Polistes Dominulus Research Articles

EUROPEAN PAPER BEES, POLISTES DOMINULA AND POLISTES NIMPHA (CHRIST, 1791) (HYMENOPTERA: VESPIDAE) PATHOGENS PRESENCE AND THEIR POTENTIAL INSECTICIDAL EFFECTS ON HONEYBEES ADULTS OF APIS MELLIFERA CAUCASIA (POLLMANN, 1889)

Honeybee (Apis mellifera) is an important element of biodiversity and terrestrial ecosystems. Any pathogenic infection in this beneficial insect can lead to major undesirable disasters. This study investigated the pathogenic bacteria and fungi from Polistes dominula and Polistes nimpha wasps and their potential insecticidal effects on Apis mellifera caucasia. For this purpose, bacteria and fungi were isolated from dead and diseased bees collected from Terme district of Samsun province in Türkiye in May and June 2020. In the study, Granulicatella adiacens, Staphylococcus xylosus, Sphingomonas paucimobilis bacteria and Cryptococcus laurentii and Candida famata fungi were obtained from the internal tissues and organs of Polistes dominula paper wasp adults. Staphylococcus xylosus and Sphingomonas paucimobilis were found to be common bacteria in both bee species. Serratia marcescens and Enterococcus faecalis bacterial species were found to have a very lethal effect on honeybees. Bioassay experiments were performed on the detected fungi, and it was observed that Cryptococcus laurentii and Candida famata fungi species also had lethal effects on honeybees. It has been revealed that entomopathogenic bacteria, which are known to be very effective in biological control against harmful insects, can cause unwanted infections in honeybees.

Future Range Expansions of Invasive Wasps Suggest Their Increasing Impacts on Global Apiculture.

Until now, no study has examined the future range dynamics of major invasive wasp species to assess their future impacts on global apiculture. Here, we developed 12 species distribution models to calibrate the future range dynamics of 12 major invasive Vespidae wasp species under a unified framework. An increase in their habitat suitability was identified in more than 75% of global land. Substantial range expansions were detected for all 12 species, and they were primarily induced by future climate changes. Notably, Polistes dominula and Vespa crabro had the largest potential ranges under all scenarios, suggesting their greater impact on global apiculture. Polistes chinensis and Vespa velutina nigrithorax had the highest range expansion ratios, so they warrant more urgent attention than the other species. Polistes versicolor and P. chinensis are expected to exhibit the largest centroid shifts, suggesting that substantial shifts in prioritizing regions against their invasions should be made. Europe and the eastern part of the USA were future invasion hotspots for all major invasive wasp species, suggesting that apiculture might face more pronounced threats in these regions than in others. In conclusion, given their substantial range shifts, invasive wasps will likely have increasingly negative impacts on global apiculture in the future.

Chronic urticaria as an atypical reaction after a vespid bite

Background: Hymenoptera stings can produce IgE-mediated reactions, toxic reactions, or atypical reactions, which are rare. Cold urticaria has been described among the cutaneous manifestations in the atypical ones, but there is only one case of chronic urticaria. Case report: A 56-year-old female patient experienced palmoplantar pruritus and generalized urticaria 60 minutes after two vespid stings, requiring medical assistance and several cycles of home treatment with oral antihistamines and corticosteroids for resolution in 12 weeks. Allergological studies showed normal tryptase and primary sensitization to Polistes dominula venom. Given the patient's profession, venom immunotherapy was started with Polistes dominula 100% without recurrence of urticaria after its administration. Conclusions: We present a case of IgE-mediated systemic reaction followed by self-limited chronic urticaria, related chronologically to the same vespid sting trigger. Keywords: Chronic urticaria; Hymenoptera; Vespid; Polistes dominula; IgE-mediated reaction.

