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Results for “Ichneumonid wasp”

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At least 19 recordsLinked to original sources

PubMed2025

The genome sequence of an ichneumonid wasp, Netelia melanura (Thomson, 1888) (Hymenoptera: Ichneumonidae).

We present a genome assembly from an individual male Netelia melanura (ichneumonid wasp; Arthropoda; Insecta; Hymenoptera; Ichneumonidae). The genome sequence has a total length of 253.87 megabases. Most of the assembly (94.81%) is scaffolded into 7 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 28.04 kilobases. This assembly was generated as part of the Darwin Tree of Life project, which produces reference genomes for eukaryotic species found in Britain and Ireland.

Netelia melanura; ichneumonid wasp; genome sequenc↗

PubMed2026

The genome sequence of an ichneumonid wasp, Ophion crassicornis Brock, 1982 (Hymenoptera: Ichneumonidae).

We present a genome assembly from an individual female Ophion crassicornis (ichneumonid wasp; Arthropoda; Insecta; Hymenoptera; Ichneumonidae). The genome sequence has a total length of 726.34 megabases. Most of the assembly (98.51%) is scaffolded into 13 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 38.03 kilobases. This assembly was generated as part of the Darwin Tree of Life project, which produces genomes for eukaryotic species found in Britain and Ireland.

Hymenoptera↗

PubMed2026

The genome sequence of an ichneumonid wasp, Promethes sulcator (Gravenhorst, 1829) (Hymenoptera: Ichneumonidae).

We present a genome assembly from an individual female Promethes sulcator (ichneumonid wasp; Arthropoda; Insecta; Hymenoptera; Ichneumonidae). The genome sequence has a total length of 278.74 megabases. Most of the assembly (99.67%) is scaffolded into 10 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 29.43 kilobases. This assembly was generated as part of the Darwin Tree of Life project, which produces genomes for eukaryotic species found in Britain and Ireland.

Hymenoptera↗

PubMed2026

The genome sequence of an ichneumonid wasp, Venturia canescens (Gravenhorst, 1829) (Hymenoptera: Ichneumonidae).

We present a genome assembly from an individual female Venturia canescens (ichneumonid wasp; Arthropoda; Insecta; Hymenoptera; Ichneumonidae). The genome sequence has a total length of 299.96 megabases. Most of the assembly (97.25%) is scaffolded into 11 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 27.35 kilobases. Gene annotation of this assembly on Ensembl identified 14 281 protein-coding genes. This assembly was generated as part of the Darwin Tree of Life project, which produces reference genomes for eukaryotic species found in Britain and Ireland.

Hymenoptera↗

PubMed1979

Penetration into caterpillar cells of virus-like particles injected during oviposition by parasitoid ichneumonid wasps.

Particles originating from the ovarial calyx epithelium of two different species of ichneumonid wasp are injected into host caterpillars during oviposition. At 1 3/4 h post oviposition, many calyx fluid particles are either associated with or have oenetrated through the basement membranes surrounding various tissues. Shortly thereafter, apparently intact particle nucleocapsids are observed in both the cytoplasm and nucleus of host cells. An unusual tubular protrusion of the viral envelope appears to be involved in either or both of penetration of basement membranes and entry of nucleocapsids into host cells.

Animals↗

PubMed2003

Overt viral diseases induced from apparent latency following parasitization by the ichneumonid wasp, Hyposoter exiguae.

Latent and/or asymptomatic viral infections are commonplace in insects, but factors inducing overt disease are poorly understood. Here we show that in Trichoplusia ni larvae parasitized by the ichneumonid wasp, Hyposoter exiguae, overt, lethal disease may on occasion be observed; however, disease has been consistently absent in control (non-parasitized) larvae. Thus far, we have detected two such diseases, one of which is caused by a granulosis virus affecting primarily fat body tissue. The other is associated with the presence of two viruses replicating together in larval midgut epithelial cells; of these, one has been identified as a non-occluded form of TnCPV. Since H. exiguae carries a polydnavirus, which is delivered to host larvae during oviposition, it is tempting to speculate that viral latency may in some cases be broken through immunosuppressive activity resulting from insect parasitism.

Animals↗

PubMed2003

Origin and evolution of polydnaviruses by symbiogenesis of insect DNA viruses in endoparasitic wasps.

