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Visible mutation induction in Mormoniella by low frequency ultrasonic energy.

Low frequency ultrasonic energy was utilized in an attempt to induce visible mutations in the parasitoid wasp Mormoniella vitripennis (Walker). Ultrasonic exposure at a frequency of 20,000 cycles per second was accomplished in aqueous medium with a commercially obtained energy source. Among the 22,396 progeny of exposed males and females, 63 phenotypically changed wasps were recovered. Three of these changes from exposed males and two from exposed females proved to be genetically transmissible. No transmissible changes were found among 4,739 control progeny. This study demonstrates that low frequency ultrasound may be used as an effective mutagenic agent with this organism, and suggests that it may have applications with other genetic systems.

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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

Systematic profiling of nudivirus-like genes reveals conserved and differentiated roles in a domesticated endogenous virus.

Cotesia vestalis bracovirus (CvBV) is a type of domesticated endogenous virus (DEV) derived from ancestral nudiviruses that is integrated into the genome of the parasitoid wasp Cotesia vestalis. The CvBV proviral genome is composed of two distinct components: one encoding genes associated with virion morphogenesis and assembly, and the other harboring virulence genes that are excised, circularized, and packaged into virions. CvBV replication and particle assembly occur exclusively in the ovaries of female wasps. While prior studies have largely focused on the function of virulence genes during parasitization, the molecular mechanisms underlying CvBV replication and assembly remain poorly understood. Here, we identified 71 nudivirus-like genes in the C. vestalis genome through integrated transcriptomic and proteomic analyses. Using gene silencing and microscopy-based imaging approaches, we functionally characterized 24 key genes involved in DNA replication (helicase, integrase-1, and integrase-2), transcriptional regulation (p47, lef-5, and lef-9), capsid formation (vp39, PmV, HzNVorf9-1, HzNVorf9-2, HzNVorf106, 38k, 27b, and K425_459), envelope formation (11k, 17a-1, 35a-1, 35a-2, and K425_461), virion assembly (vlf-1, HzNVorf140-1, and HzNVorf140-2), and viral infectivity (pif-0 and vp91). Although the functions of most nudivirus-like genes are generally conserved among baculoviruses, nudiviruses, and bracoviruses, lef-5, K425_459, 11k, and vp91 appear to have undergone functional divergence relative to their homologs in baculoviruses, nudiviruses, and Microplitis demolitor bracovirus, highlighting lineage-specific adaptations in CvBV. Collectively, our work provides a molecular framework for understanding CvBV assembly and serves as a valuable resource for investigating bracovirus evolution.

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PubMed2025

Large-scale Genome Analyses Provide Insights into Hymenoptera Evolution.

The order Hymenoptera includes a large number of species with diverse lifestyles and is known for its significant contributions to natural ecosystems. To better understand the evolution of this diverse order, we performed large-scale comparative genomics on 131 species from 13 superfamilies, covering most representative groups. We used these genomes to reveal an overall pattern of genomic change in terms of gene content and evolutionary rate throughout hymenopteran history. We identified genes that possibly contributed to the evolution of several key innovations, such as parasitoidism, wasp-waist, stinger, and secondary phytophagy. We also discovered the distinct genomic trajectories between the clade containing major parasitoid wasps (Parasitoida) and stinging species (Aculeata) since their divergence, which are involved in many aspects of genomic change, such as rapidly evolving gene families, gene gain and loss, and metabolic pathway evolution. In addition, we explored the genomic features accompanying the three independent evolution of secondary phytophagy. Our work provides insights for understanding genome evolution and the genomic basis of diversification in Hymenoptera.

Animals↗
PubMed1989

Role of virus-like particles in parasitoid-host interaction of insects.