Subtle morphological changes in the visual and antennal sensory system of bees and wasps across an urbanisation gradient

Increased temperature and fragmentation of green spaces in urban areas could drive variations in functional traits of insects. Such morphological shifts may occur for sensory systems, which were previously reported to be prone to change with habitat characteristics in non-urban contexts. Here, we measured traits related to the visual and antennal sensory systems in the bees Halictus scabiosae and Osmia cornuta and the wasp Polistes dominula along an urbanisation gradient within Milan (Italy). We hypothesised that fragmentation could filter for better visual properties, and that higher temperature could filter for fewer thermoreceptors and more olfactory hairs. While controlling for body size, results show subtle but appreciable responses to urbanisation in one or more traits in all species, though not always supporting our hypotheses. O. cornuta shows marginally higher ommatidia density and smaller ommatidia diameter (associated with better visual resolution) in more fragmented sites, as well as marginally fewer thermoreceptors in hotter sites, in agreement with our two predictions. On the other hand, H. scabiosae has marginally smaller antennae and P. dominula has smaller eyes at warmer locations, and the wasp also has smaller antennae and 9th flagellomeres in more fragmented areas. Perhaps higher temperatures accelerate development of sensory system at higher speed than the rest of body in these two species. Our results represent the first evidence of urbanisation effects on the visual and antennal sensory systems of bees and wasps and underline how such effects may involve a much broader bouquet of traits then previously observed.

Temperature differently affects body pigmentation of the paper wasp Polistes dominula along an urban and a wider geographical gradient

In insects, different pigments, such as melanins and pterins, are involved in thermoregulation. The degree of melanisation often varies along geographical gradients, according to the so-called thermal melanism hypothesis, i.e. darker forms are found in colder places because they can warm up more quickly. Similarly, pterins work as heat sinks and thus are expected to be more abundant in colder sites. Cities, which are warmer than surrounding areas (Urban Heat Island (UHI) effect), might also be expected to influence pigmentation, although studies are lacking. Here, we sampled workers of the social paper wasp Polistes dominula (Christ, 1791) (Vespidae) across an urbanisation gradient in an Italian metropolis and used iNaturalist pictures of this species across Italy to study pigmentation patterns at both urban and larger geographical scales. We found a lower yellow intensity of abdominal spots at warmer locations. Scanning Electron Microscopy strongly suggested that yellow colouration is due xanthopterin, known to be the heat sink molecule in other social vespids. Thus, wasps from warmer (i.e., urban) environments are likely to have fewer xanthopterin granules, in line with the lack of need for heat storage due to the local thermal gradient (UHI effect). At the country level, we found that wasps at higher latitudes had smaller yellow spots on the thorax and only two spots instead of four at higher altitudes, in full accordance with the thermal melanism hypothesis. In conclusion, climatic conditions seem to affect insect colour patterns both along urban and wider geographical gradients, although colour changes may affect different body parts and pigments likely according to different needs.

The role of molecular diagnosis in anaphylactic patients with dual or triple-sensitization to Hymenoptera venoms

BackgroundThe poly-sensitization to Hymenoptera venom makes it difficult to select genuine allergens for immunotherapy and increases patients’ costs. The objective of this study was to determine the culprit allergen in dual or triple-sensitized patients to three Hymenoptera venoms through molecular diagnosis and evaluating the results of incorporating the molecular diagnosis with skin tests.MethodsThirty-two patients with anaphylactic reactions and dual or triple-sensitization to Hymenoptera venoms in skin tests entered this study. IgE-sensitization to whole extracts and molecules of Apis mellifera (Api m), Vespula vulgaris (Ves v), and Polistes dominulus (Pol d) was evaluated utilizing ALEX or ImmunoCAP.ResultsTwenty-nine patients (90.6%) were male. IgE-sensitization to at least one of the allergenic molecules related to Apis mellifera, Vespula vulgaris, and Polistes dominulus was seen in 59.4, 53.1, and 21.9%, respectively. Among 32 patients, 14 (43.8) and 8 (25%), were mono-sensitized to Api m and Ves v components in ALEX, respectively. Double sensitization to Hymenoptera was identified in 18.8% of patients in ALEX. Api m 1+/Api m 2−/Api m 10− and Ves v 1+/Ves v 5+ demonstrated the most prevalent sensitizations patterns in our patients.ConclusionsThe molecular diagnosis of IgE-sensitization to Hymenoptera venoms can be valuable, especially in patients who show dual or triple-sensitization in skin tests, as the ALEX results revealed mono and double-sensitization to Hymenoptera venoms in 22 and 6 patients, respectively. Regarding the high cost and adverse reactions of venom immunotherapy, especially for two or three venoms, incorporating the molecular diagnosis alongside skin tests for accurate diagnosis of the culprit venom could help decrease costs for patients.

