Ichneumonid Wasps Research Articles

Modification of Nephila clavipes (Araneae Nephilidae) webs induced by the parasitoids Hymenoepimecis bicolor and H. robertsae (Hymenoptera Ichneumonidae)

Some polysphinctine ichneumonid wasps induce alterations in the web construction behaviour of their host spiders, and then suspend their pupal cocoons from the resulting “cocoon webs”. Cocoon webs that have been described previously appear to be designed to increase the web's mechanical stability, and thus to protect the wasp's cocoon. This study describes the cocoon webs of Nephila clavipes that are induced by two wasp species, Hymenoepimecis bicolor and H. robertsae, and shows that the alterations induced by H. bicolor make the webs more resistant to destruction. The cocoon webs of both species include a hub-like platform from which the cocoon is suspended, and are usually protected by a nearby tangle of barrier lines of variable density. The web alterations induced by H. bicolor are apparently not a consequence of parasitised spiders being in a poorer nutritional state, because orbs spun by parasitised spiders preceding the final “cocoon webs” were not significantly smaller than those of unparasitised spiders. Cocoon webs themselves were all highly reduced, and some of those induced by H. bicolor resemble the “skeleton” webs that are occasionally made by unparasitised N. clavipes. We document a possible spider defence (molting) against polysphinctine parasitisation.

Recovery of spiders from the effects of parasitic wasps: implications for fine-tuned mechanisms of manipulation

The larva of the ichneumonid wasp Polysphincta gutfreundi induces its host, the orb-weaving spider Allocyclosa bifurca , to build a highly modified, physically stable orb web, to which the larva then attaches its pupal cocoon, and to add an otherwise unusual linear silk stabilimentum to this web that may camouflage the cocoon. The effects of the larva are apparently due to a chemical product or products that it introduces into the spider. Behavioural modification is gradual, and various behavioural effects arise in a consistent order. If the wasp larva is experimentally removed just before it kills the spider, the spider's behaviour recovers gradually in the reverse order. In addition, a greater delay in removing the larva leads to more pronounced and enduring behavioural changes, so the larval effects may depend on a cumulative or dose-dependent process. Changes in numbers and lengths of radii and numbers of sticky spiral loops could result from correlated larval effects on the reduction in the amount of silk in the spider's sticky spiral silk glands (or a signal thereof), but several other types of behavioural change are probably under separate controls; multiple larval products may be involved. The larvae may affect higher levels of behavioural decisions by spiders that determine overall web ‘design’, rather than lower levels, such as control of particular behaviour patterns, as may be affected by related wasps. The larva's effects are fine-tuned to details of the host's natural history.

Symbiotic virus at the evolutionary intersection of three types of large DNA viruses; iridoviruses, ascoviruses, and ichnoviruses.

BackgroundThe ascovirus, DpAV4a (family Ascoviridae), is a symbiotic virus that markedly increases the fitness of its vector, the parasitic ichneumonid wasp, Diadromus puchellus, by increasing survival of wasp eggs and larvae in their lepidopteran host, Acrolepiopsis assectella. Previous phylogenetic studies have indicated that DpAV4a is related to the pathogenic ascoviruses, such as the Spodoptera frugiperda ascovirus 1a (SfAV1a) and the lepidopteran iridovirus (family Iridoviridae), Chilo iridescent virus (CIV), and is also likely related to the ancestral source of certain ichnoviruses (family Polydnaviridae).Methodology/Principal FindingsTo clarify the evolutionary relationships of these large double-stranded DNA viruses, we sequenced the genome of DpAV4a and undertook phylogenetic analyses of the above viruses and others, including iridoviruses pathogenic to vertebrates. The DpAV4a genome consisted of 119,343 bp and contained at least 119 open reading frames (ORFs), the analysis of which confirmed the relatedness of this virus to iridoviruses and other ascoviruses.ConclusionsAnalyses of core DpAV4a genes confirmed that ascoviruses and iridoviruses are evolutionary related. Nevertheless, our results suggested that the symbiotic DpAV4a had a separate origin in the iridoviruses from the pathogenic ascoviruses, and that these two types shared parallel evolutionary paths, which converged with respect to virion structure (icosahedral to bacilliform), genome configuration (linear to circular), and cytopathology (plasmalemma blebbing to virion-containing vesicles). Our analyses also revealed that DpAV4a shared more core genes with CIV than with other ascoviruses and iridoviruses, providing additional evidence that DpAV4a represents a separate lineage. Given the differences in the biology of the various iridoviruses and ascoviruses studied, these results provide an interesting model for how viruses of different families evolved from one another.