Insect endoparasitoids are capable of suppressing the immune reaction of their habitual hosts in a specific way. Salt (1968) characterized some of the implications: This seeming contradiction--that defence reactions against all kinds of foreign bodies are available to insects and that endophagous parasitoids are nevertheless able to develop in insect hosts--is resolved by recourse to one of the principles of host specificity. Although insects as a group react to every foreign body in the sense that any organism or substance evokes a reaction in most insects, each species of insect fails to make a reaction (or makes an ineffective reaction) to a small group of organisms, its habitual parasites. It is the common paradox of parasitology that defence reactions are least effective against the most noxious parasites, involving the tautology that the most noxious parasites are those against which defence reactions are least effective. Recently, VLP of hymenopteran wasps have been shown to play a crucial part in suppressing the cellular encapsulation reaction (Stoltz and Vinson, 1979a). In some parasitoid wasps, polydnavirus particles are involved in the phenotypic transformation of hemocytes, reducing the capability of the host to mount an immune reaction towards the parasitoid egg (Stoltz and Guzo, 1986; Davies et al., 1987). However, at least in Venturia, the eggs are effectively protected by VLP that lack significant amounts of nucleic acids, precluding any virus expression in the host. The question was raised whether VLP could have acquired properties of the host immune system, which allows specific suppression of the immune response. The finding of structural similarities between VLP proteins and a host component indicated that a host function is expressed in VLP (Feddersen et al., 1986) and this observation has subsequently permitted the identification and characterization of a protein in caterpillars, which appears to inhibit cellular defense reactions (Berg et al., 1987). On the basis of these results we continue to approach this parasitoid-host interaction, assuming that VLP have evolved in the host organism and eventually acquired the coding sequences of a host protein with properties of an inhibitor of encapsulation. Although there are several ways to explain the emergence of VLP in endophagous parasitoid wasps, a simple proposal would be that such hypothetical viruses, which were able to suppress immune reaction in lepidopteran hosts, were incorporated into a parasitoid wasp to become part of the life cycle of the parasitoid.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

An unusual virus from the parasitic wasp Cotesia melanoscela.

Certain strains of the braconid parasitoid Cotesia melanoscela carry two different viruses within their ovaries, one of which (here designated CmV2) is apparently not a polydnavirus. Virus replication occurs in the ovarian calyx and in some other tissues of both male and female parasitoids; as yet, no replication has been observed in the testis, however. In addition, CmV2 is one of only two parasitoid viruses known to replicate in host insect larvae, and we not show that this virus is also capable of replicating in vitro; the virus is nevertheless nonpathogenic for gypsy moth larvae. The virus is not transmissible per os, either to host animals or to larvae of parasitoid strains lacking it. CmV2 is stably maintained within strains carrying it apparently by a vertical transmission mode involving the maternal line; transmission via the male germ line could not be demonstrated. While purification of the virus was not achieved, preliminary work allows us to suggest the genome consists of a single double-stranded DNA molecule of approximately 125 kb.

Animals↗
PubMed1990

Effects of female wasp accessory secretions, host fat body, and host hemolymph on protein synthesis and egg viability in Microplitis croceipes (Braconidae).

Effects of female wasp reproductive gland secretions, host fat body and hemolymph, and mechanical constriction of the parasitoid egg on protein synthesis were studied in eggs of Microplitis croceipes (Braconidae) dissected from the wasp ovary. Protein synthesis was measured by 35S-methionine incorporation in eggs held in tissue culture medium for 16 h after treatment. Synthesis was stimulated in oocytes obtained from three regions of the ovary (egg tube, reservoir, and calyx) by fat body and venom gland but not by calyx fluid. A combination of fat body, venom gland, and calyx fluid did not enhance the level of synthesis relative to that of fat body or venom gland alone. Host hemolymph inhibited protein synthesis when incubated directly with the dissected eggs but not when the eggs were collected from an artificial oviposition substrate (AOS) containing hemolymph. The inhibitory effect of the hemolymph is thought to be due to the occurrence of melanization. Mechanical constriction did not alter the rate of synthesis, confirming an earlier report that synthesis in newly deposited eggs in ongoing and is not dependent on mechanical activation during the act of oviposition. Mechanisms responsible for sustaining protein synthesis in eggs for 16 h in vitro after their exposure to host hemolymph in the AOSs or fat body and venom gland are not known. Only a small percentage (less than 2%) of dissected ovarial reservoir oocytes that were mechanically constricted and exposed to the venom gland, calyx fluid, and host fat body hatched in vitro. In contrast, an earlier study demonstrated that 38% of eggs oviposited by female wasps into AOSs developed and hatched.

Animals↗
PubMed1992

[Use of parasitic wasps (Hymenoptera: Pteromalidae) in the biological control of domestic flies in pig housing].

Adaptability of two parasitoid species S. nigroaenea and M. zaraptor to conditions of stable microclimate was investigated in a farrowing house. The colony was reared in an insectary at a temperature of 24-26 degrees C and relative humidity of 60-70% in cages of the size 0.3 x 0.3 x 0.2 m. The development of the species M. zaraptor from egg to adult lasted 19 to 23 days, in S. nigroaenea it was 23 to 25 days. Rates of parasitism of house fly pupae were followed in plastic pots (8 x 4 x 9 cm) with larval medium for fly rearing. The larval medium consisted of milk powder, wheat bran and dried yeast. Both species were demonstrated to be able to penetrate to pupae in deeper layers of the medium (Tab. 1) and in this way to control the amounts of fly adults after their eclosion. The results were evaluated by Student's t-test. 98% of flies in the stable were house flies (Musca domestica L.), the remaining flies were stable flies (Stomoxys calcitrans L.). No parasitoids were observed in the stable. Two pots containing 2-3,000 pupae parasitized by S. nigroaenea and M. zaraptor were placed in the stable on 30th January 1990. Parasitoids were monitored at three locations of the stable according to parasitism rates of lab-reared house fly pupae exposed in plastic pots with larval medium. Twenty-two checks were made in 2 to 4 week intervals from February to November 1990, and one final check after a six-month interruption (Tab. II). Both species persisted in the stable for the whole period of observation (Fig. 1). The species S. nigroaenea, the population levels of which were much higher, showed the greater migration activity after its individuals had been released to the stable. Sprayings with the Alfacron insecticide were performed in the stable in March and September 1990 in the course of this experiment.