The costs of overwintering in paper wasps (Polistes dominula and Polistes gallicus): the use of energy stores

Overwintering insects are facing energetic challenges because of food shortage, low temperature, and desiccation stress. Paper wasps of the genus Polistes overwinter as mated adults (gynes) in hibernacula protecting them from predation, snow, and rain but barely from low environmental temperature. In different climates, they face differing overwintering temperature regimes, and therefore they may differ in their energy use. We investigated how much of energy resources built up until autumn is used during diapause dormancy in natural hibernacula by measuring lipid, glycogen, and free carbohydrate content in autumn and early spring in Polistes dominula from temperate European (Austrian) and warm Mediterranean (Italian) climate and Polistes gallicus from Mediterranean climate. Winter energy consumption amounted to ~ 339 and ~ 310 J per wasp in the Austrian and Italian Polistes dominula populations. The smaller Italian Polistes gallicus consumed ~ 247 J. This amounts to 2.62, 2.35, and 1.79 J per day. Of this, the energy demand was mainly fuelled by lipids (84%, 93%, and 90%, respectively), but glycogen stores contributed also considerably (16%, 6%, and 9%). Free carbohydrates decreased only by 0.7%, 1%, and 0.8%. While fat stores seem still sufficient in spring, the wasps depleted most of their carbohydrates. The energy reserves of 396, 400, and 147 J per wasp remaining in spring in the three populations seem sufficient to fuel rest or simple brood care activities for a whole summer but restrict foraging flights to a few hours (~ 3.5–6 h). Results suggest that energy supply might become challenging in expected future climate scenarios.

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%.

Urbanisation reduced body size but potentially improved flight performance in bees and wasps

Urbanisation is a main driver of land-use change, leading to rising in temperatures and fragmentation and reduction of green areas. Bees and wasps, which are important insect groups due to the ecosystem services they provide, may respond to this disturbance via changes in morphological traits which are functionally relevant. To date, studies focusing on this aspect only investigated few social bee species, and often gave contrasting results even at intra-generic level. Here, we studied how body size, wing loading, wing aspect ratio and wing fluctuating asymmetry vary in a social ground-nesting bee (Halictus scabiosae), a solitary hole-nesting bee (Osmia cornuta) and a social paper wasp (Polistes dominula) along an urbanisation gradient within Milan (Italy). By assessing the effects of temperature, green areas fragmentation and vegetation productivity on the above-listed functional traits, we found the three species to variably respond to increasing urbanisation, albeit the driving environmental parameters differed among species. More specifically, smaller individuals were sampled in warmer (for bees) and in less productive (for wasps) areas along the urbanisation gradient. Furthermore, greater wing aspect ratio values were recorded at warmer locations for H. scabiosae, lower wing loading was recorded at more fragmented sites for O. cornuta, and greater wing loading was recorded at locations with greater productivity for P. dominula. H. scabiosae and P. dominula showed greater wing fluctuating asymmetry at more fragmented sites. Although distinct species seemed sensitive to different driving factors, our results point toward a consistent response: smaller body but potentially improved flight performance in more urbanised environments.

Relationship between Nest and Body Temperature and Microclimate in the Paper Wasp Polistes dominula.