Parasitoid Complex of the Gypsy Moth (Lymantria dispar) in the Increase-phase Populations in Korea

The species composition of the parasitoid complex and the degree of parasitism by each species were analyzed for gypsy moth (Lymantria dispar) populations in the increasing phase. Total of 7,826 mid-late instar larvae and pupae were collected and reared from two collection sites in Gangwon Province, Korea. Two tachinid flies (Blepharipa schineri and Parasetigena silvestris), and the ichneumonid wasp (Coccygomimus disparis) were the most abundant parasitoids, in the order of decreasing importance. Other parasitoids occurring included Coteisa melanoscelus, Cotesia scheaferi, Glyptapanteles liparidis, Brachymeria lasus, and Exorista spp. The low incidence of the NPVirus is hypothesized to be an important factor in determining degree of parasitism rate by P. silvestris and B. schineri, and their relative dominance in the parasitoid complex.

Hammering homoplasy: multiple gains and losses of vibrational sounding in cryptine wasps (Insecta: Hymenoptera: Ichneumonidae)

Many hosts of parasitic wasps are, when attacked, either at an immobile stage, living in a concealed environment, or both, thus making their detection especially difficult. Cryptine ichneumonid wasps often parasitize beetle or moth larvae, prepupae or even pupae in tunnels in wood, and many others attack cocooned hosts in various states of concealment. The structure of the antennal tips shows a range of adaptations at least the most extreme of which appear to be involved in locating deeply concealed hosts through vibrational sounding (= echolocation through solid media). We show that, within the Cryptinae, the tips of the antenna are modified into a hammer-like structure that is suitable for knocking a substrate; this form of echo-location is typical to the tribe Cryptini, although it is also found in a few phygadeuontines and in the hemigastrine genus Echthrus. Electron micrographs are presented to illustrate the different degrees of antennal modifications found in the subfamily. Comparative analysis using independent contrasts was then used to demonstrate a statistically significant association between degree of antennal hammer development and attacking, typically wood-boring, beetle hosts of the families Cerambycidae and Buprestidae. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 82–102.

Why cross the web: decoration spectral properties and prey capture in an orb spider (Argiope keyserlingi) web

An effective visual signal elicits a strong receiver response. The visual receptors of most insects are sensitive to ultraviolet (UV), blue and green light. The decorations of certain orb web spiders may be described as a type of visual signal, a sensory trap, as they exploit visual biases in insects. We filtered UV and blue light from the decorations of Argiope keyserlingi, under field conditions, using plastic sheets to test if the UV and blue light reflected affects the type of prey caught. We found that houseflies, blowflies, stingless bees, honeybees and vespid wasps were caught more frequently in webs with decorations than webs without, while ichneumonid wasps were caught less frequently. Blowflies, stingless bees, honeybees and vespid wasps were caught more often in unfiltered decorated webs. These insects also have receptor sensitivities in the blue and UV. We showed that exploiting visual sensory biases plays an integral role in attracting insects to orb web decorations. Whether UV light, blue light, or both, are the most important cue, however, requires further study. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 221‐229.

