect molecular biology [Epub ahead of print].

Wolbachia-induced reproductive regulation in hosts has been used to control pest populations, but little is known about the molecular mechanism underlying Wolbachia regulation of host genes. Here, reproductive regulation by Wolbachia in the spider mite Tetranychus truncatus was studied at the molecular level. Infection with Wolbachia resulted in decreasing oviposition and cytoplasmic incompatibility in T. truncatus. Further RNA-seq revealed genes regulated by Wolbachia in T. truncatus. Real-time quantitative polymerase chain reaction (qPCR) showed that genes including chorion protein S38-like and Rop were down-regulated by Wolbachia. RNA interference (RNAi) of chorion protein S38-like and Rop in Wolbachia-uninfected T. truncatus decreased oviposition, which was consistent with Wolbachia-induced oviposition decrease. Interestingly, suppressing Rop in Wolbachia-infected T. truncatus led to increased Wolbachia titers in eggs; however, this did not occur after RNAi of chorion protein S38-like. This is the first study to show that chorion protein S38-like and Rop facilitate Wolbachia-mediated changes in T. truncatus fertility. In addition, RNAi of Rop turned the body color of Wolbachia-uninfected T. truncatus black, which indicates that the role of Rop is not limited to reproductive regulation of T. truncatus.

RevDate: 2020-09-19

Arham AF, Amin L, Mustapa MAC, et al (2020)

Perceived benefits and risks: A survey data set towards Wolbachia-infected Aedes Mosquitoes in Klang Valley.

Data in brief, 32:106262.

Perceived Benefits and Risks: A survey data set towards Wolbachia-infected Aedes Mosquitoes in the Klang Valley, Malaysia. Introduction: The paper presents data collected using measures of perceived benefits, perceived risks, trust in key players, attitude towards nature versus material, attitude towards technology, religiosity, and attitude towards the Wolbachia-infected Aedes mosquitoes (WiAM) technique. The validated questionnaires were used to randomly survey targeted stakeholders in the Klang Valley, Malaysia, who had been asked to voluntarily participate in face-to-face interviews. Completed questionnaires were received from 399 respondents (adults above 18 years old) and comprised two stakeholder groups: scientists (n = 202), and the public (n = 197). The detailed findings serve numerous opportunities to examine the social acceptance of Wolbachia-infected Aedes mosquitoes, to ensure the development of policy and action plans, and to encourage further study by other researchers interested in the measures and data presented.

RevDate: 2020-09-16

Shin PT, Baptista RP, O'Neill CM, et al (2020)

Comparative sequences of the Wolbachia genomes of drug-sensitive and resistant isolates of Dirofilaria immitis.

Veterinary parasitology, 286:109225 pii:S0304-4017(20)30205-3 [Epub ahead of print].

The recent identification of isolates of D. immitis with confirmed resistance to the macrocyclic lactone preventatives presents an opportunity for comparative genomic studies using these isolates, and examining the genetic diversity within and between them. We studied the genomes of Wolbachia endosymbionts of five isolates of D. immitis maintained at the University of Georgia. Missouri and Georgia-2 are maintained as drug susceptible isolates, and JYD-27, Yazoo-2013 and Metairie-2014 are resistant to the macrocyclic lactone preventatives. We used whole genome amplification followed by Illumina-based sequencing from 8 to 12 individual microfilariae from each of the five isolates, obtaining a depth of coverage of approximately 40-75 fold for each. The Illumina sequences were used to create new genome assemblies for all the Wolbachia isolates studied. Comparisons of the Wolbachia sequences revealed more than 3000 sequence variations in each isolate. We identified 67 loci specific in resistant isolates but not in susceptible isolates, including 18 genes affected.Phylogenetic analysis suggested that the endosymbionts of the drug-susceptible isolates are more closely related to each other than to those from any of the resistant parasites. This level of variation in the Wolbachia endosymbionts of D. immitis isolates suggests a potential for selection for resistance against drugs targeting them.

RevDate: 2020-09-16

Ge C, Hu J, Zhao Z, et al (2020)

Phylogeny and Density Dynamics of Wolbachia Infection of the Health Pest Paederus fuscipes Curtis (Coleoptera: Staphylinidae).

Insects, 11(9): pii:insects11090625.

The maternally inherited obligate intracellular bacteria Wolbachia infects the reproductive tissues of a wide range of arthropods and affects host reproduction. Wolbachia is a credible biocontrol agent for reducing the impact of diseases associated with arthropod vectors. Paederus fuscipes is a small staphylinid beetle that causes dermatitis linearis and conjunctivitis in humans when they come into contact with skin. Wolbachia occur in this beetle, but their relatedness to other Wolbachia, their infection dynamics, and their potential host effects remain unknown. In this study, we report the phylogenetic position and density dynamics of Wolbachia in P. fuscipes. The phylogeny of Wolbachia based on an analysis of MLST genotyping showed that the bacteria from P. fuscipes belong to supergroup B. Quantitative PCR indicated that the infection density in adults was higher than in any other life stage (egg, larva or pupa), and that reproductive tissue in adults had the highest infection densities, with similar densities in the sexes. These findings provide a starting point for understanding the Wolbachia infection dynamics in P. fuscipes, and interactions with other components of the microbiota.

RevDate: 2020-09-16
CmpDate: 2020-09-16

Kakumanu ML, DeVries ZC, Barbarin AM, et al (2020)

Bed bugs shape the indoor microbial community composition of infested homes.

The Science of the total environment, 743:140704.

Indoor pests, and the allergens they produce, adversely affect human health. Surprisingly, however, their effects on indoor microbial communities have not been assessed. Bed bug (Cimex lectularius) infestations pose severe challenges in elderly and low-income housing. They void large amounts of liquid feces into the home environment, which might alter the indoor microbial community composition. In this study, using bed bug-infested and uninfested homes, we showed a strong impact of bed bug infestations on the indoor microbial diversity. Floor dust samples were collected from uninfested and bed bug-infested homes and their microbiomes were analyzed before and after heat interventions that eliminated bed bugs. The microbial communities of bed bug-infested homes were radically different from those of uninfested homes, and the bed bug endosymbiont Wolbachia was the major driver of this difference. After bed bugs were eliminated, the microbial community gradually shifted toward the community composition of uninfested homes, strongly implicating bed bugs in shaping the dust-associated environmental microbiome. Further studies are needed to understand the viability of these microbial communities and the potential risks that bed bug-associated microbes and their metabolites pose to human health.

RevDate: 2020-09-11

Manokaran G, Flores HA, Dickson CT, et al (2020)

Modulation of acyl-carnitines, the broad mechanism behind Wolbachia-mediated inhibition of medically important flaviviruses in Aedes aegypti.

Proceedings of the National Academy of Sciences of the United States of America pii:1914814117 [Epub ahead of print].

Wolbachia-infected mosquitoes are refractory to flavivirus infections, but the role of lipids in Wolbachia-mediated virus blocking remains to be elucidated. Here, we use liquid chromatography mass spectrometry to provide a comprehensive picture of the lipidome of Aedes aegypti (Aag2) cells infected with Wolbachia only, either dengue or Zika virus only, and Wolbachia-infected Aag2 cells superinfected with either dengue or Zika virus. This approach identifies a class of lipids, acyl-carnitines, as being down-regulated during Wolbachia infection. Furthermore, treatment with an acyl-carnitine inhibitor assigns a crucial role for acyl-carnitines in the replication of dengue and Zika viruses. In contrast, depletion of acyl-carnitines increases Wolbachia density while addition of commercially available acyl-carnitines impairs Wolbachia production. Finally, we show an increase in flavivirus infection of Wolbachia-infected cells with the addition of acyl-carnitines. This study uncovers a previously unknown role for acyl-carnitines in this tripartite interaction that suggests an important and broad mechanism that underpins Wolbachia-mediated pathogen blocking.

RevDate: 2020-09-09

Caragata EP, Dong S, Dong Y, et al (2020)

Prospects and Pitfalls: Next-Generation Tools to Control Mosquito-Transmitted Disease.

Annual review of microbiology, 74:455-475.

Mosquito-transmitted diseases, including malaria and dengue, are a major threat to human health around the globe, affecting millions each year. A diverse array of next-generation tools has been designed to eliminate mosquito populations or to replace them with mosquitoes that are less capable of transmitting key pathogens. Many of these new approaches have been built on recent advances in CRISPR/Cas9-based genome editing. These initiatives have driven the development of pathogen-resistant lines, new genetics-based sexing methods, and new methods of driving desirable genetic traits into mosquito populations. Many other emerging tools involve microorganisms, including two strategies involving Wolbachia that are achieving great success in the field. At the same time, other mosquito-associated bacteria, fungi, and even viruses represent untapped sources of new mosquitocidal or antipathogen compounds. Although there are still hurdles to be overcome, the prospect that such approaches will reduce the impact of these diseases is highly encouraging.

RevDate: 2020-09-09

Ciuca L, Vismarra A, Lebon W, et al (2020)

New insights into the biology, diagnosis and immune response to Dirofilaria repens in the canine host.

Veterinary parasitology: X, 4:100029 pii:100029.

