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PubMed2005

The role of moisture in the nest thermoregulation of social wasps.

Paper nests of social wasps are intriguing constructions for both, biologists and engineers. We demonstrate that moisture and latent heat significantly influence the thermal performance of the nest construction. Two colonies of the hornet Vespa crabro were investigated in order to clarify the relation of the temperature and the moisture regime inside the nest. Next to fairly stable nest temperatures the hornets maintain a high relative humidity inside the nest. We found that in consequence a partial vapor-pressure gradient between nest and ambient drives a constant vapor flux through the envelope. The vapor flux is limited by the diffusion resistance of the envelope. The driving force of vapor flux is heat, which is consumed through evaporation inside the nest. The colony has to compensate this loss with metabolic heat production in order to maintain a stable nest temperature. However, humidity fluctuations inside the nest induce circadian adsorption and desorption cycles, which stabilize the nest temperature and thus contribute significantly to temperature homeostasis. Our study demonstrates that both mechanisms influence nest thermoregulation and need to be considered to understand the thermodynamic behavior of nests of wasps and social insects in general.

Animals↗
PubMed2006

"Winter" aggregations, colony cycle, and seasonal phenotypic change in the paper wasp Polistes versicolor in subtropical Brazil.

Social wasps from temperate zones have clear annual colony cycles, and the young queens hibernate during winter. In the subtropics, the only previously reported evidence for the existence of "hibernation" is the facultative winter aggregations of females during harsh climate conditions. As in temperate-zone species analyzed so far, we show in this study that in the paper wasp, Polistes versicolor, a subtropical species, body size increases as an unfavorable season approaches. Our morphological studies indicate that larger females come from winter aggregations--that is, they are new queens. Multivariate analyses indicate that size is the only variable analyzed that shows a relationship to the differences. Given the absence of a harsh climate, we suggest that the occurrence of winter aggregations in tropical P. versicolor functions to allow some females to wait for better environmental conditions to start a new nest, rather than all being obliged to start a new nest as soon as they emerge.

Animals↗
PubMed2005

Transplantation of a polyembryonic wasp embryo: a technique for transferring endoparasitic embryo into the host egg.

Concealed development of many animal embryos prevents examination of development and limits the application of embryo manipulation techniques aimed at understanding developmental processes. In embryos developing in utero, such as in mammals, it is necessary to dissect embryos from the mother and, upon manipulative intervention, to implant them back into the recipient. Parasitic wasps present a promising system for understanding the evolution of early developmental processes. In basal ectoparasitic species that lay eggs on the surface of the host, it is possible to adapt embryo manipulation techniques developed in Drosophila. However, their derived endoparasitic relatives, which exhibit various modifications of developmental programs, undergo concealed development within the host body. For example, the parasitic polyembryonic wasp Copidosoma floridanum oviposits an egg into the egg of the host moth Trichoplusia ni. The host larva emerges and the parasite undergoes development within the host body, preventing embryo manipulation as a means of examining developmental regulation. Here we present a protocol for embryo transfer that allows the transplantation of C. floridanum egg into the host egg. This approach opens a new avenue in the application of various embryo manipulation techniques aimed at understanding the evolution of embryogenesis in endoparasitic Hymenoptera. In addition, this approach has potential for the development of other tools in C. floridanum, such as transgenesis and reverse genetics, which can also be extended to other endoparasitic species.

Animals↗
PubMed2000

Venom gland of the digger wasp Liris niger: morphology, ultrastructure, age-related changes and biochemical aspects.

