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The Western blot is a highly sensitive and efficient technique in diagnosing allergy to wasp venom.

BACKGROUND: Diagnosis of allergy to wasp venom and decision to perform immunotherapy are based on the patient's history, along with skin and in vitro tests. OBJECTIVE: Given the high prevalence of specific IgE also in non-allergic individuals, we evaluated the sensitivity and specificity of Western blots as a possible alternative to serum analyses of venom-specific IgE. METHODS: Skin prick and/or intracutaneous tests were performed in 30 patients with allergy to wasp venom (generalized reaction following sting) along with serum analysis of venom-specific IgE (AlaSTAT microplate) and Western blots. Western blots were subsequently scanned and evaluated qualitatively and semiquantitatively by means of densitometry. Bands were scored 'positive' in cases of signal intensities beyond the mean plus 3 standard deviations of control sera. Twenty newborns (age 2-7 days) and 30 adults without systemic or increased local reactions to hymenoptera stings served as controls. RESULTS: Western blot sensitivity reached 100% in the samples studied and was thus superior to the sensitivities of serum analysis of venom-specific IgE using AlaSTAT microplate assay (90%) and skin tests (87%). The sensitivity of detection of a phospholipase A1 and antigen 5-specific band was higher compared with a hyaluronidase-specific band (97%, 97% and 86%, respectively). Twenty-four out of twenty-nine (83%) patients exhibited specific IgE antibodies against at least three distinct allergens. With regard to the specificities, skin tests as well as AlaSTAT microplate assays were comparable (90% and 93%, respectively), whereas the specificity of the Western blots was 70% if the appearance of any single band was regarded as a positive result. However, when analysing the appearance of a specific band for antigen 5 or hyaluronidase the specificity and overall diagnostic value increased markedly, making it the most efficient test (specificity 97% and 100%, efficiency 96.8% and 93.2%, respectively). CONCLUSION: As allergy to wasp venom is a severe and potentially life threatening disease, false-negative test results need to be minimized. Therefore, the superiority of the Western blot with regard to sensitivity, specificity and overall efficiency makes this technique a valuable tool for its diagnosis.

Adolescent↗

Increasing parasitism by the German yellow jacket wasp, Paravespula germanica, on dairy cattle in Israel.

During the past two decades, parasitism by the German yellow jacket wasp, Paravespula germanica, on lactating dairy cattle has occurred in Israel during August to October annually, affecting up to 65% of cows in certain herds. The nibbled and exposed tissues of teats and sometimes udders become infested by bacteria, especially Streptococcus dysgalactiae and Actinomyces pyogenes, causing clinical and subclinical mastitis. Normally, German wasps are primarily insect predators, but the urbanization around many dairy farms has reduced open space and associated standard food sources, i.e. insects, plants and carcasses. This has resulted in P. germanica nesting more often on dairy farms. In some instances, when high densities of P. germanica correspond with scarcity of prey, a segment of the wasp population preys primarily on the older and heavier cows with weak defensive behaviour. The teat feeding colonies of P. germanica may have an advantage, in that they are less dependent on fluctuations in the number of prey insects.

Animals↗

Hierarchical genetic structure of the introduced wasp Vespula germanica in Australia.

The wasp Vespula germanica is a highly successful invasive pest. This study examined the population genetic structure of V. germanica in its introduced range in Australia. We sampled 1320 workers and 376 males from 141 nests obtained from three widely separated geographical areas on the Australian mainland and one on the island of Tasmania. The genotypes of all wasps were assayed at three polymorphic DNA microsatellite markers. Our analyses uncovered significant allelic differentiation among all four V. germanica populations. Pairwise estimates of genetic divergence between populations agreed with the results of a model-based clustering algorithm which indicated that the Tasmanian population was particularly distinct from the other populations. Within-population analyses revealed that genetic similarity declined with spatial distance, indicating that wasps from nests separated by more than approximately 25 km belonged to separate mating pools. We suggest that the observed genetic patterns resulted from frequent bottlenecks experienced by the V. germanica populations during their colonization of Australia.

Animals↗

Acute tubulointerstitial nephritis after wasp stings.