Dogs are the primary host for Dirofilaria repens, therefore it is mandatory to accurately diagnose the canine infection and to expand our current knowledge on parasite biology and the immune response of the infected host for a better prevention.Thus, the aim of the present study was to provide new insights from experimental infections of dogs with D. repens, focusing on the evaluation of: 1) the pre-patent period and 2) the antibody response against D. repens somatic antigens and against the Wolbachia endosymbiont. Briefly, on Day 0, twenty purpose-bred Beagle dogs were experimentally infected with 50 infective larvae (L3) of D. repens. Starting from Day 58 until the last day of the study (Day 281), blood samples were collected on a monthly basis for detection of antibodies against D. repens (Dr) and recombinant Wolbachia surface protein (rWSP) by non-commercial IgG-ELISAs. Additional samples were collected on Days 220, 245 and 281 for the detection of microfilariae (mff) using the modified Knott's test and biomolecular analysis, following two PCR protocols: Gioia et al. (2010; protocol A) and Rishniw et al. (2006- protocol B). The results were analysed by univariate statistical analyses using 2 × 2 contingency tables and K Cohen was calculated to assess the agreement among all the diagnostic techniques. Overall, the outcome of the study revealed that out of the 20 dogs experimentally infected with D. repens, 16 (80 %) were microfilaraemic, 17 (85 %) were positive at DNA detection in the blood, 18 (90 %) had D. repens antibodies and 16 (80 %) had Wolbachia antibodies on the last day of the study. The overall k agreement between Knott's and PCR protocol B was 0.442 (P = 0.0001) and increased throughout the study, reaching 0.828 (P = 0.0001) on Day 281. To the authors knowledge, this is only the second study reporting antibody response to D. repens somatic antigen in experimentally infected dogs. ELISA results showed that an antibody response develops before the onset of patency, and steadily increases with time. Results would suggest that the development of an immunological response to infection could lead to application in epidemiological studies, risk assessment and as an aid in the diagnostic approach in dogs, in particular for early infections without mff.

RevDate: 2020-09-05

Lee JM, Yek SH, Wilson RF, et al (2020)

Characterisation of the Aedes albopictus (Diptera: Culicidae) holobiome: bacterial composition across land use type and mosquito sex in Malaysia.

Acta tropica pii:S0001-706X(20)30748-8 [Epub ahead of print].

Understanding the diversity and dynamics of the microbiota within the mosquito holobiome is of great importance to apprehend how the microbiota modulates various complex processes and interactions. This study examined the bacterial composition of Aedes albopictus across land use type and mosquito sex in the state of Selangor, Malaysia using 16S rRNA sequencing. The bacterial community structure in mosquitoes was found to be influenced by land use type and mosquito sex, with the environment and mosquito diet respectively identified to be the most likely sources of microbes. We found that approximately 70% of the microbiota samples were dominated by Wolbachia and removing Wolbachia from analyses revealed the relatively even composition of the remaining bacterial microbiota. Furthermore, microbial interaction network analysis highlighted the prevalence of co-exclusionary patterns in all networks regardless of land use and mosquito sex, with Wolbachia exhibiting co-exclusionary interactions with other residential bacteria such as Xanthomonas, Xenophilus and Zymobacter.

RevDate: 2020-09-04

Noh P, Oh SY, Park S, et al (2020)

Association between host wing morphology polymorphism and Wolbachia infection in Vollenhovia emeryi (Hymenoptera: Myrmicinae).

Ecology and evolution, 10(16):8827-8837 pii:ECE36582.

Many eusocial insects, including ants, show complex colony structures, distributions, and reproductive strategies. In the ant Vollenhovia emeryi Wheeler (Hymenoptera: Myrmicinae), queens and males are produced clonally, while sterile workers arise sexually, unlike other ant species and Hymenopteran insects in general. Furthermore, there is a wing length polymorphism in the queen caste. Despite its evolutionary remarkable traits, little is known about the population structure of this ant species, which may provide insight into its unique reproductive mode and polymorphic traits. We performed in-depth analyses of ant populations from Korea, Japan, and North America using three mitochondrial genes (COI, COII, and Cytb). The long-winged (L) morph is predominant in Korean populations, and the short-winged (S) morph is very rare. Interestingly, all L morphs were infected with Wolbachia, while all Korean S morphs lacked Wolbachia, demonstrating a association between a symbiont and a phenotypic trait. A phylogenetic analysis revealed that the S morph is derived from the L morph. We propose that the S morph is associated with potential resistance to Wolbachia infection and that Wolbachia infection does not influence clonal reproduction (as is the case in other ant species).

RevDate: 2020-09-03

Zhang D, Xi Z, Li Y, et al (2020)

Toward implementation of combined incompatible and sterile insect techniques for mosquito control: Optimized chilling conditions for handling Aedes albopictus male adults prior to release.

PLoS neglected tropical diseases, 14(9):e0008561 pii:PNTD-D-20-00097.

Combined incompatible and sterile insect technique (IIT-SIT) has been considered to be an effective and safe approach to control mosquito populations. Immobilization of male adults by chilling is a crucial process required for the packing, transportation and release of the mosquitoes during the implementation of IIT-SIT for mosquito control. In this study, effects of chilling on the Aedes albopictus males with triple Wolbachia infections (HC line), a powerful weapon to fight against the wild type Ae. albopictus population via IIT-SIT, were evaluated under both laboratory and field conditions. Irradiated HC (IHC) males were exposed to 1, 5 and 10°C for 1, 2, 3, 6 and 24 h. The survival rate of the post-chilled IHC males was then monitored. Longevity of post-chilled IHC males was compared to non-chilled males under laboratory and semi-field conditions. Mating competitiveness of IHC/HC males after exposure to 5 or 10°C for 0, 3 and 24 h was then evaluated. Effects of compaction and transportation under chilled conditions on the survival rate of IHC males were also monitored. The optimal chilling conditions for handling IHC males were temperatures between 5 and 10°C for a duration of less than 3 h with no negative impacts on survival rate, longevity and mating competitiveness when compared to non-chilled males. However, the overall quality of post-chilled IHC/HC males decreased when exposed to low temperatures for 24 h. Reduced survival was observed when IHC males were stored at 5°C under a compaction height of 8 cm. Transportation with chilling temperatures fluctuating from 8 to 12°C has no negative impact on the survival of IHC males. This study identified the optimal chilling temperature and duration for the handling and transportation of Ae. albopictus IHC male adults without any detrimental effect on their survival, longevity and mating competitiveness. Further studies are required to develop drone release systems specific for chilled mosquitoes to improve release efficiency, as well as to compare the population suppression efficiency between release of post-chilled and non-chilled males in the field.

RevDate: 2020-09-03

Castillo AM, Saltonstall K, Arias CF, et al (2020)

The Microbiome of Neotropical Water Striders and Its Potential Role in Codiversification.

Insects, 11(9): pii:insects11090578.

Insects host a highly diverse microbiome, which plays a crucial role in insect life. However, the composition and diversity of microbiomes associated with Neotropical freshwater insects is virtually unknown. In addition, the extent to which diversification of this microbiome is associated with host phylogenetic divergence remains to be determined. Here, we present the first comprehensive analysis of bacterial communities associated with six closely related species of Neotropical water striders in Panama. We used comparative phylogenetic analyses to assess associations between dominant bacterial linages and phylogenetic divergence among species of water striders. We found a total of 806 16S rRNA amplicon sequence variants (ASVs), with dominant bacterial taxa belonging to the phyla Proteobacteria (76.87%) and Tenericutes (19.51%). Members of the α- (e.g., Wolbachia) and γ- (e.g., Acinetobacter, Serratia) Proteobacteria, and Mollicutes (e.g., Spiroplasma) were predominantly shared across species, suggesting the presence of a core microbiome in water striders. However, some bacterial lineages (e.g., Fructobacillus, Fluviicola and Chryseobacterium) were uniquely associated with different water strider species, likely representing a distinctive feature of each species' microbiome. These findings indicate that both host identity and environmental context are important drivers of microbiome diversity in water striders. In addition, they suggest that diversification of the microbiome is associated with diversification in water striders. Although more research is needed to establish the evolutionary consequences of host-microbiome interaction in water striders, our findings support recent work highlighting the role of bacterial community host-microbiome codiversification.

RevDate: 2020-08-28

Brattig NW, Cheke RA, R Garms (2020)

Onchocerciasis (River Blindness) - more than a Century of Research and Control.

Acta tropica pii:S0001-706X(20)30991-8 [Epub ahead of print].

This review summarises more than a century of research on onchocerciasis, also known as river blindness, and its control. River blindness is an infection caused by the tissue filaria Onchocerca volvulus affecting the skin, subcutaneous tissue and eyes and leading to blindness in a minority of infected persons. The parasite is transmitted by its intermediate hosts Simulium spp. which breed in rivers. Featured are history and milestones in onchocerciasis research and control, state-of-the-art data on the parasite, its endobacteria Wolbachia, on the vectors, previous and current prevalence of the infection, its diagnostics, the interaction between the parasite and its host, immune responses and the pathology of onchocerciasis. Detailed information is documented on the time course of control programmes in the afflicted countries in Africa and the Americas, a long road from previous programmes to current successes in control of the transmission of this infectious disease. By development, adjustment and optimization of the control measures, transmission by the vector has been interrupted in foci of countries in the Americas, in Uganda, in Sudan and elsewhere, followed by onchocerciasis eliminations. The current state and future perspectives for control, elimination and eradication within the next 20-30 years are described and discussed. This review contributes to a deeper comprehension of this disease by a tissue-dwelling filaria and it will be helpful in efforts to control and eliminate other filarial infections.

