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Bibliography on: Invasive Species

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ESP: PubMed Auto Bibliography 18 Oct 2019 at 01:42 Created: 

Invasive Species

Standard Definition: Invasive species are plants, animals, or pathogens that are non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause harm. Although that definition allows a logical possibility that some species might be non-native and harmless, most of time it seems that invasive species and really bad critter (or weed) that should be eradicated are seen as equivalent phrases. But, there is a big conceptual problem with that notion: every species in every ecosystem started out in that ecosystem as an invader. If there were no invasive species, all of Hawaii would be nothing but bare volcanic rock. Without an invasion of species onto land, there would be no terrestrial ecosystems at all. For the entire history of life on Earth, the biosphere has responded to perturbation and to opportunity with evolutionary innovation and with physical movement. While one may raise economic or aesthetic arguments against invasive species, it is impossible to make such an argument on scientific grounds. Species movement — the occurrence of invasive species — is the way the biosphere responds to perturbation. One might even argue that species movement is the primary, short-term "healing" mechanism employed by the biosphere to respond to perturbation — to "damage." As with any healing process, the short-term effect may be aesthetically unappealing (who thinks scabs are appealing?), but the long-term effects can be glorious.

Created with PubMed® Query: "invasive species" OR "invasion biology" OR "alien species" OR "introduced species" NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-10-17

Wiese D, Escalante AA, Murphy H, et al (2019)

Integrating environmental and neighborhood factors in MaxEnt modeling to predict species distributions: A case study of Aedes albopictus in southeastern Pennsylvania.

PloS one, 14(10):e0223821 pii:PONE-D-18-27812.

Aedes albopictus is a viable vector for several infectious diseases such as Zika, West Nile, Dengue viruses and others. Originating from Asia, this invasive species is rapidly expanding into North American temperate areas and urbanized places causing major concerns for public health. Previous analyses show that warm temperatures and high humidity during the mosquito season are ideal conditions for A. albopictus development, while its distribution is correlated with population density. To better understand A. albopictus expansion into urban places it is important to consider the role of both environmental and neighborhood factors. The present study aims to assess the relative importance of both environmental variables and neighborhood factors in the prediction of A. albopictus' presence in Southeast Pennsylvania using MaxEnt (version 3.4.1) machine-learning algorithm. Three models are developed that include: (1) exclusively environmental variables, (2) exclusively neighborhood factors, and (3) a combination of environmental variables and neighborhood factors. Outcomes from the three models are compared in terms of variable importance, accuracy, and the spatial distribution of predicted A. albopictus' presence. All three models predicted the presence of A. albopictus in urban centers, however, each to a different spatial extent. The combined model resulted in the highest accuracy (74.7%) compared to the model with only environmental variables (73.5%) and to the model with only neighborhood factors (72.1%) separately. Although the combined model does not essentially increase the accuracy in the prediction, the spatial patterns of mosquito distribution are different when compared to environmental or neighborhood factors alone. Environmental variables help to explain conditions associated with mosquitoes in suburban/rural areas, while neighborhood factors summarize the local conditions that can also impact mosquito habitats in predominantly urban places. Overall, the present study shows that MaxEnt is suitable for integrating neighborhood factors associated with mosquito presence that can complement and improve species distribution modeling.

RevDate: 2019-10-14
CmpDate: 2019-10-14

Setterfield SA, Clifton PJ, Hutley LB, et al (2018)

Exotic grass invasion alters microsite conditions limiting woody recruitment potential in an Australian savanna.

Scientific reports, 8(1):6628.

Andropogon gayanus Kunth. is a large African tussock grass invading Australia's tropical savannas. Invasion results in more intense fires which increases the mortality rate of adult woody plants. Invasion may also affect community structure by altering the recruitment potential of woody plants. We investigated the effects of A. gayanus invasion on ground-level microclimate, and the carbon assimilation potential and recruitment potential of two Eucalyptus species. We compared microclimatic variables from the early wet-season and into the mid-dry season to coincide with the period of growth of A. gayanus. We assessed Eucalyptus recruitment by monitoring seedling establishment, growth and survival of experimentally sown seed, and estimating seedling density resulting from natural recruitment. A. gayanus invasion was associated with increased grass canopy height, biomass and cover. Following invasion, the understorey microclimate had significantly reduced levels of photon flux density, increased air temperatures and vapour pressure deficit. The conditions were less favourable for woody seedling with aboveground biomass of seedlings reduced by 26% in invaded plots. We estimated that invasion reduced daily carbon assimilation of woody seedlings by ~30% and reduced survivorship of Eucalyptus seedlings. Therefore, A. gayanus invasion reduces recruitment potential, contributing to the transformation of savanna to a grassland ecosystem.

RevDate: 2019-10-16

Iida Y, Abe S, Tanaka N, et al (2019)

Associations among species traits, distribution, and demographic performance after typhoon disturbance for 22 co-occurring woody species in a mesic forest on a subtropical oceanic island.

Oecologia pii:10.1007/s00442-019-04531-9 [Epub ahead of print].

To support conservation and restoration, it is important to understand how differences in species functional traits relate to the distribution and demographic performance (i.e., changes in rates of growth, survival and recruitment) of co-occurring endemic, indigenous, and alien species on oceanic islands, where species are especially vulnerable to invasion. We examined interspecific differences in leaf and wood traits, and their associations with species origin (endemic, indigenous, and alien), distribution patterns, and demographic performance after typhoon disturbance for 22 co-occurring woody species at Sekimon on Hahajima Island in the Ogasawara Islands. Principal components analysis showed that the first and second principal components were associated with trait variations along spectra of leaf and wood economics (LES and WES). Species origin was not significantly associated with these components. Conservative species with low resource acquisition along the LES were abundant before the typhoon but acquisitive species had higher recruitment after the typhoon. After the typhoon, acquisitive species along the WES showed higher recruitment, relative growth rates but low survival rates on soil substrates. Endemic and indigenous species had lower recruitment and relative growth rates and endemic species had lower survival rates than alien species. Alien, endemic and indigenous species have similar functional space along the LES and WES, but these functional differences do not simply explain high demographic performance of alien species after the typhoon under the conditions of the species composition shifting from endemic species to alien species after repeated typhoon disturbances.

RevDate: 2019-10-16

McNitt J, Chungbaek YY, Mortveit H, et al (2019)

Assessing the multi-pathway threat from an invasive agricultural pest: Tuta absoluta in Asia.

Proceedings. Biological sciences, 286(1913):20191159.

Modern food systems facilitate rapid dispersal of pests and pathogens through multiple pathways. The complexity of spread dynamics and data inadequacy make it challenging to model the phenomenon and also to prepare for emerging invasions. We present a generic framework to study the spatio-temporal spread of invasive species as a multi-scale propagation process over a time-varying network accounting for climate, biology, seasonal production, trade and demographic information. Machine learning techniques are used in a novel manner to capture model variability and analyse parameter sensitivity. We applied the framework to understand the spread of a devastating pest of tomato, Tuta absoluta, in South and Southeast Asia, a region at the frontier of its current range. Analysis with respect to historical invasion records suggests that even with modest self-mediated spread capabilities, the pest can quickly expand its range through domestic city-to-city vegetable trade. Our models forecast that within 5-7 years, Tuta absoluta will invade all major vegetable growing areas of mainland Southeast Asia assuming unmitigated spread. Monitoring high-consumption areas can help in early detection, and targeted interventions at major production areas can effectively reduce the rate of spread.

RevDate: 2019-10-16
CmpDate: 2019-10-16

Calkins TL, Tamborindeguy C, PV Pietrantonio (2019)

GPCR annotation, G proteins, and transcriptomics of fire ant (Solenopsis invicta) queen and worker brain: An improved view of signaling in an invasive superorganism.

General and comparative endocrinology, 278:89-103.

Knowledge of G protein-coupled receptors (GPCRs) and their signaling modalities is crucial to advancing insect endocrinology, specifically in highly successful invasive social insects, such as the red imported fire ant, Solenopsis invicta Buren. In the first published draft genome of S. invicta, emphasis was placed on the annotation of olfactory receptors, and only the number of predicted GPCR genes was reported. Without an organized and curated resource for GPCRs, it will be difficult to test hypotheses on the endocrine role of neuropeptide hormones, or the function of neurotransmitters and neuromodulators. Therefore, we mined the S. invicta genome for GPCRs and found 324 predicted transcripts encoded by 125 predicted loci and improved the annotation of 55 of these loci. Among them are sixteen GPCRs that are currently annotated as "uncharacterized proteins". Further, the phylogenetic analysis of class A neuropeptide receptors presented here and the comparative listing of GPCRs in the hymenopterans S. invicta, Apis mellifera (both eusocial), Nasonia vitripennis (solitary), and the solitary model dipteran Drosophila melanogaster will facilitate comparative endocrinological studies related to social insect evolution and diversity. We compiled the 24 G protein transcripts predicted (15 α, 7 β, and 2 γ) from 12 G protein genes (5 α, 5 β, and 2 γ). Reproductive division of labor is extreme in this ant species, therefore, we compared GPCR and G protein gene expression among worker, mated queen and alate virgin queen ant brain transcriptomes. Transcripts for ten GPCRs and two G proteins were differentially expressed between queen and worker brains. The differentially expressed GPCRs are candidate receptors to explore hypotheses on division of labor in this species.

RevDate: 2019-10-16
CmpDate: 2019-10-16

Scully ED, Geib SM, Mason CJ, et al (2018)

Host-plant induced changes in microbial community structure and midgut gene expression in an invasive polyphage (Anoplophora glabripennis).

Scientific reports, 8(1):9620.

Polyphagous insect herbivores possess diverse mechanisms to overcome challenges of feeding in multiple plant species including, but not limited to, transcriptional plasticity and associations with obligate or facultative symbionts. The Asian longhorned beetle (Anoplophora glabripennis) is a polyphagous wood-feeder capable of developing on over 100 tree species and, like other polyphages, its genome contains amplifications of digestive and detoxification genes. This insect also possesses a diverse gut microbial community, which has the metabolic potential to augment digestive physiology. While the genomic repertoires of A. glabripennis and its microbial community have been studied previously, comparatively less is known about how the gut transcriptome and community change in response to feeding in different hosts. In this study, we show that feeding in two suitable hosts (Acer spp. and Populus nigra) altered the expression levels of multicopy genes linked to digestion and detoxification. However, feeding in a host with documented resistance (Populus tomentosa) induced changes in the transcriptome and community beyond what was observed in insects reared in P. nigra, including the downregulation of numerous β-glucosidases, odorant binding proteins, and juvenile hormone binding proteins, the upregulation of several cuticular genes, and the loss of one major bacterial family from the gut community.

RevDate: 2019-10-15

McLaughlin GM, PK Dearden (2019)

Invasive Insects: Management Methods Explored.

Journal of insect science (Online), 19(5):.

Invasive insect species can act as a plague across the globe, capable of vast expansion and rapid, proliferate reproduction. The spread of pathogens of serious diseases such as malaria and Zika virus and damages to agricultural crops number some of the afflictions invasive insects provide to humans alone. Additionally, an escape from predators can fail to keep invasive insects in check, providing potential threats such as extra resource competition to native species when insects invade. A variety of methods are employed to combat these invasive species, each with their own varying levels of success. Here, we explore the more traditional methods of invasive insect pest control, such as pesticides and biological control. In lieu of several unintended consequences resulting from such practices, we suggest some should be abandoned. We evaluate the potential of new techniques, in particular, those with a genetic component, regarding the costs, benefits and possible consequences of implementing them. And finally, we consider which techniques should be the focus of future research, if we truly wish to manage or even eradicate invasive insects in their introduced lands.

RevDate: 2019-10-15

Chao-Qun Z, D Jian-Rong (2019)

[Progress of research on biologically invasive medical molluscs in China].

Zhongguo xue xi chong bing fang zhi za zhi = Chinese journal of schistosomiasis control, 31(4):441-445.

Invasion of alien species has increasingly become a major environmental problem that damages human health, economic development and ecological security in China, which has been paid much attention. Until now, there have been 753 invasive species reported in China, and invasive medical molluscs include Pomacea canaliculata, Achatina fulica, and Biomphalaria straminea. This review summarizes the status of biologically invasive species in China, describes the species and distribution of invasive medical molluscs, analyzes the damages of the invasive medical molluscs-transmitted diseases, and proposes the preventive and control measures.

RevDate: 2019-10-15

Motoki MT, Fonseca DM, Miot EF, et al (2019)

Population genetics of Aedes albopictus (Diptera: Culicidae) in its native range in Lao People's Democratic Republic.

Parasites & vectors, 12(1):477 pii:10.1186/s13071-019-3740-0.

BACKGROUND: The Asian tiger mosquito, Aedes (Stegomyia) albopictus (Skuse) is an important worldwide invasive species and can be a locally important vector of chikungunya, dengue and, potentially, Zika. This species is native to Southeast Asia where populations thrive in both temperate and tropical climates. A better understanding of the population structure of Ae. albopictus in Lao PDR is very important in order to support the implementation of strategies for diseases prevention and vector control. In the present study, we investigated the genetic variability of Ae. albopictus across a north-south transect in Lao PDR.

METHODS: We used variability in a 1337-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), to assess the population structure of Ae. albopictus in Lao PDR. For context, we also examined variability at the same genetic locus in samples of Ae. albopictus from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA.

RESULTS: We observed very high levels of genetic polymorphism with 46 novel haplotypes in Ae. albopictus from 9 localities in Lao PDR and Thailand populations. Significant differences were observed between the Luangnamtha population and other locations in Lao PDR. However, we found no evidence of isolation by distance. There was overall little genetic structure indicating ongoing and frequent gene flow among populations or a recent population expansion. Indeed, the neutrality test supported population expansion in Laotian Ae. albopictus and mismatch distribution analyses showed a lack of low frequency alleles, a pattern often seen in bottlenecked populations. When samples from Lao PDR were analyzed together with samples from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA, phylogenetic network and Bayesian cluster analysis showed that most populations from tropical/subtropical regions are more genetically related to each other, than populations from temperate regions. Similarly, most populations from temperate regions are more genetically related to each other, than those from tropical/subtropical regions.

CONCLUSIONS: Aedes albopictus in Lao PDR are genetically related to populations from tropical/subtropical regions (i.e. Thailand, Singapore, and California and Texas in the USA). The extensive gene flow among locations in Lao PDR indicates that local control is undermined by repeated introductions from untreated sites.

RevDate: 2019-10-15
CmpDate: 2019-10-15

Li K, Yang H, Han X, et al (2018)

Fractal features of soil particle size distributions and their potential as an indicator of Robinia pseudoacacia invasion1.

Scientific reports, 8(1):7075.

To study the fractal dimensions of the soil particle size distributions (PSDs) within different plantations (of Pinus densiflora, Quercus acutissima, Robinia pseudoacacia, and Larix kaempferi) and evaluate PSDs as an indicator of the likelihood of Robinia pseudoacacia invasion, the soil porosity of 0-20 cm soil layers was measured at different plantations in the Yaoxiang Forest Farm, Shandong Province, China. The results showed that the fractal dimension (Dm) values varied from 2.59 to 2.70 among the different plantations and were significantly negatively correlated to sand content and positively correlated to silt content and clay content. Significant negative correlations were observed between Dm and both soil organic matter (SOM) (P < 0.05) and available phosphorus (P < 0.01). The multifractal entropy dimension (D1) and entropy dimension/capacity dimension (D1/D0) parameters were not significantly correlated with SOM, although significant correlations were found between SOM and each of D0, Δα, and Δf(α). Compared with the other plantations, the Robinia pseudoacacia plantation had higher nutrient contents, higher D0 and D1 values and lower Dm values. Based on principal component analysis (PCA) ordination, we concluded that Robinia pseudoacacia and Pinus densiflora shared a similar habitat and that Robinia pseudoacacia is more likely to invade Pinus densiflora plantations for soil.

RevDate: 2019-10-14

Wagner DL (2019)

Insect Declines in the Anthropocene.

Annual review of entomology [Epub ahead of print].

Insect declines are being reported worldwide for flying, ground, and aquatic lineages. Most reports come from western and northern Europe, where the insect fauna is well-studied and there are considerable demographic data for many taxonomically disparate lineages. Additional cases of faunal losses have been noted from Asia, North America, the Arctic, the Neotropics, and elsewhere. While this review addresses both species loss and population declines, its emphasis is on the latter. Declines of abundant species can be especially worrisome, given that they anchor trophic interactions and shoulder many of essential ecosystem services of their respective communities. A review of the factors believed to be responsible for observed collapses and those perceived to be especially threatening to insects form the core of this treatment. In addition to widely recognized threats to insect biodiversity, e.g., habitat destruction, agricultural intensification (including pesticide use), climate change, and invasive species, this assessment highlights a few less commonly considered factors such as atmospheric nitrification from the burning of fossil fuels and the effects of droughts and changing precipitation patterns. Because the geographic extent and magnitude of insect declines are largely unknown, there is an urgent need for monitoring efforts, especially across ecological gradients, which will help to identify important causal factors in declines. This review also considers the status of vertebrate insectivores, reporting bias, challenges inherent in collecting and interpreting insect demographic data, and cases of increasing insect abundance. Expected final online publication date for the Annual Review of Entomology, Volume 65 is January 7, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

RevDate: 2019-10-14

Ramoejane M, Gouws G, Swartz ER, et al (2019)

Molecular and morphological evidence reveals hybridisation between two endemic cyprinid fishes.

Journal of fish biology [Epub ahead of print].

The geographic occurrence of moggel Labeo umbratus × mud fish Labeo capensis hybrids and the threat of hybridisation to the genetic integrity of L. umbratus were investigated. Genetic evidence from mtDNA cytb and nDNA s7 intron sequence data indicated probable interspecific hybridisation in two impoundments, Hardap Dam (Orange River Basin, Namibia) and Darlington Dam (Sundays River Basin, Eastern Cape, South Africa). Some putative hybrids were morphologically identifiable on account of their meristic and morphometric intermediacy to the parent species. Human activities appear to drive the observed hybridisation, either through dam construction and direct stocking of L. umbratus or via translocation of Labeo capensis and the previously isolated Orange River lineage of L. umbratus into the southern-flowing systems by inter-basin water transfers. It is recommended that further translocation of fish from these areas should be avoided. This article is protected by copyright. All rights reserved.