Production of Helicoverpa spp. (Lepidoptera, Noctuidae) from different refuge crops to accompany transgenic cotton plantings in eastern Australia

The adoption of transgenic (Bt) cotton varieties has markedly reduced feeding damage by noctuid pests, Helicoverpa armigera and H. punctigera, in Australian cotton crops. However, the potential for Bt resistance to evolve within these insect pests is a major concern. To reduce the likelihood of Bt resistance occurring, it is mandatory for growers of Bt cotton to also grow refuge crops which produce large numbers of Bt-susceptible moths. We present here findings from a series of field studies which sought to identify the relative Helicoverpa productivity of different refuge crop options. The abundance of Helicoverpa pupae (during the cotton season) was compared under crops of Ingard® (transgenic, single Bt gene) cotton, sprayed conventional cotton, and various unsprayed refuge crops (cotton, sorghum, maize, pigeon pea) from 1996 to 2003 in the major cotton-producing regions of northern New South Wales, plus St George and Dirranbandi in southern Queensland. Unsprayed, conventional cotton was used as the ‘control’ refuge in these studies. Productivity of adult Helicoverpa was estimated by surveying for pupae and discounting those that were parasitised and dead. Some supplementary experiments were also conducted to evaluate specific issues, in particular the value of additional refuge crops sown late in 2000–01 (due to accidental over-planting of Ingard® cotton that year) and the potential productivity of mixed plantings of various refuge crops which individually flowered at different times throughout the cotton season. Unsprayed refuges generally produced many more pupae than sprayed, conventional cotton and Ingard® cotton. Overall, pigeon pea, which has the advantage of prolonged flowering and thus on-going attractiveness to Helicoverpa, was the most reliable and productive refuge option, producing about twice as many pupae as unsprayed cotton. The seed mix refuge is perhaps a viable alternative option, although logistically more difficult for growers to adopt. Laboratory rearing of live pupae until moth emergence indicated that parasitism can be a substantial source of mortality in some refuge crops, especially sorghum. The most common parasitoid of Helicoverpa pupae was the ichneumonid wasp, Heteropelma scaposum. Such parasitism can greatly reduce productivity of adult Helicoverpa from refuges and needs to be taken into account when assessing relative refuge ‘value’, although such refuges will obviously contribute to the abundance of these beneficial species across the landscape.

Molecular evidence for the evolution of ichnoviruses from ascoviruses by symbiogenesis

BackgroundFemale endoparasitic ichneumonid wasps inject virus-like particles into their caterpillar hosts to suppress immunity. These particles are classified as ichnovirus virions and resemble ascovirus virions, which are also transmitted by parasitic wasps and attack caterpillars. Ascoviruses replicate DNA and produce virions. Polydnavirus DNA consists of wasp DNA replicated by the wasp from its genome, which also directs particle synthesis. Structural similarities between ascovirus and ichnovirus particles and the biology of their transmission suggest that ichnoviruses evolved from ascoviruses, although molecular evidence for this hypothesis is lacking.ResultsHere we show that a family of unique pox-D5 NTPase proteins in the Glypta fumiferanae ichnovirus are related to three Diadromus pulchellus ascovirus proteins encoded by ORFs 90, 91 and 93. A new alignment technique also shows that two proteins from a related ichnovirus are orthologs of other ascovirus virion proteins.ConclusionOur results provide molecular evidence supporting the origin of ichnoviruses from ascoviruses by lateral transfer of ascoviral genes into ichneumonid wasp genomes, perhaps the first example of symbiogenesis between large DNA viruses and eukaryotic organisms. We also discuss the limits of this evidence through complementary studies, which revealed that passive lateral transfer of viral genes among polydnaviral, bacterial, and wasp genomes may have occurred repeatedly through an intimate coupling of both recombination and replication of viral genomes during evolution. The impact of passive lateral transfers on evolutionary relationships between polydnaviruses and viruses with large double-stranded genomes is considered in the context of the theory of symbiogenesis.