RevDate: 2020-08-28

Neupane S, Bonilla SI, Manalo AM, et al (2020)

Near-Complete Genome Sequences of a Wolbachia Strain Isolated from Diaphorina citri Kuwayama (Hemiptera: Liviidae).

Microbiology resource announcements, 9(35): pii:9/35/e00560-20.

Wolbachia strains are one of three endosymbionts associated with the insect vector of "Candidatus Liberibacter asiaticus," Diaphorina citri Kuwayama (Hemiptera: Liviidae). We report three near-complete genome sequences of samples of Wolbachia from D. citri (wDi), with sizes of 1,518,595, 1,542,468, and 1,538,523 bp.

RevDate: 2020-08-28

Adegoke A, Kumar D, Bobo C, et al (2020)

Tick-Borne Pathogens Shape the Native Microbiome Within Tick Vectors.

Microorganisms, 8(9): pii:microorganisms8091299.

Ticks are blood-feeding arthropods and transmit a variety of medically important viral, bacterial, protozoan pathogens to animals and humans. Ticks also harbor a diverse community of microbes linked to their biological processes, such as hematophagy, and hence affect vector competence. The interactions between bacterial and/or protozoan pathogens and the tick microbiome is a black-box, and therefore we tested the hypothesis that the presence of a protozoan or bacterial pathogen will alter the microbial composition within a tick. Hence, this study was designed to define the microbial composition of two tick species, Hyalomma (H.) anatolicum and Rhipicephalus (R.) microplus. We used a combination of PCR based pathogen (Anaplasma marginale and Theileria species) and symbiont (Wolbachia species) identification followed by metagenomic sequencing and comparison of the microbial communities in PCR positive and negative ticks. A total of 1786 operational taxonomic units was identified representing 25 phyla, 50 classes, and 342 genera. The phylum Proteobacteria, Firmicutes, Actinobacteriota, and Bacteroidota were the most represented bacteria group. Alpha and beta diversity were not significantly affected in the presence or absence of Theileria sp. and A. marginale as see with H. anatolicum ticks. Interestingly, bacterial communities were significantly reduced in Theileria sp. infected R. microplus ticks, while also exhibiting a significant reduction in microbial richness and evenness. Putting these observations together, we referred to the effect the presence of Theileria sp. has on R. microplus a "pathogen-induced dysbiosis". We also identify the presence of Plasmodium falciparum, the causative agent of human malaria from the microbiome of both H. anatolicum and R. microplus ticks. These findings support the presence of a "pathogen-induced dysbiosis" within the tick and further validation experiments are required to investigate how they are important in the vector competence of ticks. Understanding the mechanism of "pathogen-induced dysbiosis" on tick microbial composition may aid the discovery of intervention strategies for the control of emerging tick-borne infections.

RevDate: 2020-08-27

Johnson KN (2015)

Bacteria and antiviral immunity in insects.

Current opinion in insect science, 8:97-103.

Tripartite interactions between viruses, bacteria and hosts can have significant implications for the outcome of infections. In insects recent studies have shown that these interactions can greatly influence the transmission of vector borne disease, including transmission of dengue virus. Mosquito gut bacteria modulate arbovirus infection of the mosquito host and specific bacterial isolates have been identified that negatively impact the outcome of infection. In addition, an endosymbiotic bacterium Wolbachia, which is very common in insects, protects flies and mosquitoes from virus infection. This antiviral protection has implications for both naturally infected insects and for use in disease control. This review summarises the current state of knowledge for each of these interactions with an emphasis on natural interactions.

RevDate: 2020-08-27

Altinli M, Lequime S, Atyame C, et al (2020)

Wolbachia modulates prevalence and viral load of Culex pipiens densoviruses in natural populations.

Molecular ecology [Epub ahead of print].

The inadequacy of the standard mosquito control strategies calls for ecologically safe novel approaches, like the use of biological agents such as the endosymbiotic α-proteobacteria Wolbachia or insect-specific viruses (ISVs). Understanding the ecological interactions between these "biocontrol endosymbionts" is thus a fundamental step to achieve. Wolbachia are transmitted vertically from mother to offspring and modify their hosts' phenotypes, including reproduction (e.g. cytoplasmic incompatibility) and survival (e.g. viral interference). In nature, Culex pipiens (s.l.) mosquitoes are always found infected with genetically diverse Wolbachia called wPip that belong to five phylogenetic groups. In the recent years, ISVs have also been discovered in these mosquito species, although their interactions with Wolbachia in nature are unknown. Here, we studied the interactions between a widely prevalent ISV, the Culex pipiens densovirus (CpDV, Densovirinae), and Wolbachia in Northern-Tunisian Cx. pipiens populations. We showed an influence of different Wolbachia groups on CpDV prevalence and a general positive correlation between Wolbachia and CpDV loads. By investigating the putative relation between CpDV diversification and wPip groups in the different sites, we detected a signal linked to wPip groups in CpDV phylogeny in sites where all larvae were infected by the same wPip group. However, no such signal was detected where the wPip groups co-existed, suggesting CpDV horizontal transfers between hosts. Overall, our results provide good evidence for an ecological influence of Wolbachia on an ISV, CpDV, in natural populations and highlight the importance of integrating Wolbachia in the understanding of ISV ecology in nature.

RevDate: 2020-08-27

Sim S, Ng LC, Lindsay SW, et al (2020)

A greener vision for vector control: The example of the Singapore dengue control programme.

PLoS neglected tropical diseases, 14(8):e0008428 pii:PNTD-D-19-02097.

Vector-borne diseases are a major cause of morbidity and mortality worldwide. Aedes-borne diseases, in particular, including dengue, chikungunya, yellow fever, and Zika, are increasing at an alarming rate due to urbanisation, population movement, weak vector control programmes, and climate change. The World Health Organization calls for strengthening of vector control programmes in line with the Global Vector Control Response (GVCR) strategy, and many vector control programmes are transitioning to this new approach. The Singapore dengue control programme, situated within the country's larger vision of a clean, green, and sustainable environment for the health and well-being of its citizens, provides an excellent example of the GVCR approach in action. Since establishing vector control operations in the 1960s, the Singapore dengue control programme succeeded in reducing the dengue force of infection 10-fold by the 1990s and has maintained it at low levels ever since. Key to this success is consideration of dengue as an environmental disease, with a strong focus on source reduction and other environmental management methods as the dominant vector control strategy. The programme collaborates closely with other government ministries, as well as town councils, communities, the private sector, and academic and research institutions. Community engagement programmes encourage source reduction, and house-to-house inspections accompanied by a strong legislative framework with monetary penalties help to support compliance. Strong vector and epidemiological surveillance means that routine control activities can be heightened to specifically target dengue clusters. Despite its success, the programme continues to innovate to tackle challenges such as climate change, low herd immunity, and manpower constraints. Initiatives include development of novel vector controls such as Wolbachia-infected males and spatiotemporal models for dengue risk assessment. Lessons learnt from the Singapore programme can be applied to other settings, even those less well-resourced than Singapore, for more effective vector control.

RevDate: 2020-08-27

Hubert J, Nesvorna M, Green SJ, et al (2020)

Microbial Communities of Stored Product Mites: Variation by Species and Population.

Microbial ecology pii:10.1007/s00248-020-01581-y [Epub ahead of print].

Arthropod-associated microorganisms are important because they affect host fitness, protect hosts from pathogens, and influence the host's ability to vector pathogens. Stored product mites (Astigmata) often establish large populations in various types of food items, damaging the food by direct feeding and introducing contaminants, including their own bodies, allergen-containing feces, and associated microorganisms. Here we access the microbial structure and abundance in rearing diets, eggs, feces fraction, and mite bodies of 16 mite populations belonging to three species (Carpoglyphus lactis, Acarus siro, and Tyrophagus putrescentiae) using quantitative PCR and 16S ribosomal RNA (rRNA) gene amplicon sequencing. The mite microbiomes had a complex structure dominated by the following bacterial taxa (OTUs): (a) intracellular symbionts of the genera Cardinium and Wolbachia in the mite bodies and eggs; (b) putative gut symbionts of the genera Solitalea, Bartonella, and Sodalis abundant in mite bodies and also present in mite feces; (c) feces-associated or environmental bacteria of the genera Bacillus, Staphylococcus, and Kocuria in the diet, mite bodies, and feces. Interestingly and counterintuitively, the differences between microbial communities in various conspecific mite populations were higher than those between different mite species. To explain some of these differences, we hypothesize that the intracellular bacterial symbionts can affect microbiome composition in mite bodies, causing differences between microbial profiles. Microbial profiles differed between various sample types, such as mite eggs, bodies, and the environment (spent growth medium-SPGM). Low bacterial abundances in eggs may result in stochastic effects in parent-offspring microbial transmission, except for the intracellular symbionts. Bacteria in the rearing diet had little effect on the microbial community structure in SPGM and mite bodies. Mite fitness was positively correlated with bacterial abundance in SPGM and negatively correlated with bacterial abundances in mite bodies. Our study demonstrates critical host-microbe interactions, affecting all stages of mite growth and leading to alteration of the environmental microbiome. Correlational evidence based on absolute quantitation of bacterial 16S rRNA gene copies suggests that mite-associated microorganisms are critical for modulating important pest properties of mites by altering population growth.