RevDate: 2019-10-14

Kingan SB, Urban J, Lambert CC, et al (2019)

A high-quality genome assembly from a single, field-collected spotted lanternfly (Lycorma delicatula) using the PacBio Sequel II system.

GigaScience, 8(10):.

BACKGROUND: A high-quality reference genome is an essential tool for applied and basic research on arthropods. Long-read sequencing technologies may be used to generate more complete and contiguous genome assemblies than alternate technologies; however, long-read methods have historically had greater input DNA requirements and higher costs than next-generation sequencing, which are barriers to their use on many samples. Here, we present a 2.3 Gb de novo genome assembly of a field-collected adult female spotted lanternfly (Lycorma delicatula) using a single Pacific Biosciences SMRT Cell. The spotted lanternfly is an invasive species recently discovered in the northeastern United States that threatens to damage economically important crop plants in the region.

RESULTS: The DNA from 1 individual was used to make 1 standard, size-selected library with an average DNA fragment size of ∼20 kb. The library was run on 1 Sequel II SMRT Cell 8M, generating a total of 132 Gb of long-read sequences, of which 82 Gb were from unique library molecules, representing ∼36× coverage of the genome. The assembly had high contiguity (contig N50 length = 1.5 Mb), completeness, and sequence level accuracy as estimated by conserved gene set analysis (96.8% of conserved genes both complete and without frame shift errors). Furthermore, it was possible to segregate more than half of the diploid genome into the 2 separate haplotypes. The assembly also recovered 2 microbial symbiont genomes known to be associated with L. delicatula, each microbial genome being assembled into a single contig.

CONCLUSIONS: We demonstrate that field-collected arthropods can be used for the rapid generation of high-quality genome assemblies, an attractive approach for projects on emerging invasive species, disease vectors, or conservation efforts of endangered species.

RevDate: 2019-10-14

Andriatsitohaina B, Ramsay MS, Kiene F, et al (2019)

Ecological fragmentation effects in mouse lemurs and small mammals in northwestern Madagascar.

American journal of primatology [Epub ahead of print].

Habitat loss and fragmentation are major ecological forces threatening animal communities across the globe. These issues are especially true in Madagascar, where forest loss is ongoing. We examined the effects of forest fragmentation on the distribution and abundance of sympatric, endemic gray, and golden-brown mouse lemurs (Microcebus murinus and Microcebus ravelobensis), the endemic western tuft-tailed rat (Eliurus myoxinus), and the invasive black rat (Rattus rattus) in two regions in northwestern Madagascar. We used systematic capture procedures in 40 forest fragments and four continuous forest sites which differed in size, shape, and degree of isolation. With a trapping effort of 11,567 trap nights during two dry seasons (2017-2018), we captured 929 individuals (432 M. ravelobensis, 196 M. murinus, 116 E. myoxinus, and 185 R. rattus). We examined the influence of study region, forest type (fragment vs. continuous), forest size, forest shape, the proportion of 50-m forest edge and distance to continuous forest on the abundance and interaction of the four species. Responses to fragmentation differed strongly between species, but no interaction could be detected between the abundance of the different species. Thus competition within and between native and invasive species may not be regulating abundances in these regions. On the contrary, the abundance of M. ravelobensis and E. myoxinus differed significantly between study regions and was negatively affected by fragmentation. In contrast, there was no evidence of an impact of fragmentation on the abundance of M. murinus. Finally, the invasive R. rattus responded positively to the increasing distance to the continuous forest. In conclusion, the response of small Malagasy mammals to forest fragmentation varies largely between species, and fragmentation effects need to be examined at a species-specific level to fully understand their ecological dynamics and complexity.

RevDate: 2019-10-14

Tseng SP, Wetterer JK, Suarez AV, et al (2019)

Genetic Diversity and Wolbachia Infection Patterns in a Globally Distributed Invasive Ant.

Frontiers in genetics, 10:838.

Understanding the phylogeographic history of an invasive species may facilitate reconstructing the history and routes of its invasion. The longhorn crazy ant, Paratrechina longicornis, is a ubiquitous agricultural and household pest throughout much of the tropics and subtropics, but little is known about the history of its spread. Here, we examine worldwide genetic variation in P. longicornis and its associated Wolbachia bacterial symbionts. Analyses of mtDNA sequences of 248 P. longicornis workers (one per colony) from 13 geographic regions reveal two highly diverged mtDNA clades that co-occur in most of the geographic regions. These two mtDNA clades are associated with different Wolbachia infection patterns, but are not congruent with patterns of nDNA (microsatellite) variation. Multilocus sequence typing reveals two distinct Wolbachia strains in P. longicornis, namely, wLonA and wLonF. The evolutionary histories of these two strains differ; wLonA appears to be primarily transmitted maternally, and patterns of mtDNA and nDNA variation and wLonA infection status are consistent with a relatively recent Wolbachia-induced selective sweep. In contrast, the observed patterns of mtDNA variation and wLonF infections suggest frequent horizontal transfer and losses of wLonF infections. The lack of nDNA structure among sampled geographic regions coupled with the finding that numerous mtDNA haplotypes are shared among regions implies that inadvertent long-distance movement through human commerce is common in P. longicornis and has shaped the genetic structure of this invasive ant worldwide.

RevDate: 2019-10-14
CmpDate: 2019-10-14

Kenis M, Li H, Fan JT, et al (2018)

Sentinel nurseries to assess the phytosanitary risks from insect pests on importations of live plants.

Scientific reports, 8(1):11217.

Ornamental plants represent a major pathway of invasion for alien pests worldwide. Commodity risk analyses are carried out to assess the risk posed by a new trade in a commodity, but they are restricted by our limited knowledge of the pests carried by traded plants. We used the sentinel nursery technique to identify insects attacking woody plants imported into Europe. We established two sentinel nurseries in China, with five traded Asian plants. These nurseries were monitored for two years to obtain lists of insects that can be expected on these commodities. These records were compared with those obtained from literature surveys, which are usually the sources of information available to pest risk assessors. At each site, 105 insect species and host associations were found on sentinel plants and 90% of these associations had not been found in a previous literature survey of insect pests of the five plants. Nearly 80% of these associations were not found in an a posteriori literature survey. An assessment classified 9%, 7% and 84% of the insect records as presenting a high, moderate and low likelihood of introduction, respectively. These results show the benefit of sentinel nurseries to identify potential infestation of plant commodity imports.

RevDate: 2019-10-11
CmpDate: 2019-10-11

Niwa R, Koyama T, Sato T, et al (2018)

Dissection of niche competition between introduced and indigenous arbuscular mycorrhizal fungi with respect to soybean yield responses.

Scientific reports, 8(1):7419.

Arbuscular mycorrhizal (AM) fungi associate with most land plants and deliver phosphorus to the host. Identification of biotic/abiotic factors that determine crop responses to AM fungal inoculation is an essential step for successful application of the fungi in sustainable agriculture. We conducted three field trials on soybean with a commercial inoculum and developed a new molecular tool to dissect interactions between the inoculum and indigenous fungi on the MiSeq sequencing platform. Regression analysis indicated that sequence read abundance of the inoculum fungus was the most significant factor that determined soybean yield responses to the inoculation, suggesting that dominance of the inoculum fungus is a necessary condition for positive yield responses. Agricultural practices (fallow/cropping in the previous year) greatly affected the colonization levels (i.e. read abundances) of the inoculum fungus via altering the propagule density of indigenous AM fungi. Analysis of niche competition revealed that the inoculum fungus competed mainly with the indigenous fungi that are commonly distributed in the trial sites, probably because their life-history strategy is the same as that of the inoculum fungus. In conclusion, we provide a new framework for evaluating the significance of environmental factors towards successful application of AM fungi in agriculture.

RevDate: 2019-10-12

Davies CE, Batista FM, Malkin SH, et al (2019)

Spatial and temporal disease dynamics of the parasite Hematodinium sp. in shore crabs, Carcinus maenas.

Parasites & vectors, 12(1):472 pii:10.1186/s13071-019-3727-x.

BACKGROUND: The parasitic dinoflagellates of the genus Hematodinium represent the causative agent of so-called bitter or pink crab disease in a broad range of shellfish taxa. Outbreaks of Hematodinium-associated disease can devastate local fishing and aquaculture efforts. The goal of our study was to examine the potential role of the common shore (green) crab Carcinus maenas as a reservoir for Hematodinium. Carcinus maenas is native to all shores of the UK and Ireland and the North East Atlantic but has been introduced to, and subsequently invaded waters of, the USA, South Africa and Australia. This species is notable for its capacity to harbour a range of micro- and macro-parasites, and therefore may act as a vector for disease transfer.

METHODS: Over a 12-month period, we interrogated 1191 crabs across two distinct locations (intertidal pier, semi-closed dock) in Swansea Bay (Wales, UK) for the presence and severity of Hematodinium in the haemolymph, gills, hepatopancreas and surrounding waters (eDNA) using PCR-based methods, haemolymph preparations and histopathology.

RESULTS: Overall, 13.6% were Hematodinium-positive via PCR and confirmed via tissue examination. Only a small difference was observed between locations with 14.4% and 12.8% infected crabs in the Dock and Pier, respectively. Binomial logistic regression models revealed seasonality (P < 0.002) and sex (P < 0.001) to be significant factors in Hematodinium detection with peak infection recorded in spring (March to May). Male crabs overall were more likely to be infected. Phylogenetic analyses of the partial ITS and 18S rRNA gene regions of Hematodinium amplified from crabs determined the causative agent to be the host generalist Hematodinium sp., which blights several valuable crustaceans in the UK alone, including edible crabs (Cancer pagurus) and langoustines (Nephrops norvegicus).

CONCLUSIONS: Shore crabs were infected with the host generalist parasite Hematodinium sp. in each location tested, thereby enabling the parasite to persist in an environment shared with commercially important shellfish.

RevDate: 2019-10-11

Knutson AE, Tracy JL, Ritzi C, et al (2019)

Establishment, Hybridization, Dispersal, Impact, and Decline of Diorhabda spp. (Coleoptera: Chrysomelidae) Released for Biological Control of Tamarisk in Texas and New Mexico.

Environmental entomology pii:5585908 [Epub ahead of print].

Three Diorhabda spp. tamarisk beetles (Coleoptera: Chrysomelidae) were established in Texas from 2003 to 2010 for biological control of tamarisk (Tamarix spp.): Mediterranean tamarisk beetles, D. elongata (Brullé) from Greece, also established in New Mexico; subtropical tamarisk beetles, D. sublineata (Lucas) from Tunisia; and larger tamarisk beetles, D. carinata (Faldermann) from Uzbekistan. More than one million tamarisk beetles were released at 99 sites. Species establishment success ranged from 52 to 83%. All three species now co-occur in New Mexico with the northern tamarisk beetles, D. carinulata (Desbrochers). A phenotypic hybrid scoring system was developed to assess Diorhabda phenotype distributions and character mixing in hybrid zones. Widespread field populations of bispecific hybrid phenotypes for D. carinata/D. elongata and D. sublineata/D. elongata rapidly appeared following contact of parental species. Initial distributions and dispersal of Diorhabda spp. and hybrids are mapped for Texas, New Mexico, Oklahoma, and Kansas, where they produced large-scale tamarisk defoliation and localized dieback for 3-4 yr. However, populations subsequently severely declined, now producing only isolated defoliation and allowing tamarisk to recover. Diorhabda sublineata and D. elongata temporarily produced nontarget spillover defoliation of ornamental athel, Tamarix aphylla (L.) Karst, along the Rio Grande. Hybrid phenotypes were generally bimodally distributed, indicating some degree of reproductive isolation. Additional diagnostic phenotypic characters in males allowed more precise hybrid scoring. Character mixing in some hybrid populations approached or reached that of a hybrid swarm. The significance of hybridization for tamarisk biocontrol is discussed.

RevDate: 2019-10-11

Tofangsazi N, Hogg BN, Portman SL, et al (2019)

Tritrophic Interactions Between an Invasive Weed (Lepidium latifolium), an Insect Herbivore (Bagrada hilaris), and a Plant Pathogenic Fungus (Albugo lepidii).

Environmental entomology pii:5585902 [Epub ahead of print].

Perennial pepperweed, Lepidium latifolium L. (Brassicales: Brassicaceae), is an invasive weed that can form dense stands and displace native species. Bagrada hilaris Burmeister (Hemiptera: Pentatomidae) is a serious economic pest of Brassicaceae vegetable crops. Bagrada bug also feeds on L. latifolium and may interact with the plant fungal pathogen Albugo lepidii S.I. (Peronosporales: Albuginaceae) to affect biological control of L. latifolium. A series of laboratory experiments, including Y-tube olfactometer and host-choice tests, were conducted to investigate B. hilaris host-preference behavior. Adults were attracted to the odor of healthy L. latifolium compared with A. lepidii-infected leaves. Bagrada hilaris consistently preferred to feed on healthy L. latifolium when offered both healthy and A. lepidii-infected plants. Experiments were conducted to determine the effects of A. lepidii-infected L. latifolium on B. hilaris survival and development. Survival of all B. hilaris immature stages and adults was markedly reduced for those reared on A. lepidii-infected leaves. Total development time and stage-specific development were faster on healthy L. latifolium leaves compared with A. lepidii-infected leaves. In addition, the ability of B. hilaris adults to passively transmit the rust was studied. Our data demonstrated that B. hilaris could acquire the rust spores while feeding, but it did not passively transmit the pathogen to healthy plants.

RevDate: 2019-10-11

Smith-Freedman CJ, Andersen JC, Griffin BP, et al (2019)

Rise and Fall of an Oak Gall Wasp (Hymenoptera: Cynipidae) Outbreak in Massachusetts.

Environmental entomology pii:5585912 [Epub ahead of print].

The recently described oak gall wasp Zapatella davisae Buffington & Melika (Hymenoptera: Cynipidae) has caused extensive damage and mortality to black oak trees, Quercus velutina L. (Fagales: Fagaceae), in coastal parts of New England, United States. Like many newly described and/or newly introduced species, it is unclear how long populations of Z. davisae have existed in this region. However, as this species forms galls on the woody-tissue of its host, it may be possible to obtain historical information about changes in its population size by examining the presence of galls in relation to annual growth nodes. Here, we explore the utility of this approach to determine population size changes in Z. davisae densities on Nantucket, Martha's Vineyard, and Cape Cod, Massachusetts, through dissection of black oak branches. In addition, we calculated parasitism rates during the years of study and obtained morphological and molecular identifications for the parasitoids associated with Z. davisae. Our results show significant changes in population sizes, with higher levels of parasitism at sites on Martha's Vineyard and Cape Cod compared to sites on Nantucket. In addition, morphological examinations, in combination with DNA sequencing, identified the associated parasitoids as five species in the genus Sycophila Walker (Hymenoptera: Eurytomidae). We comment that considerable morphological variation within several of these recovered species was observed, present the first record of males for a species from which only females have been described, and suggest that future work is required to clarify the species boundaries for this important parasitoid group.

RevDate: 2019-10-11

Malek R, Kaser JM, Broadley HJ, et al (2019)

Footprints and Ootheca of Lycorma delicatula Influence Host-Searching and -Acceptance of the Egg-Parasitoid Anastatus orientalis.

Environmental entomology pii:5585876 [Epub ahead of print].

The spotted lanternfly, Lycorma delicatula White (1845) (Hemiptera: Fulgoridae), is an invasive insect that was first reported in North America in Berks County, Pennsylvania, in 2014. It is a polyphagous phloem feeder that attacks over 70 plant species, threatening the agricultural, lumber, and ornamental industries of North America. Infestations of the pest have been reported in several U.S. counties, and a lack of endemic predators and parasitoids feeding on L. delicatula suggests a release from natural enemies in the invaded range. An egg-parasitoid Anastatus orientalis (Hymenoptera: Eupelmidae) was reported attacking L. delicatula at high rates in its native range and may play a key role in reducing its populations there. To better understand the foraging behavior of A. orientalis, a series of behavioral experiments were conducted to determine successful parasitism and behavioral responses to traces left by adult L. delicatula and to the oothecae which cover their eggs. Our results suggest that wasps detected chemical traces left by L. delicatula adults while walking on surfaces and exhibited a strong arrestment response. Moreover, wasps preferred to oviposit in egg masses with intact oothecae. The implications of these findings are herein discussed with regard to the exploitation of host kairomones by foraging wasps, as well as to its ability to overcome host structural defenses.

RevDate: 2019-10-11

Hussain MI, El-Keblawy A, F Mitterand Tsombou (2019)

Leaf Age, Canopy Position, and Habitat Affect the Carbon Isotope Discrimination and Water-Use Efficiency in Three C3 Leguminous Prosopis Species from a Hyper-Arid Climate.

Plants (Basel, Switzerland), 8(10): pii:plants8100402.

The present study involved measurements of the stable carbon isotope composition (δ13C) and intrinsic water-use efficiency (iWUE) of three C3 leguminous Prosopis spp. (P. juliflora, P. cineraria, and P. pallida) foliage at different canopy positions (east and west) from saline (SLH) and non-saline habitats (NSH). Integrated measurements of the stable carbon isotope composition (δ13C) of plant tissue were broadly used to study iWUE, taking into consideration the effect of leaf age and canopy position on C isotope discrimination. Mature foliage of P. pallida from an SLH with a west canopy position had significantly higher δ13C (less negative) than that from NSH. On the west side, Δ13C values ranged from 17.8‱ (P. pallida) to 22.31‱ (P. juliflora) for a west canopy position, while they varied from 18.05‱ (P. pallida) to 22.4‱ (P. cineraria) on the east canopy side. Because the patterns are similar for the three Prosopis species, the difference in carbon isotope discrimination (Δ13C) between the canopy position (west and east) is relatively consistent among species and sites, ranging between 17.8 ± 4.43‱ for the young foliage in the west and 18.05 ± 4.35‱ for the east canopy position. The iWUE of P. pallida was twice that of P. cineraria. The iWUE of P. juliflora was higher from NSH than SLH. Mature leaves possessed a higher iWUE than the young leaves. We concluded that exotic P. juliflora and P. pallida have higher iWUE values than the native P. cineraria, which might be due to the rapid below-ground development of plant roots in the Arabian deserts of the United Arab Emirates (UAE). This could enable the alien species access to deeper humid soil layers or water resources.