A 61-year-old Caucasian man presented with acute renal failure after multiple wasp stings. The patient required dialysis support temporarily. Work-up failed to show rhabdomyolysis or hemolysis and a kidney biopsy revealed acute allergic interstitial nephritis. The patient's renal function recovered completely after a short course of steroid therapy. Acute renal failure after wasp stings is typically caused by acute tubular necrosis in the setting of hemolysis or rhabdomyolysis. Compared with previously reported cases of acute renal failure associated with bee stings, our patient is unique in that his renal failure was caused by a hypersensitivity reaction apparently to the wasp venom.

Animals↗

In situ modification of herbivore-induced plant odors: a novel approach to study the attractiveness of volatile organic compounds to parasitic wasps.

Many parasitic wasps (parasitoids) exploit volatile organic compounds (VOCs) emitted by herbivore-infested plants in order to locate their hosts, but it remains largely unknown which specific compounds within the volatile blends elicit the attractiveness to parasitoids. One way of studying the importance of specific VOCs is to test the attractiveness of odor blends from which certain compounds have been emitted. We used this approach by testing the attraction of naive and experienced females of the two parasitoids Cotesia marginiventris and Microplitis rufiventris to partially altered volatile blends of maize seedlings (Zea mays var. Delprim) infested with Spodoptera littoralis larvae. Adsorbing filter tubes containing carbotrap-C or silica were installed in a four-arm olfactometer between the odor source vessels and the arms of the olfactometer. The blends breaking through were tested for chemical composition and attractiveness to the wasps. Carbotrap-C adsorbed most of the sesquiterpenes, but the breakthrough blend remained attractive to naive C. marginiventris females. Silica adsorbed only some of the more polar VOCs, but this essentially eliminated all attractiveness to naive C. marginiventris, implying that among the adsorbed compounds there are some that play key roles in the attraction. Unlike C. marginiventris, M. rufiventris was still attracted to the latter blend, showing that parasitoids with a comparable biology may employ different strategies in their use of plant-provided cues to locate hosts. Results from similar experiments with modified odor blends of caterpillar-infested cowpea (Vigna unguiculata) indicate that key VOCs in different plant species vary greatly in quality and/or quantity. Finally, experienced wasps were more strongly attracted to a specific blend after they perceived the blend while ovipositing in a host. Considering the high number of distinct adsorbing materials available today, this in situ modification of complex volatile blends provides a new and promising approach pinpointing on key attractants within these blends. Advantages and disadvantages compared to other approaches are discussed.

Adsorption↗

The adaptive significance of host location by vibrational sounding in parasitoid wasps.

Vibrational sounding, which is a form of echolocation, is a means of host location by some parasitoid wasps. The wasp taps the substrate (wood, stem or soil) and detects the position of a potential host through the returning 'echoes'. The deployment of vibrational sounding is inferred through the form of the subgenual organ in the female tibia in combination with the presence of modifications to the female antenna used for tapping the substrate. Vibrational sounding and its associated modifications were found in two families. The use of vibrational sounding by parasitoid wasps was positively correlated with the depth of the host in the substrate relative to the size of the parasitoid. There were also significant correlations between the use of vibrational sounding and parasitism of immobile and concealed hosts and between vibrational sounding and idiobiosis. The data suggested that vibrational sounding evolved under a variety of ecological conditions, being employed in the location of wood-boring, stem-boring, soil-dwelling and cocooned hosts and stem-nesting aculeates, often in situations in which the host does not produce vibrations itself.

Acoustics↗

Selfish element maintains sex in natural populations of a parasitoid wasp.