RevDate: 2020-08-27

Esteban-Mendoza MV, Arcila-Quiceno V, Albarracín-Navas J, et al (2020)

Current Situation of the Presence of Dirofilaria immitis in Dogs and Humans in Bucaramanga, Colombia.

Frontiers in veterinary science, 7:488.

The cardiopulmonary dirofilariosis caused by Dirofilaria immitis, is a vector-borne infection, which can be transmitted to humans. The main hosts are both domestic and wild canids. This species mainly occurs in tropical and subtropical climates, and temperature and humidity are the main factors that favor the presence and proliferation of culicid mosquitoes as vectors of the disease. There are few reports of cardiopulmonary dirofilariosis in dogs and humans in Colombia, a region with favorable climatic conditions which favors the presence of mosquitoes that act as vectors of the disease. Therefore, this study aimed to examine its current prevalence in dogs and the risk of human exposure to the disease in Bucaramanga, one of the most populated areas in Colombia located at the center of the country. Furthermore, its demographic and environmental characteristics could be useful as a study model for other similar locations and neighboring countries. Serum samples from 351 dogs and 506 humans from the Bucaramanga Metropolitan area were analyzed. All dog samples were analyzed by Knott's technique and tested with a commercial immunochromatographic to detect the presence of circulating antigens of D. immitis. Human samples were analyzed using a non-commercial ELISA test kit to detect IgG against the somatic antigens of adult D. immitis and Wolbachia. Positive results were further confirmed using western blot analysis. Thirty-eight dogs tested positive with a overall prevalence of 10.82%. Of these dogs, 18 showed D. immitis microfilariae, being 5.12% of the total population. The overall seroprevalence in humans was 6.71%; seroprevalence was significantly higher in individuals aged 16-34 years-old and in women than in men. To our knowledge, this study describes seropositivity to D. immitis for the first time in a Colombian human population located in the same area as that of dogs infected with D. immitis, which represents a potential threat to public health. In humans, age and gender can be considered risk factors for exposure to D. immitis.

RevDate: 2020-08-27

Lu P, Sun Q, Fu P, et al (2020)

Wolbachia Inhibits Binding of Dengue and Zika Viruses to Mosquito Cells.

Frontiers in microbiology, 11:1750.

As traditional approaches to the control of dengue and Zika are insufficient, significant efforts have been made to develop utilization of the endosymbiotic bacterium Wolbachia to reduce the ability of mosquitoes to transmit pathogens. Although Wolbachia is known to inhibit flaviviruses in mosquitoes, including dengue virus (DENV) and Zika virus (ZIKV), it remains unclear how the endosymbiont interferes with viral replication cycle. In this study, we have carried out viral binding assays to investigate the impact of the Wolbachia strain wAlbB on the attachment of DENV serotype 2 (DENV-2) and ZIKV to Aedes aegypti Aag-2 cells. RNA interference (RNAi) was used to silence a variety of putative mosquito receptors of DENV that were differentially regulated by wAlbB in Aag-2 cells, in order to identify host factors involved in the inhibition of viral binding. Our results showed that, in addition to suppression of viral replication, Wolbachia strongly inhibited binding of both DENV-2 and ZIKV to Aag-2 cells. Moreover, the expression of two putative mosquito DENV receptors - dystroglycan and tubulin - was downregulated by wAlbB, and their knock-down resulted in the inhibition of DENV-2 binding to Aag-2 cells. These results will aid in understanding the Wolbachia-DENV interactions in mosquito and the development of novel control strategies for mosquito-borne diseases.

RevDate: 2020-08-24

Wuliandari JR, Hoffmann AA, Tantowijoyo W, et al (2020)

Frequency of kdr mutations in the voltage-sensitive sodium channel (VSSC) gene in Aedes aegypti from Yogyakarta and implications for Wolbachia-infected mosquito trials.

Parasites & vectors, 13(1):429 pii:10.1186/s13071-020-04304-x.

BACKGROUND: In the inner city of Yogyakarta, Indonesia, insecticide resistance is expected in the main dengue vector, Aedes aegypti, because of the intensive local application of pyrethroid insecticides. However, detailed information about the nature of resistance in this species is required to assist the release of Wolbachia mosquitoes in a dengue control program, so that we can ensure that insecticide resistance in the strain of Ae. aegypti being released matches that of the background population.

METHODS: High-resolution melt genotyping was used to screen for kdr mutations associated with pyrethroid resistance in the voltage-sensitive sodium channel (VSSC) gene in Ae. aegypti of some areas in the inner city of Yogyakarta.

RESULTS: The results show that the V1016G mutation predominated, with individuals homozygous for the 1016G allele at a frequency of 82.1% and the mutant allele G at a frequency of 92%. Two patterns of co-occurrence of mutations were detected in this study, homozygous individuals V1016G/S989P; and heterozygous individuals V1016G/F1534C/S989P. We found the simultaneous occurrence of kdr mutations V1016G and F1534C at all collection sites, but not within individual mosquitoes. Homozygous mutants at locus 1016 were homozygous wild-type at locus 1534 and vice versa, and heterozygous V1016G were also heterozygous for F1534C. The most common tri-locus genotype co-occurrences were homozygous mutant 1016GG and homozygous wild-type FF1534, combined with homozygous mutant 989PP (GG/FF/PP) at a frequency of 38.28%.

CONCLUSIONS: Given the relatively small differences in frequency of resistance alleles across the city area, locality variations in resistance should have minor implications for the success of Wolbachia mosquito trials being undertaken in the Yogyakarta area.

RevDate: 2020-08-22

Bykov R, Kerchev I, Demenkova M, et al (2020)

Sex-Specific Wolbachia Infection Patterns in Populations of Polygraphus proximus Blandford (Coleoptera; Curculionidae: Scolytinae).

Insects, 11(8): pii:insects11080547.

Wolbachia symbionts are maternally inherited bacteria that are widely distributed among Arthropoda hosts. Wolbachia influence their host biology in diverse ways. They may induce reproductive abnormalities, protect hosts against pathogens and parasites, or benefit hosts through metabolic provisioning. The progeny of an infected female are ordinarily infected with Wolbachia; however, Wolbachia have no future in male host progeny because they cannot transmit the symbiont to the next generation. Here, we analyze native and invasive populations of the four-eyed fir bark beetle (Polygraphus proximus) for Wolbachia prevalence and symbiont genetic diversity. This species is a dangerous pest of Siberian fir (Abies sibirica) forests. The native range of P. proximus includes the territories of the Russian Far East, Japan, Korea, and Northeast China, whereas its invasive range includes West Siberia, with further expansion westward. Surprisingly, we revealed a difference in the patterns of Wolbachia prevalence for males and females. Infection rate and Wolbachia titers were higher in females than in males. ST-533, the only haplotype of Wolbachia supergroup B, was associated with a minimum of three out of the five described mitochondrial haplotypes.

RevDate: 2020-08-22

Dally M, Lalzar M, Belausov E, et al (2020)

Cellular Localization of Two Rickettsia Symbionts in the Digestive System and within the Ovaries of the Mirid Bug, Macrolophous pygmaeus.

Insects, 11(8): pii:insects11080530.

Bacterial symbionts in arthropods are common, vary in their effects, and can dramatically influence the outcome of biological control efforts. Macrolophus pygmaeus (Heteroptera: Miridae), a key component of biological control programs, is mainly predaceous but may also display phytophagy. M. pygmaeus hosts symbiotic Wolbachia, which induce cytoplasmic incompatibility, and two Rickettsia species, R. bellii and R. limoniae, which are found in all individuals tested. To test possible involvement of the two Rickettsia species in the feeding habits of M. pygmaeus, we first showed that the microbiome of the insect is dominated by these three symbionts, and later described the distribution pattern of the two Rickettsia species in its digestive system. Although both Rickettsia species were located in certain gut bacteriocyes, in caeca and in Malpighian tubules of both sexes, each species has a unique cellular occupancy pattern and specific distribution along digestive system compartments. Infrequently, both species were found in a cell. In females, both Rickettsia species were detected in the germarium, the apical end of the ovarioles within the ovaries, but not in oocytes. Although the cause for these Rickettsia distribution patterns is yet unknown, it is likely linked to host nutrition while feeding on prey or plants.