RevDate: 2019-10-10

Logan ML, Minnaar IA, Keegan KM, et al (2019)

The evolutionary potential of an insect invader under climate change.

Evolution; international journal of organic evolution [Epub ahead of print].

Although the impacts of climate change and invasive species are typically studied in isolation, they likely interact to reduce the viability of plant and animal populations. Indeed, invasive species, by definition, have succeeded in areas outside of their native range, and may therefore have higher adaptive capacity relative to native species. Nevertheless, the genetic architecture of the thermal niche, which sets a limit to the potential for populations to evolve rapidly under climate change, has never been measured in an invasive species in its invasive range. Here, we estimate the genetic architecture of thermal performance in the harlequin beetle (Harmonia axyridis), a Central Asian species that has invaded four continents. We measured thermal performance curves in more than 400 third generation offspring from a paternal half-sib breeding experiment and analyzed the genetic variance-covariance matrix. We show that while the critical thermal limits in this species have an additive genetic basis, most components of the thermal performance curve have low heritability. Moreover, we found evidence that genetic correlations may constrain the evolution of beetles under climate change. Our results suggest that some invasive species may have limited evolutionary capacity under climate change, despite their initial success in colonizing novel environments. This article is protected by copyright. All rights reserved.

RevDate: 2019-10-11
CmpDate: 2019-10-11

Anton A, Geraldi NR, Lovelock CE, et al (2019)

Global ecological impacts of marine exotic species.

Nature ecology & evolution, 3(5):787-800.

Exotic species are a growing global ecological threat; however, their overall effects are insufficiently understood. While some exotic species are implicated in many species extinctions, others can provide benefits to the recipient communities. Here, we performed a meta-analysis to quantify and synthesize the ecological effects of 76 exotic marine species (about 6% of the listed exotics) on ten variables in marine communities. These species caused an overall significant, but modest in magnitude (as indicated by a mean effect size of g < 0.2), decrease in ecological variables. Marine primary producers and predators were the most disruptive trophic groups of the exotic species. Approximately 10% (that is, 2 out of 19) of the exotic species assessed in at least three independent studies had significant impacts on native species. Separating the innocuous from the disruptive exotic species provides a basis for triage efforts to control the marine exotic species that have the most impact, thereby helping to meet Aichi Biodiversity Target 9 of the Convention on Biological Diversity.

RevDate: 2019-10-11
CmpDate: 2019-10-11

Sitzia T, Campagnaro T, Kotze DJ, et al (2018)

The invasion of abandoned fields by a major alien tree filters understory plant traits in novel forest ecosystems.

Scientific reports, 8(1):8410.

The abandonment of agricultural use is a common driver of spontaneous reforestation by alien trees. The N-fixing black locust (Robinia pseudoacacia L.) is a major alien invader of old fields in Europe. Here we show that canopy dominance by this tree may filter the frequency distribution of plant functional traits in the understory of secondary woodlands. Higher soil C/N ratio and available P are associated with black locust stands, while higher soil phenols associate with native tree stands. These environmental effects result in differences in understory flowering periods, reproduction types and life forms. Our findings emphasize the effect of a major alien tree on functional plant trait composition in the early stages of spontaneous reforestation of abandoned lands, implying the development of a novel forest ecosystem on a large geographical scale.

RevDate: 2019-10-09

Wilber MQ, Chinn SM, Beasley JC, et al (2019)

Predicting functional responses in agro-ecosystems from animal movement data to improve management of invasive pests.

Ecological applications : a publication of the Ecological Society of America [Epub ahead of print].

Functional responses describe how changing resource availability affects consumer resource use, thus providing a mechanistic approach to prediction of the invasibility and potential damage of invasive alien species (IAS). However, functional responses can be context-dependent, varying with resource characteristics and availability, consumer attributes, and environmental variables. Identifying context-dependencies can allow invasion and damage risk to be predicted across different ecoregions. Understanding how ecological factors shape the functional response in agro-ecosystems can improve predictions of hotspots of highest impact and inform strategies to mitigate damage across locations with varying crop types and availability. We linked heterogeneous movement data across different agro-ecosystems to predict ecologically-driven variability in the functional responses. We applied our approach to wild pigs (Sus scrofa), one of the most successful and detrimental IAS worldwide where agricultural resource depredation is an important driver of spread and establishment. We used continental-scale movement data within agro-ecosystems to quantify the functional response of agricultural resources relative to availability of crops and natural forage. We hypothesized that wild pigs would selectively use crops more often when natural forage resources were low. We also examined how individual attributes such as sex, crop type, and resource stimulus such as distance to crops altered the magnitude of the functional response. There was a strong agricultural functional response where crop use was an accelerating function of crop availability at low density (Type III) and was highly context-dependent. As hypothesized, there was a reduced response of crop use with increasing crop availability when non-agricultural resources were more available, emphasizing that crop damage levels are likely to be highly heterogeneous depending on surrounding natural resources and temporal availability of crops. We found significant effects of crop type and sex - with males spending 20% more time and visiting crops 58% more often than females, and both sexes showing different functional responses depending on crop type. Our application demonstrates how commonly collected animal movement data can be used to understand context-dependencies in resource use to improve our understanding of pest foraging behavior, with implications for prioritizing spatio-temporal hotspots of potential economic loss in agro-ecosystems.

RevDate: 2019-10-09

Root HT, Miller JED, R Rosentreter (2019)

Grazing disturbance promotes exotic annual grasses by degrading soil biocrust communities.

Ecological applications : a publication of the Ecological Society of America [Epub ahead of print].

Exotic invasive plants threaten ecosystem integrity, and their success depends on a combination of abiotic factors, disturbances, and interactions with existing communities. In dryland ecosystems, soil biocrusts (communities of lichens, bryophytes and microorganisms) can limit favorable microsites needed for invasive species establishment, but the relative importance of biocrusts for landscape-scale invasion patterns remains poorly understood. We examine effects of livestock grazing in habitats at high risk for invasion to test the hypothesis that disturbance indirectly favors exotic annual grasses by reducing biocrust cover. We present some of the first evidence that biocrusts increase site resistance to invasion at a landscape scale and mediate the effects of disturbance. Biocrust species richness, which is reduced by livestock grazing, also appears to promote native perennial grasses. Short mosses, as a functional group, appeared to be particularly valuable for preventing invasion by exotic annual grasses. Our study suggests that maintaining biocrust communities with high cover, species richness, and cover of short mosses can increase resistance to invasion. These results highlight the potential of soil surface communities to mediate invasion dynamics and suggest promising avenues for restoration in dryland ecosystems.

RevDate: 2019-10-09

Holman L (2019)

Evolutionary simulations of Z-linked suppression gene drives.

Proceedings. Biological sciences, 286(1912):20191070.

Synthetic gene drives may soon be used to suppress or eliminate populations of disease vectors, pathogens, invasive species, and agricultural pests. Recent proposals have focused on using Z-linked gene drives to control species with ZW sex determination, which include Lepidopteran pests, parasitic trematodes, and cane toads. These proposals include Z-linked 'W-shredders', which would suppress populations by cleaving the W chromosome and causing females to produce only sons, as well as Z-linked female-sterilizing gene drives. Here, I use eco-evolutionary simulations to evaluate the potential of some proposed Z-linked gene drives, and to produce recommendations regarding their design and use. The simulations show that W-shredders are likely to be highly effective at eradicating populations provided that resistance to W-shredding cannot evolve. However, W-shredder alleles can invade populations from very low frequencies, making it difficult to eliminate specific populations while leaving nearby populations untouched; this issue may restrict their possible uses.

RevDate: 2019-10-09

Brady OJ, SI Hay (2019)

The Global Expansion of Dengue: How Aedes aegypti Mosquitoes Enabled the First Pandemic Arbovirus.

Annual review of entomology [Epub ahead of print].

Dengue is an emerging viral disease principally transmitted by the Aedes (Stegomyia) aegypti mosquito. It is one of the fastest-growing global infectious diseases, with 100-400 million new infections a year, and is now entrenched in a growing number of tropical megacities. Behind this rapid rise is the simple adaptation of Ae. aegypti to a new entomological niche carved out by human habitation. This review describes the expansion of dengue and explores how key changes in the ecology of Ae. aegypti allowed it to become a successful invasive species and highly efficient disease vector. We argue that characterizing geographic heterogeneity in mosquito bionomics will be a key research priority that will enable us to better understand future dengue risk and design control strategies to reverse its global spread. Expected final online publication date for the Annual Review of Entomology, Volume 65 is January 7, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

RevDate: 2019-10-08

Tsiamis K, Palialexis A, Stefanova K, et al (2019)

Non-indigenous species refined national baseline inventories: A synthesis in the context of the European Union's Marine Strategy Framework Directive.

Marine pollution bulletin, 145:429-435.

Refined baseline inventories of non-indigenous species (NIS) are set per European Union Member State (MS), in the context of the Marine Strategy Framework Directive (MSFD). The inventories are based on the initial assessment of the MSFD (2012) and the updated data of the European Alien Species Information Network, in collaboration with NIS experts appointed by the MSs. The analysis revealed that a large number of NIS was not reported from the initial assessments. Moreover, several NIS initially listed are currently considered as native in Europe or were proven to be historical misreportings. The refined baseline inventories constitute a milestone for the MSFD Descriptor 2 implementation, providing an improved basis for reporting new NIS introductions, facilitating the MSFD D2 assessment. In addition, the inventories can help MSs in the establishment of monitoring systems of targeted NIS, and foster cooperation on monitoring of NIS across or within shared marine subregions.

RevDate: 2019-10-08
CmpDate: 2019-10-08

Fraimout A, Jacquemart P, Villarroel B, et al (2018)

Phenotypic plasticity of Drosophila suzukii wing to developmental temperature: implications for flight.

The Journal of experimental biology, 221(Pt 13): pii:221/13/jeb166868.

Phenotypic plasticity has been proposed as a mechanism that facilitates the success of biological invasions. In order to test the hypothesis of an adaptive role for plasticity in invasions, particular attention should be paid to the relationship between the focal plastic trait, the environmental stimulus and the functional importance of the trait. The Drosophila wing is particularly amenable to experimental studies of phenotypic plasticity. Wing morphology is known for its plastic variation under different experimental temperatures, but this plasticity has rarely been investigated in a functional context of flight. Here, we investigate the effect of temperature on wing morphology and flight in the invasive pest species Drosophila suzukii Although the rapid invasion of both Europe and North America was most likely facilitated by human activities, D. suzukii is also expected to disperse actively. By quantifying wing morphology and individual flight trajectories of flies raised under different temperatures, we tested whether (1) invasive populations of D. suzukii show higher phenotypic plasticity than their native counterparts, and (2) wing plasticity affects flight parameters. Developmental temperature was found to affect both wing morphology and flight parameters (in particular speed and acceleration), leaving open the possibility of an adaptive value for wing plasticity. Our results show no difference in phenotypic plasticity between invasive and native populations, rejecting a role for wing plasticity in the invasion success.

RevDate: 2019-10-08
CmpDate: 2019-10-08

Moran CJ, Gerry SP, O'Neill MW, et al (2018)

Behavioral and physiological adaptations to high-flow velocities in chubs (Gila spp.) native to Southwestern USA.

The Journal of experimental biology, 221(Pt 10): pii:jeb.158972.

Morphological streamlining is often associated with physiological advantages for steady swimming in fishes. Though most commonly studied in pelagic fishes, streamlining also occurs in fishes that occupy high-flow environments. Before the installation of dams and water diversions, bonytail (Cyprinidae, Gila elegans), a fish endemic to the Colorado River (USA), regularly experienced massive, seasonal flooding events. Individuals of G. elegans display morphological characteristics that may facilitate swimming in high-flow conditions, including a narrow caudal peduncle and a high aspect ratio caudal fin. We tested the hypothesis that these features improve sustained swimming performance in bonytail by comparing locomotor performance in G. elegans with that of the closely related roundtail chub (Gila robusta) and two non-native species, rainbow trout (Oncorhynchus mykiss) and smallmouth bass (Micropterus dolomieu), using a Brett-style respirometer and locomotor step-tests. Gila elegans had the lowest estimated drag coefficient and the highest sustained swimming speeds relative to the other three species. There were no detectible differences in locomotor energetics during steady swimming among the four species. When challenged by high-velocity water flows, the second native species examined in this study, G. robusta, exploited the boundary effects in the flow tank by pitching forward and bracing the pelvic and pectoral fins against the acrylic tank bottom to 'hold station'. Because G. robusta can station hold to prevent being swept downstream during high flows and G. elegans can maintain swimming speeds greater than those of smallmouth bass and rainbow trout with comparable metabolic costs, we suggest that management agencies could use artificial flooding events to wash non-native competitors downstream and out of the Colorado River habitat.

RevDate: 2019-10-07
CmpDate: 2019-10-07

Bunke M, Dick JTA, Hatcher MJ, et al (2019)

Parasites influence cannibalistic and predatory interactions within and between native and invasive amphipods.

Diseases of aquatic organisms, 136(1):79-86.

In Northern Ireland, the amphipods Gammarus duebeni celticus (native) and G. pulex (invasive) coexist in some places, whilst in others the native species has been replaced by the invader. We explored the role of parasites in mediating interactions between these amphipods, which demonstrate mutual intraguild predation (IGP: predation between animals that also compete for prey). IGP and cannibalism can be important factors in structuring populations and communities. We investigated the effects of parasitism on rates of IGP between G. d. celticus and G. pulex and on cannibalism within each species by comparing functional responses (FRs: relationships between the use of a prey resource and its availability). Infection with the microsporidian Pleistophora mulleri caused an increase in IGP and cannibalism by G. d. celticus, which showed increased attack rates and reduced prey handling times. In contrast, infection with the acanthocephalan parasite Echinorhynchus truttae did not alter IGP or cannibalism by G. pulex. A prey preference experiment revealed that both amphipods were more likely to feed on heterospecific rather than conspecific prey, and this was also corroborated by the fact that overall IGP FRs were higher than cannibalism FRs. This may be selectively advantageous, as feeding on heterospecific prey removes possible competitors without the risk of consuming juvenile kin or acquiring parasites from infected conspecifics. Infection of the native G. d. celticus with P. mulleri enhanced IGP on the invasive G. pulex, which is likely to facilitate the coexistence of the 2 species.

RevDate: 2019-10-07
CmpDate: 2019-10-07

Nędzarek A, Czerniejewski P, A Tórz (2019)

Microelements and macroelements in the body of the invasive Harris mud crab (Rhithropanopeus harrisii, Maitland, 1874) from the central coast of the South Baltic Sea.

Environmental monitoring and assessment, 191(8):499 pii:10.1007/s10661-019-7564-3.

In this study, we determined the levels of essential and non-essential elements in the Harris mud crab (Rhithropanopeus harrisii, Maitland, 1874) from the southern Baltic Sea. Results revealed high levels of Ca (246,000 ppm), Mg (11,000 ppm), Na (8160 ppm), K (3,780 ppm), and Fe (1830 ppm). The concentrations of essential metals such as Zn (62.5 ppm) and Cu (25 ppm) were similar to those recorded in other crab species. The concentrations of non-essential metals such as Pb (0.140 ppm), Cd (0.0017 ppm), and As (0.288 ppm) were well below the International Standards for Maximum Levels for Food. In view of the above, the Harris mud crab from the southern Baltic is safe to be used as a component of well-balanced feeds for terrestrial and aquatic animals.

RevDate: 2019-10-07
CmpDate: 2019-10-04

Turgeon K, Turpin C, I Gregory-Eaves (2019)

Dams have varying impacts on fish communities across latitudes: a quantitative synthesis.

Ecology letters, 22(9):1501-1516.

Dams are recognised to impact aquatic biodiversity, but the effects and conclusions diverge across studies and locations. By using a meta-analytical approach, we quantified the effects of impoundment on fish communities distributed across three large biomes. The impacts of dams on richness and diversity differed across biomes, with significant declines in the tropics, lower amplitude but similar directional changes in temperate regions, and no changes in boreal regions. Our analyses showed that non-native species increased significantly in tropical and temperate regulated rivers, but not in boreal rivers. In contrast, temporal trajectories in fish assemblage metrics were common across regions, with all biomes showing an increase in mean trophic level position and in the proportion of generalist species after impoundment. Such changes in fish assemblages may affect food web stability and merit closer study. Across the literature examined, predominant mechanisms that render fish assemblages susceptible to impacts from dams were: (1) the transformation of the lotic environment into a lentic environment; (2) habitat fragmentation and (3) the introduction of non-native species. Collectively, our results highlight that an understanding of the regional context and a suite of community metrics are needed to make robust predictions about how fish will respond to river impoundments.

RevDate: 2019-10-07
CmpDate: 2019-10-07

Vetter BJ, Rogers LS, AF Mensinger (2019)

The effect of light stimuli on dark-adapted visual sensitivity in invasive silver carp Hypophthalmichthys molitrix and bighead carp H. nobilis.

Journal of fish biology, 95(1):256-262.

Non-physical barriers, including the use of underwater strobe lights alone or paired with sound or bubbles, are being considered as a means to prevent the upstream migration of invasive silver carp Hypophthalmichthys molitrix and bighead carp H. nobilis. To optimize potential optical deterrents, it is necessary to understand the visual sensitivity of the fishes. Dark-adapted H. molitrix and H. nobilis were found to possess broad visual sensitivity between 470 to 620 nm with peak spectral sensitivity at 540 nm for H. molitrix and 560 nm in H. nobilis. To assess the effect of a strobe light on vision, dark-adapted H. molitrix, H. nobilis and common carp Cyprinus carpio, were exposed to three different 5 s trains (100, 200, or 500 ms on-off flashes) of white light and the recovery of visual sensitivity was determined by measuring the b-wave amplitude of the electroretinogram (ERG). For all species, the longest recoveries were observed in response to the 500 ms flash trains (H. molitrix mean ± SE = 702.0 ± 89.8 s; H. nobilis 648.0 ± 116.0 s; C. carpio 480 ± 180.0 s). The results suggest that strobe lights can temporarily depress visual sensitivity, which may render optical barriers less effective.

RevDate: 2019-10-07
CmpDate: 2019-10-03

Comer S, Speldewinde P, Tiller C, et al (2018)

Evaluating the efficacy of a landscape scale feral cat control program using camera traps and occupancy models.

Scientific reports, 8(1):5335.

The impact of introduced predators is a major factor limiting survivorship and recruitment of many native Australian species. In particular, the feral cat and red fox have been implicated in range reductions and population declines of many conservation dependent species across Australia, including ground-nesting birds and small to medium-sized mammals. The impact of predation by feral cats since their introduction some 200 years ago has altered the structure of native fauna communities and led to the development of landscape-scale threat abatement via baiting programs with the feral cat bait, Eradicat. Demonstrating the effectiveness of broad-scale programs is essential for managers to fine tune delivery and timing of baiting. Efficacy of feral cat baiting at the Fortescue Marsh in the Pilbara, Western Australia was tested using camera traps and occupancy models. There was a significant decrease in probability of site occupancy in baited sites in each of the five years of this study, demonstrating both the effectiveness of aerial baiting for landscape-scale removal of feral cats, and the validity of camera trap monitoring techniques for detecting changes in feral cat occupancy during a five-year baiting program.

RevDate: 2019-10-06

Joo R, Boone ME, Clay TA, et al (2019)

Navigating through the R packages for movement.

The Journal of animal ecology [Epub ahead of print].

The advent of miniaturized biologging devices has provided ecologists with unprecedented opportunities to record animal movement across scales, and led to the collection of ever-increasing quantities of tracking data. In parallel, sophisticated tools have been developed to process, visualize and analyse tracking data, however many of these tools have proliferated in isolation, making it challenging for users to select the most appropriate method for the question in hand. Indeed, within the R software alone, we listed 58 packages created to deal with tracking data or 'tracking packages'. Here we reviewed and described each tracking package based on a workflow centered around tracking data (i.e. spatio-temporal locations (x,y,t)), broken down into three stages: pre-processing, post-processing and analysis, the latter consisting of data visualization, track description, path reconstruction behavioral pattern identification, space use characterization, trajectory simulation and others. Supporting documentation is key to render a package accessible for users. Based on a user survey, we reviewed the quality of packages' documentation, and identified 11 packages with good or excellent documentation. Links between packages were assessed through a network graph analysis. Although a large group of packages showed some degree of connectivity (either depending on functions or suggesting the use of another tracking package), one third of the packages worked in isolation, reflecting a fragmentation in the R movement-ecology programming community. Finally, we provide recommendations for users when choosing packages, and for developers to maximize the usefulness of their contribution and strengthen the links within the programming community.

RevDate: 2019-10-05

Schaerer LG, Ghannam RB, Butler TM, et al (2019)

A global comparison of the bacterial communities of bilge water, boat surfaces, and external port water.

Applied and environmental microbiology pii:AEM.01804-19 [Epub ahead of print].

In the past, ballast water has been a key vector in the ship-mediated dispersal of invasive species. Here we evaluate the potential for port microorganisms to enter into and colonize the hull and bilge water of ships. Due to the small size and ubiquitous nature of bacteria, they also have potential to be spread through hull fouling and bilge water discharge. The goal of this study was to identify the extent to which the boat microbial community is shaped by the microbial community in the port water where the boat spends most of its time. Here we compared the microbial community of the hull and bilge compartments of 20 boats to the port water in 20 different ports in five regions around the world. We found that there was a significant difference in microbial diversity between boat and port microbial communities. Despite these differences, we found that Cyanobacteria were present at high abundances in the bilge water of most vessels. Due to the limited light in the bilge, the presence of Cyanobacteria suggests that port microorganisms can enter into the bilge. Using source tracking software, we found that on average 40% of the bilge and 52% of the hull microbial communities were derived from water. These findings suggest that the bilge of a vessel contains a diverse microbial community that is influenced by the port microbial community and has the potential to serve as an underappreciated vector for dispersal of life.Importance Invasive species have been a world-wide problem for many years. However, the potential for microorganisms to become invasive is relatively underexplored. As the tools to study bacterial communities become more affordable, we are able to perform large-scale studies and examine bacterial communities in higher resolution than was previously practical. This study looked at the potential for bacteria to colonize both boat surfaces and bilge water. We describe the bacterial communities on boats in twenty shipping ports in five regions around the world, describing how these microorganisms were similar to microorganisms found in port water. This suggests that the water influences the bacterial community of a boat and that microorganisms living on the boat could be moved from place to place when the boat travels.

RevDate: 2019-10-04

Traveset A, Escribano-Avila G, Gómez JM, et al (2019)

Conflicting selection on Cneorum tricoccon (Rutaceae) seed size caused by native and alien seed dispersers.

Evolution; international journal of organic evolution [Epub ahead of print].

The disappearance of native seed dispersers due to anthropogenic activities is often accompanied by the introduction of alien species, which may to some extent replace the ecological service provided by the extinct ones. Yet, little empirical evidence exists demonstrating the evolutionary consequences of such alien 'replacement'. Here, we document the conflicting selection exerted on seed size by two native lizards (Podarcis lilfordi and P. pityusensis) and an alien mammal species (Martes martes), all acting as legitimate seed dispersers of the Mediterranean relict Cneorum tricoccon. While lizards mostly exerted a negative directional selection on seed diameter, especially P. pityusensis, the much larger pine marten exerted positive selection on seed size. Our findings suggest that this among-disperser variation in the selection regimes, together with the occurrence of spatial variation in the presence of each of seed disperser, help to create the geographical variation observed for seed size of C. tricoccon. To our knowledge, this is the first empirical evidence showing opposing selective pressures between native and alien species in the seed dispersal process in an invaded ecosystem. This article is protected by copyright. All rights reserved.

RevDate: 2019-10-04

Wang P, Yan Z, Yang S, et al (2019)

Environmental DNA: An Emerging Tool in Ecological Assessment.

Bulletin of environmental contamination and toxicology pii:10.1007/s00128-019-02720-z [Epub ahead of print].

Environmental DNA (eDNA), as a recent research hotspot in environmental science, the use of eDNA in biological monitoring has the advantages of sensitivity and time/labor saving. The eDNA technology combined with scientific advancement has been applied in investigations of target species (such as invasive species, endangered species and other rare species), biomass, and biodiversity. In addition, ecotoxicology studies and environmental pollution impact assessments based on the development of eDNA technology have gradually emerged in recent years. In this article, we summarizes the application of eDNA in ecological assessment, include species diversity assessment and chemical contamination impacts assessment, provide guiding questions for study design. We additionally discuss current challenges associated with eDNA. Finally, looking to the future, we discuss the opportunities of eDNA technology in environmental protein, environmental sample processor and ecogenomic sensors.

RevDate: 2019-10-04

Ripley BS, Edwardes A, Rossouw MW, et al (2019)

Invasive grasses of sub-Antarctic Marion Island respond to increasing temperatures at the expense of chilling tolerance.

Annals of botany pii:5580782 [Epub ahead of print].

BACKGROUND AND AIMS: Global warming has large effects on the performance and spatial distribution of plants and increasingly facilitates the spread of invasive species. Particularly vulnerable is the vegetation of cold environments where indigenous plants selected for cold tolerance can have reduced phenotypic plasticity and associated lower capacity to respond to warming temperatures. In contrast, invasive species can be phenotypically plastic and respond positively to climate change, but at the expense of stress tolerance.

METHODS: We investigate this trade-off in traits, measuring the photosynthetic response to warming, chilling tolerance and specific leaf area (SLA) of Pooid grasses. We compare this between invasive and non-invasive grasses and correlate this to their range expansions on a cold Sub-Antarctic island that has warmed significantly in the past-five decades. We determined whether these responses remained consistent after temperature acclimation.

KEY RESULTS: Invasive species responded strongly to warming, increasing photosynthetic rates by up to two-fold, while non-invasive species did not respond. The response was associated with increased stomatal conductance, but not with modified photosynthetic metabolism. Electrolyte leakage and SLA were higher in invasive than non-invasive species. Acclimation altered photosynthetic response and invasive species responded to warm temperatures irrespective of acclimation, while non-invasive species responded only after acclimation to warm temperature.

CONCLUSIONS: Traits scaled linearly with rates of range expansion and demonstrate that under sub-Antarctic conditions, anthropogenic warming over the last 50 years may have favoured species with greater capacity to respond photosynthetically to warming to the detriment of species that cannot and negated the advantage that chilling tolerance would have conferred on endemic species in the past. This suggests that species of cold ecosystems could be particularly vulnerable to warming as selection for stress tolerance has limited their responsiveness to environmental change, while introduced invasive species may have no such limitations. We show mechanistic evidence of the physiology that underpins an apparent trade-off between warming and chilling tolerance traits.

RevDate: 2019-10-04

Hawes NA, Amadorou A, Tremblay LA, et al (2019)

Epigenetic patterns associated with an ascidian invasion: a comparison of closely related clades in their native and introduced ranges.

Scientific reports, 9(1):14275 pii:10.1038/s41598-019-49813-7.

Environmentally induced epigenetic modifications have been proposed as one mechanism underlying rapid adaptive evolution of invasive species. Didemnum vexillum is an invasive colonial ascidian that has established in many coastal waters worldwide. Phylogenetic analyses have revealed that D. vexillum populations consist of two distinct clades; clade B appears to be restricted to the native range (Japan), whereas clade A is found in many regions throughout the world, including New Zealand. The spread of D. vexillum clade A suggests that it might be intrinsically more invasive than clade B, despite low levels of genetic diversity compared to populations from the native region. This study investigated whether D. vexillum clade A exhibits epigenetic signatures (specifically differences in DNA methylation) associated with invasiveness. Global DNA methylation patterns were significantly different between introduced clade A colonies, and both clades A and B in the native range. Introduced colonies also showed a significant reduction in DNA methylation levels, which could be a mechanism for increasing phenotypic plasticity. High levels of DNA methylation diversity were maintained in the introduced population, despite reduced levels of genetic diversity, which may allow invasive populations to respond quickly to changes in new environments. Epigenetic changes induced during the invasion process could provide a means for rapid adaptation despite low levels of genetic variation in introduced populations.

RevDate: 2019-10-04

Zwerschke N, Eagling L, Roberts D, et al (2019)

Can an invasive species compensate for the loss of a declining native species? Functional similarity of native and introduced oysters.

Marine environmental research pii:S0141-1136(19)30115-1 [Epub ahead of print].

The widespread introduction of the Pacific oyster, Magallana gigas, has raised concerns regarding its potential impact on the functioning of invaded ecosystems. Concurrently, populations of the European oyster, Ostrea edulis, are in decline. We quantified the functional role of the native oyster, O. edulis, in terms of nutrient cycling and associated infaunal biodiversity and compared it directly to that of the invading oyster, M. gigas. The presence and density of both species were manipulated in the field and we tested for differences in concentration of ammonium, phosphate, total oxidised nitrogen and silicate in pore-water; total organic nitrogen and carbon in sediment; microbial activity; chlorophyll concentration; and the assemblage structure and richness of associated benthic taxa. No differences in nutrient cycling rates or associated benthic assemblages were identified between both oyster species. Nutrient concentrations were mostly affected by differences in oyster density and their significance varied among sampling events. Our findings suggest that M. gigas could compensate for the loss of ecosystem functions performed by O. edulis in areas where native oysters have been extirpated.

RevDate: 2019-10-03

Juarez-Sanchez D, Blake JG, EC Hellgren (2019)

Variation in Neotropical river otter (Lontra longicaudis) diet: Effects of an invasive prey species.

PloS one, 14(10):e0217727 pii:PONE-D-19-13529.

Predation is one of the main barriers that exotic species may face in newly colonized areas and may help stop or control the potential negative impacts of invasive species in the environment. We evaluated if the consumption of an invasive prey (armored catfish: Pterygoplichtys sp.) affects the dietary niche breadth and trophic level of a native predator (Neotropical river otter: Lontra longicaudis) in northern Guatemala. We examined otter scats from three rivers: two where the invasive armored catfish occurred and one without the invasive fish. Samples were collected two and seven years after the first report of the catfish in the area. We performed gross scat analysis and stable isotope analyses of nitrogen and carbon of fecal matter. Where the invasive armored catfish occurred, it was the main prey item for L. longicaudis. Particularly in the river outside of protected areas seven years after the first report of the catfish, where it accounted for 49% of the otter diet. Concordance was found between the two techniques to estimate dietary niche breadth and trophic level. The dietary niche breath of otters was narrower seven years after the invasion in comparison to two years after the invasion in both invaded rivers, but the extent of the reduction was lesser inside the protected area. Finally, the trophic level of otters also showed a reduction related to the occurrence of the armored catfish in their diet.

RevDate: 2019-10-02

Yee DA, Nelsen JA, Deerman JH, et al (2019)

Oviposition Responses and Potential Larval Control Methods of Aedes albopictus (Diptera: Culicidae) in Downspout Extensions.

Journal of medical entomology pii:5580097 [Epub ahead of print].

Aedes albopictus (Skuse) is an important invasive species and vector of several important arboviruses across the globe. This species uses small water-holding cryptic containers as egg laying sites, which pose serious challenges to effective control of adult mosquito populations. Herein, we examined the response of gravid female Ae. albopictus to various features of common downspout extension tubes associated with human dwellings and the effectiveness of control efforts to eliminate larvae. Controlled field trials quantified oviposition in 1) extensions versus rubber bowls meant to mimic other container types, 2) among different shapes and materials of extensions, and 3) among different colors of extensions. We also investigated how flushing and use of Bti larvicides could control larvae. Females were more likely to lay eggs in flat plastic or metal extensions compared to rubber bowls. Eggs were also more plentiful in flat plastic extensions versus either corrugated or metal, and dark brown corrugated extensions had more eggs compared to tan or white. Flushing reduced nearly all larvae when the extensions were properly angled, and applications of Bti pellets or dunks were effective at killing most larvae. We show that dark extensions were preferred over other colors, and that larvae can be effectively removed with minimal effort. However, effective control will likely only come from better education of the public about proper installation of extensions.

RevDate: 2019-10-02

Jaskuła R, Sulikowska-Drozd A, Jabłońska A, et al (2019)

Undesirable immigrants: hobbyist vivaria as a potential source of alien invertebrate species.

PeerJ, 7:e7617 pii:7617.

Background: Small size and large diversity of adaptations make invertebrates a group of animals which can be easily transported by different human activities. Many species can travel as "hitchhikers" with plant material (both on plant surfaces and in the soil), including plants used for decoration in vivaria. Vivaria are often tropical in nature environments, with high temperatures and humidity, suitable for invertebrates from tropical regions. Although many of such invertebrates cannot survive in temperate regions where harsh weather conditions are present, it is also known that some can successfully acclimatise. As a result, their negative impact on local flora and fauna cannot be excluded.

Material and methods: Terrestrial invertebrates were collected in several cities of Poland from tropical vivaria where poison dart frogs (Dendrobatidae) and/or orchids (Orchidaceae) were kept by hobbyists. Collecting of the material was preceded by a simple questionnaire placed on the biggest Polish forum devoted to poison dart frogs. Moreover, we contacted some Polish wholesalers offering tropical invertebrates (Isopoda and Collembola), used as the food source for frogs, hoping to receive information about locations where those invertebrates were delivered, over the period of one year. We obtained mtDNA barcodes using the COI marker (cytochrome c oxidase subunit I gene) for seven potential morphospecies.

Results: In total, 12 taxa classified as Turbellaria, Annelida, Gastropoda, Isopoda, Diplopoda, Chilopoda and Collembola were collected and preserved in pure ethanol. We collected material and/or information from 65 locations, including 56 cities to which exotic isopods and springtails were sold by wholesalers over the period of nine months (average number per month = 18 cities). We obtained 18 COI sequences which were assigned to seven BINs and thus confirmed identification of seven species. The results indicate that the number of species transported with exotic plants is not small and can be observed regularly. Species noted as "hitchhikers" on plant structures and/or as inhabitants of soil in plant pots, originally came from South and Central America, Africa, Asia and possibly from North America or Southern Europe. Three taxa were noted for the first time from Poland, including Rhynchodemus sylvaticus (Rhynchodemidae), Trichorhina sp.1 (Platharthridae), and Guppya gundlachi (Euconulidae).

Discussion: The presented study clearly shows that an exotic hobby such as keeping tropical poison dart frogs and/or orchids may promote fast and uncontrolled dispersion of a high number of invertebrates classified in different taxonomical groups. Plant material (green elements of plants and the soil in which they are planted) used in vivaria can be an important source of such animals.

RevDate: 2019-10-02

Legrand P, Vanderplanck M, FJ Verheggen (2019)

Comparison of the Sex Pheromone Composition of Harmonia axyridis Originating from Native and Invaded Areas.

Insects, 10(10): pii:insects10100326.

The multicolored Asian lady beetle, Harmonia axyridis (Coleoptera: Coccinellidae), originates from South-East Asia and is now considered as an invasive species at a worldwide scale, with populations encountered in North and South America, Africa, and Europe. Several previous studies suggested that invasive populations display different behavioral and physiological traits, leading to a better fitness than native individuals. H. axyridis sex pheromone was identified recently, but only from individuals established in Europe. In this study, we compare the composition of the female sex pheromone of H. axyridis from two populations: (i) an invasive population in North America, and (ii) a native population in South-East China. We found the females originating from both populations to release in similar proportions the same five pheromonal compounds, namely β-caryophyllene, β-elemene, methyl-eugenol, α-humulene, and α-bulnesene. However, females from the North American strain release all five compounds in larger amount than the Chinese ones. Whether invasive individuals were selected during the process of invasion through their capacity to better call and find sexual partners remains to be confirmed.

RevDate: 2019-10-01
CmpDate: 2019-10-01

MacDougall AS, McCune JL, Eriksson O, et al (2018)

The Neolithic Plant Invasion Hypothesis: the role of preadaptation and disturbance in grassland invasion.

The New phytologist, 220(1):94-103.

A long-standing hypothesis is that many European plants invade temperate grasslands globally because they are introduced simultaneously with pastoralism and cultivation, to which they are 'preadapted' after millennia of exposure dating to the Neolithic era ('Neolithic Plant Invasion Hypothesis' (NPIH)). These 'preadaptations' are predicted to maximize their performance relative to native species lacking this adaptive history. Here, we discuss the explanatory relevance of the NPIH, clarifying the importance of evolutionary context vs other mechanisms driving invasion. The NPIH makes intuitive sense given established connections between invasion and agricultural-based perturbation. However, tests are often incomplete given the need for performance contrasts between home and away ranges, while controlling for other mechanisms. We emphasize six NPIH-based predictions, centring on trait similarity of invaders between home vs away populations, and differing perturbation responses by invading and native plants. Although no research has integrated all six predictions, we highlight studies suggesting preadaptation influences on invasion. Given that many European grasslands are creations of human activity from the past, current invasions by these flora may represent the continuation of processes dating to the Neolithic. Ironically, European Neolithic-derived grasslands are becoming rarer, reflecting changes in management and illustrating the importance of human influences on these species.

RevDate: 2019-09-30

Cappa F, Cini A, Pepiciello I, et al (2019)

Female volatiles as sex attractants in the invasive population of Vespa velutina nigrithorax.

Journal of insect physiology pii:S0022-1910(19)30039-3 [Epub ahead of print].

Due to its huge invasion potential and specialization in honeybee predation, the invasive hornet Vespa velutina nigrithorax represents a high-concern species under both an ecological and economical perspective. In light of the development of specific odorant attractants to be used in sustainable control strategies, we carried out both behavioural assays and chemical analyses to investigate the possibility that, in the invasive population of V. velutina nigrithorax, reproductive females emit volatile pheromones to attract males, as demonstrated in a Chinese non-invasive population. We focused on the secretions produced by sternal and venom glands; because of the volatility and complexity of their composition, both of them could potentially allow an attraction and a species-specific response, decreasing therefore non-target species by-catches. Results of chemical analyses and behavioural assays showed that venom volatiles, although population-specific, are unlikely candidates as male attractants since they do not differ in composition or in quantity between reproductive females and workers and do not attract males. Conversely, sternal gland secretion differs between female castes for the presence of some ketoacids exclusive of gynes already reported as sex pheromones for the non-invasive subspecies V. velutina auraria. Despite such a difference, males are attracted by the sternal gland secretion of both workers and gynes. These results provide a first step to understand the reproductive biology of V. velutina nigrithorax in its invasive range and to develop effective and sustainable management strategies for the species.

RevDate: 2019-09-30

Giordano BV, Gasparotto A, Liang P, et al (2019)

Discovery of an Aedes (Stegomyia) albopictus population and first records of Aedes (Stegomyia) aegypti in Canada.

Medical and veterinary entomology [Epub ahead of print].

A population of Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae), a vector of chikungunya, dengue, yellow fever, and Zika and West Nile viruses, has been detected in Windsor, Ontario, Canada from 2016 onwards. Here, we describe its seasonal distribution, as well as the various aquatic habitats from which this species was collected and its larval co-habitation. We collected immatures from tires, treeholes, extruded polystyrene foam containers, discarded plastic cups, old recycling bins and oviposition traps. Aedes albopictus larvae were collected with Aedes japonicus (Theobald), Anopheles punctipennis (Say), Culex pipiens Linnaeus, Ochlerotatus hendersoni (Cockerell), Ochlerotatus triseriatus (Say) and Orthopodomyia signifera (Coquillett). Adult female and male specimens were collected from Biogents sentinel traps (Biogents AG, Regensburg, Germany), as well as Centers for Disease Control and Prevention miniature light traps (CDC, Atlanta, GA, U.S.A.), and also as they alighted on the investigators. Peak adult collections occurred in September during epidemiological week 37. We also collected Aedes (Stegomyia) aegypti (Linnaeus), a new record for Canada, in 2016 and from two new collection sites in 2017. The 2017 collections were 3.5 km north and 19.4 km south of the index site. The present study adds to the increasing number of studies reporting range expansions of these mosquito species.

RevDate: 2019-09-30

Hiatt D, SL Flory (2019)

Populations of a widespread invader and co-occurring native species vary in phenotypic plasticity.

The New phytologist [Epub ahead of print].

Phenotypic plasticity can promote plant invasions and enhance impacts on native species but little is known about variation in plasticity among invader populations compared to native species. Variation in plasticity among invader populations could inform more precise predictions of invader spread and impacts across heterogeneous resource environments. We used a common garden experiment with sun and shade treatments to test for variation in plasticity among 12 populations of an invasive grass (Imperata cylindrica), and to determine if the invader exhibited greater plasticity than six native species that co-occur in the Southeast US. Principal component analysis revealed that invader populations from different native ranges consistently varied from each other and native species in traits linked to more favorable phenotypes under resource limitation. Overall, the invader exhibited greater plasticity than native species, as demonstrated by higher plasticity index values for traits such as plant height, leaf mass ratio, and root shoot ratio. Variation in phenotypic plasticity among invader populations suggests the potential for evolution of plasticity, and greater plasticity of invader populations than native species may underlie invader dominance. Differences in plasticity among populations appears to play an important role in predictions of the spread and potentially the impacts of invasive species.

RevDate: 2019-09-30
CmpDate: 2019-09-30

Poidatz J, Bressac C, Bonnard O, et al (2018)

Comparison of reproductive traits of foundresses in a native and an invasive hornet in Europe.

Journal of insect physiology, 109:93-99.

The population dynamics of annual social hymenoptera such as vespids depend largely on the fertility of the foundresses, which, in turn, is a key factor in the context of biological invasions. The native European hornet Vespa crabro (Vc) and the invasive Asian hornet Vespa velutina (Vv) have generally similar ecological traits, e.g. nesting and feeding habits, although they differ in colony size, which is higher in Vv. Furthermore, in contrast to Vc, Vv is more specialized in its predatory habits, intensively hunting honey bees at the hive. Comparing the morphological and reproductive traits of two closely related species occupying the same ecological niche, one of which is a native species and the other an alien, can help us to gain an understanding of the invasion process. To this end, we here compare reproductive (ovarian size and maturation, fat level, spermatheca size and sperm stock, fecundity) and morphological traits (head size, weight) of the foundresses of these two hornet species. We observed that ovarian maturation began approximately one month earlier in Vv than in Vc, and that the fat level in the former was lower. We found twice the number of sperm in the mated foundresses of Vv than in those of Vc (more than 100 × 103 and less than 50 × 103 sperm, respectively), in a 16% smaller spermatheca in Vc. Furthermore, the sperm of Vv was found to be 65% shorter than that of Vc. The precocity and higher potential fecundity of Vv queens may have favoured this species over Vc in terms of predatory behaviour, and thereby contributed to its invasiveness.

RevDate: 2019-09-30
CmpDate: 2019-09-30

Pérez-Portela R, Bumford A, Coffman B, et al (2018)

Genetic homogeneity of the invasive lionfish across the Northwestern Atlantic and the Gulf of Mexico based on Single Nucleotide Polymorphisms.

Scientific reports, 8(1):5062.

Despite the devastating impact of the lionfish (Pterois volitans) invasion on NW Atlantic ecosystems, little genetic information about the invasion process is available. We applied Genotyping by Sequencing techniques to identify 1,220 single nucleotide polymorphic sites (SNPs) from 162 lionfish samples collected between 2013 and 2015 from two areas chronologically identified as the first and last invaded areas in US waters: the east coast of Florida and the Gulf of Mexico. We used population genomic analyses, including phylogenetic reconstruction, Bayesian clustering, genetic distances, Discriminant Analyses of Principal Components, and coalescence simulations for detection of outlier SNPs, to understand genetic trends relevant to the lionfish's long-term persistence. We found no significant differences in genetic structure or diversity between the two areas (FST p-values > 0.01, and t-test p-values > 0.05). In fact, our genomic analyses showed genetic homogeneity, with enough gene flow between the east coast of Florida and Gulf of Mexico to erase previous signals of genetic divergence detected between these areas, secondary spreading, and bottlenecks in the Gulf of Mexico. These findings suggest rapid genetic changes over space and time during the invasion, resulting in one panmictic population with no signs of divergence between areas due to local adaptation.

RevDate: 2019-09-29

Seymour CL, Gillson L, Child MF, et al (2019)

Horizon scanning for South African biodiversity: A need for social engagement as well as science.

Ambio pii:10.1007/s13280-019-01252-4 [Epub ahead of print].

A horizon scan was conducted to identify emerging and intensifying issues for biodiversity conservation in South Africa over the next 5-10 years. South African biodiversity experts submitted 63 issues of which ten were identified as priorities using the Delphi method. These priority issues were then plotted along axes of social agreement and scientific certainty, to ascertain whether issues might be "simple" (amenable to solutions from science alone), "complicated" (socially agreed upon but technically complicated), "complex" (scientifically challenging and significant levels of social disagreement) or "chaotic" (high social disagreement and highly scientifically challenging). Only three of the issues were likely to be resolved by improved science alone, while the remainder require engagement with social, economic and political factors. Fortunately, none of the issues were considered chaotic. Nevertheless, strategic communication, education and engagement with the populace and policy makers were considered vital for addressing emerging issues.

RevDate: 2019-09-29

Sandvik H (2019)

Expansion Speed as a Generic Measure of Spread for Alien Species.

Acta biotheoretica pii:10.1007/s10441-019-09366-8 [Epub ahead of print].

The ecological impact of alien species is a function of the area colonised. Impact assessments of alien species are thus incomplete unless they take the spatial component of invasion processes into account. This paper describes a measure, termed expansion speed, that quantifies the speed with which a species increases its spatial presence in an assessment area. It is based on the area of occupancy (AOO) and can be estimated from grid occupancies. Expansion speed is defined as the yearly increase in the radius of a coherent circle having the same area as the AOO, irrespective of whether the increase is due to natural dispersal or anthropogenic transport. Two methods for estimating expansion speed are presented: one that requires several years of spatio-temporal observation data and explicitly takes detection rates into account; and one that can be used under a situation with sparse data. Using simulations and real-world data from natural history collections, it is shown that the method provides a good fit to observational datasets. Expansion speed has several valuable properties. Being based on AOO, it is an intuitive measure; as it only requires occupancy data, it is comparatively easy to estimate; and because it is a quantitative and generic measure, it increases the testability and comparability of impact assessments of alien species.

RevDate: 2019-09-28

Dobson A, Richardson J, B Blossey (2019)

Effects of earthworms and white-tailed deer on roots, arbuscular mycorrhizae, and forest seedling performance.

Ecology [Epub ahead of print].

Changes in understory plant composition and biodiversity declines in northeastern North American forests are widespread. Preserving species and ecosystem function requires appropriate identification and management of important stressors. Co-existence of stressors, among them earthworm invasions and white-tailed deer, make correct identification of mechanisms that cause diversity declines challenging. We used an established factorial experiment to assess survival and growth of native seedlings (Actaea pachypoda, Aquilegia canadensis, Cornus racemosa, Quercus rubra and Prenanthes alba) in response to presence/absence of deer and earthworms. We expected deer and earthworms to reduce seedling survival and biomass, and we evaluated potential pathways to explain this impact (soil N and P concentrations and pools, root architecture, and arbuscular mycorrhizal fungi [AMF] colonization). We developed structural equation models (SEM) to identify specific pathways through which earthworms and deer were impacting plant species with different life histories. Seedling survival was not affected by our treatments nor the plant and soil variables we tested. Actaea biomass was smaller in earthworm-invaded plots, and with larger total N pools. In contrast, both deer and earthworm treatments were associated with lower soil nutrient concentrations, and earthworm invaded plots had smaller N and extractable P pools. Actaea, Cornus, Prenanthes and Quercus seedlings had a lower proportion of fine roots in earthworm-invaded plots, while fine roots in Aquilegia made up a higher proportion of the root system. AMF colonization in Quercus was reduced in sites colonized by earthworms, but AMF in other species were unaffected. Our SEMs showed high correlation among soil variables, but because we do not know which variables are drivers of this change and which are the passengers, we can only conclude that they are changing together as deer and earthworms exert their respective influence. Different plant species responded in idiosyncratic ways to earthworm and deer effects on soil fertility, root architecture and limited effects on AMF colonization. While earthworm and deer-mediated changes to fine roots, soil nutrients, and AMF may lead to changes in plant performance over time, these changes rarely translated to lower plant performance in our seedlings.

RevDate: 2019-09-27

Spyra A, Cieplok A, Strzelec M, et al (2019)

Freshwater alien species Physella acuta (Draparnaud, 1805) - A possible model for bioaccumulation of heavy metals.

Ecotoxicology and environmental safety, 185:109703 pii:S0147-6513(19)31034-6 [Epub ahead of print].

In this study we focused on Physella acuta, an alien snail species in order to determine their ability of bioaccumulation of heavy metals in their shells, bodies, the difference in accumulation in relation to age classes, and the influence of ecological variables on the community composition and density. On the basis of the results of ecological, toxicological, and experimental analyses we aimed to study the potential invasive features of P. acuta in comparision with the native species Stagnicola palustris. The content of Cu and Zn in the substratum and ammonia in the water was strongly related to the patterns of distribution of P. acuta. The content of Cd, Pb, and Cu in the shell fraction was always significantly lower than in the body fraction. A comparison of accumulation with respect to the size classes of P. acuta indicated that the lowest metal concentration in the body was typical for the largest individuals, except for Zn. Metal content in the bodies of the native species did not differ from the content measured in their analogous group of the largest individuals of P. acuta. The lowest value of bioaccumulation factor (BAF) was found for the large class of specimens of this species for each metal. A distinct decrease in the value of BAF in relation to the size of snails was found for cadmium. A 100% hatching success found in masses collected from pond confirmed the high reproductive potential of P. acuta which can be a factor that promotes its invasive features following its ability to occur in very high densities, but not necessarily the ability of metal accumulation in the body. Physella acuta can be used as a model organism in the studies on the accumulation of heavy metals however, the extend of accumulation can differ among the age classes. Because of the high tolerance of P. acuta to heavy metal pollution, in the future this species can be found in significantly polluted habitats, inhabiting free ecological niches, and occurring in high densities in snail communities.

RevDate: 2019-09-27

Pieterse W, Manrakhan A, Terblanche JS, et al (2019)

Comparative demography of Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) on deciduous fruit.

Bulletin of entomological research pii:S0007485319000592 [Epub ahead of print].

Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann) are highly polyphagous fruit fly species and important pests of commercial fruit in regions of the world where they are present. In South Africa, B. dorsalis is now established in the north and northeastern parts of the country. B. dorsalis is currently absent in other parts of the country including the Western Cape Province which is an important area for the production of deciduous fruit. C. capitata is widespread in South Africa and is the dominant pest of deciduous fruit. The demographic parameters of B. dorsalis and C. capitata on four deciduous fruit types Prunus persica (L.) Batsch, Prunus domestica L., Malus domestica Borkh. and Pyrus communis L. were studied to aid in predicting the potential population establishment and growth of B. dorsalis in a deciduous fruit growing environment. All deciduous fruit types tested were suitable for population persistence of both B. dorsalis and C. capitata. Development was fastest and survival highest on nectarine for both species. B. dorsalis adults generally lived longer than those of C. capitata, irrespective of the fruit types that they developed from. B. dorsalis had a higher net reproductive rate (Ro) on all deciduous fruit tested compared to C. capitata. However, the intrinsic rate of population increase was estimated to be higher for C. capitata than for B. dorsalis on all fruit types tested primarily due to C. capitata's faster generation time. Provided abiotic conditions are optimal, B. dorsalis would be able to establish and grow in deciduous fruit growing areas.

RevDate: 2019-09-27

Huang X, Hu L, X Wu (2019)

Identification of a novel effector BxSapB3 that enhances the virulence of pine wood nematode Bursaphelenchus xylophilus.

Acta biochimica et biophysica Sinica pii:5574626 [Epub ahead of print].

Pine wilt disease, caused by the pine wood nematode Bursaphelenchus xylophilus, leads to severe damage to pine forests in China. In our previous study, effectors secreted by this pathogen were shown to play roles in the different infection stages of pine wilt disease, and a series of candidate effectors were predicted by transcriptome sequencing. This study identified and characterized a novel effector, BxSapB3, which was among these candidate effectors. Agrobacterium-mediated transient expression was used to identify BxSapB3. BxSapB3 was secreted by B. xylophilus and found to be capable of inducing cell death in Nicotiana benthamiana. Quantitative real-time PCR (qRT-PCR) analysis revealed that BxSapB3 was upregulated in a highly virulent strain of B. xylophilus and expressed at lower levels in a weakly virulent strain at the early stages of infection. When BxSapB3 was silenced in B. xylophilus, the process of infection was delayed. These results indicate that BxSapB3 acts as an effector and contributes to virulence at the early stages of B. xylophilus infection.

RevDate: 2019-09-27

Infante-Izquierdo MD, Castillo JM, Grewell BJ, et al (2019)

Differential Effects of Increasing Salinity on Germination and Seedling Growth of Native and Exotic Invasive Cordgrasses.

Plants (Basel, Switzerland), 8(10): pii:plants8100372.

Soil salinity is a key environmental factor influencing germination and seedling establishment in salt marshes. Global warming and sea level rise are changing estuarine salinity, and may modify the colonization ability of halophytes. We evaluated the effects of increasing salinity on germination and seedling growth of native Spartinamaritima and invasive S.densiflora from wetlands of the Odiel-Tinto Estuary. Responses were assessed following salinity exposure from fresh water to hypersaline conditions and germination recovery of non-germinated seeds when transferred to fresh water. The germination of both species was inhibited and delayed at high salinities, while pre-exposure to salinity accelerated the speed of germination in recovery assays compared to non-pre-exposed seeds. S.densiflora was more tolerant of salinity at germination than S.maritima. S.densiflora was able to germinate at hypersalinity and its germination percentage decreased at higher salinities compared to S.maritima. In contrast, S.maritima showed higher salinity tolerance in relation to seedling growth. Contrasting results were observed with differences in the tidal elevation of populations. Our results suggest S.maritima is a specialist species with respect to salinity, while S.densiflora is a generalist capable of germination of growth under suboptimal conditions. Invasive S.densiflora has greater capacity than native S.maritima to establish from seed with continued climate change and sea level rise.

RevDate: 2019-09-27
CmpDate: 2019-09-27

Xiao T, Yu H, Song YB, et al (2019)

Nutrient enhancement of allelopathic effects of exotic invasive on native plant species.

PloS one, 14(1):e0206165 pii:PONE-D-18-19091.

Many ecosystems may suffer from both nutrient enrichment and exotic plant invasions simultaneously. Much has been known that nutrient inputs can promote growth and expansion of exotic invasive plants in wetlands, and that allelopathic effects of the exotic invasive plants can inhibit the growth of coexisting native plants, contributing to their invasion success. Thus, we hypothesized that allelopathic effects of exotics on natives in invaded ecosystems can be enhanced by nutrient enrichment. To test this hypothesis, we conducted two greenhouse hydroponic experiments. One is the monoculture experiment in which a widespread exotic invasive perennial Alternanthera philoxeroides and a native perennial Ludwigia peploides subsp. stipulacea in monoculture were subjected to five levels of nutrient supply. The other is the mixture experiment in which the two species in mixture were subjected to five levels of nutrient supply, each with and without activated carbon addition. Both A. philoxeroides and L. peploides grew better under higher level of nutrient availability in monoculture experiment. In the mixture experiment, A. philoxeroides formed less total and root biomass while L. peploides formed more in response to activated carbon addition and all of the responses had larger degree at higher level of nutrient availability, indicating A. philoxeroides had significant allelopathic effects on L. peploides and the effects was significantly enhanced by nutrient enrichment. Such results support our hypothesis and reveal a novel mechanism for exotic plant invasion in eutrophicated and invaded wetlands, i.e. nutrient enhancement of allelopathic effects of exotics on natives.

RevDate: 2019-09-27
CmpDate: 2019-09-27

Westfall AK, Miller MA, Murray CM, et al (2019)

Host-specific phenotypic variation of a parasite co-introduced with invasive Burmese pythons.

PloS one, 14(1):e0209252 pii:PONE-D-18-05529.

Invasive Burmese pythons (Python bivittatus Kuhl, 1820) have introduced a lung parasite, Raillietiella orientalis, (Hett, 1915) from the python's native range in Southeast Asia to its introduced range in Florida, where parasite spillover from pythons to two families and eight genera of native snakes has occurred. Because these novel host species present a diversity of ecological and morphological traits, and because these parasites attach to their hosts with hooks located on their cephalothorax, we predicted that R. orientalis would exhibit substantial, host-associated phenotypic plasticity in cephalothorax shape. Indeed, geometric morphometric analyses of 39 parasites from five host species revealed significant variation among host taxa in R. orientalis cephalothorax shape. We observed differences associated with host ecology, where parasites from semi-aquatic and aquatic snakes exhibited the greatest morphological similarity. Morphological analyses of R. orientalis recovered from invasive pythons, native pit vipers, and terrestrial snakes each revealed distinct shapes. Our results suggest R. orientalis can exhibit significant differences in morphology based upon host species infected, and this plasticity may facilitate infection with this non-native parasite in a wide array of novel squamate host species.

RevDate: 2019-09-27
CmpDate: 2019-09-27

Ortega-Morales AI, Bond G, Méndez-López R, et al (2018)

First Record of Invasive Mosquito Aedes albopictus in Tabasco and Yucatan, Mexico.

Journal of the American Mosquito Control Association, 34(2):120-123.

The invasive mosquito Aedes albopictus is currently distributed in most of the southern Mexican region. Since the species was first recorded in the state of Tamaulipas, in northeastern Mexico in 1988, it has expanded its distribution throughout the Sierra Madre Oriental and Gulf of Mexico to the Neotropical region of the country. Currently the species occurs in the states of Tamaulipas, Coahuila, Nuevo Leon, Veracruz, Chiapas, Morelos, Quintana Roo, Sinaloa, San Luis Potosi, and Hidalgo. This is the first report of the mosquito in the states of Tabasco and Yucatan and the confirmation of its presence in Quintana Roo state. Aedes albopictus has been incriminated as a secondary vector of diseases such as those caused by dengue, chikungunya, and Zika viruses, which have caused epidemic outbreaks in most tropical and subtropical regions of Mexico; therefore, surveillance for the detection of Ae. albopictus is paramount so that targeted control strategies can be implemented for its control throughout Mexico.

RevDate: 2019-09-27
CmpDate: 2019-09-27

Rodrigues TB, Duan JJ, Palli SR, et al (2018)

Identification of highly effective target genes for RNAi-mediated control of emerald ash borer, Agrilus planipennis.

Scientific reports, 8(1):5020.

Recent study has shown that RNA interference (RNAi) is efficient in emerald ash borer (EAB), Agrilus planipennis, and that ingestion of double-stranded RNA (dsRNA) targeting specific genes causes gene silencing and mortality in neonates. Here, we report on the identification of highly effective target genes for RNAi-mediated control of EAB. We screened 13 candidate genes in neonate larvae and selected the most effective target genes for further investigation, including their effect on EAB adults and on a non-target organism, Tribolium castaneum. The two most efficient target genes selected, hsp (heat shock 70-kDa protein cognate 3) and shi (shibire), caused up to 90% mortality of larvae and adults. In EAB eggs, larvae, and adults, the hsp is expressed at higher levels when compared to that of shi. Ingestion of dsHSP and dsSHI caused mortality in both neonate larvae and adults. Administration of a mixture of both dsRNAs worked better than either dsRNA by itself. In contrast, injection of EAB.dsHSP and EAB.dsSHI did not cause mortality in T. castaneum. Thus, the two genes identified cause high mortality in the EAB with no apparent phenotype effects in a non-target organism, the red flour beetle, and could be used in RNAi-mediated control of this invasive pest.

RevDate: 2019-09-27
CmpDate: 2019-09-27

Alemayehu D, Reyes T, EJ Haas-Stapleton (2018)

Field Evaluation of a Redesigned Oviposition Trap to Monitor Gravid Invasive Aedes Mosquitoes in a Suburban Environment.

Journal of the American Mosquito Control Association, 34(1):67-69.

Oviposition cup traps (OCT) are commonly used to detect gravid invasive Aedes mosquitoes. Employing OCT during hot summer months or over broad geographic areas is labor intensive because the water in these small-volume traps must be frequently replenished to maintain their attractiveness to mosquitoes. We developed low-cost and simple-to-build oviposition bucket traps (OBT) that attract mosquitoes for more than 1 wk. Comparison of adjacently placed OCT and OBT in the city of Madera, CA, showed OBT captured significantly more Ae. aegypti eggs per trap-night relative to the OCT (8.8 ± 2.6 and 4.1 ± 1.1, respectively; paired t-test, P = 0.0076), and a significantly greater proportion of OBT contained Ae. aegypti eggs relative to OCT (83% of OBT and 65% of OCT; Fisher's exact test, P = 0.0214). The results suggest that OBT can collect larger quantities of Ae. aegypti eggs relative to OCT while potentially offering greater flexibility in scheduling trap inspections.

RevDate: 2019-09-27
CmpDate: 2019-09-27

Huang F, Lankau R, S Peng (2018)

Coexistence via coevolution driven by reduced allelochemical effects and increased tolerance to competition between invasive and native plants.

The New phytologist, 218(1):357-369.

Coevolution can promote long-term coexistence of two competing species if selection acts to reduce the fitness inequality between competitors and/or strengthen negative frequency dependence within each population. However, clear coevolution between plant competitors has been rarely documented. Plant invasions offer opportunities to capture the process of coevolution. Here we investigated how the developing relationship between an invasive forb, Alliaria petiolata, and a native competitor, Pilea pumila, may affect their long-term coexistence, by testing the competitive effects of populations of varying lengths of co-occurrence on each other across a chronosequence of invasion history. Alliaria petiolata and P. pumila tended to develop greater tolerance to competition over invasion history. Their coexistence was promoted more by increases in stabilizing relative to equalizing processes. These changes likely stem in part from reductions in allelopathic traits in the invader and evolution of tolerance in the native. These results suggested that some native species can evolve tolerance against the competitive effects of strong invaders, which likely promoted their persistence in invaded communities. However, the potential for coevolutionary rescue of competing populations is likely to vary across native species, and evolutionary processes should not be expected to compensate for the ecological consequences of exotic invasions.

RevDate: 2019-09-26

Giakoumi S, Pey A, Thiriet P, et al (2019)

Patterns of predation on native and invasive alien fish in Mediterranean protected and unprotected areas.

Marine environmental research, 150:104792 pii:S0141-1136(19)30370-8 [Epub ahead of print].

Worldwide, the loss of predatory fish due to overexploitation has altered the structure of native communities and caused ecosystem shifts. Ecosystems deprived of high-level predators may be more vulnerable to invasive alien species as the latter are subject to reduced predation control. Marine protected areas (MPAs), and particularly no-take reserves where fishing is banned, can be effective tools for the restoration of predatory relationships within their boundaries. We explored whether the restoration of high-level predatory fish populations within Mediterranean MPAs can exert top-down control on alien fish. Fish tethering experiments, including native (Sardina pilchardus, Boops boops) and alien (Siganus rivulatus) dead specimens, were conducted to quantify predation within the no-take zones of three MPAs and in unprotected areas, and to assess potential differences in predation rates and prey type preferences. A subsample of experimental units was filmed to document predation events and related fish behaviour. More high-level predators interacted with the tethered fish inside the MPAs than in unprotected areas. Yet we did not find significant differences in the consumption of alien or native fishes between MPAs and unprotected areas. The native S. pilchardus was consumed more in comparison to the other tethered fishes, regardless of protection status and location. Interestingly, the alien S. rivulatus was consumed by native predators in the western Mediterranean locations where this alien fish is not established. Despite its limitations, our study provides evidence on the ability of some native predators to feed on and potentially control certain alien species without requiring 'adaptive' time-lag periods.

RevDate: 2019-09-26

Fall PL, TD Drezner (2019)

Vascular plant species of the Kingdom of Tonga by vegetation type, species origin, growth form, and dispersal mechanism.

Ecology [Epub ahead of print].

The aim of this research is to compile a database of vascular plants found in the Kingdom of Tonga in western Polynesia, a phyto-geographic subregion of the South Pacific. The Tongan islands are spread over approximately 600,000 km2 of the Pacific Ocean between 15-23º S latitude and 173-177º W longitude. The archipelago is comprised of 171 islands with an aggregate land area of about 720 km2 . Since there is no comprehensive or updated flora for Tonga, we use 143 published sources to compile a database for 1020 plant species, of which more than 450 are indigenous to these islands. Tonga is noteworthy for its low proportion of endemics, accounting for < 5% of the indigenous species and < 2% of the total plant species. Our database documents species presence in Tonga as a whole, and more specifically on 11 Tongan islands or island groups. We have assembled ecological information for each plant species according to growth form, vegetation type, origin (endemic, indigenous, and introduced species), and dispersal mechanisms. We include introduced species in our database because they represent over half of the plant species growing in Tonga. Species origins reflect human alteration of Tongan ecosystems in which endemic and indigenous species represent pre-human vegetation and introduced species indicate plants brought by either Polynesian or European settlers. For example, on Tongatapu, the largest and longest occupied island, more than half the plants are introduced, whereas on the sparsely populated, more remote islands, 70 to 90% of the species are indigenous. Dispersal mechanisms, which may include more than one mechanism per species, are documented in over 100 publications. Our database provides information on the whole suite of plant dispersal mechanisms over entire communities or island groups in Tonga. Plant species dispersal differs across environmental variables, including island geology, topography, vegetation type, and species origin. The older limestone islands have more bird, water, and human-dispersed plants, while the youngest volcanic islands have the most wind-dispersed species. Our database documents plant species endemism, introductions, vegetation types and dispersal mechanisms that reveal key biogeographic dynamics of the Tongan archipelago in the South Pacific. Please cite this Ecology Data Paper if the data are used in publication, presentation, or teaching activities. There are no copyright restrictions.

RevDate: 2019-09-25

Cinege G, Lerner Z, Magyar LB, et al (2019)

Cellular Immune Response Involving Multinucleated Giant Hemocytes with Two-Step Genome Amplification in the Drosophilid Zaprionus indianus.

Journal of innate immunity pii:000502646 [Epub ahead of print].

Previously, a novel cell type, the multinucleated giant hemocyte (MGH) was identified in the ananassae subgroup of Drosophilidae. These cells share several features with mammalian multinucleated giant cells, a syncytium of macrophages formed during granulomatous inflammation. We were able to show that MGHs also differentiate in Zaprionus indianus, an invasive species belonging to the vittiger subgroup of the family, highly resistant to a large number of parasitoid wasp species. We have classified the MGHs of Z. indianusas giant hemocytes belonging to a class of cells which also include elongated blood cells carrying a single nucleus and anuclear structures. They are involved in encapsulating parasites, originate from the lymph gland, can develop by cell fusion, and generally carry many nuclei, while possessing an elaborated system of canals and sinuses, resulting in a spongiform appearance. Their nuclei are all transcriptionally active and show accretion of genetic material. Multinucleation and accumulation of the genetic material in the giant hemocytes represents a two-stage amplification of the genome, while their spongy ultrastructure substantially increases the contact surface with the extracellular space. These features may furnish the giant hemocytes with a considerable metabolic advantage, hence contributing to the mechanism of the effective immune response.

RevDate: 2019-09-25

Suárez-Mariño A, Arceo-Gómez G, Sosenski P, et al (2019)

Patterns and effects of heterospecific pollen transfer between an invasive and two native plant species: the importance of pollen arrival time to the stigma.

American journal of botany [Epub ahead of print].

PREMISE: Invasive plant species can integrate into native plant-pollinator communities, but the underlying mechanisms are poorly understood. Competitive interactions between invasive and native plants via heterospecific pollen (HP) and differential invasive HP effects depending on HP arrival time to the stigma may mediate invasion success, but these have been little studied.

METHODS: We evaluated patterns and effects of HP receipt on pollen tube growth in two native and one invasive species in the field. We also used hand-pollination experiments to evaluate the effect of invasive HP pollen and its arrival time on native reproductive success.

RESULTS: Native species receive smaller and less-diverse HP loads (5-7 species) compared to invasive species (10 species). The load size of HP had a negative effect on the proportion of pollen tubes in both native species but not in the invasive, suggesting higher HP tolerance in the latter. Invasive HP arrival time differentially affected pollen tube success in native species.

CONCLUSIONS: Our results highlight the need to study reciprocal HP effects between invasive and native species and the factors that determine differential responses to HP receipt to fully understand the mechanisms facilitating invasive species integration into native plant-pollinator communities.

RevDate: 2019-09-25

Deforet M, Carmona-Fontaine C, Korolev KS, et al (2019)

Evolution at the Edge of Expanding Populations.

The American naturalist, 194(3):291-305.

Predicting the evolution of expanding populations is critical to controlling biological threats such as invasive species and cancer metastasis. Expansion is primarily driven by reproduction and dispersal, but nature abounds with examples of evolution where organisms pay a reproductive cost to disperse faster. When does selection favor this "survival of the fastest"? We searched for a simple rule, motivated by evolution experiments where swarming bacteria evolved into a hyperswarmer mutant that disperses ∼100% faster but pays a growth cost of ∼10% to make many copies of its flagellum. We analyzed a two-species model based on the Fisher equation to explain this observation: the population expansion rate (v) results from an interplay of growth (r) and dispersal (D) and is independent of the carrying capacity: v = 2 (rD) 1 / 2 . A mutant can take over the edge only if its expansion rate (v2) exceeds the expansion rate of the established species (v1); this simple condition (v 2 > v 1) determines the maximum cost in slower growth that a faster mutant can pay and still be able to take over. Numerical simulations and time-course experiments where we tracked evolution by imaging bacteria suggest that our findings are general: less favorable conditions delay but do not entirely prevent the success of the fastest. Thus, the expansion rate defines a traveling wave fitness, which could be combined with trade-offs to predict evolution of expanding populations.

RevDate: 2019-09-25

Treasure AM, le Roux PC, Mashau MH, et al (2019)

Species-energy relationships of indigenous and invasive species may arise in different ways - a demonstration using springtails.

Scientific reports, 9(1):13799 pii:10.1038/s41598-019-48871-1.

Although the relationship between species richness and available energy is well established for a range of spatial scales, exploration of the plausible underlying explanations for this relationship is less common. Speciation, extinction, dispersal and environmental filters all play a role. Here we make use of replicated elevational transects and the insights offered by comparing indigenous and invasive species to test four proximal mechanisms that have been offered to explain relationships between energy availability, abundance and species richness: the sampling mechanism (a null expectation), and the more individuals, dynamic equilibrium and range limitation mechanisms. We also briefly consider the time for speciation mechanism. We do so for springtails on sub-Antarctic Marion Island. Relationships between energy availability and species richness are stronger for invasive than indigenous species, with geometric constraints and area variation playing minor roles. We reject the sampling and more individuals mechanisms, but show that dynamic equilibrium and range limitation are plausible mechanisms underlying these gradients, especially for invasive species. Time for speciation cannot be ruled out as contributing to richness variation in the indigenous species. Differences between the indigenous and invasive species highlight the ways in which deconstruction of richness gradients may usefully inform investigations of the mechanisms underlying them. They also point to the importance of population size-related mechanisms in accounting for such variation. In the context of the sub-Antarctic our findings suggest that warming climates may favour invasive over indigenous species in the context of changes to elevational distributions, a situation found for vascular plants, and predicted for springtails on the basis of smaller-scale manipulative field experiments.

RevDate: 2019-09-25

Zhang B, Qian W, Qiao X, et al (2019)

Invasion biology, ecology, and management of Frankliniella occidentalis in China.

Frankliniella occidentalis is an economically important invasive pest worldwide, which can damage various horticultural crops and ornamental plants. F. occidentalis was first intercepted in Kunming, Yunnan province in 2000, and first reported to establish a population in Beijing, China in 2003. Since then, this pest is currently distributed across tens of provinces in mainland China and cause increasingly serious damage and loss. To control this pest, invasion biology, monitoring, and integrated pest management have been generally and intensively studied for 15 years in China. Furthermore, western flower thrips (WFT) as an important invasive insect pest, the research achievements on WFT has contributed to the promotion of technological innovation and development for invasive alien species management strategies and techniques in China. This review provides an overview for research on the biology, ecology, prevention, and management of this pest during 15 years in China. Meanwhile, China's "4E action" strategy on F. occidentalis is also discussed in this review.

RevDate: 2019-09-24

Lauchlan SS, Burckard G, Cassey P, et al (2019)

Climate change erodes competitive hierarchies among native, alien and range-extending crabs.

Marine environmental research pii:S0141-1136(19)30255-7 [Epub ahead of print].

Global warming and ocean acidification alter a wide range of animal behaviours, yet the effect on resource competition among species is poorly understood. We tested whether the combination of moderate levels of ocean acidification and warming altered the feeding success of co-occurring native, alien, and range-extending crab species, and how these changes affected their hierarchical dominance. Under contemporary conditions the range-extending species spent more time feeding, than the alien and the native species. Under conditions simulating future climate there was no difference in the proportion of time spent feeding among the three species. These behavioural changes translated to alterations in their dominance hierarchy (based on feeding success) with the most dominant species under present day conditions becoming less dominant under future conditions, and vice versa for the least dominant species. While empirical studies have predicted either reversal or strengthening of hierarchical dominance in animal species, we suggest that even moderate increases in ocean temperature and acidification can drive a homogenisation in behavioural competitiveness, eroding dominance differences among species that are linked to fitness-related traits in nature and hence important for their population persistence.

RevDate: 2019-09-25
CmpDate: 2019-09-24

Hughes KA, Convey P, Pertierra LR, et al (2019)

Human-mediated dispersal of terrestrial species between Antarctic biogeographic regions: A preliminary risk assessment.

Journal of environmental management, 232:73-89.

The distribution of terrestrial biodiversity within Antarctica is complex, with 16 distinct biogeographic regions (Antarctic Conservation Biogeographic Regions) currently recognised within the Antarctic continent, Peninsula and Scotia Arc archipelagos of the Antarctic Treaty area. Much of this diversity is endemic not only to Antarctica as a whole, but to specific regions within it. Further complexity is added by inclusion of the biodiversity found on the islands located in the Southern Ocean north of the Treaty area. Within Antarctica, scientific, logistic and tourism activities may inadvertently move organisms over potentially long distances, far beyond natural dispersal ranges. Such translocation can disrupt natural species distribution patterns and biogeography through: (1) movement of spatially restricted indigenous species to other areas of Antarctica; (2) movement of distinct populations of more generally distributed species from one area of Antarctica to another, leading to genetic homogenisation and loss of assumed local patterns of adaptation; and (3) further dispersal of introduced non-native species from one area of Antarctica to another. Species can be moved between regions in association with people and cargo, by ship, aircraft and overland travel. Movement of cargo and personnel by ship between stations located in different biogeographic regions is likely to present one of the greatest risks, particularly as coastal stations may experience similar climatic conditions, making establishment more likely. Recognising that reducing the risk of inter-regional transfer of species is a priority issue for the Antarctic Treaty Consultative Meeting, we make practical recommendations aimed at reducing this risk, including the implementation of appropriate biosecurity procedures.

RevDate: 2019-09-25
CmpDate: 2019-09-23

Marcora PI, Ferreras AE, Zeballos SR, et al (2018)

Context-dependent effects of fire and browsing on woody alien invasion in mountain ecosystems.

Oecologia, 188(2):479-490.

Anthropogenic activities have increased disturbances and alien woody invasion in mountain ecosystems worldwide. Whether disturbances promote or counteract upward movement of woody aliens is poorly understood. We assessed if the most successful woody invader of low mountains of central Argentina (Gleditsia triacanthos) might expand its elevational distribution in response to the principal disturbances of these ecosystems (fire and livestock browsing) across increasing climatic severity. We assessed seedling emergence, growth and mycorrhizal colonization on sown plots distributed in burned and unburned sites, with and without browsing at the lower and upper elevation belts (i.e. 1000 and 2400 m a.s.l.). Additionally, several abiotic variables were measured to relate their influence on the seedling establishment. Disturbances reduced seedling emergence at both elevations. Burned conditions increased seedling growth and arbuscular colonization only in the lower belt. Seedling success (total seedling biomass per plot) was not modified by disturbances at the upper elevation, but was reduced by browsing and enhanced by fire in the lower elevation. The overall reduction in seedling emergence and growth in the upper elevation despite the higher soil nutrient content places climate as the strongest regulator of G. triacanthos seedling establishment. Accordingly, climate rather than disturbances would be the main limiting factor of upward expansion of this woody alien. Our findings differ from general patterns described for mountain invasion by herbaceous species, highlighting that mountain invasibility is highly growth-form dependent, and that upper range expansion by woody aliens interacting with multiple disturbances should be assessed worldwide.

RevDate: 2019-09-25
CmpDate: 2019-09-23

Vergara-Tabares DL, Toledo M, García E, et al (2018)

Aliens will provide: avian responses to a new temporal resource offered by ornithocorous exotic shrubs.

Oecologia, 188(1):173-182.

Frugivorous birds are able to track spatiotemporal changes in fruit availability. Food resource fluctuations, characteristic of seasonal environments, can be affected by the naturalization of exotic ornithocorous plants. In the mountain forest of central Argentina, invasive shrubs of the genus Pyracantha provide a new temporal resource that modifies fluctuations of natural resource availability because the invasives fructify in autumn-winter (largely uncoupled with the fruiting of native species). The contrasting patterns of resource fluctuation between non-invaded and invaded areas throughout the year provide a good study system to test predictions of the fruit-tracking hypothesis, and to understand the relationship between food resources offered by fleshy fruited invasives and abundances of avian trophic guilds. By means of point counts conducted during five time periods at invaded and non-invaded sites we found that the presence of Pyracantha, and time periods, significantly affected frugivorous bird abundance, which in autumn-winter was greater in invaded sites and in spring-summer similar between invaded and non-invaded sites. On the other hand, granivores and insectivores did not show a significant relationship with the presence of Pyracantha. Abundances of the most common seed disperser were significantly affected by the interaction between time period and presence of Pyracantha. These results indicate that the abundances of birds that legitimately disperse Pyracantha seeds are temporally and spatially associated with fruit abundance provided by this exotic plant. This underscores fruit availability as an important ecological factor affecting frugivorous bird abundance, and suggests that Pyracantha seed dispersers are capable of detecting changes in the availability of its fruit, likely contributing to the effectiveness of its dispersal.

RevDate: 2019-09-23

Ellstrand NC (2019)

The evolution of crops that do not need us anymore.

The New phytologist, 224(2):550-551.

RevDate: 2019-09-23
CmpDate: 2019-09-23

Verbeek JD, PM Kotanen (2019)

Soil-mediated impacts of an invasive thistle inhibit the recruitment of certain native plants.

Oecologia, 190(3):619-628.

Invasive plants may outcompete and replace native plant species through a variety of mechanisms. Recent evidence indicates that soil microbial pathways such as pathogen accumulation may have a considerable role in facilitating competition between native and invasive plants. To assess microbe-mediated pathways of invasion, we tested the impacts of invaded and non-invaded field soils on plant establishment using naturally occurring populations of the common Eurasian invader Cirsium arvense (Canada thistle) in Southern Ontario, Canada. Linked field and greenhouse experiments were used to quantify differences in the germinability and early growth rates of native plant species, depending on exposure to the microbial community in invaded or non-invaded soils. The invaded microbial community significantly reduced early growth rates for two of the seven native species surveyed, and decreased seed germination for another. In contrast, the germination and growth of invasive Cirsium were not affected by its own soil microbial community. These results demonstrate that the invasion of C. arvense can reduce the performance of some native plant species through changes to the soil microbial community. Different effects on different species suggest that this invader may also change the relative importance of certain natives in the invaded community. If these effects influence plant abundance in the field, microbially mediated interactions in the soil may aid the invasion of C. arvense and facilitate the disruption of invaded communities.

RevDate: 2019-09-23
CmpDate: 2019-09-23

Moyano J, Chiuffo MC, Nuñez MA, et al (2019)

Seed predation does not explain pine invasion success.

Oecologia, 189(4):981-991.

Why some non-native plant species invade, and others fail remains an elusive question. Plant invasion success has been associated with specific species traits. Yet, we have limited knowledge of the mechanisms relating these traits to invasion potential. General patterns of biotic resistance by seed predation may provide a mechanism that helps separate invasive from non-invasive plants. Seed predation is an important barrier against plant establishment for many plant species. It may, therefore, create a selective filter against non-native plant establishment based on plant traits related to seed predation rate. In two cafeteria-style seed predation experiments in a steppe ecosystem in Patagonia (Argentina) we provided seeds of 16 non-native Pinaceae covering a 300-fold variation in seed mass, a 200-fold variation in seed volume and 75-fold variation in seed toughness. Seed removal decreased with seed mass and seed volume. Seed toughness was not a significant predictor while seed volume was the best predictor of predators' preference. However, for species of this family small seed size is the most important predictor of species invasiveness. Our results show that seed predation does not explain Pinaceae invasive success. In our system, species that have smaller seeds (i.e., more invasive) are preferentially consumed by seed predators. Seed mass was not the best predictor of granivory rates, despite being the seed trait on which most studies have been focused. Our ability to predict future invasion and understand invasion success could benefit from other studies that focus on the mechanisms behind invasive traits.

RevDate: 2019-09-23
CmpDate: 2019-09-23

Zhao T, Villéger S, J Cucherousset (2019)

Accounting for intraspecific diversity when examining relationships between non-native species and functional diversity.

Oecologia, 189(1):171-183.

Quantifying changes in functional diversity, the facet of biodiversity accounting for the biological features of organisms, has been advocated as one of the most integrative ways to unravel how communities are affected by human-induced perturbations. The present study assessed how functional diversity patterns varied among communities that differed in the degree to which non-native species dominated the community in temperate lake fish communities and whether accounting for intraspecific functional variability could provide a better understanding of the variation of functional diversity across communities. Four functional diversity indices were computed for 18 temperate lake fish communities along a gradient of non-native fish dominance using morphological functional traits assessed for each life-stage within each species. First, we showed that intraspecific variability in functional traits was high and comparable to interspecific variability. Second, we found that non-native fish were functionally distinct from native fish. Finally, we demonstrated that there was a significant relationship between functional diversity and the degree to which non-native fish currently dominated the community and that this association could be better detected when accounting for intraspecific functional variability. These findings highlighted the importance of incorporating intraspecific variability to better quantify the variation of functional diversity patterns in communities facing human-induced perturbations.

RevDate: 2019-09-23
CmpDate: 2019-09-23

Larson CD, Lehnhoff EA, Noffsinger C, et al (2018)

Competition between cheatgrass and bluebunch wheatgrass is altered by temperature, resource availability, and atmospheric CO2 concentration.

Oecologia, 186(3):855-868.

Global change drivers (elevated atmospheric CO2, rising surface temperatures, and changes in resource availability) have significant consequences for global plant communities. In the northern sagebrush steppe of North America, the invasive annual grass Bromus tectorum (cheatgrass) is expected to benefit from projected warmer and drier conditions, as well as increased CO2 and nutrient availability. In growth chambers, we addressed this expectation using two replacement series experiments designed to test competition between B. tectorum and the native perennial bunchgrass Pseudoroegneria spicata. In the first experiment, we tested the effects of elevated temperature, decreased water and increased nutrient availability, on competition between the two species. In the second, we tested the effects of elevated atmospheric CO2 and decreased water availability on the competitive dynamic. In both experiments, under all conditions, P. spicata suppressed B. tectorum, though, in experiment one, warmer and drier conditions and elevated nutrient availability increased B. tectorum's competitiveness. In experiment two, when grown in monoculture, both species responded positively to elevated CO2. However, when grown in competition, elevated CO2 increased P. spicata's suppressive effect, and the combination of dry soil conditions and elevated CO2 enhanced this effect. Our findings demonstrate that B. tectorum competitiveness with P. spicata responds differently to global change drivers; thus, future conditions are unlikely to facilitate B. tectorum invasion into established P. spicata communities of the northern sagebrush steppe. However, disturbance (e.g., fire) to these communities, and the associated increase in soil nutrients, elevates the risk of B. tectorum invasion.

RevDate: 2019-09-22

Laas M, Adamson K, R Drenkhan (2019)

A look into the genetic diversity of Lecanosticta acicola in northern Europe.

Fungal biology, 123(10):773-782.

For northern Europe Lecanosticta acicola is an emerging pine needle pathogen. This study gives a first look into the population genetics of the pathogen in Estonia, the first population documented in that region. The main aim of this study was to investigate the genetic diversity and population structure of the pathogen in this new region for the fungus. For this purpose, 104 isolates from 2010 to 2017 were analysed with 11 microsatellite and mating type markers. The stand where the pathogen's jump from an exotic host to the native Scots pine was recorded was also involved in this analysis. The analysis revealed low genetic diversity and a high number of clones that indicated L. acicola is an invasive species in northern Europe. Results suggest that several separate introductions have taken place and anthropogenic activity has apparently affected the spread of the pathogen. Clonal reproduction is dominating and although sexual reproduction is possible, it probably takes place infrequently.

RevDate: 2019-09-21

Mittelberger C, Stellmach H, Hause B, et al (2019)

A Novel Effector Protein of Apple Proliferation Phytoplasma Disrupts Cell Integrity of Nicotiana spp. Protoplasts.

International journal of molecular sciences, 20(18): pii:ijms20184613.

Effector proteins play an important role in the virulence of plant pathogens such as phytoplasma, which are the causative agents of hundreds of different plant diseases. The plant hosts comprise economically relevant crops such as apples (Malus × domestica), which can be infected by 'Candidatus Phytoplasma mali' (P. mali), a highly genetically dynamic plant pathogen. As the result of the genetic and functional analyses in this study, a new putative P. mali effector protein was revealed. The so-called "Protein in Malus Expressed 2" (PME2), which is expressed in apples during P. mali infection but not in the insect vector, shows regional genetic differences. In a heterologous expression assay using Nicotiana benthamiana and Nicotiana occidentalis mesophyll protoplasts, translocation of both PME2 variants in the cell nucleus was observed. Overexpression of the effector protein affected cell integrity in Nicotiana spp. protoplasts, indicating a potential role of this protein in pathogenic virulence. Interestingly, the two genetic variants of PME2 differ regarding their potential to manipulate cell integrity. However, the exact function of PME2 during disease manifestation and symptom development remains to be further elucidated. Aside from the first description of the function of a novel effector of P. mali, the results of this study underline the necessity for a more comprehensive description and understanding of the genetic diversity of P. mali as an indispensable basis for a functional understanding of apple proliferation disease.

RevDate: 2019-09-21

Joshi NK, Leslie TW, DJ Biddinger (2019)

Parasitism of the Invasive Brown Marmorated Stink Bug, Halyomorpha halys (Hemiptera: Pentatomidae), by the Native Parasitoid, Trichopoda pennipes (Diptera: Tachinidae).

Biology, 8(3): pii:biology8030066.

The invasive brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae), has been an important agricultural pest in the Mid-Atlantic United States since its introduction in 1996. Biological control by native species may play an important role in suppressing H. halys populations and reduce reliance on chemical control. We collected H. halys adults in agricultural areas of five Pennsylvania counties over two years to examine the extent and characteristics of adult stink bug parasitism by Trichopoda pennipes (Diptera: Tachinidae), a native parasitoid of hemipterans. The overall parasitism rate (in terms of T. pennipes egg deposition) was 2.38 percent. Rates differed among counties and seasons, but not between years. Instances of supernumerary oviposition were evident, and eggs were more commonly found on the ventral side of the thorax, although no differences in egg deposition were found between males and female hosts. T. pennipes has begun to target H. halys adults in Pennsylvania and has the potential to play a role in regulating this pest. Adult parasitism of H. halys by T. pennipes should continue to be monitored, and landscape management and ecological pest management practices that conserve T. pennipes populations should be supported in agricultural areas where H. halys is found.

RevDate: 2019-09-21

Iannella M, De Simone W, D'Alessandro P, et al (2019)

Investigating the Current and Future Co-Occurrence of Ambrosia artemisiifolia and Ophraella communa in Europe through Ecological Modelling and Remote Sensing Data Analysis.

International journal of environmental research and public health, 16(18): pii:ijerph16183416.

The common ragweed Ambrosia artemisiifolia has spread throughout Europe since the 1800s, infesting croplands and causing severe allergic reactions. Recently, the ragweed leaf beetle Ophraella communa was found in Italy and Switzerland; considering that it feeds primarily on A. artemisiifolia in its invaded ranges, some projects started biological control of this invasive plant through the adventive beetle. In this context of a 'double' invasion, we assessed the influence of climate change on the spread of these alien species through ecological niche modelling. Considering that A. artemisiifolia mainly lives in agricultural and urbanized areas, we refined the models using satellite remote-sensing data; we also assessed the co-occurrence of the two species in these patches. A. artemisiifolia is predicted to expand more than O. communa in the future, with the medium and high classes of suitability of the former increasing more than the latter, resulting in lower efficacy for O. communa to potentially control A. artemisiifolia in agricultural and urbanized patches. Although a future assessment was performed through the 2018 land-cover data, the predictions we propose are intended to be a starting point for future assessments, considering that the possibility of a shrinkage of target patches is unlikely to occur.

RevDate: 2019-09-20

Ortíz-Ceballos AI, Ortiz-Gamino D, Andrade-Torres A, et al (2019)

Pontoscolex corethrurus: A homeless invasive tropical earthworm?.

PloS one, 14(9):e0222337 pii:PONE-D-19-15357.

The presence of earthworm species in crop fields is as old as agriculture itself. The earthworms Pontoscolex corethrurus (invasive) and Balanteodrilus pearsei (native) are associated with the emergence of agriculture and sedentism in the region Amazon and Maya, respectively. Both species have shifted their preference from their natural habitat to the cropland niche. They contrast in terms of intensification of agricultural land use (anthropic impact to the symbiotic soil microbiome). P. corethrurus inhabits conventional agroecosystems, while B. pearsei thrives in traditional agroecosystems, i.e., P. corethrurus has not yet been recorded in soils where B. pearsei dwells. The demographic behavior of these two earthworm species was assessed in the laboratory over 100 days, according to their origin (OE; P. corethrurus and B. pearsei) food quality (FQ; soil only, maize stubble, Mucuna pruriens), and soil moisture (SM; 25, 33, 42%). The results showed that OE, FQ, SM, and the OE x FQ interaction were highly significant for the survival, growth, and reproduction of earthworms. P. corethrurus showed a lower survival rate (> mortality). P. corethrurus survivors fed a diet of low-to-intermediate nutritional quality (soil and stubble maize, respectively) showed a greater capacity to grow and reproduce; however, it was surpassed by the native earthworm when fed a high-quality diet (M. pruriens). Besides, P. corethrurus displayed a low cocoon hatching (emergence of juveniles). These results suggest that the presence of the invasive species was associated with a negative interaction with the soil microbiota where the native species dwells, and with the absence of natural mutualistic bacteria (gut, nephridia, and cocoons). These results are consistent with the absence of P. corethrurus in milpa and pasture-type agricultural niches managed by peasants (agroecologists) to grow food regularly through biological soil management. Results reported here suggest that P. corethrurus is an invasive species that is neither wild nor domesticated, that is, its eco-evolutionary phylogeny needs to be derived based on its symbionts.

RevDate: 2019-09-20

Shang C, E Wang (2019)

Recent progress in Pt and Pd-based hybrid nanocatalysts for methanol electrooxidation.

Physical chemistry chemical physics : PCCP [Epub ahead of print].

Although Pt and Pd nanocrystals are among the most popular candidates for anode catalysts in direct methanol fuel cells, their catalytic properties still need to be further improved in order to reduce the costs. In view of this, fabricating hybrid nanomaterials by integrating noble metal nanocrystals and other species turns out to be a powerful way to produce unprecedented catalysts which could combine the merits of different components and modulate the electronic states of Pt or Pd at the same time. In this review, we list recent studies in the construction of heterostructured hybrid nanocatalysts through introducing external components into the noble metal nanocrystals. The mentioned external components include heteroatom doped carbon nanomaterials, metal oxides and hydroxides, as well as transition metal carbides, nitrides, phosphides, and sulfides. The construction methodologies and functions that these introduced species played in the catalytic processes of methanol electrooxidation are discussed. The attempts to maximize the catalytically active interfaces and utilization efficiencies of noble metals are also presented. Finally, the conclusions and existing problems in relevant nanocatalysts are provided.

RevDate: 2019-09-19

Reitz SR, Gao Y, Kirk WDJ, et al (2019)

Invasion Biology, Ecology, and Management of Western Flower Thrips.

Annual review of entomology [Epub ahead of print].

Western flower thrips, Frankliniella occidentalis, first arose as an important invasive pest of many crops during the 1970s-1980s. The tremendous growth in international agricultural trade that developed then fostered the invasiveness of western flower thrips. We examine current knowledge regarding the biology of western flower thrips, with an emphasis on characteristics that contribute to its invasiveness and pest status. Efforts to control this pest and the tospoviruses that it vectors with intensive insecticide applications have been unsuccessful and have created significant problems because of the development of resistance to numerous insecticides and associated outbreaks of secondary pests. We synthesize information on effective integrated management approaches for western flower thrips that have developed through research on its biology, behavior, and ecology. We further highlight emerging topics regarding the species status of western flower thrips, as well as its genetics, biology, and ecology that facilitate its use as a model study organism and will guide development of appropriate management practices. Expected final online publication date for the Annual Review of Entomology, Volume 65 is January 7, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

RevDate: 2019-09-19

Measey J, Visser V, Dgebuadze Y, et al (2019)

The world needs BRICS countries to build capacity in invasion science.

PLoS biology, 17(9):e3000404 pii:PBIOLOGY-D-19-01715 [Epub ahead of print].

Developed countries are producing policies to reduce the flow of invasive species and control or eradicate existing invasions, but most developing countries are under-resourced to tackle either aspect without help. Emerging economies, such as Brazil, Russia, India, China, and South Africa (BRICS), are responsible for donating many of the world's invasive species that have the potential to reach nearly all terrestrial biomes. Implementing a proactive 'facilitated network' model is urgently required to build capacity and stimulate effective appropriate invasion science. We contend that creating a BRICS network of invasion scientists will have the immediate impact required to meet future policy demands.

RevDate: 2019-09-19

Liu C, Scursoni JA, Moreno R, et al (2019)

An individual-based model of seed- and rhizome-propagated perennial plant species and sustainable management of Sorghum halepense in soybean production systems in Argentina.

Ecology and evolution, 9(17):10017-10028 pii:ECE35578.

Perennial plants which propagate through both seeds and rhizomes are common in agricultural and nonagricultural systems. Due to their multifaceted life cycle, few population models are available for studying such species. We constructed a novel individual-based model to examine the effects of ecological, evolutionary, and anthropogenic factors on the population dynamics of perennial species. To exemplify the application of the model, we presented a case study of an important weed, Sorghum halepense (L.) Pers. (Johnsongrass), in soybean productions in Argentina. The model encompasses a full perennial weed life cycle with both sexual (seeds) and asexual (rhizomes) propagations. The evolution of herbicide resistance was modeled based on either single genes or quantitative effects. Field experiments were conducted in the species' native environment in Argentina to parameterize the model. Simulation results showed that resistance conferred by single-gene mutations was predominantly affected by the initial frequency of resistance alleles and the associated fitness cost. Population dynamics were influenced by evolved resistance, soil tillage, and rhizome fecundity. Despite the pivotal role of rhizomes in driving the population dynamics of Johnsongrass, most herbicides target the aboveground biomass, and chemical solutions to control rhizomes are still very limited. To maintain effective (short-term) and sustainable (long-term) weed management, it is recommended to combine soil tillage with herbicide applications for suppressing the rhizomes and delaying the evolution of resistance. This novel model of seed- and rhizome-propagated plants will also be a useful tool for studying the evolutionary processes of other perennial weeds, cash crops, and invasive species.

RevDate: 2019-09-19

Du L, Liu H, Guan W, et al (2019)

Drought affects the coordination of belowground and aboveground resource-related traits in Solidago canadensis in China.

Ecology and evolution, 9(17):9948-9960 pii:ECE35536.

Quantifying patterns of variation and coordination of plant functional traits can help to understand the mechanisms underlying both invasiveness and adaptation of plants. Little is known about the coordinated variations of performance and functional traits of different organs in invasive plants, especially in response to their adaptation to environmental stressors. To identify the responses of the invasive species Solidago canadensis to drought, 180 individuals were randomly collected from 15 populations and 212 ramets were replanted in a greenhouse to investigate both the response and coordination between root and leaf functional traits. Drought significantly decreased plant growth and most of the root and leaf functional traits, that is, root length, surface area, volume and leaf size, number, and mass fraction, except for the root length ratio and root mass fraction. Phenotypic plasticity was higher in root traits than in leaf traits in response to drought, and populations did not differ significantly. The plasticity of most root functional traits, that is, root length (RL), root surface area (RSA), root volume (RV), and root mass fraction (RMF), were significantly positively correlated with biomass between control and drought. However, the opposite was found for leaf functional traits, that is, specific leaf area (SLA), leaf area ratio (LAR), and leaf mass fraction (LMF). Drought enhanced the relationship between root and leaf, that is, 26 pairwise root-leaf traits were significantly correlated under drought, while only 15 pairwise root-leaf traits were significantly correlated under control conditions. Significant correlations were found between biomass and all measured functional traits except for leaf size. RV, root length ratio, RMF, total area of leaves, and LMF responded differently to water availability. These responses enable S. canadensis to cope with drought conditions and may help to explain the reason of the vast ecological amplitude of this species.

RevDate: 2019-09-19

Paterson JE, Baxter-Gilbert J, Beaudry F, et al (2019)

Road avoidance and its energetic consequences for reptiles.

Ecology and evolution, 9(17):9794-9803 pii:ECE35515.

Roads are one of the most widespread human-caused habitat modifications that can increase wildlife mortality rates and alter behavior. Roads can act as barriers with variable permeability to movement and can increase distances wildlife travel to access habitats. Movement is energetically costly, and avoidance of roads could therefore impact an animal's energy budget. We tested whether reptiles avoid roads or road crossings and explored whether the energetic consequences of road avoidance decreased individual fitness. Using telemetry data from Blanding's turtles (Emydoidea blandingii; 11,658 locations of 286 turtles from 15 sites) and eastern massasaugas (Sistrurus catenatus; 1,868 locations of 49 snakes from 3 sites), we compared frequency of observed road crossings and use of road-adjacent habitat by reptiles to expected frequencies based on simulated correlated random walks. Turtles and snakes did not avoid habitats near roads, but both species avoided road crossings. Compared with simulations, turtles made fewer crossings of paved roads with low speed limits and more crossings of paved roads with high speed limits. Snakes made fewer crossings of all road types than expected based on simulated paths. Turtles traveled longer daily distances when their home range contained roads, but the predicted energetic cost was negligible: substantially less than the cost of producing one egg. Snakes with roads in their home range did not travel further per day than snakes without roads in their home range. We found that turtles and snakes avoided crossing roads, but road avoidance is unlikely to impact fitness through energetic expenditures. Therefore, mortality from vehicle strikes remains the most significant impact of roads on reptile populations.

RevDate: 2019-09-19

Herden J, Eckert S, Stift M, et al (2019)

No evidence for local adaptation and an epigenetic underpinning in native and non-native ruderal plant species in Germany.

Ecology and evolution, 9(17):9412-9426 pii:ECE35325.

Many invasive species have rapidly adapted to different environments in their new ranges. This is surprising, as colonization is usually associated with reduced genetic variation. Heritable phenotypic variation with an epigenetic basis may explain this paradox.Here, we assessed the contribution of DNA methylation to local adaptation in native and naturalized non-native ruderal plant species in Germany. We reciprocally transplanted offspring from natural populations of seven native and five non-native plant species between the Konstanz region in the south and the Potsdam region in the north of Germany. Before the transplant, half of the seeds were treated with the demethylation agent zebularine. We recorded survival, flowering probability, and biomass production as fitness estimates.Contrary to our expectations, we found little evidence for local adaptation, both among the native and among the non-native plant species. Zebularine treatment had mostly negative effects on overall plant performance, regardless of whether plants were local or not, and regardless of whether they were native or non-native. Synthesis. We conclude that local adaptation, at least at the scale of our study, plays no major role in the success of non-native and native ruderal plants. Consequently, we found no evidence yet for an epigenetic basis of local adaptation.

RevDate: 2019-09-19

Walcott J, Bissada C, HA Oxenford (2019)

Initial sightings and derby data from the red lionfish invasion (Pterois volitans) (Scorpaeniformes: Scorpaenidae) in Barbados.

Biodiversity data journal, 7:e38219 pii:38219.

Background: Native to the Indo-Pacific region, the lionfish (Pterois volitans and P. miles) has been classified as an alien invasive species which has rapidly invaded the North-western Atlantic and the Caribbean. The primary concerns regarding lionfish pertain to their broad diet, general habitat use and their potential threat on fisheries resources, native fish communities and human health. Away from natural predators, lionfish populations can easily become established and pose a serious threat to local fish species and ecosystem functioning. The first confirmed sighting of the red lionfish (Pterois volitans) in Barbados was in November 2011. Throughout 2012, fishermen and recreational divers were encouraged to report sightings of lionfish via an established hotline. Where possible, sightings were confirmed by way of the fish being captured and handed over to the Barbados Fisheries Division or the East Coast Conservation Organisation (ECCO) Inc. (an environmental NGO) for confirmation. In addition to confirmation, biological data (such as length, weight, sex and maturity) were also collected. Genetic research conducted on confirmed specimens collected between 2011-2013 identified the presence of only one species, P. volitans. Since the first confirmed sighting of the red lionfish in Barbados, it is believed that population numbers have steadily increased. One of the methods utilised in Barbados to control this alien invasive lionfish species is that of an annual derby. On 5 and 6 December 2015 and 13 November 2016, teams of divers (both free divers and SCUBA divers) took to the local waters to hunt for and kill lionfish. Caught lionfish were landed at scoring stations to be counted and allowed for the collection of basic biological data (such as length, weight, sex and maturity). In addition to biological data, teams (observers) also provided information on dive sites (locations) and associated geographic information (i.e. GPS coordinates), where available.

New information: These two datasets, initial sightings (2012) and derby data (2015 and 2016), present the first collected data for the red lionfish (P. volitans) in Barbados. The two datasets are occurrence datasets which document the identification of >1500 lionfish removed from the waters of Barbados between 2011 and 2016.

RevDate: 2019-09-19

Hu J, Yang M, Ye ER, et al (2019)

First record of the New Guinea flatworm Platydemus manokwari (Platyhelminthes, Geoplanidae) as an alien species in Hong Kong Island, China.

ZooKeys, 873:1-7 pii:36458.

The New Guinea flatworm (Platydemus manokwari) caused extinction of the native land snails on several Pacific island in past decades, and therefore it has been listed among the top 100 of the world's worst invasive alien species. Using morphological and molecular methods, New Guinea flatworms were discovered and identified for the first time in Hong Kong Island during a field investigation in July and August 2018. The flatworms were 32-60 mm long, 3-5 mm wide, and 1-2 mm thick. The dorsal side of the flatworm was dark brown with a thin yellow central line, and its ventral side appeared pale grey. To further verify this species, both 18S rDNA and mitochondrial cytochrome c oxidase subunit I gene (COX1) obtained from three specimens of P. manokwari were sequenced and analysed. While comparing these sequences with those previously deposited in GenBank, these 18S rDNA sequences shared 100% identity with the single available 18S rDNA sequence of P. manokwari; and the obtained COX1 sequences were identical to those of P. manokwari world genotype. Two native snails, Criptosoma imperator and Bradybaena similaris, have been found to be the prey of this predator during this investigation. Therefore, the invasive New Guinea flatworm certainly will cause a serious impact on the biodiversity of native snail populations, and an economic and environmental risk assessment for P. manokwari need to be completed in the near future in Hong Kong.

RevDate: 2019-09-19

Gomez-Zavaglia A, Prieto Lage MA, Jimenez-Lopez C, et al (2019)

The Potential of Seaweeds as a Source of Functional Ingredients of Prebiotic and Antioxidant Value.

Antioxidants (Basel, Switzerland), 8(9): pii:antiox8090406.

Two thirds of the world is covered by oceans, whose upper layer is inhabited by algae. This means that there is a large extension to obtain these photoautotrophic organisms. Algae have undergone a boom in recent years, with consequent discoveries and advances in this field. Algae are not only of high ecological value but also of great economic importance. Possible applications of algae are very diverse and include anti-biofilm activity, production of biofuels, bioremediation, as fertilizer, as fish feed, as food or food ingredients, in pharmacology (since they show antioxidant or contraceptive activities), in cosmeceutical formulation, and in such other applications as filters or for obtaining minerals. In this context, algae as food can be of help to maintain or even improve human health, and there is a growing interest in new products called functional foods, which can promote such a healthy state. Therefore, in this search, one of the main areas of research is the extraction and characterization of new natural ingredients with biological activity (e.g., prebiotic and antioxidant) that can contribute to consumers' well-being. The present review shows the results of a bibliographic survey on the chemical composition of macroalgae, together with a critical discussion about their potential as natural sources of new functional ingredients.

RevDate: 2019-09-18

Ribeiro LP, Carvalho T, Becker CG, et al (2019)

Bullfrog farms release virulent zoospores of the frog-killing fungus into the natural environment.

Scientific reports, 9(1):13422 pii:10.1038/s41598-019-49674-0.

Bullfrog farming and trade practices are well-established, globally distributed, and economically valuable, but pose risks for biodiversity conservation. Besides their negative impacts on native amphibian populations as an invasive species, bullfrogs play a key role in spreading the frog-killing fungus Batrachochytrium dendrobatidis (Bd) in the natural environment. Bullfrogs are tolerant to Bd, meaning that they can carry high infection loads without developing chytridiomycosis. To test the potential of bullfrog farms as reservoirs for diverse and virulent chytrid genotypes, we quantified Bd presence, prevalence and infection loads across approximately 1,500 farmed bullfrogs and in the water that is released from farms into the environment. We also described Bd genotypic diversity within frog farms by isolating Bd from dozens of infected tadpoles. We observed individuals infected with Bd in all sampled farms, with high prevalence (reaching 100%) and high infection loads (average 71,029 zoospore genomic equivalents). Average outflow water volume from farms was high (60,000 L/day), with Bd zoospore concentration reaching approximately 50 million zoospores/L. Because virulent pathogen strains are often selected when growing in tolerant hosts, we experimentally tested whether Bd genotypes isolated from bullfrogs are more virulent in native anuran hosts compared to genotypes isolated from native host species. We genotyped 36 Bd isolates from two genetic lineages and found that Bd genotypes cultured from bullfrogs showed similar virulence in native toads when compared to genotypes isolated from native hosts. Our results indicate that bullfrog farms can harbor high Bd genotypic diversity and virulence and may be contributing to the spread of virulent genotypes in the natural environment. We highlight the urgent need to implement Bd monitoring and mitigation strategies in bullfrog farms to aid in the conservation of native amphibians.

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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.

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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.

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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.

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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.

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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.

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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.

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This is a must read book for anyone with an interest in invasion biology. The full title of the book lays out the author's premise — The New Wild: Why Invasive Species Will Be Nature's Salvation. Not only is species movement not bad for ecosystems, it is the way that ecosystems respond to perturbation — it is the way ecosystems heal. Even if you are one of those who is absolutely convinced that invasive species are actually "a blight, pollution, an epidemic, or a cancer on nature", you should read this book to clarify your own thinking. True scientific understanding never comes from just interacting with those with whom you already agree. R. Robbins

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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).

Timelines

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

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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.

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