Polistes Dominulus Research Articles

Carbohydrates are Important in IgE Binding to the Venom Serine Protease from Polistes dominulus

Carbohydrates are Important in IgE Binding to the Venom Serine Protease from Polistes dominulus

An anticoagulant serine protease from the wasp venom of Vespa magnifica

Wasp is an important venomous animal that can induce human fatalities. Coagulopathy is a clinical symptom after massive wasp stings, but the reason leading to the envenomation manifestation is still not known. In this paper, a toxin protein is purified and characterized by Sephadex G-75 gel filtration, CM-Sephadex C-25 cationic exchange and fast protein liquid chromatography (FPLC) from the venom of the wasp, Vespa magnifica (Smith). This protein, named magnvesin, contains serine protease-like activity and inhibits blood coagulation. The cDNA encoding magnvesin is cloned from the venom sac cDNA library of the wasp. The deduced protein from the cDNA is composed of 305 amino acid residues. Magnvesin shares 52% identity with allergen serine protease from the wasp Polistes dominulus. Magnvesin exerted its anti-coagulant function by hydrolyzing coagulant factors TF, VII, VIII, IX and X.

Two experimental tests of the relationship between group stability and aggressive conflict in Polistes wasps

Two field experiments were used to examine how the relative benefits of cooperation influence within-group conflict in foundress associations of the paper wasp Polistes dominulus. P. dominulus foundresses can either nest alone or cooperate with other foundresses. We experimentally manipulated the relative benefits of co-foundress associations vs independent reproduction and tested the effect on aggressive within-group conflict. First, we examined aggression between alpha and beta co-foundresses before and after lower-ranking foundresses were removed. Removal of subordinates increases the relative contributions of the remaining subordinates to group reproductive output as there are fewer adults to care for the brood. Transactional models predict that group conflict over reproductive shares will increase as the relative benefits of grouping increase. As predicted, aggression between the co-foundresses significantly increased following subordinate removal. Second, we experimentally reduced ecological constraints on independent nesting by placing a previously orphaned, adoptable nest comb near the occupied nests. Providing an independent breeding opportunity is predicted to increase the benefits of independent reproduction relative to those of cooperating, thereby reducing group stability and aggression. As predicted, aggression between dominant and subordinate foundresses significantly decreased after the orphaned comb was presented. Therefore, group members sense variation in ecological constraints and relative productivity contributions and quickly modulate their behavior in response. Overall, these two experiments suggest that paper wasps behave as if within-group competition is limited by the threat of group dissolution such that stable groups where cooperation is strongly favored can withstand higher levels of conflict than unstable groups.

Circulating hemocytes from larvae of the paper wasp Polistes dominulus (Hymenoptera, Vespidae)

Circulating hemocytes from larval stages of the paper wasp Polistes dominulus were characterized by light and transmission electron microscopy. Three types were identified: prohemocytes, plasmatocytes and granulocytes. The first two are agranular cells while the latter present typical cytoplasmic inclusions called granules. Plasmatocytes differ from prohemocytes being larger, showing lower nucleus/cytoplasm ratio and they possess many phagolysosomes. The substantial uniformity of most subcellular features and the presence of “intermediate forms” support the “single-cell theory” i.e., there is only one cell line that originates from the prohemocyte and leads to the granular cell passing through the plasmatocyte. This hypothesis seems to be confirmed by functional tests. Indeed, most part of cells adheres to the glass and is able to phagocytize fluorescent microspheres.

Modes of colony foundation by females of different morphotypes in the paper wasps (Hymenoptera, Vespidae, Polistes Latr.)