RevDate: 2020-08-22

Ahmad NA, Endersby-Harshman NM, Mohd Mazni NR, et al (2020)

Characterization of Sodium Channel Mutations in the Dengue Vector Mosquitoes Aedesaegypti and Aedesalbopictus within the Context of Ongoing Wolbachia Releases in Kuala Lumpur, Malaysia.

Insects, 11(8): pii:insects11080529.

Specific sodium channel gene mutations confer target site resistance to pyrethroid insecticides in mosquitoes and other insects. In Aedes mosquito species, multiple mutations that contribute to resistance vary in their importance around the world. Here, we characterize voltage sensitive sodium channel (Vssc) mutations in populations of Aedesaegypti from Kuala Lumpur, Malaysia, and look at their persistence in populations affected by ongoing Wolbachia releases (a dengue control measure). We also describe a Vssc mutation in Aedesalbopictus (F1534L) found for the first time in Malaysia. We show that there are three predominant Vssc haplotypes in Aedesaegypti in this region, which all persist with regular backcrossing, thereby maintaining the original genetic composition of the populations. We identify changes in genotype frequency in closed populations of Ae. aegypti maintained for multiple generations in laboratory culture, suggesting different fitness costs associated with the genotypes, some of which may be associated with the sex of the mosquito. Following population replacement of Ae. aegypti by Wolbachia in the target area, however, we find that the Vssc mutations have persisted at pre-release levels. Mosquitoes in two genotype classes demonstrate a type I pyrethroid resistance advantage over wildtype mosquitoes when exposed to 0.25% permethrin. This resistance advantage is even more pronounced with a type II pyrethroid, deltamethrin (0.03%). The results point to the importance of these mutations in pyrethroid resistance in mosquito populations and the need for regular backcrossing with male mosquitoes from the field to maintain similarity of genetic background and population integrity during Wolbachia releases.

RevDate: 2020-08-21

Filipović I, Hapuarachchi HC, Tien WP, et al (2020)

Using spatial genetics to quantify mosquito dispersal for control programs.

BMC biology, 18(1):104 pii:10.1186/s12915-020-00841-0.

BACKGROUND: Hundreds of millions of people get a mosquito-borne disease every year and nearly one million die. Transmission of these infections is primarily tackled through the control of mosquito vectors. The accurate quantification of mosquito dispersal is critical for the design and optimization of vector control programs, yet the measurement of dispersal using traditional mark-release-recapture (MRR) methods is logistically challenging and often unrepresentative of an insect's true behavior. Using Aedes aegypti (a major arboviral vector) as a model and two study sites in Singapore, we show how mosquito dispersal can be characterized by the spatial analyses of genetic relatedness among individuals sampled over a short time span without interruption of their natural behaviors.

RESULTS: Using simple oviposition traps, we captured adult female Ae. aegypti across high-rise apartment blocks and genotyped them using genome-wide SNP markers. We developed a methodology that produces a dispersal kernel for distance which results from one generation of successful breeding (effective dispersal), using the distance separating full siblings and 2nd- and 3rd-degree relatives (close kin). The estimated dispersal distance kernel was exponential (Laplacian), with a mean dispersal distance (and dispersal kernel spread σ) of 45.2 m (95% CI 39.7-51.3 m), and 10% probability of a dispersal > 100 m (95% CI 92-117 m). Our genetically derived estimates matched the parametrized dispersal kernels from previous MRR experiments. If few close kin are captured, a conventional genetic isolation-by-distance analysis can be used, as it can produce σ estimates congruent with the close-kin method if effective population density is accurately estimated. Genetic patch size, estimated by spatial autocorrelation analysis, reflects the spatial extent of the dispersal kernel "tail" that influences, for example, the critical radii of release zones and the speed of Wolbachia spread in mosquito replacement programs.

CONCLUSIONS: We demonstrate that spatial genetics can provide a robust characterization of mosquito dispersal. With the decreasing cost of next-generation sequencing, the production of spatial genetic data is increasingly accessible. Given the challenges of conventional MRR methods, and the importance of quantified dispersal in operational vector control decisions, we recommend genetic-based dispersal characterization as the more desirable means of parameterization.

RevDate: 2020-08-19

Shropshire JD, Kalra M, SR Bordenstein (2020)

Evolution-guided mutagenesis of the cytoplasmic incompatibility proteins: Identifying CifA's complex functional repertoire and new essential regions in CifB.

PLoS pathogens, 16(8):e1008794 pii:PPATHOGENS-D-20-00986 [Epub ahead of print].

Wolbachia are the world's most common, maternally-inherited, arthropod endosymbionts. Their worldwide distribution is due, in part, to a selfish drive system termed cytoplasmic incompatibility (CI) that confers a relative fitness advantage to females that transmit Wolbachia to their offspring. CI results in embryonic death when infected males mate with uninfected females but not infected females. Under the Two-by-One genetic model of CI, males expressing the two phage WO proteins CifA and CifB cause CI, and females expressing CifA rescue CI. While each protein is predicted to harbor three functional domains, there is no knowledge on how sites across these Cif domains, rather than in any one particular domain, contribute to CI and rescue. Here, we use evolution-guided, substitution mutagenesis of conserved amino acids across the Cif proteins, coupled with transgenic expression in uninfected Drosophila melanogaster, to determine the functional impacts of conserved residues evolving mostly under purifying selection. We report that amino acids in CifA's N-terminal unannotated region and annotated catalase-related domain are important for both complete CI and rescue, whereas C-terminal residues in CifA's putative domain of unknown function are solely important for CI. Moreover, conserved CifB amino acids in the predicted nucleases, peptidase, and unannotated regions are essential for CI. Taken together, these findings indicate that (i) all CifA amino acids determined to be crucial in rescue are correspondingly crucial in CI, (ii) an additional set of CifA amino acids are uniquely important in CI, and (iii) CifB amino acids across the protein, rather than in one particular domain, are all crucial for CI. We discuss how these findings advance an expanded view of Cif protein evolution and function, inform the mechanistic and biochemical bases of Cif-induced CI/rescue, and continue to substantiate the Two-by-One genetic model of CI.

RevDate: 2020-08-19

Seabourn P, Spafford H, Yoneishi N, et al (2020)

The Aedes albopictus (Diptera: Culicidae) microbiome varies spatially and with Ascogregarine infection.

PLoS neglected tropical diseases, 14(8):e0008615 pii:PNTD-D-19-01818.

The mosquito microbiome alters the physiological traits of medically important mosquitoes, which can scale to impact how mosquito populations sustain disease transmission. The mosquito microbiome varies significantly within individual mosquitoes and among populations, however the ecological and environmental factors that contribute to this variation are poorly understood. To further understand the factors that influence variation and diversity of the mosquito microbiome, we conducted a survey of the bacterial microbiome in the medically important mosquito, Aedes albopictus, on the high Pacific island of Maui, Hawai'i. We detected three bacterial Phyla and twelve bacterial families: Proteobacteria, Acitinobacteria, and Firmicutes; and Anaplasmataceae, Acetobacteraceae, Enterobacteriaceae, Burkholderiaceae, Xanthobacteraceae, Pseudomonadaceae, Streptomycetaceae, Staphylococcaceae, Xanthomonadaceae, Beijerinckiaceae, Rhizobiaceae, and Sphingomonadaceae. The Ae. albopictus bacterial microbiota varied among geographic locations, but temperature and rainfall were uncorrelated with this spatial variation. Infection status with an ampicomplexan pathosymbiont Ascogregarina taiwanensis was significantly associated with the composition of the Ae. albopictus bacteriome. The bacteriomes of mosquitoes with an A. taiwanensis infection were more likely to include several bacterial symbionts, including the most abundant lineage of Wolbachia sp. Other symbionts like Asaia sp. and several Enterobacteriaceae lineages were less prevalent in A. taiwanensis-infected mosquitoes. This highlights the possibility that inter- and intra-domain interactions may structure the Ae. albopictus microbiome.

RevDate: 2020-08-17

Indriani C, Tantowijoyo W, Rancès E, et al (2020)

Reduced dengue incidence following deployments of Wolbachia-infected Aedes aegypti in Yogyakarta, Indonesia: a quasi-experimental trial using controlled interrupted time series analysis.

Gates open research, 4:50.

Background:Ae. aegypti mosquitoes stably transfected with the intracellular bacterium Wolbachiapipientis (wMel strain) have been deployed for biocontrol of dengue and related arboviral diseases in multiple countries. Field releases in northern Australia have previously demonstrated near elimination of local dengue transmission from Wolbachia-treated communities, and pilot studies in Indonesia have demonstrated the feasibility and acceptability of the method. We conducted a quasi-experimental trial to evaluate the impact of scaled Wolbachia releases on dengue incidence in an endemic setting in Indonesia. Methods: In Yogyakarta City, Indonesia, following extensive community engagement, wMel Wolbachia-carrying mosquitoes were released every two weeks for 13-15 rounds over seven months in 2016-17, in a contiguous 5 km 2 area (population 65,000). A 3 km 2 area (population 34,000) on the opposite side of the city was selected a priori as an untreated control area. Passive surveillance data on notified hospitalised dengue patients was used to evaluate the epidemiological impact of Wolbachia deployments, using controlled interrupted time-series analysis. Results: Rapid and sustained introgression of wMel Wolbachia into local Ae. aegypti populations was achieved. Thirty-four dengue cases were notified from the intervention area and 53 from the control area (incidence 26 vs 79 per 100,000 person-years) during 24 months following Wolbachia deployment. This corresponded in the regression model to a 73% reduction in dengue incidence (95% confidence interval 49%,86%) associated with the Wolbachia intervention. Exploratory analysis including 6 months additional post-intervention observations showed a small strengthening of this effect (30 vs 115 per 100,000 person-years; 76% reduction in incidence, 95%CI 60%,86%). Conclusions: We demonstrate a significant reduction in dengue incidence following successful introgression of Wolbachia into local Ae. aegypti populations in an endemic setting in Indonesia. These findings are consistent with previous field trials in northern Australia, and support the effectiveness of this novel approach for dengue control.

