Search results for "wasp"
showing 10 items of 102 documents
Low parasitism rates in parthenogenetic bagworm moths do not support the parasitoid hypothesis for sex
2012
The parasite hypothesis for sex is one of the many theories that have been suggested to solve the mystery of the widespread occurrence of sex despite its high short-term costs. It suggests that sexual lineages have an evolutionary advantage over parthenogens because they can frequently generate new genotypes that are temporarily less prone to coevolving parasites. In this study, we looked for further supporting evidence for the parasite hypothesis of sex in an attempt to understand the coexistence of sexual and parthenogenetic bagworm moths (Naryciinae). The bagworm moths and their parasitoids form one of the few natural host-parasite systems where sexual and parthenogenetic hosts are appar…
Insect venom immunotherapy induces interleukin-10 production and a Th2-to-Th1 shift, and changes surface marker expression in venom-allergic subjects.
1997
Abstract The current study was carried out to elucidate the immunoregulatory changes induced by venom immunotherapy (VIT) in bee or wasp allergic subjects. All subjects included in this study had a history of severe systemic allergic reactions to stings of the respective insect as well as positive skin tests with the respective venom or venom-specific IgE in the sera. Parameters assessed in peripheral blood mononuclear cells (PBMC) before and after initiation of VIT (rush therapy reaching a maintenance dose of 100 micrograms venom injected subcutaneously within 1 week) were expression of CD3, CD4, CD8, CD45RA, CD45RO, interleukin (IL)-2 receptor (R) alpha, IL-4R, IL-12R, Fc epsilon RII, CD4…
Host chemical footprints induce host sex discrimination ability in egg parasitoids
2013
Trissolcus egg parasitoids, when perceiving the chemical footprints left on a substrate by pentatomid host bugs, adopt a motivated searching behaviour characterized by longer searching time on patches were signals are present. Once in contact with host chemical footprints, Trissolcus wasps search longer on traces left by associated hosts rather than non-associated species, and, in the former case, they search longer on traces left by females than males. Based on these evidences, we hypothesized that only associated hosts induce the ability to discriminate host sex in wasps. To test this hypothesis we investigated the ability of Trissolcus basalis, T. brochymenae, and Trissolcus sp. to disti…
The response of Trissolcus basalis to footprint contact kairomones from Nezara viridula females is mediated by leaf epicuticular waxes.
2009
Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula's cuticular hydrocarbons (CHC) and furthermore that the wasp's ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC(19)). In this study, the effect of epicuticular waxes of leaves…
Effects of Kaolin on Ophelimus maskelli (Hymenoptera: Eulophidae) in Laboratory and Nursery Experiments
2011
Although recent research has demonstrated that clays provide satisfactory control of some agricultural insect pests, the effect of clays on gall wasps that damage forest trees has not been previously reported. The aim of the current study is to evaluate the effectiveness of the clay kaolin in the laboratory and in the field in reducing the damage caused by the eulophid Ophelimus maskelli (Ashmead) on seedlings of eucalyptus (Eucalyptus L'Hér.) species. In the laboratory, kaolin + wetting agent significantly reduced the percentage of infested leaves and the number of galls per leaf. In the nursery, gall number per leaf was not correlated with leaf area with kaolin + wetting agent but was rel…
All-day activity of Dolichovespula saxonica (Hymenoptera, Vespidae) colonies in Central Finland
2022
In social vespid wasps, colony activity varies at many temporal scales. We studied the peak season activity (number of individuals entering the nest per min) of colonies of the social vespine wasp Dolichovespula saxonica in its native range in boreal Finland. Six colonies were monitored non-stop for a full day, starting before sunrise and ending after sunset. Shorter monitoring was carried out before and/or after the full-day monitoring. All colonies were active before sunrise and after sunset, and the overall activity was positively linked with colony size. Activity showed irregular minute-to-minute cycles in all colonies. The broader within-day dynamics were idiosyncratic among the coloni…
Optimum and Maximum Host Sizes at Parasitism for the Endoparasitoid <I>Hyposoter didymator</I> (Hymenoptera: Ichneumonidae) Differ Greatl…
2007
Host size is considered a reliable indicator of host quality and an important determinant of parasitoid fitness. Koinobiont parasitoids attack hosts that continue feeding and growing during parasitism. In contrast with hemolymph-feeding koinobionts, tissue-feeding koinobionts face not only a minimum host size for successful development but also a maximum host size, because consumption of the entire host is often necessary for successful egression. Here we study interactions between a generalist tissue-feeding larval endoparasitoid, Hyposoter didymator Thunberg (Hymenoptera: Ichneumonidae) and two of its natural hosts, Spodoptera exigua Hübner and Chrysodeixis chalcites Esper (Lepidoptera: N…
External and internal elimination of supernumerary larvae in the whitefly parasitoid Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae)
2008
Abstract The solitary parasitoid Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) is one of the key biological control agents of the whitefly Bemisia argentifolii Bellows & Perring, also known as B. tabaci (Gennadius) B-biotype (Homoptera: Aleyrodidae). We present new information on its biology, and particularly about larval elimination during the first instar in cases of superparasitism. For the first time, physical elimination of supernumerary larvae was observed, both outside and inside the host. These findings are documented with confocal microscopy images and video recordings. We observed more than 350 B. argentifolii nymphs, parasitized with one, two or more than two larvae. Physi…
The evolutionary dynamics of adaptive virginity, sex-allocation and altruistic helping in haplodiploid animals
2018
In haplodiploids, females can produce sons from unfertilized eggs without mating. However, virgin reproduction is usually considered to be a result of a failure to mate, rather than an adaptation. Here, we build an analytical model for evolution of virgin reproduction, sex-allocation, and altruistic female helping in haplodiploid taxa. We show that when mating is costly (e.g., when mating increases predation risk), virginity can evolve as an adaptive female reproductive strategy. Furthermore, adaptive virginity results in strongly divergent sex-ratios in mated and virgin queen nests ("split sex ratios"), which promotes the evolution of altruistic helping by daughters in mated queen nests. H…
A female-produced short-range sex pheromone in the egg parasitoid Trissolcus brochymenae
2012
The potential for short-range sex pheromone communication by the egg parasitoid wasp Trissolcus brochymenae (Hymenoptera: Platygastridae) was investigated in closed arena bioassays. Males of this parasitoid showed more antennal drumming and more frequent mounting behaviour on 1- to 2-d-old virgin females compared with 8-d-old virgin females. Male copulation attempts were fewer with previously mated females than with virgin females. Males courted and made copulation attempts with 1- to 2-d-old female cadavers, but not with male cadavers or with female cadavers rinsed in organic solvents of different polarities. Male attraction to female cadavers was re-established by treating cadavers with a…