Host searching behavior and potential of an aquatic ichneumonid pupal parasitoid of rice caseworm (Parapoynx stagnalis) in an upland rice paddy agro-ecosystem of the Western Ghats, India

Parapoynx stagnalis (Zeller) (=Nymphula depunctalis (Guenée), is a sporadic rice paddy pest of south and southeast Asian rice paddy fields, and widely known as rice caseworm. A recent outbreak of the pest was observed in the upland rice paddy agro-ecosystem of the central Western Ghats, India. No potential natural enemies of this pest have so far been reported, mainly due to the semi-aquatic behavior of the larvae and pupae. However, an undescribed aquatic ichneumonid wasp species (belonging to a genus near Litochila) is reported as a potentially useful early stage pupal parasitoid of this pest in our study. The host searching behavior and potential of the parasitoid wasp was studied in detail using both field and laboratory experiments. The adult female wasps usually dive into the water in search of the host pupae, remaining under water for a maximum of 90.2s, while searching for rice caseworm pupae. In field and laboratory experiments, we found 73% of the parasitized pupae of P. stagnalis kept under water yielded adult parasitic wasps. However, no parasitoids emerged from parasitized host pupae maintained in dry terrariums. Sex ratio was 2.8:1. The present discovery of the semi-aquatic parasitoid wasp could aid in better management of the rice caseworm population in rice paddy fields.

Swarming Behavior of Two Parasitic Wasps, Leurus caeruliventris (Hymenoptera: Ichneumonidae) and Conura sp. (Hymenoptera: Chalcididae), at the Same Site

Swarming behavior, in which individuals of one sex form groups at sites lacking resources but where they are likely to encounter receptive individuals of the other sex, is common in some orders of insects such as Ephemeroptera and Diptera (Thornhill and Alcock, 1983; Sivinski and Petersson, 1997). For reasons that are unclear it is less common in others, such as Hymenoptera (except, again for apparently unknown reasons, in Formicidae). In the family Braconidae, males of several species of Blacus form swarms (van Achterberg, 1975, 1977). There are scattered reports of swarming in several other species of parasitoids (Godfray, 1994). Because nothing is known of the mating behavior of most species of Ichneumonidae and Chalcididae, especially in the tropics, it seems worthwhile recording brief observations of swarming in two species, Leurus caeruliventris (Cresson) (Ichneumonidae: Metopiinae), and Conura sp. (Chalcidae) in Costa Rica. Leurus are endoparasitic koinobionts of microlepidopterans; L. caeruliventris is a common, widespread species ranging from the United States to Argentina (I. D. Gauld, pers. comm.). Conura is a huge genus (estimated 250–300 species in Costa Rica, .1000 species in the Neotropics) that are parasitoids of the pupae of Lepidoptera, Chrysomelidae, and their primary parasitoids (Delvare, 1995), and also of ichneumonid wasp pupae (Eberhard, 2000).

Role of venom and ovarian proteins in immune suppression of Ostrinia furnacalis (Lepidoptera: Pyralidae) larvae parasitized by Macrocentrus cingulum (Hymenoptera: Braconidae), a polyembryonic parasitoid

AbstractVenom and ovarian proteins in braconid and ichneumonid wasps play an important role in the successful parasitism of their host, especially for immune suppression immediately after oviposition. In this study, we compared the effect of venom and ovarian proteins collected from the female wasps of Macrocentrus cingulum, a polyembryonic parasitoid of the larvae of Ostrinia funacalis, on the encapsulation capacity of Sephadex A‐25 beads at 4 h and 24 h post‐injection both in vivo and in vitro. The results showed that the ovarian proteins significantly interfered with the encapsulation capacity of hemocytes in a dose‐dependent manner. Spreading and viability of hemocytes in O. furnacalis was not disrupted by venom and ovarian proteins at various concentrations injected. It seems likely that the ovarian proteins from M. cingulum play a role in suppressing the encapsulation capacity of host hemocytes.