Paper wasps of the genus Polistes exhibit wide variability both of the color and size of foundresses, and the mode of colony foundation. The colony foundation and social hierarchy were studied in populations of two Palaearctic species, Polistes dominulus (Christ) and P. nimphus (Christ) (April–May 2006, the Crimean Peninsula, Ukraine), and one Neotropical species, P. lanio (F.) (October 2004–January 2005, Trinidad Island). It was shown that foundresses of various color and size morphs tended to found nests in a peculiar way: singly (haplometrosis), by groups (pleometrosis), or occupying several nests simultaneously (polycaly). The relationship between coloration, size, and mode of colony foundation was species-specific. P. dominulus foundresses with a darker clypeus and a paler mesonotum preferred to found nests alone and had a dominant position in pleometrosis. The haplometrotic P. nimphus foundresses more often displayed darker variants of the clypeus and paler variants of the mesonotum than did foundresses from pleometrotic colonies. P. lanio foundresses from pleometrotic colonies differed from those from polycalic colonies in the coloration variability of the scutum, propodeum, and the 2nd metasomal tergite. The dominant and subordinate P. nimphus and P. lanio foundresses differed in the size of head and wings. The possible significance of the subdivision of foundresses into the “generalists” and “specialists” for the variability structuring in the population is considered.

Not only cuticular lipids: First evidence of differences between foundresses and their daughters in polar substances in the paper wasp Polistes dominulus

Several studies have shown that differences in the relative abundance of cuticular hydrocarbons occur between reproductives and non-reproductives in many social insects. These differences also exist between Polistes dominulus foundresses and their first emerged daughters (usually indicated as workers), but they gradually disappear when workers from orphaned colonies develop their ovaries and assume a reproductive role in the colony. However, hydrocarbons are not the exclusive components of cuticular layer of wasps. Mass-spectrometry analysis of cuticular methanol extracts from Polistes paper wasps showed a complex pattern of polar substances, partly or totally proteinaceous in nature. We found that these compounds, ranging from 918 to 2679 Da, showed a clear caste differentiation between foundresses and their first emerged daughters (usually indicated as “workers”), both in queen-right and in orphaned colonies. Conversely to hydrocarbons, workers from orphaned colonies maintain a significant difference from foundresses in the pattern of the medium molecular weight (MW) polar compounds obtained by MALDI-TOF. On the basis of such results we hypothesize that a reliable cue to identify foundresses from daughters, and not only their reproductive status, may exist in Polistes wasps. Although the great majority of previous work on social insect communication has focused on cuticular hydrocarbons, our findings suggest that the medium MW component of cuticular substances may be involved in recognition.

FUNCTIONAL RESPONSES: A QUESTION OF ALTERNATIVE PREY AND PREDATOR DENSITY

Throughout the study of ecology, there has been a growing realization that indirect effects among species cause complexity in food webs. Understanding and predicting the behavior of ecosystems consequently depends on our ability to identify indirect effects and their mechanisms. The present study experimentally investigates indirect interactions arising between two prey species that share a common predator. In a natural field experiment, we introduced different densities of mealworms (Tenebrio molitor), an alternative prey, to a previously studied predator-prey system in which paper wasps (Polistes dominulus) preyed on shield beetle larvae (Cassida rubiginosa). We tested if alternative prey affects predation on the first prey (i.e., the predator-dependent functional response of paper wasps) by modifying either interference among predators or the effective number of predators foraging on shield beetles. Presence of mealworms significantly reduced the effective number of predators, whereas predator interference was not affected. In this way, the experimentally introduced alternative prey altered the wasps' functional response and thereby indirectly influenced C. rubiginosa density. In all prey-density combinations offered, paper wasps constantly preferred T. molitor. This led to an asymmetrical, indirect interaction between both prey species: an increase in mealworm density significantly relaxed predation on C. rubiginosa, whereas an increase in C. rubiginosa density intensified predation on mealworms. Such asymmetrical outcomes of a fixed food preference can significantly affect the population dynamics of the species involved. In spite of the repeated finding of a Type III functional response in this system, our experiment did not reveal switching behavior in paper wasps. The variety of mechanisms underlying direct and indirect interactions within our study system exemplifies the importance of incorporating alternative prey when investigating the impact of a generalist predator on a focal prey population under realistic field conditions.