RevDate: 2020-08-15

Martinez J, Klasson L, Welch JJ, et al (2020)

Life and death of selfish genes: comparative genomics reveals the dynamic evolution of cytoplasmic incompatibility.

Molecular biology and evolution pii:5892770 [Epub ahead of print].

Cytoplasmic incompatibility is a selfish reproductive manipulation induced by the endosymbiont Wolbachia in arthropods. In males Wolbachia modifies sperm, leading to embryonic mortality in crosses with Wolbachia-free females. In females, Wolbachia rescues the cross and allows development to proceed normally. This provides a reproductive advantage to infected females, allowing the maternally-transmitted symbiont to spread rapidly through host populations. We identified homologs of the genes underlying this phenotype, cifA and cifB, in 52 of 71 new and published Wolbachia genomes sequences. They are strongly associated with cytoplasmic incompatibility. There are up to seven copies of the genes in each genome, and phylogenetic analysis shows that Wolbachia frequently acquires new copies due to pervasive horizontal transfer between strains. In many cases the genes have subsequently acquired loss-of-function mutations to become pseudogenes. As predicted by theory, this tends to occur first in cifB, whose sole function is to modify sperm, and then in cifA, which is required to rescue the cross in females. Although cif genes recombine, recombination is largely restricted to closely related homologs. This is predicted under a model of coevolution between sperm modification and embryonic rescue, where recombination between distantly related pairs of genes would create a self-incompatible strain. Together, these patterns of gene gain, loss and recombination support evolutionary models of cytoplasmic incompatibility.

RevDate: 2020-08-15

Straub TJ, Shaw WR, Marcenac P, et al (2020)

The Anopheles coluzzii microbiome and its interaction with the intracellular parasite Wolbachia.

Scientific reports, 10(1):13847 pii:10.1038/s41598-020-70745-0.

Wolbachia, an endosymbiotic alpha-proteobacterium commonly found in insects, can inhibit the transmission of human pathogens by mosquitoes. Biocontrol programs are underway using Aedes aegypti mosquitoes trans-infected with a non-natural Wolbachia strain to reduce dengue virus transmission. Less is known about the impact of Wolbachia on the biology and vectorial capacity of Anopheles mosquitoes, the vectors of malaria parasites. A naturally occurring strain of Wolbachia, wAnga, infects populations of the major malaria vectors Anopheles gambiae and Anopheles coluzzii in Burkina Faso. Previous studies found wAnga infection was negatively correlated with Plasmodium infection in the mosquito and wAnga influenced mosquito egg-laying behavior. Here, we investigate wAnga in natural populations of An. coluzzii and its interactions with other resident microbiota using targeted 16S sequencing. Though we find no major differences in microbiota composition associated with wAnga infection, we do find several taxa that correlate with the presence or absence of wAnga in female mosquitoes following oviposition, with the caveat that we could not rule out batch effects due to the unanticipated impact of wAnga on oviposition timing. These data suggest wAnga may influence or interact with the Anopheles microbiota, which may contribute to the impact of wAnga on Anopheles biology and vectorial capacity.

RevDate: 2020-08-14

Ferguson KB, Kursch-Metz T, Verhulst EC, et al (2020)

Hybrid Genome Assembly and Evidence-Based Annotation of the Egg Parasitoid and Biological Control Agent Trichogramma brassicae.

G3 (Bethesda, Md.) pii:g3.120.401344 [Epub ahead of print].

Trichogramma brassicae (Bezdenko) are egg parasitoids that are used throughout the world as biological control agents and in laboratories as model species. Despite this ubiquity, few genetic resources exist beyond COI, ITS2, and RAPD markers. Aided by a Wolbachia infection, a wild-caught strain from Germany was reared for low heterozygosity and sequenced in a hybrid de novo strategy, after which several assembling strategies were evaluated. The best assembly, derived from a DBG2OLC-based pipeline, yielded a genome of 235 Mbp made up of 1,572 contigs with an N50 of 556,663 bp. Following a rigorous ab initio-, homology-, and evidence-based annotation, 16,905 genes were annotated and functionally described. As an example of the utility of the genome, a simple ortholog cluster analysis was performed with sister species T. pretiosum, revealing over 6000 shared clusters and under 400 clusters unique to each species. The genome and transcriptome presented here provides an essential resource for comparative genomics of the commercially relevant genus Trichogramma, but also for research into molecular evolution, ecology, and breeding of T. brassicae.

RevDate: 2020-08-13

N Miyata M, Nomura M, D Kageyama (2020)

Wolbachia have made it twice: Hybrid introgression between two sister species of Eurema butterflies.

Ecology and evolution, 10(15):8323-8330 pii:ECE36539.

Wolbachia, cytoplasmically inherited endosymbionts of arthropods, are known to hijack their host reproduction in various ways to increase their own vertical transmission. This may lead to the selective sweep of associated mitochondria, which can have a large impact on the evolution of mitochondrial lineages. In Japan, two different Wolbacahia strains (wCI and wFem) are found in two sister species of pierid butterflies, Eurema mandarina and Eurema hecabe. In both species, females infected with wCI (C females) produce offspring with a nearly 1:1 sex ratio, while females infected with both wCI and wFem (CF females) produce all-female offspring. Previous studies have suggested the historical occurrence of hybrid introgression in C individuals between the two species. Furthermore, hybrid introgression in CF individuals is suggested by the distinct mitochondrial lineages between C females and CF females of E. mandarina. In this study, we performed phylogenetic analyses based on nuclear DNA and mitochondrial DNA markers of E. hecabe with previously published data on E. mandarina. We found that the nuclear DNA of this species significantly diverged from that of E. mandarina. By contrast, mitochondrial DNA haplotypes comprised two clades, mostly reflecting Wolbachia infection status rather than the individual species. Collectively, our results support the previously suggested occurrence of two independent historical events wherein the cytoplasms of CF females and C females moved between E. hecabe and E. mandarina through hybrid introgression.

RevDate: 2020-08-13

Wong ML, Liew JWK, Wong WK, et al (2020)

Natural Wolbachia infection in field-collected Anopheles and other mosquito species from Malaysia.

Parasites & vectors, 13(1):414 pii:10.1186/s13071-020-04277-x.

BACKGROUND: The endosymbiont bacterium Wolbachia is maternally inherited and naturally infects some filarial nematodes and a diverse range of arthropods, including mosquito vectors responsible for disease transmission in humans. Previously, it has been found infecting most mosquito species but absent in Anopheles and Aedes aegypti. However, recently these two mosquito species were found to be naturally infected with Wolbachia. We report here the extent of Wolbachia infections in field-collected mosquitoes from Malaysia based on PCR amplification of the Wolbachia wsp and 16S rRNA genes.

METHODS: The prevalence of Wolbachia in Culicinae mosquitoes was assessed via PCR with wsp primers. For some of the mosquitoes, in which the wsp primers failed to amplify a product, Wolbachia screening was performed using nested PCR targeting the 16S rRNA gene. Wolbachia sequences were aligned using Geneious 9.1.6 software, analyzed with BLAST, and the most similar sequences were downloaded. Phylogenetic analyses were carried out with MEGA 7.0 software. Graphs were drawn with GraphPad Prism 8.0 software.

RESULTS: A total of 217 adult mosquitoes representing 26 mosquito species were screened. Of these, infections with Wolbachia were detected in 4 and 15 mosquito species using wsp and 16S rRNA primers, respectively. To our knowledge, this is the first time Wolbachia was detected using 16S rRNA gene amplification, in some Anopheles species (some infected with Plasmodium), Culex sinensis, Culex vishnui, Culex pseudovishnui, Mansonia bonneae and Mansonia annulifera. Phylogenetic analysis based on wsp revealed Wolbachia from most of the mosquitoes belonged to Wolbachia Supergroup B. Based on 16S rRNA phylogenetic analysis, the Wolbachia strain from Anopheles mosquitoes were more closely related to Wolbachia infecting Anopheles from Africa than from Myanmar.

CONCLUSIONS: Wolbachia was found infecting Anopheles and other important disease vectors such as Mansonia. Since Wolbachia can affect its host by reducing the life span and provide resistance to pathogen infection, several studies have suggested it as a potential innovative tool for vector/vector-borne disease control. Therefore, it is important to carry out further studies on natural Wolbachia infection in vector mosquitoes' populations as well as their long-term effects in new hosts and pathogen suppression.