Characterization of the IκB-like gene family in polydnaviruses associated with wasps belonging to different Braconid subfamilies

Polydnaviruses (PDVs) are obligate symbionts of hymenopteran parasitoids of lepidopteran larvae that induce host immunosuppression and physiological redirection. PDVs include bracoviruses (BVs) and ichnoviruses (IVs), which are associated with braconid and ichneumonid wasps, respectively. In this study, the gene family encoding IkappaB-like proteins in the BVs associated with Cotesia congregata (CcBV) and Toxoneuron nigriceps (TnBV) was analysed. PDV-encoded IkappaB-like proteins (ANK) are similar to insect and mammalian IkappaB, an inhibitor of the transcription factor nuclear factor kappaB (NF-kappaB), but display shorter ankyrin domains and lack the regulatory domains for signal-mediated degradation and turnover. Phylogenetic analysis of ANK proteins indicates that those of IVs and BVs are closely related, even though these two taxa are believed to lack a common ancestor. Starting from a few hours after parasitization, the transcripts of BV ank genes were detected, at different levels, in several host tissues. The structure of the predicted proteins suggests that they may stably bind NF-kappaB/Rel transcription factors of the tumour necrosis factor (TNF)/Toll immune pathway. Accordingly, after bacterial challenge of Heliothis virescens host larvae parasitized by T. nigriceps, NF-kappaB immunoreactive material failed to enter the nucleus of host haemocytes and fat body cells. Moreover, transfection experiments in human HeLa cells demonstrated that a TnBV ank1 gene product reduced the efficiency of the TNF-alpha-induced expression of a reporter gene under NF-kappaB transcriptional control. Altogether, these results suggest strongly that TnBV ANK proteins cause retention of NF-kappaB/Rel factors in the cytoplasm and may thus contribute to suppression of the immune response in parasitized host larvae.

Temperature affects interaction of visual and vibrational cues in parasitoid host location

Parasitoid host location in nature is facilitated by simultaneously using different information sources. How multisensory orientation on the same spatial scale is influenced by environmental conditions is however poorly understood. Here we test whether changes in reliability of cues can cause parasitoids to alter multisensory orientation and to switch to cues that are more reliable under extreme temperatures. In the ichneumonid wasp Pimpla turionellae, multisensory use of thermally insensitive vision and thermally sensitive mechanosensory host location by vibrational sounding (echolocation on solid substrate) was investigated with choice experiments on plant-stem models under optimum temperature (18 degrees C), at high- (28 degrees C) and low-temperature limits (8 degrees C) of vibrational sounding. Temperature affected relative importance of vibrational sounding whereas visual orientation did not vary. At 18 degrees C, parasitoids used visual and vibrational cues with comparable relative importance. At 8 and 28 degrees C, the role of vibrational sounding in multisensory orientation was significantly reduced in line with decreased reliability. Wasps nearly exclusively chose visual cues at 8 degrees C. The parasitoids switch between cues and sensory systems depending on temperature. As overall precision of ovipositor insertions was not affected by temperature, the parasitoids fully compensate the loss of one cue provided another reliable cue is available on the same spatial scale.

Divergences in Protein Activity and Cellular Localization within the Campoletis sonorensis Ichnovirus Vankyrin Family

Ichnoviruses (IVs) occur in obligate symbiotic associations with endoparasitic ichneumonid wasps. IVs are injected with eggs during parasitization, where viral infection and gene expression alter host physiology to ensure endoparasitoid survival. The seven Campoletis sonorensis IV (CsIV) vankyrin genes encode proteins that possess ankyrin repeat domains resembling the inhibitory domains of NF-kappaB transcription factor inhibitors (IkappaBs). The CsIV vankyrins are divided into two subclasses: those expressed primarily in the host fat body (three genes) and those expressed in host hemocytes (four genes). CsIV vankyrin proteins showed limited antigenic similarity when analyzed by Western blotting. Cellular localization and expression patterns of recombinant vankyrin proteins in High Five and Sf9 insect cells differed within and between the subclasses and in cells exposed to lipopolysaccharide, laminarin, or viral immune challenge. In unstimulated Sf9 cells, five vankyrins were detected in cell nuclei. The remaining two proteins localized predominantly to cytoplasmic granules. Immune stimulation of cells resulted in a nuclear-to-cytoplasmic shift of three vankyrins but did not affect localization of other variants. When expressed from recombinant Autographa californica multiple nucleopolyhedroviruses (AcMNPVs), all vankyrins showed a nuclear localization during early stages of infection with patterns resembling those of immune-challenged cells as the infection progressed. Two fat body vankyrins also produced unique biological effects when expressed from recombinant AcMNPV. Insect cells infected with these viruses exhibited enhanced longevity compared to those infected with viruses expressing other vankyrins. Together, these data suggest that vankyrin proteins in CsIV have divergent physiological functions.