The paper wasp Polistes dominula is a thermophilic species originating from the Mediterranean climate, but is now widely spread in Europe. They live in quite differing habitats; and as synanthropic species, they have been established in human settlement areas. They build a single small comb at protected places with a favorable microclimate. We measured the temperature of the wasps, the nests and their environment at typical nesting sides in Austria (Europe) in the temperate climate, in order to reveal relationships between nest and body temperature and the habitats' microclimate. The temperatures of the comb and of the wasps' body were in a wide range (~20-37 °C) above the ambient air temperature at the nest. This is an advantage as higher temperatures accelerate the development speed of the brood. However, the mean comb temperature did not exceed approximately 38.6 °C. This was managed by cooling efforts of the adult wasps. The ambient air temperature near the nest (~1-2 cm) was always clearly elevated above the ambient air temperature at a local standard weather station in the habitat. A comparison with climate-model-generated macroclimate data revealed the necessity of measuring microclimate data for a reliable description of the insects' thermal environment.

Adverse effects of the fungal biopesticide Beauveria bassiana on a predatory social wasp

Biopesticides are considered eco-friendly alternatives to synthetic agrochemicals. However, their impact on non-target organisms is still poorly understood. Social wasps, in particular, are a largely neglected group when it comes to risk assessment of plant protection products, despite the relevant ecological and economic services provided by these insects. In the present study, we evaluated the impact of a common biopesticide, the entomopathogenic fungus Beauveria bassiana, on the paper wasp Polistes dominula. We adopted a holistic approach in ecotoxicology by focusing not only on the detrimental effects on isolated individuals, but also on the whole colony. Both adult wasps belonging to different castes and immature larvae were topically exposed to a field-realistic concentration of fungal spores from the commercial strain of B. bassiana ATCC 74040 to assess the impact of the biopesticide on their survival, behavior and physiology. Our results showed that the fungus causes a number of adverse effects on P. dominula, that include increased mortality, altered locomotion and feeding rate, selective ejection of exposed larvae from nests, reduced oviposition rate and ovary development in foundresses, and colony failure. Our findings provide new insights on the often-neglected sublethal effects of pollutants that can jeopardize not only individual beneficial insects, but also the delicate social balance of their colonies and their valuable ecosystem services, highlighting that the natural origin of plant-protection products does not always guarantee environmental safety.

Using wasps as a tool to restore a functioning vine grape mycobiota and preserve the mycobial “terroir”

In the last one-hundred years, the exponential expansion of wine making has artificialized the agricultural landscape as well as its microbial diversity, spreading human selected Saccharomyces cerevisiae strains. Evidence showed that social wasps can harbor a significant fraction of the yeast phenotypic diversity of a given area of wine production, allowing different strains to overwinter and mate in their gut. The integrity of the wasp-yeast ecological interaction is of paramount importance to maintain the resilience of microbial populations associated to wine aromatic profiles. In a field experiment, we verified whether Polistes dominula wasps, reared in laboratory and fed with a traceable S. cerevisiae strain, could be a useful tool to drive the controlled yeast dispersion directly on grapes. The demonstration of the biotechnological potential of social insects in organic wine farming lays the foundations for multiple applications including maintenance of microbial biodiversity and rewilding vineyards through the introduction of wasp associated microbiomes.

A clear-cut difference in nuptial strategies may shape sperm traits in two paper wasps

Abstract Spermatozoa vary in quantity, quality and design across species and individuals. Here, we reported the first detailed analysis of sperm traits in two primitively eusocial paper wasps, Polistes dominula and Polistes gallicus, which differ in their nuptial strategies and body size as follows: lek-territoriality of the large P. dominula males, defending exclusive territories at landmarks; scramble competition of the small P. gallicus, where serial mating may occur because males interfere with rivals and replace them during copulation. We compared the number, viability, and length of sperm, and its coefficient of variation, between these sympatric paper wasps patrolling and marking the same landmarks during the same summer: a good opportunity to analyse sperm across species while controlling for environmental variables. Spermatozoa were more numerous and longer in P. dominula than in P. gallicus males. Viability was similar in both species and positively covaried with male body size. Intra-male variation in sperm length was significantly reduced in P. gallicus, as predicted in the case of selection for an optimal sperm design. We hypothesized that precopulatory sexual selection (lek-territoriality vs. scramble competition) may affect sperm traits.