Females of the parasitoid digger wasp species Liris niger hunt crickets as food for their future brood. The wasps paralyse the prey by injecting their venom directly into the CNS. The venom is produced in a gland consisting of two ramified glandular tubules terminating in a common reservoir. The reservoir contents enter the sting bulb via a ductus venatus. Secretory units of dermal gland type III line the two free gland tubules, the afferent ducts to the reservoir and the cap region within the reservoir. Secretion products of tubules reach the reservoir through the cuticle-lined central funnel. Secretory cells in the distal and middle parts of the tubules contain extensive rough endoplasmic reticulum and numerous electron-dense vesicles, whereas secretory cells of the afferent ducts and the cap region of the reservoir lack electron-dense vesicles and the endoplasmic reticulum is poorly developed. The secretory apparatus undergoes age-related changes. The secretory units in the venom gland tubules and inside the reservoir complete differentiation 1 day after imaginal ecdysis. After 30 days, massive autolytic processes occur in the secretory cells and in the epithelial cells of the reservoir. Analysis of the polypeptide composition demonstrates that the venom reservoir contains numerous proteins ranging from 3.4 to 200 kDa. A dominant component is a glycoprotein of about 90 kDa. In contrast the polypeptide composition of Dufour's gland is completely different and contains no glycoproteins. Comparison of the venom reservoir contents with the polypeptide pattern of venom droplets reveals that all of the major proteinaceous constituents become secreted. Thus the secreted venom contains exclusively proteins present in the soluble contents of the venom gland.

Aging↗
PubMed2003

Consumption of snowdrop lectin (Galanthus nivalisagglutinin) causes direct effects on adult parasitic wasps.

Honeydew is a common sugar-rich excretion of aphids and other phloem-feeding insects and represents the primary sugar in many agricultural systems. When honeydew-producing insects feed on genetically modified plants, the honeydew can contain amounts of the transgene product. Here we address whether this route of exposure poses a risk for non-target insects. Three species of parasitic wasps were selected: i.e. Aphidius colemani, Trichogramma brassicae and Cotesia glomerata, all of which are known to use honeydew as a carbohydrate source in the field. Wasps were fed sucrose solutions with varying concentrations of snowdrop lectin ( Galanthus nivalisagglutinin, GNA), a protein that has been engineered into crops to confer resistance against homopteran pests and that has been detected in honeydew. Parameters evaluated included gustatory response, longevity, fecundity, progeny emergence and sex ratio. While A. colemani and T. brassicae, but not C. glomerata, were able to detect GNA, this gustatory recognition had no effect on the acceptance of a GNA-sucrose solution. In all three species, GNA ingestion reduced parasitoid survival significantly. However, in respect to fecundity, negative effects were observed for T. brassicae but not for A. colemani. The results suggest that the effect of GNA consumption may depend on the specifics of a parasitoid's biology, especially its longevity and its mode of egg maturation.

Animals↗
PubMed2006

The influence of temperature and host availability on the host exploitation strategies of sexual and asexual parasitic wasps of the same species.

In the hymenopteran parasitoid Venturia canescens, asexual (obligate thelytoky not induced by Wolbachia bacteria) and sexual (arrhenotokous) wasps coexist in field conditions despite the demographic cost incurred due to the production of males by sexual females. Arrhenotoky predominates in field conditions, whereas populations in indoor conditions (mills, granaries) are exclusively thelytokous. These differences in the relative abundance of the two modes of reproduction between environments suggest that the individuals of each reproductive mode may have developed strategies adapted to the conditions prevailing in each kind of habitat. The two environments contrast in temperature variability and in the spatial heterogeneity of host availability. In this study, we considered the combined effect of temperature and host availability on host patch exploitation by thelytokous and arrhenotokous V. canescens. As expected, arrhenotokous females were more sensitive to temperature changes. If the temperature decreased before foraging, they remained longer and exploited patches more thoroughly. This is consistent with the expected behaviour of parasitoids in response to signs of unfavourable conditions that entail increasing risk of time limitation or a reduced probability of attaining further patches. Both arrhenotokous and thelytokous females increased patch exploitation with host availability. However, unexpectedly, we found no difference in the way the two types of wasp responded to differences in host availability. Differences in the strategies adopted under different environmental conditions may indicate divergence of niche-specific life history traits between the two modes of reproduction. Niche displacement may partly account for the coexistence of these two modes of reproduction at a geographical scale.

Animals↗
PubMed2005

The role of fresh versus old leaf damage in the attraction of parasitic wasps to herbivore-induced maize volatiles.