Genomic conflicts between heritable elements with different modes of inheritance are important in the maintenance of sex and in the evolution of sex ratio. Generally, we expect sexual populations to exhibit a 1:1 sex ratio. However, because of their biology, parasitoid wasps often exhibit a female-biased sex ratio. Sex-ratio distorters can further alter this optimum, sometimes leading to the complete loss of sexual reproduction. In the parasitoid wasp Trichogramma kaykai ca. 4-26% of females in field populations are infected with a bacterial sex-ratio distorter, Wolbachia, allowing virgin mothers to produce daughters. In some micro-Hymenoptera these infections have led to the complete loss of sex, but in field populations of T. kaykai the proportion of individuals infected remains relatively stable. We tested several hypotheses to explain this low infection level, including inefficient and horizontal transmission of Wolbachia, suppressor genes negating the effect of Wolbachia and the presence of male-biasing sex-ratio distorters. Here, a male-biasing sex-ratio distorter, a parasitic B chromosome, causing females to produce only sons, keeps the frequency of Wolbachia low. The male-biasing factor of T. kaykai is the second known case of a B chromosome manipulating the reproduction of a parasitoid wasp.

Animals↗

Complex social behaviour can select for variability in visual features: a case study in Polistes wasps.

The ability to recognize individuals is common in animals; however, we know little about why the phenotypic variability necessary for individual recognition has evolved in some animals but not others. One possibility is that natural selection favours variability in some social contexts but not in others. Polistes fuscatus wasps have variable facial and abdominal markings used for individual recognition within their complex societies. Here, I explore whether social behaviour can select for variability by examining the relationship between social behaviour and variability in visual features (marking variability) across social wasp taxa. Analysis using a concentrated changes test demonstrates that marking variability is significantly associated with nesting strategy. Species with flexible nest-founding strategies have highly variable markings, whereas species without flexible nest-founding strategies have low marking variability. These results suggest that: (i) individual recognition may be widespread in the social wasps, and (ii) natural selection may play a role in the origin and maintenance of the variable distinctive markings. Theoretical and empirical evidence suggests that species with flexible nesting strategies have reproductive transactions, a type of complex social behaviour predicted to require individual recognition. Therefore, the reproductive transactions of flexible species may select for highly variable individuals who are easy to identify as individuals. Further, selection for distinctiveness may provide an alternative explanation for the evolution of phenotypic diversity.

Animals↗

Convergent incidences of Wolbachia infection in fig wasp communities from two continents.

Wide surveys suggest that Wolbachia bacteria infect ca. 20% of all insect species, but particular taxonomic or ecological groups may display significantly higher or lower incidences. We studied 61 fig wasp species in Australia and found the highest known incidence (67%) of infection in a targeted study of this nature. A comparable study in Panama reported a similar figure (59%), confirming the exceptionally high incidence of Wolbachia in fig wasps. Importantly, these are two independent estimates of Wolbachia incidence in fig wasp communities, because no host species, or even genera, are shared between localities. The high level of infection may reflect enhanced opportunities for horizontal transmission inside fig fruits. Although incidence was similar in Panama and Australia, the actual strains involved were different and region-specific. Local strains were shared by several host species, although there was often no obvious (direct) ecological link between two hosts with the same infection.

Animals↗

Biological and molecular features of the relationships between Diadromus pulchellus ascovirus, a parasitoid hymenopteran wasp (Diadromus pulchellus) and its lepidopteran host, Acrolepiopsis assectella.

The Diadromus pulchellus ascovirus (DpAV) has been isolated from laboratory strains of Diadromus pulchellus and in natural wild populations collected from the Antibes locality (southern France). The DpAV genome was found in the cells of the head, thorax and abdomen of this hymenopteran wasp. DpAV virions are present in the female genitalia and are transmitted to the nymphal lepidopteran host, Acrolepiopsis assectella, at each oviposition of the female wasp. The presence of the DpAV genome in all Diadromus somatic cells suggests that it is inherited by vertical transmission. DpAV is amplified in the host tissues during the larval development of D. pulchellus in A. assectella. Cell lysis due to amplification of the virus does not prevent the development of the hymenopteran larva. Virus amplification appears to be slower in nymphs parasitized by D. pulchellus than in nymphs artificially infected with DpAV alone. Lysis of the nymphal cells due to viral replication seems to be synchronous with egg hatching and the development of the hymenopteran larva. The features of DpAV and its relationship with the parasitoid wasp D. pulchellus during its development are compared to those of the ichnoviruses.

Animals↗

Ovary development and polydnavirus morphogenesis in the parasitic wasp Chelonus inanitus. I. Ovary morphogenesis, amplification of viral DNA and ecdysteroid titres.