During oviposition, many endoparasitic wasps inject virus-like particles into their insect hosts that enable these parasitoids to evade or directly suppress their hosts' immune system, especially encapsulation by hemocytes. These particles are defined as virions that belong to viruses of the two genera that comprise the family Polydnaviridae, bracoviruses (genus Bracovirus) transmitted by braconid wasps, and ichnoviruses (genus Ichnovirus) transmitted by ichneumonid wasps. Structurally, bracovirus virions resemble nudivirus and baculovirus virions (family Baculoviridae), and ichnovirus virions resemble those of ascoviruses (family Ascoviridae). Whereas nudiviruses, baculoviruses and ascoviruses replicate their DNA and produce progeny virions, polydnavirus DNA is integrated into and replicated from the wasp genome, which also directs virion synthesis. The structural similarity of polydnavirus virions to those of viruses that attack the wasps' lepidopteran hosts, along with polydnavirus transmission and replication biology, suggest that these viruses evolved from insect DNA viruses by symbiogenesis, the same process by which mitochondia and chloroplasts evolved from bacteria. Molecular evidence supporting this hypothesis comes from similarities among structural proteins of ascoviruses and the Campoletis sonorensis ichnovirus. Implications of this hypothesis are that polydnaviruses evolved from viruses, but are no longer viruses, and that DNA packaged into polydnavirus virions is not viral genomic DNA per se, but rather wasp genomic DNA consisting primarily of wasp genes and non-coding DNA. Thus, we suggest that a better understanding of polydnaviruses would result by viewing these not as viruses, but rather as a wasp organelle system that evolved to shuttle wasp genes and proteins into hosts to evade and suppress their immune response.

Amino Acid Sequence↗

PubMed2007

Characterization of the IkappaB-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.

Animals↗

PubMed2004

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↗

PubMed2006

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.

Animals↗

PubMed2006

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.

Animals↗

PubMed1995

Polydnaviruses: potent mediators of host insect immune dysfunction.

Endoparasitic insects are used as biological control agents to kill many species of insect pest. One key to the success of parasitoids that develop in the hemocoel of their host is their ability to knock out the host's immune system, inducing a decline in the responsiveness of a variety of cellular and humoral components so that parasitoid eggs are not encapsulated. In many species parasitized by braconid and ichneumonid wasps, host immunosuppression appears to be mediated by polydnaviruses (PDVs) injected by the female parasitoid into the host hemocoel. The viruses exhibit a complex and intimate genetic relationship with the wasp, since viral sequences are integrated within the wasp's chromosomal DNA. Here Mark Lavine and Nancy Beckage summarize the current evidence for mechanisms of virally induced host immunosuppression in parasitized insects, as well as the roles of other factors including wasp ovarian proteins and venom components, in suppressing hemocyte-mediated and humoral immune responses. Interestingly, in some species, the PDV-induced host immunosuppression appears transitory, with older parasitoid larvae probably exploiting other mechanisms to protect themselves from the host's immune system during the final stages of parasitism. During the final stages of parasitism, the parasitoids likely exploit other mechanisms of immunoevasion via antigen masking, antigen mimicry, or production of active inhibitors of the hemocyte-mediated encapsulation response as well as inhibiting melanization.

Journal Article↗

PubMed2003

Characterization of Campoletis sonorensis ichnovirus unique segment B and excision locus structure.

Polydnaviruses (PDVs) are segmented, symbiotic, double-stranded DNA viruses that are vertically transmitted as proviruses within the genomes of some parasitoid Hymenoptera. The PDV associated with the ichneumonid wasp Campoletis sonorensis (CsIV) consists of 24 non-redundant DNA segments varying in size from approximately 6 to 20 kbp. CsIV segment B, one of the smallest genome segments, was sequenced and the excision sites of the proviral segment were characterized. The segment B sequence was 83.2% non-coding with only two open reading frames (ORFs). Some non-coding sequences have similarities to database sequences and were likely pseudogenic, but most were unrelated to known nucleic acid or predicted protein sequences. One ORF, BHv0.9, encodes a member of the rep gene family and was expressed only in parasitized insects while transcription of the other ORF could not be detected. Previously, a third region of the segment was shown to hybridize to 0.6 and 1.2 kb poly A+ RNAs from female wasps during virus replication (Theilmann and Summers, 1988) but this region did not have an identifiable ORF in the determined sequence. In contrast to CsIV segment W, segment B had little repetitive sequence. The segment B proviral integration locus contains a 59 bp direct imperfect repeat. Further analyses of this integration locus demonstrated that segment B was excised from wasp genomic DNA with flanking sequences at the integration site rejoined after segment excision. The segment B "excision locus" retained one of the two copies of the 59 bp repeat sequence with the other repeat present in the excised segment. The data indicate that Ichnovirus segments have distinctive characteristics possibly reflecting functional co-evolution between the wasp and individual types of polydnavirus segments.