Predatory Behavior of Polistes dominulus Wasps in Response to Cardenolides and Glucosinolates in Pieris napi Caterpillars

To examine how plant allelochemicals in prey affect foraging choices made by generalist predator paper wasps, Polistes dominulus (Vespidae), we compared predation on Pieris napi (Pieridae) caterpillars reared on host plants with different allelochemicals. In naturalistic behavioral choice experiments, free-flying wasps chose between living pierids reared on cabbage (Brassica oleracea), which lacks deterrent allelochemicals, or alternate host plants with potentially deterrent allelochemicals. The alternative host plants were: wormwood mustard, (Erysimum cheiranthoides: Brassicaceae), which contains cardenolides; nasturtium (Tropaeolum majus: Tropaeolaceae) with high concentrations of chlorogenic acid; and black mustard (Brassica nigra: Brassicaceae) with high concentrations of the aliphatic glucosinolate, sinigrin. Although wasps captured equal numbers of caterpillars reared on cabbage and each alternate host plant, they spent significantly longer handling prey from the alternate host plants as they selectively removed the caterpillar's gut, which contained the plant material. This was true even if the caterpillar did not sequester toxins in its tissues, as revealed by high performance liquid chromatography (HPLC) analysis of Erysimum-reared pierids. Because handling time is longer, predators that capture pierids containing non-sequestered allelochemicals experience an overall reduction in foraging rate that may translate into a fitness cost.

Trade‐offs in oviposition choice? Food‐dependent performance and defence against predators of a herbivorous sawfly

AbstractThe sawfly Athalia rosae L. (Hymenoptera: Tenthredinidae) is a feeding specialist on plant species of the Brassicaceae, which are characterised by secondary metabolites, called glucosinolates. The larvae can take up the respective glucosinolates of their hosts and concentrate them in their haemolymph to protect themselves against predators. Oviposition preferences of naïve females were tested for three species, Sinapis alba L., Brassica nigra (L.) Koch, and Barbarea stricta Andrz., and were related to larval performance patterns. Larvae were reared on either one of these plants and it was investigated how host‐plant quality influences both the developmental times and growth of larvae (bottom‐up) and the defence efficiency against predators (top‐down). Innately, almost all adult females avoided B. stricta for oviposition and clearly preferred B. nigra over S. alba. On average, larvae developed best on B. nigra. Female larvae reached similar final body masses on all host‐plant species, but males reared on S. alba were slightly lighter. The developmental time of larvae reared on B. stricta was significantly longer than on the other two plants. However, larvae reared on B. stricta were best protected against the predatory wasp Polistes dominulus Christ (Hymenoptera: Vespidae). The wasps rejected these larvae most often, while they attacked larvae reared on S. alba most frequently. Thus, larvae feeding on B. stricta theoretically run a higher risk of predation due to a prolonged developmental time, but in practice they are better protected against predators. Overall, oviposition preferences of A. rosae seem to be more influenced by bottom‐up effects on larval performance than by top‐down effects.

Ventricular fibrillation after a hymenoptera sting

A 54-year-old male, who had presented 2 ventricular fibrillation (VF) episodes with post-anoxic coma and later a return to consciousness and to a sinusal rhythm after defibrillation, have been placed a ventricular intracavitary stimulator (AICD). Since all the tests including the coronarygraphy have been found normal, we have paid attention to the anamnesis revealing an Apis mellifera sting before both VF episodes, previously considered irrelevant for the absence of relevant local symptoms. Intracutaneous tests were negative to Vespula sp. and positive to A. mellifera extract at a concentration of 0.01 μg/ml. Specific IgE for A. mellifera venom presented values of 2,36 U/ml for A. mellifera and < 0.35 U/ml per Vespula sp. and Polistes dominulus. The patient was then submitted to ITS with A. mellifera aqueous extract. During the RASH treatment no adverse reactions have been observed, whereas we witnessed a major adverse reaction, 3 min after the first 100 mcg maintenance dose, controlled with anti-H1 and cortisone reaction, nevertheless no reactions were observed during the 3 years the same dosage has been repeated monthly. Our case supports the hypothesis of an anaphylactic reaction as trigger of vasoconstriction in individuals affected by ventricular arrhythmia not explained with other causes such as a coronary disease, a myocardiopathy or a pharmacological toxicity. Arrhythmia can be a serious outbreak of a mediated IgE allergic reaction even without any relevant local symptoms. The diagnostics with lyophilized A. mellifera venom has been proven safe in a patient who suffered a cardiac anaphylaxis.