P233 ACUTE CORONARY SYNDROME AFTER WASP BITE (KOUNIS SYNDROME)

Abstract Kounis syndrome (KS) is defined as an acute coronary syndrome (SCA) associated with an anaphylactic reaction. A 64–year–old sports man with no previous cardiovascular disease arrived at the emergency room of our Hospital for dyspnoea and chest pain arising during physical activity e preceded by a syncopal episode. During the physical activity (cycling) the patient reported that he had felt an insect bite sensation, with no possibility of precisely identify it. Parameters an admission were: BP 85/45 mmHg, HR 70 bpm, on ECG signs of early repolarization (Fig. 1), blood tests rise in hsTNI (328 ng/L), normal D–dimer. The transthoracic echocardiogram showed no motion abnormalities. In the suspicion of KS, therapy was set up only with ASA and statin, avoiding any drug commonly used to treat allergic reactions that could have worsen the hemodynamic and vasomotor situation by further reducing the coronary perfusion. During hospitalization, in consideration of the clinical picture and cardiovascular risk factors (dyslipidemia and previous smoking), was performed coronary angiography, which showed no obstructive lesions, but during the first injection of contrast showed vasospasm of the ostium of the right coronary artery, dominant (Fig. 2 – left), resolved spontaneously (Fig. 2 – right). The post–procedural hsTNI peak (3953 ng/L) and the presence of the European paper wasp i77 antigen to the serological dosage of the allergens supported the pathophysiology of acute coronary syndrome concomitant with allergic reaction and supported the diagnostic hypothesis of KS type I (without underlying coronary artery disease). The patient was discharged with calcium channel blocker therapy, to reduce coronary vasospasm which characterizes KS, and short–term follow–up was planned with blood tests, exercise stress test and cardiological visit which were normal. KS, though rare, is a clinical entity that should not be underestimated, especially in allergic patients with evidence of SCA without coronary occlusions. The data available in the literature are scarce and it is not clear the medium and long term prognosis. It therefore seems reasonable to follow up the patients as outpatient cardiology visits especially in the first months after the event and schedule instrumental tests control.

Test di attivazione dei basofili (BAT): quale utilità nella diagnostica dell'allergia a veleno di imenotteri?

BACKGROUND: The diagnosis of Hymenoptera venom allergy (HVA) relies on detailed anamnesis, skin tests and determination of specific IgE (sIgE) with extractive and molecular allergens of Apidae and Vespidae. In many patients, however, multiple venoms sIgE positivity is detected and it is not always possible to clearly determine the primary sensitization or whether there is true double sensitization, and therefore to prescribe a proper venom-specific immunotherapy (VIT). In these cases, the in vitro sIgE inhibition test can add valuable information. However, this test requires extensive experience and has some limitations in case of low sIgE values and in case of high levels of sIgE anti-cross reactive carbohydrate determinants (CCD). Recently, the use of basophil activation test (BAT) has been recommended in order to identify the primary sensitization in subjects in which molecular testing and/or sIgE inhibition have been inconclusive. Aim of the study was to evaluate the usefulness of BAT in a selected cohort of subjects who experienced allergic reactions following hymenoptera sting, history suggestive of Vespid sting and inconclusive sIgE assay.METHODS: Nineteen subjects with allergic reactions following hymenoptera sting (17 with systemic reactions and two with extensive local reactions) were studied. Of those, six patients showed multiple sIgE positivity for Vespidae and positivity sIgE for Apis mellifera (Apis m) and anti-CCD (5/6) too; six patients complained reactions after hymenoptera sting but with negativity of Apis m and Vespidae sIgE (≤0.10 kU/L), and seven patients showed very low sIgE levels (0.11-0.84 kU/L) for extractive and/or molecular Vespidae allergens. In all subjects, the following were performed: the sIgE assay for Vespula sp, Polistes dominulus (Polistes d), Vespa crabro, Apis m, Ves v 1, Ves v 5 and Pol d 5 (ImmunoCAP 1000, Thermofisher Scientific), and BAT in which extractive venoms of Vespula sp (BAG2-I3) and Polistes d (BAG2-I77), (Bühlmann Laboratories AG), were used for basophil stimulation. The response, measured as percentage of activated basophils (CD63+) at the different venom concentrations, was evaluated by cytofluorimetric method with FACSCanto™ II (Becton Dickinson). The sIgE inhibition assay was performed by overnight incubation at 4 °C of serum with venom extract in solution (Anallergo), at decreasing concentrations of 300, 30, 3 and 0.3 µg/mL, followed by sIgE assay.RESULTS: BAT detected the primary sensitizer in 6/19 (32%) subjects including one with negative sIgE and three with very low sIgE, while sIgE assay identified the primary sensitizer in 5/19 (26%) including four concordant with BAT. BAT in 6/19 (32%) cases allowed diagnosis of dual sensitization, of which half (3/6) confirmed by inhibition test, five concordant with sIgE assay by molecular technique, and one with negative sIgE. In one of seven cases of dual sensitization evidenced by molecular testing, BAT was decisive and in one case negative. In 2/7 (29%) patients with negative sIgE for molecular allergens, BAT was positive for Vespula sp (in one of these, similar activation was obtained for Vespula sp and Polistes d at different venom concentrations).CONCLUSIONS: This study proved that BAT is useful in confirming true double sensitizations and slightly more sensitive than molecular testing in identifying single sensitization to Vespidae venom, both in cases with negative sIgE (≤ 0.10 kU/l), and in subjects with multiple positivities for Vespidae, even where anti-CCD antibodies are present. These data, therefore, confirm the importance of combining multiple laboratory methods for precision diagnosis of HVA and more accurate choice of VIT.

Insights into the prey of Vespa mandarinia (Hymenoptera: Vespidae) in Washington state, obtained from metabarcoding of larval feces.

The northern giant hornet, Vespa mandarinia (Hymenoptera: Vespidae), was detected for the first time in North America in 2019. Four nests have since been located and removed in northwestern Washington State as part of an extensive survey and eradication program. This recent introduction into North America has prompted new research on the biology and ecology of V. mandarinia to help inform management strategies. In its native range, V. mandarinia is known to prey on a variety of insects including the economically important honey bee species Apis cerana and Apis mellifera. Although A. cerana has developed defense mechanisms against attack by V. mandarinia, A. mellifera have no such defenses and an entire hive can be quickly destroyed by only a few hornets. In North America the hornet has been observed foraging on paper wasps (Polistes dominula) and honey bees, but little else is known about prey use in its novel range. To address this knowledge gap, we employed a DNA metabarcoding approach to characterize species detected in larval feces collected from 3 of the 4 Washington V. mandarinia nests found to date. Sequences were recovered for 56 species across fourteen orders, of which 36 species were likely prey items and 20 were suspected inquilines. The most frequently detected species were other social Hymenoptera, with Dolichovespula maculata, P. dominula, and A. mellifera present in most samples. All of the species detected, except for A. mellifera, represent new prey records for V. mandarinia, with eight families of insects newly associated with giant hornets. These results suggest that V. mandarinia in Washington preys on an assortment of insects similar to those documented in its native range, and that this new invader has readily incorporated novel species into its foraging and diet.

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.

Gene silencing for invasive paper wasp management: Synthesized dsRNA can modify gene expression but did not affect mortality.