Animals↗

PubMed2006

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.

Animals↗

PubMed2006

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

BACKGROUND: Genomic 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. RESULTS: Results 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). CONCLUSION: This 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.

Animals↗

PubMed2001

Association of insects and ergot (Claviceps purpurea) in Kentucky bluegrass seed production fields.

Insects in Kentucky bluegrass seed production fields in Oregon, Idaho, and Washington were sampled just before harvest and their association with ergot conidia of Claviceps purpurea Fr. (Tul.) was evaluated during 1996-1998. A diversity of insects was observed at all three locations. The most abundant beneficial insects collected with sweep nets were Nysium spp., Nabis spp., ichneumonid wasps, and Hippodamia spp. The cranberry girdler, Chrysoteuchia topiaria (Zeller), was the only important pest on grass seed collected by sweep net. Numbers of aphids such as Sitobion avenae (F.), cicadellids and thrips such as Anaphothrips spp. and Aptinothrips spp. that were collected with all aphid sampler were below economic thresholds. Other insect groups occurred in low numbers. Noctuid moths collected in universal blacklight traps included nine species of cutworms and armyworms. Protogrotis obscura (B. & McD.) was the most common cutworm species and was present in all fields. The moth Chortodes rufostrigata (Pack.) previously reported only from wet meadows in northeast and south central Oregon was found in Kentucky bluegrass fields in central Oregon, suggesting that irrigated Kentucky bluegrass seed production fields may simulate a montane meadow habitat. Conidia of C. purpurea were found on a diversity of insects, including moths, flies, leafhoppers, and thrips. Up to 100% of moths and 75% of flies collected from some fields carried conidia of C. purpurea. No correlation between ergot honeydew present in a field and number of insects with conidia of C. purpurea was detected.

Animals↗

PubMed1999

Free serosal cells originating from the embryo of the wasp Diadromus pulchellus in the pupal body of parasitized leek-moth, Acrolepiosis assectella. Are these cells teratocyte-like?

In braconid species, teratocytes are derived from a serosal cell membrane which envelops the developing parasitoid embryo. On hatching, this membrane dissociates into individual cells, the teratocytes, which then circulate in the haemolymph of the host. We describe herein such a membrane, surrounding the embryo in eggs of the ichneumonid parasitoid wasp, Diadromus pulchellus. This membrane consisted of a single sheet of tightly packed cells with large 12+/-1.4 &mgr;m nuclei. These cells were released after hatching in vitro and cells of the same size were detected in vivo, in the vicinity of the D. pulchellus embryo. The number of nuclei detected suggests that the serosal membrane consists of about 450+/-150 cells. These cells did not grow after hatching of the parasitoid egg in the parasitized host, Acrolepiosis assectella, during the development of the parasitoid wasp larva. Southern blot experiments, using D. pulchellus satellite DNA or the ribosomal genes as probes, showed that free-living floating cells of wasp origin were present in the body of the parasitized host. This is the first time that free-floating teratocyte-like cells have been described in species of the Ichneumonidae.

Journal Article↗

PubMedDate not supplied

Single-locus complementary sex determination in Diadegma chrysostictos (Gmelin) (Hymenoptera: Ichneumonidae).

Following the establishment of isofemale lines and subsequent inbreeding, the ichneumonid parasitoid wasp Diadegma chrysostictos (Gmelin) was shown by segregation of polymorphic alloenzyme loci to have single-locus complementary sex determination (sl-CSD). This and the biparental nature of diploid males was confirmed using two independent Mendelian recessive phenotypic markers. The existence of diploid males, sl-CSD, and the abrogation of diploid males following outbreeding was further confirmed by flow cytometry, a potentially general method that is independent of the maternal sex allocation or the need for genetic markers. Estimates of the number of sex alleles in several British populations demonstrated 17-19 alleles in Britain, with a decline toward the northerly limit of the parasitoid's range, varying from 16 in the south of England to 4-5 in central Scotland, in broad agreement with the rate of attainment of a male-biased sex ratio when used to establish en masse laboratory cultures. These data represent the second confirmation of the existence of sl-CSD in the Ichneumonidae (and the first in the Campopleginae subfamily), lending further support to the notion that sl-CSD was the ancestral condition in the Aculeata/Ichneumonoidea clade (Cook 1993a; Periquet et al. 1993).

Alleles↗