Developmental strategy of the endoparasite Xenos vesparum (strepsiptera, Insecta): Host invasion and elusion of its defense reactions

To successfully complete its endoparasitic development, the strepsipteran Xenos vesparum needs to elude the defense mechanisms of its host, the wasp Polistes dominulus. SEM and TEM observations after artificial infections allow us to outline the steps of this intimate host-parasite association. Triungulins, the mobile 1st instar larvae of this parasite, are able to "softly" overcome structural barriers of the larval wasp (cuticle and epidermis) without any traumatic reaction at the entry site, to reach the hemocoel where they settle. The parasite molts 48 h later to a 2nd instar larva, which moves away from the 1st instar exuvium, molts twice more without ecdysis (a feature unique to Strepsiptera) and pupates, if male, or develops into a neotenic female. Host encapsulation involves the abandoned 1st larval exuvium, but not the living parasite. In contrast to the usual process of encapsulation, it occurs only 48 h after host invasion or later, and without any melanization. In further experiments, first, we verified Xenos vesparum's ability to reinfect an already parasitized wasp larva. Second, 2nd instar larvae implanted in a new host did not evoke any response by hemocytes. Third, we tested the efficiency of host defense mechanisms by implanting nylon filaments in control larval wasps, excluding any effect due the dynamic behavior of a living parasite; within a few minutes, we observed the beginning of a typical melanotic encapsulation plus an initial melanization in the wound site. We conclude that the immune response of the wasp is manipulated by the parasite, which is able to delay and redirect encapsulation towards a pseudo-target, the exuvia of triungulins, and to elude hemocyte attack through an active suppression of the immune defense and/or a passive avoidance of encapsulation by peculiar surface chemical properties.

Evaluation of the IgE cross‐reactions among vespid venoms. A possible approach for the choice of immunotherapy

Hymenoptera venom allergy can be effectively cured with specific immunotherapy, thus the correct identification of the allergen is essential. In the case of multiple skin and serum positivities it is important to know if a cross-reaction among venoms is present. We studied by CAP-inhibition assays the degree of cross-reactivity between Vespula vulgaris and Polistes dominulus. Serum samples were obtained from consecutive patients with a clinical history of grade III-IV reactions to hymenoptera sting and with nondiscriminative skin/CAP positivity to both Vespula and Polistes. Inhibition assays were carried out with a CAP method, incubating the sera separately with both venoms and subsequently measuring the specific immunoglobulin E (IgE) to venoms themselves. Forty-five patients (33 male, mean age 40 years, age range 12-74, total serum IgE 242 +/- 168 kU/l) were included. Their specific IgE to Vespula and Polistes were 12.03 +/- 5.70 kU/l and 10.7 +/- 2.0 kU/l (P = NS), respectively. At the CAP-inhibition assays, in 25 patients a >75% heterologous inhibition by P. dominulus venom against V. vulgaris-specific IgE was found. In six subjects V. vulgaris venom effectively inhibited the P. dominulus-specific IgE. In the remaining 14 cases the CAP-inhibition test provided intermediate and not discriminative results. In 31/45 patients, the double sensitizations to venoms were probably the result of cross-reactions and the CAP-inhibition allowed identifying the true double sensitizations. This approach may be helpful for the correct prescription of immunotherapy in the case of V. vulgaris and P. dominulus double positivity.