Invasive paper wasps such as Polistes dominula are a major pest and problem for biodiversity around the globe. Safe and highly targeted methods for the control of these and other social wasp populations are needed. We attempted to identify potentially-lethal gene targets that could be used on adult paper wasps in a gene silencing or RNA interference (RNAi) approach. Double-stranded RNA (dsRNA) was designed to target genes for which silencing has proven lethal in other insects. dsRNA was provided either orally to foragers or directly injected into the wasps. We also provided the dsRNA unprotected or protected from degradation by gut nucleases in two different forms (lipofectamine and carbon quantum dots). The effects of oral delivery of 22 different gene targets to forager wasps was evaluated. The expression of five different genes was successfully reduced following dsRNA ingestion or injection. These gene targets included the FACT complex subunit spt16 (DRE4) and RNA-binding protein fusilli (FUSILLI), both of which have been previously shown to have potential as lethal targets for pest control in other insects. However, we found no evidence of significant increases in adult wasp mortality following ingestion or injection of dsRNA for these genes when compared with control treatments in our experiments. The methods we used to protect the dsRNA from digestive degradation altered gene expression but similarly did not influence wasp mortality. Our results indicate that while many of the same gene targets can be silenced and induce mortality in other insects, dsRNA and RNAi approaches may not be useful for paper wasp control.

Automated detection of the yellow-legged hornet (Vespa velutina) using an optical sensor with machine learning.

The yellow-legged hornet (Vespa velutina) is native to Southeast Asia and is an invasive alien species of concern in many countries. More effective management of populations of V. velutina could be achieved through more widespread and intensive monitoring in the field, however current methods are labor intensive and costly. To address this issue, we have assessed the performance of an optical sensor combined with a machine learning model to classify V. velutina and native wasps/hornets and bees. Our aim is to use the results of the present work as a step towards the development of a monitoring solution for V. velutina in the field. We recorded a total 935 flights from three bee species: Apis mellifera, Bombus terrestris and Osmia bicornis; and four wasp/hornet species: Polistes dominula, Vespula germanica, Vespa crabro and V. velutina. The machine learning model achieved an average accuracy for species classification of 80.1 ± 13.9% and 74.5 ± 7.0% for V. velutina. V. crabro had the highest level of misclassification, confused mainly with V. velutina and P. dominula. These results were obtained using a 14-value peak and valley feature derived from the wingbeat power spectral density. This study demonstrates that the wingbeat recordings from a flying insect sensor can be used with machine learning methods to differentiate V. velutina from six other Hymenoptera species in the laboratory and this knowledge could be used to help develop a tool for use in integrated invasive alien species management programs. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Гильдии жалоносных перепончатокрылых (Hymenoptera: Aculeata) - посетителей соцветий золотарников (Solidago L.) в условиях открытых биотопов Национального парка «Нарочанский»

The study of anthophilous insects carried out in 2019-2021 in open field areas in the territory of Narochansky National Park revealed 42 species for the flower visitor guild of native European goldenrod (Solidago virgaurea L.) and for the flower-visitor guild of invasive goldenrods Solidago canadensis s. l. - 50 species of Aculeata (Hymenoptera). The taxonomic structure of guilds is different: only 11 species are present in both guilds, among visitors of S. virgaurea inflorescences the species richness of Apoidea is higher (38 species, 90 % of their total number), whereas for S. canadensis inflorescences -of Vespoidea s. l. (31 species, 62 %). There were no dominant species in the studied guilds; in the guild of S. virgaurea inflorescence visitors, the group of common species included bumblebees Bombus lucorum L. and Bombus (Psithyrus) bohemicus Seidl, the group of numerous species - bumblebees Bombus humilis Ill., Bombus lapidarius L., Bombus pratorum L., Bombus terrestris L. and Cuckoo bumblebee Bombus (Psithyrus) rupestris F. Polistine wasps Polistes nimpha Christ and Polistes dominula Christ were common among visitors of S. canadensis inflorescences; Ancistrocerus trifasciatus Mull., Philanthus triangulum F., Lasioglossum varipes Morawitz, and B. terrestris were numerous. The relative abundance of B. terrestris was the highest, approaching the threshold value for assignment to the group of numerous species. It is suggested that high relative abundance of Vespoidea s. l. visiting inflorescences of invasive goldenrods is connected to the fact that adult wasps not only feed on flowers, but prey on small insects that are numerous here.