Polydnaviruses are unique symbiotic viruses that are replicated in the calyx cells of the ovary of some parasitic wasps. They have a segmented genome of circular double-stranded DNA and are injected along with the wasp's egg into the host, where they are essential for successful parasitism. Polydnaviruses replicate from integrated proviral DNA, and after excision of viral segments, flanking DNA is rejoined. Little is known about ovarian morphogenesis, the mode of amplification of the viral DNA and the involvement of ecdysteroids. Here we have analysed these parameters in the course of pupal-adult development in the braconid wasp Chelonus inanitus. Immediately after pupation, ovarian cells proliferated and calyx cells began to differentiate; at this stage ecdysteroids, in particular 20-hydroxyecdysone, were highest. Thereafter, calyx cells began to increase in size and DNA content and eventually became gigantic. Amplification of non-viral DNA (actin) and viral DNA in its integrated and excised form and of corresponding rejoined flanking regions was measured by quantitative real-time PCR. In the early phase of calyx cell differentiation, copy numbers of actin and integrated viral DNA increased to a similar extent. This, along with the increase in nuclear volume and DNA content in the absence of extensive cell proliferation, suggested polyploidization of the early stage calyx cells. In the following phase, integrated viral DNA was selectively and intensively amplified and eventually excised and circularized. As copy numbers of excised circular viral DNA and rejoined flanking DNA reached similarly high levels, excised viral DNA appeared not to replicate. After adult eclosion, amplification of viral DNA declined.

Animals↗

Establishment of cell lines from the wasp Hyposoter didymator (Hym., Ichneumonidae) containing the symbiotic polydnavirus H. didymator ichnovirus.

Cell lines derived from polydnavirus-associated wasps should constitute a valuable tool for investigations of polydnavirus replication, but none is yet available. In this work, we describe the first cell lines, named Hd-AA, -AD, -BBA and -K, to have been established from the ichneumonid wasp Hyposoter didymator, associated with the polydnavirus H. didymator ichnovirus (HdIV). Southern blot analysis indicated that the viral DNA was present in all four cell lines and co-localized with high molecular mass DNA, probably the wasp chromosomes. Northern blot analysis of mRNAs extracted from the AA cell line showed transcription of some HdIV-encoded genes, although at low level. The effects of ecdysone treatment, HdIV re-infection and 42 degrees C heat-shock were analysed in the AA cell line. No effect was detected at the DNA (virus replication) or RNA (gene expression) levels, which may be due to the limitation of the present available tools.

Animals↗

Mating system and population structure of the primitively eusocial wasp Ropalidia revolutionalis: a model system for the evolution of complex societies.

Mating systems are important determinants of genetic structure in cooperative groups, and their effects can influence profoundly the interactions of group members. The primitively eusocial wasp, Ropalidia revolutionalis, has an interesting genetic and social structure that makes it an excellent model system for examining the evolution of more complex societies. In particular, its colonies sometimes have multiple queens, a key characteristic of more advanced wasp societies. In this study, we have characterized the mating system of the social wasp Ropalidia revolutionalis to understand better its colony genetic structure. R. revolutionalis females nearly always mate singly and they are unrelated to their mates. However, different females in the same colony do mate with males, on average, who are related as cousins. Single mating will help to maintain high relatedness, which should be important for continued cooperation in multiple queen societies, but it creates potential conflicts in single queen colonies over the production of males as well as over the timing of male production. We have also characterized the population structure of R. revolutionalis from Townsville, in tropical north Queensland, to Brisbane in the subtropics. Even at such a large scale, the population is remarkably unstructured with an average F(ST) of 0.0546. There is weak isolation by distance, and evidence for subtle differentiation between a southern region with no dry season, which extends as far north as Rockhampton, and a northern region with a severe to moderate dry season. This may reflect historical effects of extreme aridity on the population structure.

Analysis of Variance↗

Assessment of prey overlap between a native (Polistes humilis) and an introduced (Vespula germanica) social wasp using morphology and phylogenetic analyses of 16S rDNA.