Gene expression profiling of Spodoptera frugiperda hemocytes and fat body using cDNA microarray reveals polydnavirus-associated variations in lepidopteran host genes transcript levels

BackgroundGenomic approaches provide unique opportunities to study interactions of insects with their pathogens. We developed a cDNA microarray to analyze the gene transcription profile of the lepidopteran pest Spodoptera frugiperda in response to injection of the polydnavirus HdIV associated with the ichneumonid wasp Hyposoter didymator. Polydnaviruses are associated with parasitic ichneumonoid wasps and are required for their development within the lepidopteran host, in which they act as potent immunosuppressive pathogens. In this study, we analyzed transcriptional variations in the two main effectors of the insect immune response, the hemocytes and the fat body, after injection of filter-purified HdIV.ResultsResults show that 24 hours post-injection, about 4% of the 1750 arrayed host genes display changes in their transcript levels with a large proportion (76%) showing a decrease. As a comparison, in S. frugiperda fat body, after injection of the pathogenic JcDNV densovirus, 8 genes display significant changes in their transcript level. They differ from the 7 affected by HdIV and, as opposed to HdIV injection, are all up-regulated. Interestingly, several of the genes that are modulated by HdIV injection have been shown to be involved in lepidopteran innate immunity. Levels of transcripts related to calreticulin, prophenoloxidase-activating enzyme, immulectin-2 and a novel lepidopteran scavenger receptor are decreased in hemocytes of HdIV-injected caterpillars. This was confirmed by quantitative RT-PCR analysis but not observed after injection of heat-inactivated HdIV. Conversely, an increased level of transcripts was found for a galactose-binding lectin and, surprisingly, for the prophenoloxidase subunits. The results obtained suggest that HdIV injection affects transcript levels of genes encoding different components of the host immune response (non-self recognition, humoral and cellular responses).ConclusionThis analysis of the host-polydnavirus interactions by a microarray approach indicates that the presence of HdIV induces, directly or indirectly, variations in transcript levels of specific host genes, changes that could be responsible in part for the alterations observed in the parasitized host physiology. Development of such global approaches will allow a better understanding of the strategies employed by parasites to manipulate their host physiology, and will permit the identification of potential targets of the immunosuppressive polydnaviruses.

Understanding the evolution of polydnaviruses

Described in thousands of parasitoid wasp species polydnaviruses (PDVs) are unique viruses having both a segmented DNA genome in viral particles and an integrated form that persists as a provirus in the wasp genome. Parasitoid wasps inject their eggs in another insect host and along with them, the virus particles that are essential to ensure parasitism success. Two phylogenetically unrelated genera of polydnaviruses exist, the bracoviruses (BVs) and the ichnoviruses (IVs) associated with braconid and ichneumonid wasps respectively. New data on the genomes of two bracoviruses (Microplitis demolitor BV and Cotesia congregata BV) and an ichnovirus associated with Campoletis sonorensis (CsIV) offers us new elements to discuss the central questions concerning the origin and the evolution of these viral entities. The results indicate that the tens of millions of years of mutualistic associations between PDVs and wasps has had a strong impact on PDV genomes that now ressemble an eukaryotic region.