RevDate: 2020-08-13

Sucupira PHF, Ferreira ÁGA, Leite THJF, et al (2020)

The RNAi Pathway Is Important to Control Mayaro Virus Infection in Aedes aegypti but not for Wolbachia-Mediated Protection.

Viruses, 12(8): pii:v12080871.

Mayaro virus (MAYV), a sylvatic arbovirus belonging to the Togaviridae family and Alphavirus genus, is responsible for an increasing number of outbreaks in several countries of Central and South America. Despite Haemagogus janthinomys being identified as the main vector of MAYV, laboratory studies have already demonstrated the competence of Aedes aegypti to transmit MAYV. It has also been demonstrated that the WolbachiawMel strain is able to impair the replication and transmission of MAYV in Ae. aegypti. In Ae. aegypti, the small interfering RNA (siRNA) pathway is an important antiviral mechanism; however, it remains unclear whether siRNA pathway acts against MAYV infection in Ae. aegypti. The main objective of this study was to determine the contribution of the siRNA pathway in the control of MAYV infection. Thus, we silenced the expression of AGO2, an essential component of the siRNA pathway, by injecting dsRNA-targeting AGO2 (dsAGO2). Our results showed that AGO2 is required to control MAYV replication upon oral infection in Wolbachia-free Ae. aegypti. On the other hand, we found that Wolbachia-induced resistance to MAYV in Ae. aegypti is independent of the siRNA pathway. Our study brought new information regarding the mechanism of viral protection, as well as on Wolbachia mediated interference.

RevDate: 2020-08-13

Shi Y, J Yu (2020)

Wolbachia infection enhancing and decaying domains in mosquito population based on discrete models.

Journal of biological dynamics, 14(1):679-695.

In this article, we formulate and study a discrete equation model depicting the pattern of Wolbachia infection in a mosquito population. A domain in [Formula: see text] is called a Wolbachia infection enhancing (or decaying) domain if in which the Wolbachia infection frequency of the next generation is always bigger (or smaller) than that of the current generation. We first give a complete analysis of the equivalent Wolbachia infection frequency curves. And then we clearly characterize the Wolbachia infection enhancing domain and decaying domain for all of the parameters, respectively. Finally, some numerical examples are also provided to illustrate our theoretical results.

RevDate: 2020-08-11

Curran DM, Grote A, Nursimulu N, et al (2020)

Modeling the metabolic interplay between a parasitic worm and its bacterial endosymbiont allows the identification of novel drug targets.

eLife, 9: pii:51850.

The filarial nematode Brugia malayi represents a leading cause of disability in the developing world, causing lymphatic filariasis in nearly 40 million people. Currently available drugs are not well-suited to mass drug administration efforts, so new treatments are urgently required. One potential vulnerability is the endosymbiotic bacteria Wolbachia-present in many filariae-which is vital to the worm. Genome scale metabolic networks have been used to study prokaryotes and protists and have proven valuable in identifying therapeutic targets, but have only been applied to multicellular eukaryotic organisms more recently. Here, we present iDC625, the first compartmentalized metabolic model of a parasitic worm. We used this model to show how metabolic pathway usage allows the worm to adapt to different environments, and predict a set of 102 reactions essential to the survival of B. malayi. We validated three of those reactions with drug tests and demonstrated novel antifilarial properties for all three compounds.

RevDate: 2020-08-10

Duan R, Xu H, Gao S, et al (2020)

Effects of Different Hosts on Bacterial Communities of Parasitic Wasp Nasonia vitripennis.

Frontiers in microbiology, 11:1435.

Parasitism is a special interspecific relationship in insects. Unlike most other ectoparasites, Nasonia vitripennis spend most of its life cycle (egg, larvae, pupae, and early adult stage) inside the pupae of flies, which is covered with hard puparium. Microbes play important roles in host development and help insect hosts to adapt to various environments. How the microbes of parasitic wasp respond to different fly hosts living in such close relationships motivated this investigation. In this study, we used N. vitripennis and three different fly pupa hosts (Lucilia sericata, Sarcophaga marshalli, and Musca domestica) to address this question, as well as to illustrate the potential transfer of bacteria through the trophic food chains. We found that N. vitripennis from different fly pupa hosts showed distinct microbiota, which means that the different fly hosts could affect the bacterial communities of their parasitic wasps. Some bacteria showed potential horizontal transfer through the trophic food chains, from the food through the fly to the parasitic wasp. We also found that the heritable endosymbiont Wolbachia could transferred from the fly host to the parasite and correlated with the bacterial communities of the corresponding parasitic wasps. Our findings provide new insight to the microbial interactions between parasite and host.

RevDate: 2020-08-09

Thongprem P, Davison HR, Thompson DJ, et al (2020)

Incidence and Diversity of Torix Rickettsia-Odonata Symbioses.

Microbial ecology pii:10.1007/s00248-020-01568-9 [Epub ahead of print].

Heritable microbes are an important component of invertebrate biology, acting both as beneficial symbionts and reproductive parasites. Whilst most previous research has focussed on the 'Wolbachia pandemic', recent work has emphasised the importance of other microbial symbionts. In this study, we present a survey of odonates (dragonflies and damselflies) for torix group Rickettsia, following previous research indicating that this clade can be common in other aquatic insect groups. PCR assays were used to screen a broad range of odonates from two continents and revealed 8 of 76 species tested were infected with Rickettsia. We then conducted further deeper screening of UK representatives of the Coenagrionidae damselfly family, revealing 6 of 8 UK coenagrionid species to be positive for torix Rickettsia. Analysis of Rickettsia gene sequences supported multiple establishments of symbiosis in the group. Some strains were shared between UK coenagrionid species that shared mtDNA barcodes, indicating a likely route for mitochondrial introgression between sister species. There was also evidence of coinfecting Rickettsia strains in two species. FISH analysis indicated Rickettsia were observed in the ovarioles, consistent with heritable symbiosis. We conclude that torix Rickettsia represent an important associate of odonates, being found in a broad range of species from both Europe and South America. There is evidence that coinfection can occur, vertical transmission is likely, and that symbiont movement following hybridisation may underpin the lack of 'barcoding gap' between well-established species pairs in the genus. Future work should establish the biological significance of the symbioses observed.

RevDate: 2020-08-08

Liang X, Liu J, Bian G, et al (2020)

Wolbachia Inter-Strain Competition and Inhibition of Expression of Cytoplasmic Incompatibility in Mosquito.

Frontiers in microbiology, 11:1638.

Successful field trials have been reported as part of the effort to develop the maternally transmitted endosymbiontic bacteria Wolbachia as an intervention agent for controlling mosquito vectors and their transmitted diseases. In order to further improve this novel intervention, artificially transinfected mosquitoes must be optimized to display maximum pathogen blocking, the desired cytoplasmic incompatibility (CI) pattern, and the lowest possible fitness cost. Achieving such optimization, however, requires a better understanding of the interactions between the host and various Wolbabachia strains and their combinations. Here, we transferred the Wolbachia wMel strain by embryonic microinjection into Aedes albopictus, resulting in the successful establishment of a transinfected line, HM (wAlbAwAlbBwMel), with a triple-strain infection comprising wMel, wAlbA, and wAlbB. Surprisingly, no CI was induced when the triply infected males were crossed with the wild-type GUA females or with another triply infected HC females carrying wPip, wAlbA, and wAlbB, but specific removal of wAlbA from the HM (wAlbAwAlbBwMel) line resulted in the expression of CI after crosses with lines infected by either one, two, or three strains of Wolbachia. The transinfected line showed perfect maternal transmission of the triple infection, with fluctuating egg hatch rates that improved to normal levels after repeated outcrosses with GUA line. Strain-specific qPCR assays showed that wMel and wAlbB were present at the highest densities in the ovaries and midguts, respectively, of the HM (wAlbAwAlbBwMel) mosquitoes. These finding suggest that introducing a novel strain of Wolbachia into a Wolbachia-infected host may result in complicated interactions between Wolbachia and the host and between the various Wolbachia strains, with competition likely to occur between strains in the same supergroup.

RevDate: 2020-08-07

Dew RM, McFrederick QS, SM Rehan (2020)

Diverse Diets with Consistent Core Microbiome in Wild Bee Pollen Provisions.

Insects, 11(8): pii:insects11080499.

Bees collect pollen from flowers for their offspring, and by doing so contribute critical pollination services for our crops and ecosystems. Unlike many managed bee species, wild bees are thought to obtain much of their microbiome from the environment. However, we know surprisingly little about what plant species bees visit and the microbes associated with the collected pollen. Here, we addressed the hypothesis that the pollen and microbial components of bee diets would change across the range of the bee, by amplicon sequencing pollen provisions of a widespread small carpenter bee, Ceratina calcarata, across three populations. Ceratina calcarata was found to use a diversity of floral resources across its range, but the bacterial genera associated with pollen provisions were very consistent. Acinetobacter, Erwinia, Lactobacillus, Sodalis, Sphingomonas and Wolbachia were among the top ten bacterial genera across all sites. Ceratina calcarata uses both raspberry (Rubus) and sumac (Rhus) stems as nesting substrates, however nests within these plants showed no preference for host plant pollen. Significant correlations in plant and bacterial co-occurrence differed between sites, indicating that many of the most common bacterial genera have either regional or transitory floral associations. This range-wide study suggests microbes present in brood provisions are conserved within a bee species, rather than mediated by climate or pollen composition. Moving forward, this has important implications for how these core bacteria affect larval health and whether these functions vary across space and diet. These data increase our understanding of how pollinators interact with and adjust to their changing environment.