The odor produced by a plant under herbivore attack is often used by parasitic wasps to locate hosts. Any type of surface damage commonly causes plant leaves to release so-called green leaf volatiles, whereas blends of inducible compounds are more specific for herbivore attack and can vary considerably among plant genotypes. We compared the responses of naïve and experienced parasitoids of the species Cotesia marginiventris and Microplitis rufiventris to volatiles from maize leaves with fresh damage (mainly green leaf volatiles) vs. old damage (mainly terpenoids) in a six-arm olfactometer. These braconid wasps are both solitary endoparasitoids of lepidopteran larvae, but differ in geographical origin and host range. In choice experiments with odor blends from maize plants with fresh damage vs. blends from plants with old damage, inexperienced C. marginiventris showed a preference for the volatiles from freshly damaged leaves. No such preference was observed for inexperienced M. rufiventris. After an oviposition experience in hosts feeding on maize plants, C. marginiventris females were more attracted by a mixture of volatiles from fresh and old damage. Apparently, C. marginiventris has an innate preference for the odor of freshly damaged leaves, and this preference shifts in favor of a blend containing a mixture of green leaf volatiles plus terpenoids, after experiencing the latter blend in association with hosts. M. rufiventris responded poorly after experience and preferred fresh damage odors. Possibly, after associative learning, this species uses cues that are more directly related with the host presence, such as volatiles from host feces, which were not present in the odor sources offered in the olfactometer. The results demonstrate the complexity of the use of plant volatiles by parasitoids and show that different parasitoid species have evolved different strategies to exploit these signals.

Animals↗
PubMed2006

The role of indole and other shikimic acid derived maize volatiles in the attraction of two parasitic wasps.

After herbivore attack, plants release a plethora of different volatile organic compounds (VOCs), which results in odor blends that are attractive to predators and parasitoids of these herbivores. VOCs in the odor blends emitted by maize plants (Zea mays) infested by lepidopteran larvae are well characterized. They are derived from at least three different biochemical pathways, but the relative importance of each pathway for the production of VOCs that attract parasitic wasps is unknown. Here, we studied the importance of shikimic acid derived VOCs for the attraction of females of the parasitoids Cotesia marginiventris and Microplitis rufiventris. By incubating caterpillar-infested maize plants in glyphosate, an inhibitor of the 5-enolpyruvylshikimate-3-phospate (EPSP) synthase, we obtained induced odor blends with only minute amounts of shikimic acid derived VOCs. In olfactometer bioassays, the inhibited plants were as attractive to naive C. marginiventris females as control plants that released normal amounts of shikimic acid derived VOCs, whereas naive M. rufiventris females preferred inhibited plants to control plants. By adding back synthetic indole, the quantitatively most important shikimic acid derived VOC in induced maize odors, to inhibited plants, we showed that indole had no effect on the attraction of C. marginiventris and that M. rufiventris preferred blends without synthetic indole. Exposing C. marginiventris females either to odor blends of inhibited or control plants during oviposition experiences shifted their preference in subsequent olfactometer tests in favor of the experienced odor. Further learning experiments with synthetic indole showed that C. marginiventris can learn to respond to this compound, but that this does not affect its choices between natural induced blends with or without indole. We hypothesize that for naïve wasps the attractiveness of an herbivore-induced odor blend is reduced due to masking by nonattractive compounds, and that during oviposition experiences in the presence of complex odor blends, parasitoids strongly associate some compounds, whereas others are largely ignored.

Animals↗
PubMed1999

In vitro analysis of venom from the wasp Nasonia vitripennis: susceptibility of different cell lines and venom-induced changes in plasma membrane permeability.