Unfolding the evolutionary story of polydnaviruses

Polydnaviruses (PDVs) are fascinating viruses. Described in thousands of parasitoid wasp species they are unique viruses having both a segmented DNA genome in viral particles and an integrated form that persists as a provirus in the wasp genome. Parasitoid wasps inject their eggs in another insect host typically a lepidopteran. In these host–parasitoid interactions, the virus particles are co-injected along with the eggs and are essential to ensure wasp parasitism success. PDVs do not replicate in the lepidopteran host, but expression of viral gene products confers protection from the host immune defence response. Two genera of PDVs phylogenetically unrelated exist, the bracoviruses (BVs) and the ichnoviruses (IVs), associated with braconid and ichneumonid wasps, respectively. New data on the genomes of two bracoviruses ( Microplitis demolitor BV and Cotesia congregata BV) and an ichnovirus associated with Campoletis sonorensis (CsIV) offers us new elements to discuss the central questions concerning the origin of these viral entities and how they have evolved. The results of sequencing approaches indicate that the tens of millions of years of mutualistic associations between PDVs and wasps have had a strong impact on PDV genomes that now ressemble eukaryotic regions both in organization and gene content.

Harmful occurrence of Rosy rustic moth (Hydraecia micacea) (Noctuidae: Lepidoptera) on hop in the Czech Republic

The Rosy rustic moth (<I>Hydraecia micacea</I>) has been a pest of hop in Czech hop regions for a long time. It causes most severe damages in hop gardens infested by quackgrass (<I>Elytrigia repens</I>) on waterlogged<B> </B>areas. Larvae emerge from the second half of April to the middle of May. The sum of effective temperatures (SET) necessary for hatching larvae has been determined to be 78.6C over a 4-year average. Young larvae first feed on leaves of quackgrass, and later move to hop plants where they feed inside the shoots and rootstocks. Occurrence and damage are<B> </B>most frequent at the edges of hop gardens and in places with anchorages between two hop gardens. The ichneumonid wasp <I>Ichneumon sarcitorius</I> and the fly <I>Lidella thompsoni</I> are the most common parasitoids of this pest. Numbers of males caught in pheromone traps were very low. More males were trapped near hop gardens typical for repeated harmful occurrence of the rosy rustic moth. Females trapped in a light trap from the second half of August to the last decade of September had already full-developed eggs in their ovaries.

Polydnavirus genomes reflect their dual roles as mutualists and pathogens

Symbionts often exhibit significant reductions in genome complexity while pathogens often exhibit increased complexity through acquisition and diversification of virulence determinants. A few organisms have evolved complex life cycles in which they interact as symbionts with one host and pathogens with another. How the predicted and opposing influences of symbiosis and pathogenesis affect genome evolution in such instances, however, is unclear. The Polydnaviridae is a family of double-stranded (ds) DNA viruses associated with parasitoid wasps that parasitize other insects. Polydnaviruses (PDVs) only replicate in wasps but infect and cause severe disease in parasitized hosts. This disease is essential for survival of the parasitoid's offspring. Thus, a true mutualism exists between PDVs and wasps as viral transmission depends on parasitoid survival and parasitoid survival depends on viral infection of the wasp's host. To investigate how life cycle and ancestry affect PDVs, we compared the genomes of Campoletis sonorensis ichnovirus ( CsIV) and Microplitis demolitor bracovirus ( MdBV). CsIV and MdBV have no direct common ancestor, yet their encapsidated genomes share several features including segmentation, diversification of virulence genes into families, and the absence of genes required for replication. In contrast, CsIV and MdBV share few genes expressed in parasitized hosts. We conclude that the similar organizational features of PDV genomes reflect their shared life cycle but that PDVs associated with ichneumonid and braconid wasps have likely evolved different strategies to cause disease in the wasp's host and promote parasitoid survival.

Egg Predation Fuels Unique Species Association at Deep-Sea Hydrocarbon Seeps

(Bivalvia; Limidae), that has evolved special-ized mechanisms to exploit a unique source of nutritionderived ultimately from chemosynthesis: the energy-richeggs of giant tubeworms. Opportunistic egg or embryopredators are common among terrestrial vertebrates (2, 3)and marine invertebrates (4). Egg specialists are found insome groups of insects, including ichneumonid wasps (5)and phorid flies (6) and at least one genus of nemertean (7),but we know of no marine animals other than