Animals↗
PubMed1991

Parasite-induced enhancement of hemolymph tyrosinase activity in a selected immune reactive strain of Drosophila melanogaster.

Larval hemolymph tyrosinase activity in Drosophila melanogaster was detected with high performance liquid chromatography with electrochemical detection. The enzyme hydroxylated L-tyrosine, and oxidized the diphenol substrates L-dopa and dopamine. In larvae of a selected immune-reactive strain the rates of tyrosine hydroxylation, dopa oxidation, and dopamine oxidation were markedly increased during the early stages of melanotic encapsulation of the eggs of the parasitic wasp Leptopilina boulardi. Tyrosinase activity was not modified in parasitized larvae of a selected susceptible strain of D. melanogaster, in which hosts the parasitoids developed unmolested. During the same period of parasitization, the amount of free tyrosine in immune reactive larvae was approximately three times higher than in susceptible hosts. These data indicate that the tyrosinase system of the immune reactive strain is activated during parasitization, and this results in the synthesis of some precursors which ultimately produce a melanotic and sclerotic capsule around the eggs of the parasite. Based on known genetic information of the enzyme system in Drosophila, it appears that at least two genes may be involved in the activation process, one associated with the proenzyme for monophenol oxidase activity, and the second with the proenzyme for diphenol oxidase activity.

Animals↗
PubMed1991

Development of continuous cell lines from the egg parasitoids Trichogramma confusum and T. exiguum.

Although numerous insect cell lines have been developed over the past three decades, few of these have been from the order Hymenoptera. This report describes two new continuous cell lines from trichogrammid wasps. The extremely small size of these insects has made physiological and biochemical studies difficult. Now, with the development of the cell lines, a limitless supply of biologically active material is available for a wide variety of basic biological studies. The Trichogramma confusum and T. exiguum cell lines (designated IPLB-Tcon1 and IPLB-Tex2) were characterized by chromosome and isozymes techniques. Evidence of their utility is shown by morphological response to the developmental hormone, 20-hydroxyecdysone. The morphological change in IPLB-Tex2 is accompanied by an induction of highly contractile cells which indicates this cell line may be composed of myoblast cells.

Animals↗
PubMed1991

Developmental disruption of Pseudoplusia includens and Heliothis virescens larvae by the calyx fluid and venom of Microplitis demolitor.

Calyx fluid and venom from the braconid parasitoid Microplitis demolitor differentially affected the development of Pseudoplusia includens and Heliothis virescens. P. includens exhibited delays in larval development, supernumerary instars, and formed larval-pupal intermediates when injected with 0.01-0.10 wasp equivalents of calyx fluid. In contrast, H. virescens was relatively unaffected by calyx fluid regardless of dose. Venom did not affect the development of either host species, but appeared to synergize the activity of calyx fluid. This was particularly evident in H. virescens, where injection of 0.10-0.20 wasp equivalents of calyx fluid and venom induced the formation of a large number of intermediates while the same amount of calyx fluid did not. The particulate portion of M. demolitor calyx fluid was the only component that caused developmental delays and the formation of intermediates in both host species. Purified virus caused developmental alterations in P. includens, while trioxsalen treated calyx fluid did not affect development of P. includens or H. virescens. These data suggest the requirement for venom in parasitism may differ between host species, and that dosage plays an important role in interpreting the interaction between calyx and venom components.

Animals↗
PubMed1987

The parasitoid Apanteles kariyai inhibits pupation of its host, Pseudaletia separata, via disruption of prothoracicotropic hormone release.