Abstract In newly invaded communities, interspecific competition is thought to play an important role in determining the success of the invader and its impact on the native community. In southern Australia, the native Polistes humilis was the predominant social wasp prior to the arrival of the exotic Vespula germanica (Hymenoptera: Vespidae). Both species forage for similar resources (water, pulp, carbohydrate and protein prey), and concerns have arisen about potential competition between them. The aim of this study was to identify the protein foods that these wasps feed on. As many prey items are masticated by these wasps to the degree that they cannot be identified using conventional means, morphological identification was complemented by sequencing fragments of the mitochondrial 16S rRNA gene. GenBank searches using blast and phylogenetic analyses were used to identify prey items to at least order level. The results were used to construct complete prey inventories for the two species. These indicate that while P. humilis is restricted to feeding on lepidopteran larvae, V. germanica collects a variety of prey of invertebrate and vertebrate origin. Calculated values of prey overlap between the two species are used to discuss the implications of V. germanica impacting on P. humilis. Results obtained are compared to those gained by solely 'conventional' methods, and the advantages of using DNA-based taxonomy in ecological studies are emphasized.

Animals↗

Use of RAST technique in wasp sting hypersensitivity. Cross-reactions between various insect antigens are specially considered.

Clinical hypersensitivity to wasp stings was found to be fairly well correlated with the presence of serum IgE-antibodies against yellow jacket venom as detected by the RAST technique. Such antibodies were never found in a control group of non-allergic blood donors, but they were detected in a surprisingly large proportion of patients with bee sting allergy without known allergic reactions to wasps. Studies using RAST inhibition technique failed to prove cross-reactions between bee and wasp venoms. Considerably better results were obtained when venom antigens instead of whole body antigens were used in the RAST. RAST inhibition studies suggested that IgE-antibodies detected with RAST using whole body antigen are directed against bee venom constituents in the whole body extract.

Antibodies↗

Cytokine modulation of basophil histamine release in wasp-venom allergy.

We report the effect of interleukin-3 (IL-3) and of other cytokines on antigen-induced basophil histamine release in wasp-venom-allergic subjects. Leukocytes from 12 patients with documented anaphylactic sensitivity to wasp venom were preincubated in the presence or absence of IL-3, granulocyte/macrophage-colony stimulating factor (GM-CSF), IL-5, IL-8, or stem cell factor (SCF). Washed cells were then exposed to venom and to other secretagogues, and histamine release in the supernatant was measured fluorometrically. Preincubation of leukocytes with IL-3, GM-CSF, or IL-5 (0.02-2 ng/ml), but not with IL-8 and SCF, caused a dose-dependent enhancement of antigen-induced basophilic histamine release in all subjects tested. Mean maximum increase was about 100% for IL-3, IL-5, and GM-CSF. The priming effect of IL-3 was rapid, persisted up to 12 h, and was not accompanied by a change in cellular histamine. IL-3 had a comparable enhancing effect when basophils were triggered with anti-IgE or N-formylmethionylphenylalanine (FMP). By contrast, IL-3 had no effect on substance-P-induced histamine release. The significant enhancement of basophil releasability to antigen in wasp-venom allergy by very low concentrations of IL-3, GM-CSF, and IL-5 suggests that cytokines in the basophil (mast-cell?) microenvironment could be critical factors in determining the variability of sting reactions in Hymenoptera-venom-allergic subjects.

Adolescent↗

Swarming behavior: evidence for communication in social wasps.

Behavior of wasps at sites around swarms and along emigration routes suggests the use of odor marks. Wasps perform breaking runs through swarms, resulting in dispersal of clustered wasps. Orientation in flight of swarm mates to specific trail sites facilitates swarm emigration to the new nest.

Animal Communication↗

Visualization of polydnavirus sequences in a parasitoid wasp chromosome.

Polydnaviruses, obligatorily associated with endoparasitoid wasps, are unique in that their segmented genome is composed of multiple double-stranded DNA circles. We present here the first cytological evidence that virus segments are integrated in the wasp genome, obtained by using in situ hybridization of virus probes with viral sequences in the chromosomes of a wasp from the braconid family of hymenopterans.

Animals↗