Polistes dominulus (Hymenoptera: Vespidae) larvae possess their own chemical signatures

Social insects use cuticular hydrocarbons (CHCs) as recognition cues in a variety of social contexts, such as species and nestmate recognition. Discrimination of nestmates is an important requisite to avoid exploitation by unrelated individuals. In social wasps, use of CHCs in nestmate recognition has been demonstrated only among adults, whereas very little is known regarding brood recognition. We performed gas chromatography–mass spectrometry analyses of the CHCs of adults and larvae of the social wasp Polistes dominulus and found that larvae possess a characteristic chemical colony-specific pattern distinct from that of adults. Behavioural assays confirmed that these are recognized and discriminated by adults. Larval epicuticular substances are therefore sufficient for recognition of nestmate larvae by adults and demonstrate that wasps are able to discriminate between alien and nestmate larval odours.

Rearing conditions influence quality signals but not individual identity signals in Polistes wasps

Given the diversity of animal signals, there has been recent interest in categorizing signals into probable functions according to their properties. For example, models predict that signals of quality should be costly and condition dependent, whereas signals of individual identity should be cheap and expressed independently of condition. Here, we test these predictions by comparing the condition dependence of signals of individual identity and quality in Polistes wasps. Polistes fuscatus wasps have black and yellow patterns on the face and abdomen that signal individual identity, whereas Polistes dominulus wasps have black and yellow facial patterns that signal aspects of quality related to dominance. We reared both species with and without supplemental food and examined the facial patterns of the resulting offspring. As predicted, food availability did not influence the development of identity signals in P. fuscatus. In strong contrast, P. dominulus wasps reared with supplemental food had facial patterns that signaled higher levels of quality than P. dominulus reared without supplemental food. Interestingly, the identity and quality signals have different condition dependence, despite being composed of similar pigments, suggesting that signal function has a stronger influence on signal properties than pigmentation. Because body size is often correlated with quality signal elaboration, we also tested how food supplementation influenced offspring size. In both species, supplemented colonies produced smaller offspring than nonsupplemented colonies, suggesting that queens may invest in producing fewer, larger offspring in stressful environments.

Bionomics and morphological and molecular characterization of Elasmus schmitti and Baryscapus elasmi (Hymenoptera: Chalcidoidea, Eulophidae), parasitoids associated with a paper wasp, Polistes dominulus (Vespoidea, Vespidae)

Abstract Elasmus schmitti and Baryscapus elasmi have been recorded in southern Ukraine as gregarious parasitoids in the nests of the paper wasps Polistes dominulus and Polistes nimphus. Polistes dominulus nests infested with E. schmitti were less productive than uninfested nests in only one year (2004) of the three years of the present study, when an increase in the host population size occurred. Females of E. schmitti are synovigenic, and they lay their eggs on the skins of P. dominulus last instar larvae, without paralyzing the host. Rather, the parasitoid larvae feed on young host pupae. The pupae of E. schmitti are isolated from the host remnants by a thin fecal partition as in Elasmus polistis and Elasmus japonicus, other paper wasp parasitoids. Baryscapus elasmi is a pupal endoparasitoid of E. schmitti. The females of B. elasmi emerge without mature eggs in their ovaries and mate with males. They penetrate the paper wasp’s cells with their ovipositor and feed on the extracted hemolymph exudate. Pupation of B. elasmi occurs inside or outside the pupa of the host, E. schmitti. If inside, then the cranial end of the pupa and the adult emergence hole of B. elasmi are situated in the caudal ends of the pupae of their hosts. Comparative notes and illustrations on the morphology of adults are provided, and DNA sequences of three genes (nuclear 28S D2 rDNA, mitochondrial cytochrome oxidase subunit I, and mitochondrial cytochrome b) were obtained for both parasitoid species. The similarity of the 28S D2 sequences of E. schmitti and E. polistis relative to other available Elasmus sequences suggests a single origin of parasitism on paper wasps in this genus.

Unusual reaction to hymenoptera sting: a case of Schönlein‐Henoch purpura

Here is a case of Schonlein-Henoch syndrome, a secondary unusual reaction of allergy to the bite of a stinging hymenoptera. A 12-year-old patient has come under our observation for the appearance of nettle-rash papule and later on of palpable purpura with small bruises on the lower limbs and gluteuses, reporting nonspecific abdominal pains. After 3 days, we have observed association of arthralgias on both ankles and knees. A similar occurrence had already happened a year earlier and had been interpreted as secondary to acute streptococcal tonsillopharyngitis. To an accurate anamnesis following the second event, we found out that the patient had been stung by a bee just a few days earlier. The same thing had happened the year before but this detail at the time had not been considered important and therefore not studied more carefully. The patient though was normally tolerant to Dyptera bites. The skin tests with hymenoptera dehydrated extract (1) have been proved positive to 0,1 mcg/ml, with a 3rd Class RAST, to Apis mellifera, but negative to Vespula sp, Polistes dominulus and Tabanus sp. The skin biopsy specimen revealed a leukocytoclastic vasculitis (Fig. 1). All these clinical data, their follow-up and the bioptical result have enabled us to diagnose a SchonleinHenoch (SHP) relapsing purpura. The SHP is a form of vasculitis to hypersensitivity characterized by smallvessels inflammation, with a mainly cutaneous clinical interest, usually observed in children, with tissue depositing of immunocomplex (ICC) containing IgA. The main clinical manifestations are characterized by a symptomatological tetrad: (i) cutaneous purpura, a must criteria for the diagnosis, mainly on the lower limbs and glutaeuses; (ii) arthralgia, occuring in 75% of the cases; (iii) abdominal pain colitis type (in 70%) with intestinal bleedings (in 40%); (iv) kydney alterations nephritis like (in 30%) with hematuria episodes. The aetiology is unknown, but it is considered as main unleashing factors, the role played by viral and bacterial infections, the use of medicines and drugs, coldness, some nonspecific toxins, systemic diseases, tumoural pathologies and insect stings. A fundamental element of the damage because of ICC is the increasing vascular permeability, which allows their passage among the endothelium cells. Cochrane et al. (2) demonstrated that both histamine and serotonine are the chemical mediators responsible for the vessel-permeabilization process. They are also allowing to fix a considerable quantity of ICC. Furthermore, also mast cells, triggered eosinophils and basophiles are able to release externally a wide range of inflammation mediators such as vasoactive amines, metabolites of arachidonic acid, cytokines (3). The further activation of the complement amplifies the inflammatory process with the production of chemiotactic factors for neutrophiles, which once triggered releases lysosomial enzymes. We believe that this vasculitis has been secondary to the release of mediators from mast cells in an individual allergic to hymenoptera venom and not secondary to the toxicity of the venom itself. Our case is the third one reported in literature (4,5) of this unusual reaction triggered by an insect sting, but the first one reported after anhymenoptera sting in a patient allergic to Apis m. In fact, in our case, the urticaria has shortly preceeded the ourbreak of petechial eruption connected to the vasculitis pathology development, representing therefore an initial stage of hypersensitivity of the III type more than an aspect of the IgE-mediated reaction, which acted as a trigger factor. Even the histological examination gave evidence of a vasculitis but void of a relevant eosinophil reaction. This is why our patient underwent only one pharmacological treatment but has not been addressed to any specific immunotherapy (6).