The lethal effects of crude venom prepared from the ectoparasitic wasp Nasonia vitripennis were examined with cultured cells from six insect and two vertebrate species. Venom caused cells from Sarcophaga peregrina (NIH SaPe4), Drosophila melanogaster (CRL 1963), Trichoplusia ni (TN-368 and BTI-TN-5B1-4), Spodoptera frugiperda (SF-21AE), and Lymantria dispar (IPL-Ldfbc1) to round up, swell, and eventually die. Despite similar sensitivities and overlapping LC50 values [0.0004-0.0015 venom reservoir equivalents (VRE)/microl], profound differences were noted at the onset of cytotoxicity among the six insect cell lines: over 80% of the NIH SaPe4 and SF21AE cells were nonviable within 1 h after addition of an LC99 dose of venom, whereas the other cells required a 5-10-fold longer incubation period to produce mortality approaching 100%. In contrast, cells from the grass frog, Rana pipiens (ICR-2A), and goldfish, Carassius auratus (CAR), showed little sensitivity to the venom: six venom reservoir equivalents were needed to induce 50% mortality in ICR-2A cells [50% lethal concentration (LC50) = 0.067 VRE/microl), and 9 VRE did not yield sufficient mortality in CAR cells for us to calculate an LC50. All susceptible cells showed similar responses when incubated with wasp venom: retraction of cytoplasmic extensions (when present), blebbing of the plasma membrane, swelling of the plasma and nuclear membranes, condensation of nuclear material, and eventual cell death attributed to lysis. The rate of swelling and lysis in NIH SaPe4 and BTI-TN-5B1-4 cells exposed to venom appeared to be dependent on the diffusion potential of extracellular solutes (Na+ = choline > sucrose > or = raffinose > K+), which is consistent with a colloid-osmotic lysis mechanism of cell death. When T. ni cells were cotreated with venom and the K+ channel blocker 4-aminopyridine, cell swelling and lysis increased with increasing drug concentration. In contrast, cells from S. peregrina were protected from the effects of the venom when treated in a similar manner. Addition of certain divalent cations (Zn+2 and Ca+2) to the extracellular media 1 h postvenom incubation rescued both BTI-TN-5B1-4 and NIH SaPe4 cells, suggesting that protection was gained from closure of open pores rather than prevention of pore formation. Venom from N. vitripennis displayed no hemolytic activity toward sheep erythrocytes, supporting the view that venom intoxication is not by a nondiscriminate mechanism. A possible mode of action of the venom is discussed.

4-Aminopyridine↗
PubMed1986

Soluble copolymer of wasp venom with human albumin for venom immunotherapy.

Polymerization of allergens decreases allergenicity while retaining immunogenicity, as we have demonstrated for ragweed, grass, and tree pollens. We have also polymerized bee venom with human albumin to form soluble, high-molecular-weight copolymers that are immunogenic in rabbits. We now have prepared a soluble wasp venom-albumin polymer (WVAP), molecular weight greater than or equal to 240,000 daltons, by glutaraldehyde treatment and Sephacryl S-300 column fractionation. Rabbits immunized with WVAP produced IgG to both WVAP and wasp venom (WV), as measured by ELISA. IgG against WVAP was totally inhibitable by a mixture of WV and albumin, demonstrating both retention of native antigens and absence of new antigenic determinants in WVAP. IgG against WV in serum from patients receiving maintenance doses of WV immunotherapy was inhibited by WVAP. In summary, we have synthesized a soluble, high-molecular-weight copolymer of WV that retains the immunogenicity of native WV, contains no new antigenic determinants, and has potential value in the treatment of patients with WV anaphylaxis.

Animals↗
PubMed1993

Effects of parasitism by the braconid wasp Cotesia congregata on host hemolymph proteins of the tobacco hornworm, Manduca sexta.