RevDate: 2020-08-05

Laidoudi Y, Medkour H, Levasseur A, et al (2020)

New Molecular Data on Filaria and its Wolbachia from Red Howler Monkeys (Alouatta macconnelli) in French Guiana-A Preliminary Study.

Pathogens (Basel, Switzerland), 9(8): pii:pathogens9080626.

Previous studies have reported filarial parasites of the genus Dipetalonema and Mansonella from French Guiana monkeys, based on morphological taxonomy. In this study, we screened blood samples from nine howler monkeys (Alouatta macconnelli) for the presence of filaria and Wolbachia DNA. The infection rates were 88.9% for filaria and 55.6% for wolbachiae. The molecular characterization, based on the 18S gene of filariids, revealed that A. macconnelli are infected with at least three species (Mansonella sp., Brugia sp. and an unidentified Onchocercidae species.). Since the 18S and cox1 generic primers are not very effective at resolving co-infections, we developed ITS genus-specific PCRs for Mansonella and Brugia genus. The results revealed coinfections in 75% of positives. The presence of Mansonella sp. and Brugia sp. was also confirmed by the 16S phylogenetic analysis of their associated Wolbachia. Mansonella sp., which close to the species from the subgenus Tetrapetalonema encountered in New World Monkeys, while Brugia sp. was identical to the strain circulating in French Guiana dogs. We propose a novel ITS1Brugia genus-specific qPCR. We applied it to screen for Brugia infection in howler monkeys and 66.7% were found to be positive. Our finding highlights the need for further studies to clarify the species diversity of neotropics monkeys by combining molecular and morphological features. The novel Brugia genus-specific qPCR assays could be an effective tool for the surveillance and characterization of this potential zoonosis.

RevDate: 2020-08-04

Huang M, L Hu (2020)

Modeling the suppression dynamics of Aedes mosquitoes with mating inhomogeneity.

Journal of biological dynamics, 14(1):656-678.

A novel strategy for controlling mosquito-borne diseases, such as dengue, malaria and Zika, involves releases of Wolbachia-infected mosquitoes as Wolbachia cause early embryo death when an infected male mates with an uninfected female. In this work, we introduce a delay differential equation model with mating inhomogeneity to discuss mosquito population suppression based on Wolbachia. Our analyses show that the wild mosquitoes could be eliminated if either the adult mortality rate exceeds the threshold [Formula: see text] or the release amount exceeds the threshold [Formula: see text] uniformly. We also present the nonlinear dependence of [Formula: see text] and [Formula: see text] on the parameters, respectively, as well as the effect of pesticide spraying on wild mosquitoes. Our simulations suggest that the releasing should be started at least 5 weeks before the peak dengue season, taking into account both the release amount and the suppression speed.

RevDate: 2020-08-04

Ashour DS, AA Othman (2020)

Parasite-bacteria interrelationship.

Parasitology research pii:10.1007/s00436-020-06804-2 [Epub ahead of print].

Parasites and bacteria have co-evolved with humankind, and they interact all the time in a myriad of ways. For example, some bacterial infections result from parasite-dwelling bacteria as in the case of Salmonella infection during schistosomiasis. Other bacteria synergize with parasites in the evolution of human disease as in the case of the interplay between Wolbachia endosymbiont bacteria and filarial nematodes as well as the interaction between Gram-negative bacteria and Schistosoma haematobium in the pathogenesis of urinary bladder cancer. Moreover, secondary bacterial infections may complicate several parasitic diseases such as visceral leishmaniasis and malaria, due to immunosuppression of the host during parasitic infections. Also, bacteria may colonize the parasitic lesions; for example, hydatid cysts and skin lesions of ectoparasites. Remarkably, some parasitic helminths and arthropods exhibit antibacterial activity usually by the release of specific antimicrobial products. Lastly, some parasite-bacteria interactions are induced as when using probiotic bacteria to modulate the outcome of a variety of parasitic infections. In sum, parasite-bacteria interactions involve intricate processes that never cease to intrigue the researchers. However, understanding and exploiting these interactions could have prophylactic and curative potential for infections by both types of pathogens.

RevDate: 2020-08-03

Wang Z, Li H, Zhou X, et al (2020)

Comparative characterization of microbiota between the sibling species of tea geometrid moth Ectropis obliqua Prout and E. grisescens Warren.

Bulletin of entomological research pii:S0007485320000164 [Epub ahead of print].

For a wide range of insect species, the microbiota has potential roles in determining host developmental programme, immunity and reproductive biology. The tea geometrid moths Ectropis obliqua and E. grisescens are two closely related species that mainly feed on tea leaves. Although they can mate, infertile hybrids are produced. Therefore, these species provide a pair of model species for studying the molecular mechanisms of microbiotal involvement in host reproductive biology. In this study, we first identified and compared the compositions of microbiota between these sibling species, revealing higher microbiotal diversity for E. grisescens. The microbiota of E. obliqua mainly comprised the phyla Firmicutes, Proteobacteria and Cyanobacteria, whereas that of E. grisescens was dominated by Proteobacteria, Actinobacteria and Firmicutes. At the genus level, the dominant microbiota of E. grisescens included Wolbachia, Enterobacter and Pseudomonas and that of E. obliqua included Melissococcus, Staphylococcus and Enterobacter. Furthermore, we verified the rate of Wolbachia to infect 80 samples from eight different geographical populations, and the results supported that only E. grisescens harboured Wolbachia. Taken together, our findings indicate significantly different microbiotal compositions for E. obliqua and E. grisescens, with Wolbachia possibly being a curial factor influencing the reproductive isolation of these species. This study provides new insight into the mechanisms by which endosymbiotic bacteria, particularly Wolbachia, interact with sibling species.

RevDate: 2020-08-02

Zheng X (2020)

Unveiling mosquito cryptic species and their reproductive isolation.

Insect molecular biology [Epub ahead of print].

Mosquitoes are major vectors of many infectious pathogens or parasites. Understanding cryptic species and the speciation of disease vectors has important implications for vector management, evolution, and host-pathogen and/or host-parasite interactions. Currently, mosquito cryptic species have been reported in many studies, most of which focus on the reproductive isolation of cryptic species and mainly on Anopheles gambiae sensu lato complex. Emerging species within the primary malaria vector Anopheles gambiae show different ecological preferences and significant prezygotic reproductive isolation, while Aedes mariae and Aedes zammitii show postmating reproductive isolation. However, data reporting the reproductive isolation in Culex and Aedes albopictus mosquito cryptic species is absent. The lack of systematic studies leaves many questions open, such as whether cryptic species are more common in particular habitats, latitudes, or taxonomic groups; what mosquito cryptic species evolutionary processes bring about reproductive isolation in the absence of morphological differentiation? How does Wolbachia infection affect in mosquitoes' reproductive isolation? In this review, we provide a summary of recent advances in the discovery and identification of sibling or cryptic species within mosquito genera.

RevDate: 2020-08-01

Takamatsu T, Arai H, Abe N, et al (2020)

Coexistence of Two Male-Killers and Their Impact on the Development of Oriental Tea Tortrix Homona magnanima.

Microbial ecology pii:10.1007/s00248-020-01566-x [Epub ahead of print].

Male-killing, the death of male offspring induced by maternally transmitted microbes, is classified as early, or late, male-killing. The primary advantage afforded by early male-killing, which typically occurs during embryogenesis, is the reallocation of resources to females, that would have otherwise been consumed by males. Meanwhile, the key advantage of late male-killing, which typically occurs during late larval development, is the maximized potential for horizontal transmission. To date, no studies have reported on the associated developmental and physiological effects of host coinfection with early and late male-killers, which may have a significant impact on the population dynamics of the male-killers. Here we used a lepidopteran tea pest Homona magnanima as a model, which is a unique system wherein an early male-killer (a Spiroplasma bacterium) and a late male-killer (an RNA virus) can coexist in nature. An artificially established matriline, coinfected with both Spiroplasma and RNA virus, exhibited embryonic death (early male-killing) as seen in the host line singly infected with Spiroplasma. Moreover, the coinfected line also exhibited developmental retardation and low pupal weight similar to the host line singly infected with the RNA virus. A series of field surveys revealed that Spiroplasma-RNA virus coinfection occurs in nature at a low frequency. Hence, although the two male-killers are capable of coexisting within the H. magnanima population independently, high associated fitness cost appears to limit the prevalence of male-killer coinfection in the field host population.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

Electronic Scholarly Publishing
961 Red Tail Lane
Bellingham, WA 98226

E-mail: RJR8222 @

Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )