Invasive Social Wasp Research Articles

Cognitive abilities related to foraging behavior in Vespula vulgaris (Hymenoptera: Vespidae)

Vespula vulgaris is an invasive social wasp that has become established in many parts of the world. Plastic cognitive systems are expected to be advantageous for invasive species, given that they continuously face dynamic and unpredictable environments. We analyzed foraging behavior associated with undepleted and depleted resources. The wasps were trained to associate a certain location with food and we recorded their behavior after successive displacement of it. We also studied how long wasps continued to search for food that was no longer available and whether it was dependent on experience. We found that when wasps associated a certain location with food, they returned to the same site even though food was no longer available or had been displaced. Handling time remained constant, while relocation time and learning flights decreased with experience. With a food position change, learning flights increased and searching time varied with experience. When food was removed, hovering and landings were greatest in wasps that had the most experience with the resource, although extinction of the searching response was not dependent on experience. Our results illustrate the plasticity of wasp behavior in uncertain foraging contexts, which could have allowed the species to establish successfully in new habitats.

Worker trapping: a sustainable management tool for invasive social wasps?

The invasive social wasp Vespula germanica is a harmful pest, mainly in urban environments. Despite extensive research on ecology and control, there are currently no effective, sustainable strategies to manage populations in the invaded range. We evaluated the effects of worker trapping on V. germanica abundance and nest activity in Southern Argentina. During two consecutive years, a high-density trapping was deployed in four plots of one hectare each. The procedure consisted of placing 25 non-toxic meat-baited traps, creating a grid of 5 × 5 traps for 4 weeks. Worker wasp abundance and the traffic rate of all the nests in the plots were measured 1 week before and one after trapping. Our results showed that worker catches resulted in a 65% reduction in local wasp abundance and a 48% in traffic rate of nests within the treated area. Similarly, a decrease in wasp abundance was obtained one year after trapping. Employing worker trapping as a tool could prove useful and environmentally friendly in reducing local wasp abundance during peak activity.

Potential control of Vespula germanica and Polistes dominula (Hymenoptera: Vespidae) using entomopathogens

ABSTRACT The first recordings in South Africa of the invasive social wasps, Vespula germanica and Polistes dominula (Hymenoptera: Vespidae) were in 1974 and again in 2008. These wasps are known to represent a significant threat to the biodiversity of ecosystems and socio-economic activities in countries they invade. Here, the susceptibility of V. germanica and P. dominula larvae to indigenous species of entomopathogenic nematodes (EPNs), namely Heterorhabditis bacteriophora, H. noenieputensis and Steinernema yirgalemense, and entomopathogenic fungus (EPF) Beauveria bassiana was tested both in laboratory bioassays and in situ wasp nests application in the Western Cape province. The bioassay results indicate that both P. dominula and V. germanica larvae are susceptible to all biocontrol agents used. All larvae of both wasp species were dead and infected after exposure to 200 IJ/insect within four days after inoculation. Similar results were obtained seven days after inoculation with B. bassiana. To test in-field pathogenicity against P. dominula, wasp nests were treated with B. bassiana, H. bacteriophora, a mixture of the EPF and EPN species and a control of distilled water. The number of larvae and pupae infected 168 h after application were determined. In both cases, the mixture of EPF/EPN performed best, with a mean percentage of 31.39% ± 4.75% larvae infected, and only 3.42% ± 0.68% of pupae infected. The results obtained suggest that higher concentrations of selected biologicals can be used as inundative biological control agents within an integrated management programme for the control of P. dominula and V. germanica in South Africa. Highlights At 48 h after inoculation, 100% of the wasp larvae treated with EPN were infected After 168 h, 74–98% of EPF-treated larvae showed visual infection of Beauveria bassiana Heterorhabditis bacteriophora outperformed other biocontrol agents tested Combined EPN and EPF in situ nest application achieved larval infection of 31% ± 4.75%.

The outlook for control of New Zealand’s most abundant, widespread and damaging invertebrate pests: social wasps

Invasive social wasps (Vespula germanica and V. vulgaris) are probably the most damaging, widespread invertebrate pests in New Zealand. In large areas of beech forests they can attain a biomass as great as, or greater than, the combined biomasses of birds, rodents and stoats. Wasps are effective and voracious predators and pose a significant risk to human health. Here, we highlight the scale and diversity of wasp impacts and the opportunities to develop cost effective landscape-scale tools for wasp control. Toxic baits can be extremely effective for wasp control, though the most effective pesticide (fipronil) is currently not commercially available for wasp control within New Zealand. Significant progress has been made to enhance lures for toxin delivery, including the use of synthetic lures. Biological control could offer the possibility of controlling wasps over huge areas at reasonable cost, though previous releases of biocontrol agents have not been successful. Avenues for further biological control work, such as the use of pathogens or parasitoids, are encouraged. We believe it is necessary and strategic to develop a suite of control tools. We urge government and the public to take action to control the wasp problem and to designate one agency as having the prime responsibility for doing this. Given that wasps are harming our natural heritage and inhibiting or adversely affecting people’s enjoyment of natural areas, we look to the natural resource sector to drive research and implement solutions. This includes Department of Conservation, Ministry of Primary Industry and Councils.

Sugar responsiveness could determine foraging patterns in yellowjackets

Sympatric-related species often exhibit resource partitioning. This can occur through different mechanisms, such as behavioral, morphological, and sensory variations, leading to qualitative, temporal, or spatial differences in resource exploitation, such as consuming different types of food. Sensory-based niche partitioning could be the underlying mechanism through which closely related species effectively reduce niche overlap. Here we ask whether variations in sensory responses to carbohydrates could reflect differences in the foraging patterns of two Vespula species present in Patagonia. For this, we established (i) the response thresholds toward carbohydrate solutions of foraging V. germanica and V. vulgaris in the laboratory, (ii) the sugar concentration of foraged carbohydrates in the field, and (iii) possible effects of incoming sugar concentration and performance at individual and colony levels. Results indicate a higher sucrose response threshold in V. germanica than V. vulgaris. Field results indicate that higher carbohydrate concentrations foraged by V. germanica, with 57% of V. germanica foragers returning with concentrations above 50% w/w, while only 23% of V. vulgaris foragers did so. These differences in sucrose sensitivity and foraging patterns positively correlate with colony size, irrespective of the species. Our results suggest that competition could be reduced in these closely related invasive social wasp species through sensory differences in their sugar perception levels, which would lead to them foraging different carbohydrate sources. This study suggests that sensory niche partitioning could promote species coexistence in these social wasps.

Polistes dominula (Hymenoptera: Vespidae) paper wasps detect native grasshoppers using olfactory cues

AbstractPolistes dominula is an invasive social wasp that preys on the grasshopper Dichroplus elongatus, which constitutes a potential agricultural pest in Northwest Patagonia. This grasshopper feeds on a wide variety of plants, the ‘Dandelion’ (Taraxacum officinale) being one of the main food resources. In this study, by means of a Y‐tube olfactometer, we analysed the use of olfactory cues by P. dominula in the detection of grasshoppers. Specifically, we evaluated the attractiveness of live grasshoppers, their traces (i.e. leaves with herbivory traces + prey faeces or only faeces) and herbivory‐free leaves. The results showed that foragers equally chose olfactory cues emitted by grasshoppers and leaves with herbivory traces + faeces and herbivory‐free leaves, suggesting that the leaves of the host plant also have an important role in the searching behaviour. The current research is the first to demonstrate that the invasive paper wasp orients its search towards either the presence of grasshopper prey or the volatiles of plant leaves. These findings shed new light on predator‐prey interactions mediated by olfactory cues in P. dominula, which may play a biological role as a natural controller of D. elongatus, phytophagous pest in the invaded ecosystems.

Allee effects in an invasive social wasp: an experimental study in colonies of Vespula germanica

Allee effects rely on the existence of mutually beneficial intraspecific interactions that increase individual fitness and per capita growth rate, as the number of individuals in a population or group increases. When the number of individuals falls below a given number, the success of a group or population drops. Social insects heavily rely on cooperation between individuals for various tasks such as foraging and breeding. In this study, we experimentally explored component Allee effects and the underlying mechanisms in colonies of the social wasp Vespula germanica. After the removal of workers, we counted the number of gynes produced, estimated the body mass index as a proxy of their quality, and registered the protein-food collected by foragers in colonies. Our research revealed a correlation between the decrease in worker population and a subsequent decrease in the production of gynes. However, the removal of workers did not impact the quality of the produced gynes or the quantity of protein-food collected by the colonies. These findings highlight the crucial role of the worker caste in the success of eusocial species and suggested an ability of workers to perform multiple tasks that enable colonies to respond to disturbances. Additionally, our study provides the first evidence of Allee effects at the colony level of V. germanica, with potential practical implications for managing this invasive species.

Gene drives for invasive wasp control: Extinction is unlikely, with suppression dependent on dispersal and growth rates.

Gene drives offer a potentially revolutionary method for pest control over large spatial extents. These genetic modifications spread deleterious variants through a population and have been proposed as methods for pest suppression or even eradication. We examined the influence of local dispersal, long-distance and/or human-mediated dispersal, and variation in population growth on the success of a gene drive for the control of invasive social wasps (Vespula vulgaris). Our simulations incorporated a spatially realistic environment containing variable habitat quality in New Zealand. Pest eradication was not observed, except in extreme and unrealistic scenarios of constant, widespread, and spatially intense releases of genetically modified individuals every year for decades. Instead, the regional persistence of genetically modified and wild-type wasps was predicted. Simulations using spatially homogeneous versus realistic landscapes (incorporating uninhabitable areas and dispersal barriers) showed little difference in overall population dynamics. Overall, little impact on wasp abundance was observed in the first 15 years after introduction. After 25 years, populations were suppressed to levels <95% of starting populations. Populations exhibited "chase dynamics" with population cycles in space, with local extinction occurring in some areas while wasps became abundant in others. Increasing the wasps' local dispersal distance increased the spatial and temporal variability of the occupied area and population suppression. Varying levels of human-associated long-distance dispersal had little effect on population dynamics. Increasing intrinsic population growth rates interacted with local dispersal to cause higher mean populations and substantially higher levels of variation in population suppression and the total amount of landscape occupied. Gene drives appear unlikely to cause a rapid and widespread extinction of this and probably other pests but could offer long-term and cost-effective methods of pest suppression. The predicted level of <95% pest suppression would substantially reduce the predation pressure and competitive interactions of this invasive wasp on native species. However, the predicted long-term persistence of genetically modified pests will influence the ethics and likelihood of using gene drives for pest control, especially given concerns that modified wasps would eventually be transported back to their home range.

Gustatory responsiveness in Vespula germanica workers: exploring the interplay between sensory perception and task specialization.

Workers' task specialization and division of labor are critical features of social insects' ecological success. It has been proposed that the division of labor relies on response threshold models: individuals varying their sensitivity (and responsiveness) to biologically relevant stimuli and performing a specific task when a stimulus exceeds an internal threshold. In this work, we study carbohydrate and protein responsiveness and their relation to worker task specialization in Vespula germanica, an invasive social wasp. The sucrose and peptone responsiveness of two different subcastes, preforagers and foragers, was determined by stimulating the antenna of the wasps with increasing concentrations of the solution and quantifying whether each concentration elicited a licking response. We studied responsiveness in five different ways: (1) response threshold, (2) concentration 50 (concentration to which at least 50% of wasps responded), (3) maximum response, (4) mean scores and (5) median scores. Our results suggest that V. germanica foragers are more sensitive to sucrose (lower thresholds) than preforager workers. However, we found no differences for peptone thresholds (i.e., a protein resource). Nonetheless, this is the first study to investigate response thresholds for protein resources. The intercaste variation in sucrose responsiveness shown in our work contributes to the existing knowledge about response threshold theory as a mechanism for task specialization observed in V. germanica.

Assessment of the consumption of the exotic Asian Hornet Vespa velutina by the European Honey Buzzard Pernis apivorus in southwestern Europe

ABSTRACT Capsule The Asian Hornet Vespa velutina was the second most important species in the diet of the European Honey Buzzard Pernis apivorus in southwestern Europe, just four years after the appearance of the exotic wasp in the study area. Aims To assess the consumption of the invasive Asian Hornet by the European Honey Buzzard in southwestern Europe, following the Asian Hornet’s appearance there in 2014. Methods In northwestern Spain, we installed trail cameras in, and collected wasp comb remains from, nine nests of European Honey Buzzards (five in 2018 and four in 2019). We estimated the representation of the Asian Hornet in the birds’ diet, as well as the number of colonies attacked. We also compared the nesting frequency and density of breeding pairs before (2004–13) and after (2014–20) the Asian Hornet’s appearance. Results We detected consumption of the Asian Hornet at all the nests we examined. The Asian Hornet was the second most abundant wasp species in the diet and it was the most abundant in 2018 based on biomass. During the breeding season, each pair of European Honey Buzzards attacked 34–61 colonies in 2018 and 15–28 in 2019. Nesting frequency rose from 60% before the Hornet’s appearance to 100% afterward, while the density of breeding pairs increased by 300%. Conclusion Our results suggest that the Asian Hornet is becoming an important part of the diet of the European Honey Buzzard. This finding opens a research avenue to assess the potential role of the raptor in the management of the invasive social wasp.

The suppressive potential of a gene drive in populations of invasive social wasps is currently limited

Social insects are very successful invasive species, and the continued increase of global trade and transportation has exacerbated this problem. The yellow-legged hornet, Vespa velutina nigrithorax (henceforth Asian hornet), is drastically expanding its range in Western Europe. As an apex insect predator, this hornet poses a serious threat to the honey bee industry and endemic pollinators. Current suppression methods have proven too inefficient and expensive to limit its spread. Gene drives might be an effective tool to control this species, but their use has not yet been thoroughly investigated in social insects. Here, we built a model that matches the hornet’s life history and modelled the effect of different gene drive scenarios on an established invasive population. To test the broader applicability and sensitivity of the model, we also incorporated the invasive European paper wasp Polistes dominula. We find that, due to the haplodiploidy of social hymenopterans, only a gene drive targeting female fertility is promising for population control. Our results show that although a gene drive can suppress a social wasp population, it can only do so under fairly stringent gene drive-specific conditions. This is due to a combination of two factors: first, the large number of surviving offspring that social wasp colonies produce make it possible that, even with very limited formation of resistance alleles, such alleles can quickly spread and rescue the population. Second, due to social wasp life history, infertile individuals do not compete with fertile ones, allowing fertile individuals to maintain a large population size even when drive alleles are widespread. Nevertheless, continued improvements in gene drive technology may make it a promising method for the control of invasive social insects in the future.

New records and an annotated checklist of the thick-headed flies from Algeria (Conopidae, Brachycera, Diptera)

BackgroundThe Conopidae are an interesting family of small- to large-sized endoparasitic flies, commonly known as thick-headed flies. These flies have been proposed as potential biological control agents of invasive social wasps (subfamilies: Polistinae and Vespinae, family: Vespidae).ResultsAll known Algerian thick-headed flies (family Conopidae) are listed in the present study. Four subfamilies, nine genera and 23 species were treated. Three of these species are recorded herein from Algeria for the first time, namely Myopa pellucida (Robineau-Desvoidy), M. picta Panzer and Thecophora fulvipes (Robineau-Desvoidy). As far as they are known, Algerian localities and collection dates are provided, which comprise some new locality records. The data for this study were compiled from both available literature and material collected from some Algerian localities.ConclusionThe family Conopidae (thick-headed flies) is hitherto represented in Algeria by four subfamilies, nine genera and 23 species. Three of these species are recorded herein for the first time.

Microbiome of the wasp Vespula pensylvanica in native and invasive populations, and associations with Moku virus.

Invasive species present a worldwide concern as competition and pathogen reservoirs for native species. Specifically, the invasive social wasp, Vespula pensylvanica, is native to western North America and has become naturalized in Hawaii, where it exerts pressures on native arthropod communities as a competitor and predator. As invasive species may alter the microbial and disease ecology of their introduced ranges, there is a need to understand the microbiomes and virology of social wasps. We used 16S rRNA gene sequencing to characterize the microbiome of V. pensylvanica samples pooled by colony across two geographically distinct ranges and found that wasps generally associate with taxa within the bacterial genera Fructobacillus, Fructilactobacillus, Lactococcus, Leuconostoc, and Zymobacter, and likely associate with environmentally-acquired bacteria. Furthermore, V. pensylvanica harbors—and in some cases were dominated by—many endosymbionts including Wolbachia, Sodalis, Arsenophonus, and Rickettsia, and were found to contain bee-associated taxa, likely due to scavenging on or predation upon honey bees. Next, we used reverse-transcriptase quantitative PCR to assay colony-level infection intensity for Moku virus (family: Iflaviridae), a recently-described disease that is known to infect multiple Hymenopteran species. While Moku virus was prevalent and in high titer, it did not associate with microbial diversity, indicating that the microbiome may not directly interact with Moku virus in V. pensylvanica in meaningful ways. Collectively, our results suggest that the invasive social wasp V. pensylvanica associates with a simple microbiome, may be infected with putative endosymbionts, likely acquires bacterial taxa from the environment and diet, and is often infected with Moku virus. Our results suggest that V. pensylvanica, like other invasive social insects, has the potential to act as a reservoir for bacteria pathogenic to other pollinators, though this requires experimental demonstration.

Emerging patterns in social wasp invasions.

Invasive species are a main driver of biodiversity loss and ecological change globally. Consequently, there is a need to understand how invaders damage ecosystems and to develop effective management strategies. Social wasps (Hymenoptera: Vespidae) include some of the world's most ecologically damaging invasive insects. In recent decades, the invasive social wasp literature has grown rapidly. This may be due in part to increased rate of introduction as well as greater public awareness of invasive wasps and their potential negative impacts on bees. Here, we investigate trends in invasive social wasp research, identifying the emergence of Vespa invasions, the mechanism-based inquiry into Vespula invasions, and the increased application of molecular methods to track invasive species through the invasion process.

High-Quality Assemblies for Three Invasive Social Wasps from the Vespula Genus.

Social wasps of the genus Vespula have spread to nearly all landmasses worldwide and have become significant pests in their introduced ranges, affecting economies and biodiversity. Comprehensive genome assemblies and annotations for these species are required to develop the next generation of control strategies and monitor existing chemical control. We sequenced and annotated the genomes of the common wasp (Vespula vulgaris), German wasp (Vespula germanica), and the western yellowjacket (Vespula pensylvanica). Our chromosome-level Vespula assemblies each contain 176–179 Mb of total sequence assembled into 25 scaffolds, with 10–200 unanchored scaffolds, and 16,566–18,948 genes. We annotated gene sets relevant to the applied management of invasive wasp populations, including genes associated with spermatogenesis and development, pesticide resistance, olfactory receptors, immunity and venom. These genomes provide evidence for active DNA methylation in Vespidae and tandem duplications of venom genes. Our genomic resources will contribute to the development of next-generation control strategies, and monitoring potential resistance to chemical control.

The potential for a CRISPR gene drive to eradicate or suppress globally invasive social wasps

CRISPR gene drives have potential for widespread and cost-efficient pest control, but are highly controversial. We examined a potential gene drive targeting spermatogenesis to control the invasive common wasp (Vespula vulgaris) in New Zealand. Vespula wasps are haplodiploid. Their life cycle makes gene drive production challenging, as nests are initiated by single fertilized queens in spring followed by several cohorts of sterile female workers and the production of reproductives in autumn. We show that different spermatogenesis genes have different levels of variation between introduced and native ranges, enabling a potential ‘precision drive’ that could target the reduced genetic diversity and genotypes within the invaded range. In vitro testing showed guide-RNA target specificity and efficacy that was dependent on the gene target within Vespula, but no cross-reactivity in other Hymenoptera. Mathematical modelling incorporating the genetic and life history traits of Vespula wasps identified characteristics for a male sterility drive to achieve population control. There was a trade-off between drive infiltration and impact: a drive causing complete male sterility would not spread, while partial sterility could be effective in limiting population size if the homing rate is high. Our results indicate that gene drives may offer viable suppression for wasps and other haplodiploid pests.

Biogeography and anthropogenic impact shape the success of invasive wasps on New Zealand's offshore islands

AbstractAimThe theory of island biogeography predicts that the susceptibility of an island to invasion is determined by its isolation and size. However, many island ecosystems have been intensely modified by humans. Here, we investigated the biogeographic, biotic and anthropogenic drivers of invasive social wasps on 36 offshore islands.LocationIslands off the east coast of New Zealand's North Island.TaxaVespula germanica(Fabricius, 1793),Vespula vulgaris(Linnaeus, 1758) andPolistes chinensis antennalis(Fabricius, 1793), Polistes humilis(Fabricius, 1781).MethodsWe used GIS software for in situ randomization of plots on each island (36 islands, 409 plots) and conducted 5‐min wasp counts to estimate wasp abundance. Wasp abundance and canopy cover were recorded at each plot. Island isolation was measured using GIS software. Data on island size, human settlement and the presence of introduced rats (Rattusspp.) were collated from the literature and island managers. The number of boat docks per island was counted from satellite images. A generalized linear mixed‐effect model (GLMM) was fitted to identify drivers ofVespulaandPolistesabundance on offshore islands.ResultsThe abundance ofVespulawas negatively correlated with island isolation and canopy cover, yet positively correlated with island size.Vespulawere also more abundant on islands that have been settled by humans. The abundance ofPolisteswas negatively correlated with canopy cover. Finally, results did not support the notion that invasive wasps were associated with introduced rats on New Zealand's offshore islands.ConclusionsOur findings highlight the importance of biogeographic factors, such as island size and isolation, for species invasions, and suggest that intact forest cover could contribute to biotic resistance to invasive wasps in island ecosystems. Studies of invasive species should consider the joint effects of biogeographic, biotic and anthropogenic factors to best inform conservation management.

Antibacterial potential of Nidus vespae built by invasive alien hornet, Vespa velutina nigrithorax, against food‐borne pathogenic bacteria

AbstractThe yellow‐legged hornet, Vespa velutina nigrithorax, is an invasive social wasp found in temperate regions and is recognized as a hazardous insect, as it often attacks humans and honeybees. Nidus vespae (nests of social wasps) are traditionally used as a medicinal ingredient; thus, V. v. nigrithorax may be useful as a biological resource. Extracts of Nidus vespae built by V. v. nigrithorax were examined for their antibacterial activity screening against six food‐borne pathogenic bacteria, and the ethyl acetate and butanol layer of the extract exhibited inhibitory activity against the pathogenic bacteria. We determined the antibacterial activity of Nidus vespae built by V. v. nigrithorax for the first time.

Foraging niche separation of social wasps in an invaded area: Implications for their management

AbstractForaging niche separation may be a mechanism to promote coexistence of two competing species by concentrating intraspecific competition relative to interspecific competition. The present study investigated foraging behaviour and microhabitat use of two coexisting species of invasive social wasps, Vespula germanica and Vespula vulgaris, when foraging for two different food resources. Also, we tested the attractiveness of traps baited with a synthetic lure for those two species. We found that V. germanica wasps prefer to forage at ground level regardless of the resource, while V. vulgaris prefers protein resources at the shrubland level given a choice between a protein bait at ground or at shrubland level. However, when baited with the synthetic lure, the species caught was not affected by the height at which traps were placed. That is, in a no choice scenario, the traps were sufficiently attractive to lure both species of wasps to both microhabitats (ground and shrubland levels). Thus, our results support the existence of spatial niche differentiation at least in protein foraging and suggest that the synthetic lure evaluated could be used to trap both species of Vespula wasps present in Argentina. These results could help to improve management strategies of these social wasps in an invaded area.

Invasive social wasps

Invasive social wasps