The midgut ultrastructure of the endoparasite Xenos vesparum (Rossi) (Insecta, Strepsiptera) during post-embryonic development and stable carbon isotopic analyses of the nutrient uptake

Females of the endoparasite Xenos vesparum (Strepsiptera, Stylopidae) may survive for months inside the host Polistes dominulus (Hymenoptera, Vespidae). The midgut structure and function in larval instars and neotenic females has been studied by light and electron microscope and by stable carbon isotopic technique. The 1st instar larva utilizes the yolk material contained in the gut lumen, whereas the subsequent larval instars are actively involved in nutrient uptake from the wasp hemolymph and storage in the adipocytes. At the end of the 4th instar, the neotenic female extrudes with its anterior region from the host; the midgut progressively degenerates following an autophagic cell death program. First the midgut epithelial cells accumulate lamellar bodies and then expel their nuclei into the gut lumen; the remnant gut consists of a thin epithelium devoid of nuclei but still provided with intercellular junctions. We fed the parasitized wasps with sugar from different sources (beet or cane), characterized by their distinctive carbon isotope compositions, and measured the bulk 13C/ 12C ratios of both wasps and parasites. Female parasites developing inside the wasp hemocoel are able to absorb nutrients from the host but, after their extrusion, they stop incorporating nutrients and survive thanks to the adipocytes content.

Behaviour and chemical signature of pre-hibernating females of Polistes dominulus infected by the strepsipteran Xenos vesparum

Polistes dominulus are social wasps which are the host of the strepsipteran endoparasite Xenos vesparum. In the hibernating phase, unparasitized and parasitized wasps leave natal nests and aggregate together in sheltered quarters. In aggregations, wasps are socially active, and some individuals perform helping behaviour. Here we investigated if castrated parasitized wasps perform worker tasks in mixed aggregations. Moreover, by gas chromatography and mass spectrometry, we examined the cuticular hydrocarbons of unparasitized and parasitized wasps to evaluate if the infection alters the composition of cuticular waxes that are recognition cues in social insects. In clusters, infected females do not perform helping behaviour and they are less active than unparasitized wasps. Cuticular hydrocarbons are slightly differentiated between unparasitized and parasitized wasps but, generally, unparasitized wasps are more similar to wasps infected by Xenos females compared to wasps infected by Xenos males. Wasps infected by Xenos males do not usually survive the winter. This chemical similarity is probably a consequence of the similar physiological condition of unparasitized and female-affected Polistes wasps. At this stage, it is difficult to affirm whether these modifications are a true parasite manipulation or a consequence of infection.

Attraction to Ornamental Peony (Paeonia lactiflora, Paeoniaceae) by Polistes dominulus Christ (Hymenoptera: Vespidae) Demonstrated Using Olfactometers

Observations were made of Polistes dominulus Christ (Hymenoptera: Vespidae) on budding Paeonia lactiflora plants (Paeoniaceae). Y-tube and parallel tube olfactometer experiments were performed on field-collected queens and workers to determine if peony odor is attractive to P. dominulus. In Y-tube olfactometer experiments, the wasps showed a significant orientation response toward peony bud odor but they did not show a significant response toward peony foliage odor, when compared to the control. Peony bud volatiles were collected in an adsorbent trap and tested in a parallel tube olfactometer for attractiveness to P. dominulus females. The wasp took significantly less time to travel upwind in the peony bud volatile tube compared to the control tube. Chemicals that produce peony bud odor could serve as a feeding attractant lure for trapping P. dominulus.

Wolbachia in the invasive European paper wasp Polistes dominulus

The European paper wasp Polistes dominulus has been expanding its North American range since its introduction in the 1970s. We screened P. dominulus from Italy and the northeastern U.S. for the presence of the intracellular reproductive symbiont Wolbachia. Infection rates among females varied from 16% to 87% among U.S. sites and from 33% to 71% in Italy. We also found infected haploid and diploid males, indicating that this is not a male-killing Wolbachia infection. Our data show that infected individuals from New York, Massachusetts, and Italy carry the same Wolbachia strain, and that some mtDNA haplotypes include both infected and uninfected individuals. We discuss possible implications of Wolbachia infection in this invasive social hymenopteran.