Parasitism by the braconid wasp Cotesia congregata causes major alterations in the hemolymph proteins of host tobacco hornworm larvae. Earlier studies showed that the total amount of hemolymph protein is reduced during parasitism, beginning almost immediately after the host is parasitized. Simultaneously, parasitism induces synthesis of large amounts of novel proteins that appear in the blood as early as 1-2 h post-parasitization. The present report confirms earlier studies describing the presence of novel proteins in last instar hosts, and also characterizes the effects of parasitism in altering the titers of several endogenous host hemolymph proteins normally produced by the fat body and other tissues. Analysis of hemolymph plasma using SDS-PAGE and densitometry, as well as immunodiffusion assays, showed that in terminal stage fifth instar host larvae, the titers of serpins and arylphorin were dramatically reduced relative to the levels of these proteins detected in nonparasitized gate II fifth instar larvae of the same age. The relative differences between parasitized and nonparasitized larvae increased with time following ecdysis to the fifth instar, so that the day 4 nonparasitized larvae had arylphorin titers of c. 30 mg/ml, whereas parasitized day 4 larvae with newly emerged wasps had only one sixth that amount of storage protein circulating in the hemolymph. Similarly, in nonparasitized larvae the hemolymph serpin concentration increased from c. 200 micrograms/ml (on day 0) to > 600 micrograms/ml (on day 4) in prewandering gate II larvae, but in parasitized larvae the hemolymph serpin concentration was maintained in the range of 100-200 micrograms per ml hemolymph until the pharate third instar parasites emerged from the host larva on day 4. In contrast, the level of hemolymph lipophorin was unaffected by parasitism, and lipophorin increased from c. 1.3 to > 3 mg/ml during the time interval between days 0 and 4 in both nonparasitized and parasitized larvae. Hemolymph titers of insecticyanin also were not significantly different in parasitized vs nonparasitized larvae, and in both types of larvae the concentration of this pigment decreased by c. 50% during the same time interval when lipophorin was increased significantly. Instead of causing a generalized inhibition of host hemolymph protein synthesis, parasitism causes a complex array of changes in the hemolymph protein profile of Manduca sexta, possibly via the mediation of hormonal modulators of host protein synthesis, or transcriptional or translational regulation of host gene expression by factors associated with the polydnavirus or molecules secreted by the parasites.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Pollen waste and unrelated traits in a fig-fig wasp symbiosis: a new behaviour suggesting a host shift.

In a fig-fig wasp symbiosis, we have discovered that male fig pollinators (Alfonsiella fimbriata Waterston) bite into the dehiscent anthers of Ficus natalensis leprieuri Miq., thus scattering the pollen grains throughout the syconium. Female pollinators are the only ones to transfer pollen to conspecific trees, and collect pollen actively from the anthers only. Thus, this male behaviour appears to be antagonistic to the pollination process. We compare different wasp pollinating behaviours between fig species exhibiting dehiscent and non-dehiscent anthers and conclude that this male behaviour is new and not required with spontaneously dehiscent anthers. These findings could suggest a host shift of Alfonsiella fimbriata.

Animals↗
PubMed2005

Symbiotic bacteria protect wasp larvae from fungal infestation.

Symbiotic associations between different organisms are of great importance for evolutionary and ecological processes [1-4]. Bacteria are particularly valuable symbiotic partners owing to their huge diversity of biochemical pathways that may open entirely new ecological niches for higher organisms [1-3]. Here, we report on a unique association between a new Streptomyces species and a solitary hunting wasp, the European beewolf (Philanthus triangulum, Hymenoptera, Crabronidae). Beewolf females cultivate the Streptomyces bacteria in specialized antennal glands and apply them to the brood cell prior to oviposition. The bacteria are taken up by the larva and occur on the walls of the cocoon. Bioassays indicate that the streptomycetes protect the cocoon from fungal infestation and significantly enhance the survival probability of the larva, possibly by producing antibiotics. Behavioral observations strongly suggest a vertical transmission of the bacteria. Two congeneric beewolf species harbor closely related streptomycetes in their antennae, indicating that the association with protective bacteria is widespread among philanthine wasps and might play an important role in other insects as well. This is the first report on the cultivation of bacteria in insect antennae and the first case of a symbiosis involving bacteria of the important antibiotic-producing genus Streptomyces.

Animals↗
PubMed2004

Variation in cuticular hydrocarbon signatures, hormonal correlates and establishment of reproductive dominance in a polistine wasp.