When the parasitoid Apanteles kariyai laid eggs into host Pseudaletia separata larvae, before prothoracicotropic hormone (PTTH) was released in the last instar preparatory to metamorphosis, the host did not pupate and the larvae of the wasps emerged. The ecdysteroid titer of unparasitized intact larvae increased up to 1 microgram/ml 1 day before pupation, whereas the titer of parasitized larvae was maintained at a low level without the surge. Isolated prothoracic glands from intact larvae synthesized much more ecdysone than those of parasitized larvae both in vivo and in vitro. Administration of exogenous PTTH caused the activation of the prothoracic glands seen during parasitization. Injection of 20-hydroxyecdysone (20-HE) into the parasitized larvae caused by host's pupation, but did not affect the development of the wasp larvae. However, the sensitivity of the integument to 20-HE was lower in parasitized than in unparasitized larvae. Injection of a mixture of adult wasp calyx and venom fluids into last instar unparasitized larvae delayed their pupation, suggesting that calyx and venom fluids are factors contributing to disturbance of the normal function of brain-prothoracic gland system. These results show that parasitization inhibits secretion and/or synthesis of PTTH and also delays the larval-pupal commitment of the integument by keeping the ecdysteroid level low.

Animals↗
PubMed1991

[The secondary action of neporex on the pupa of parasitoids of stable flies].

In field tests for the control of house fly larvae in dung heaps of a pig fattening and breeding farm with Neporex SP 50 revealed, that the same species of parasitoids (Muscidifurax raptor, Spalangia nigroaenea, S. cameroni, Phygadeuon fumator) were capable to develop in cyromazine-damaged, larviform host puparia as in undamaged puparia. The parasitization rate is, however, about 3 times and the hatch of flies is twice as high in normal formed puparia compared with larviform puparia. Comparing the attractivity of untreated normal puparia with cyromazine-damaged, larviform puparia under laboratory conditions showed that the mentioned puparia gave rise to 2-3 times as much parasitoids. Rearing M. raptor and M. zaraptor on larviform host puparia in the laboratory led to a distinct decrease in the development of the parasitoid between populations within 3 ... 5 generations. Parasitoids emerged from larviform and from undamaged puparia showed not differences in their life dates in the F1 generation.

Animals↗
PubMed1991

Evidence for a chromosomal location of polydnavirus DNA in the ichneumonid parasitoid Hyposoter fugitivus.

Evidence is presented in support of a chromosomal location for sequences homologous to polydnavirus DNA in the ichneumonid parasitoid Hyposoter fugitivus. In this study, four different viral genome segments were cloned and used as probes against genomic DNA extracted from male parasitoids and digested with a variety of restriction enzymes. Each probe typically identified a single off-size fragment (OSF) in the case of enzymes not cutting viral genome segments, while two OSFs were generated by enzymes cutting at one and two sites. While extra OSFs were occasionally observed, these were invariably found to be due to the presence of polymorphic restriction sites in flanking chromosomal DNA. Analysis of these data suggests that a single, stable chromosomal locus exists for sequences homologous to each viral genome segment; the data also indicate that viral and cognate parasitoid genomic DNAs are largely if not entirely colinear.

Animals↗
PubMed1990

Leptopilina heterotoma and L. boulardi: strategies to avoid cellular defense responses of Drosophila melanogaster.

Eggs of three strains of the cynipid parasitoid Leptopilina heterotoma and a Tunisian strain (G317) of L. boulardi are not encapsulated by hemocytes of Drosophila melanogaster hosts, but the eggs of a Congolese strain (L104) of L. boulardi are encapsulated. To determine the reason for the difference in host response against the parasitoid eggs, lamellocytes (hemocytes that encapsulate foreign objects and form capsules around endogenous tissues in melanotic tumor mutants) were examined in host larvae parasitized by the five Leptopilina strains. Parasitization by the three L. heterotoma strains affected the morphology of host lamellocytes and suppressed endogenous melanotic capsule formation in melanotic tumor hosts. L104 did not alter the morphology of host lamellocytes nor block tumor formation in melanotic tumor mutant hosts. The morphology of some lamellocytes was affected by G317 parasitization but host lamellocytes were still capable of forming melanotic tumors and encapsulating dead supernumerary parasitoid larvae. Therefore, the eggs of strains affecting lamellocyte morphology are protected from encapsulation by the host's blood cells. L. heterotoma eggs float freely in the host hemocoel but L. boulardi eggs are attached to host tissue surfaces. Lamellocytes cannot infiltrate the attachment site so the capsule around the L104 egg remains incomplete. The wasp larva uses this gap in the capsule as an escape hatch for emergence.

Animals↗
PubMed1992

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.

Animals↗
PubMed1985

Encapsulation ability of Drosophila melanogaster: a genetic analysis.

Insects are able to effectively recognize parasitoid eggs or larvae and to eliminate them by formation of a hemocytic capsule. Although the cellular process is now well documented, the genetic aspects of recognition of foreignness and the encapsulation process are still poorly understood. Experiments using the isofemale-strain method showed that the encapsulating ability of Drosophila melanogaster exercised against a parasitic wasp varies within a given population and that this variability is under partial genetic control.

Animals↗