In many social insects the relationship between reproductive dominance and physiological correlates is poorly understood. Recent evidence now strongly suggests that cuticular hydrocarbons are important in reproductive differentiation in these societies where they are used as signals of ovarian activity in reproductive females. In this study we investigated the relationship between reproductive dominance, size of the corpora allata (CA, producer of Juvenile Hormone, JH) and the proportions of cuticular hydrocarbons present on the cuticle in overwintering foundresses and both associative (polygynous) and solitary (monogynous) pre-emergence colonies of the social wasp Polistes dominulus. Size of the CA was positively correlated with ovarian development in polygynous colonies. In contrast, solitary foundresses possessed significantly smaller CAs than dominant foundresses from polygynous nests, yet ovarian activity was similar for both female types. CA size variation was associated with variation in cuticular hydrocarbon proportions. Overwintering, solitary, dominant and subordinate (from associative nests) females all possessed distinctive cuticular chemical profiles revealed by multivariate discriminant analyses. Our data indicate that the social environment strongly affects reproductive physiology in this wasp, and we discuss the role of cuticular hydrocarbons in reproductive signaling in P. dominulus and other social insects.

Animals↗
PubMed2005

Gene expression changes in Ephestia kuehniella caterpillars after parasitization by the endoparasitic wasp Venturia canescens analyzed through cDNA-AFLPs.

To understand the transcriptional response of Ephestia kuehniella caterpillars to parasitization by the endoparasitic wasp Venturia canescens, we examined patterns of gene expression in parasitized and unparasitized host caterpillars using the cDNA-AFLP (cDNA-amplified fragment length polymorphism) technique. Among the approximately 1860 cDNA-fragments detected by using 88 different AFLP primer combinations, we identified 13 transcripts in parasitized caterpillars that showed a suppressed expression pattern with cDNA-AFLP results being confirmed by virtual Northern blot or RT-PCR analysis. Apparently, two different wasp genotypes (RP, RM) seem to differ in their ability to regulate host physiology with regard to suppression of certain genes. Sequence analysis of the cDNA fragments revealed that some of the respective genes are likely to be involved in energy metabolism, protein synthesis, or in signal transduction. In addition, one sequence corresponds to a gene encoding the lepidopteran silk protein fibroin. The putative function of these genes in the interactions between endoparasitoids and their host insects is discussed.

Animals↗
PubMed1991

Chemotactic peptide from ropalidian wasp as well as the authentic chemotactic tripeptide stimulates two distinct pathways in neutrophils, but the [LYS7] analog does only one of them.

In our previous study on chemotactic peptide isolated from Ropalidian wasp, it was found to induce not only chemotaxis but also other cellular responses, such as superoxide generation and lysosomal enzyme release, but [Lys7] analog was found to induce only chemotaxis but not others. Here, studies on intracellular Ca2+ changes and receptor-binding revealed that the wasp chemotactic peptide and the authentic tripeptide stimulated two distinct receptors, but that the [Lys7] peptide could have access to only one of them.

Animals↗
PubMed2000

Use of solid-phase microextraction in the investigation of chemical communication in social wasps.

Solid-phase microextraction has been used to investigate chemical communication in several social wasp species. Using the technique to analyse exocrine gland secretions, we demonstrate that the results are comparable with those obtained with the more classical methods that use solvents, eliminating, in many cases, the shortcomings of these methods in insect pheromone analysis. As a result of its simplicity this technique is very suitable for research on the chemical ecology of social wasps, and on insect communication in general.

Animal Communication↗
PubMed2000

Optic neuropathy occurring after bee and wasp sting.

OBJECTIVE: To inform ophthalmologists about bee and wasp sting-related optic neuropathy. DESIGN: Two case reports and literature review. METHODS: Review of two cases, clinical history, laboratory testing, and follow-up. RESULTS: Two cases of bee and wasp sting optic neuritis are described and five additional cases of optic neuritis occurring after Hymenoptera sting are reviewed from the English language literature. These cases share certain characteristics, including acute to subacute onset of symptoms; moderate to severe visual loss followed by significant visual recovery; edematous and hemorrhagic optic discs; and central or cecocentral scotomas. CONCLUSIONS: Acute optic neuropathy may follow Hymenoptera sting to the face.

Adult↗