Parasitization of granulosis‐virus infected and noninfected Agrotis segetum larvae and the virus transmission by three hymenopteran parasitoids

Abstract

Apanteles telengai Tobias, Aleiodes gasteratus (Jurine) and Campoletis annulata Tschek parasitized significantly more healthy than granulosis virus (GV)‐infected Agrotis segetum D. & Schiff. larvae. Females of the three parasitoid species that had oviposited previously in GV‐infected A. segetum larvae transmitted the virus to healthy A. segetum larvae in subsequent oviposition. A. telengai and A. gasteratus females also transmitted the GV on unsuccessful oviposition attempts. Male parasites did not transmit the GV. Résumé Taux de parasitisme des chenilles d'Agrotis segetum saines et infectées par le virus de la granulose et possibilités de transmission du virus par 3 parasitoïdes hyménoptères Apanteles telengai, Aleiodes gasteratus et Campoletis annulata parasitent significativement plus les chenilles saines d'A. segetum que les chenilles infectées par le virus de la granulose. Les femelles des 3 espèces ayant pondu préalablement dans des chenilles contaminées par le virus ont transmis le virus à des chenilles saines lors de pontes ultérieures. Les femelles de A. telengai et A. gasteratus transmettent le virus lors de perforations d'hôtes non suivies de pontes. Les mâles ne transmettent pas le virus.

Interaction between a nucleopolyhedrovirus and the braconid parasitoid Meteorus pulchricornis (Hymenoptera: Braconidae) in the larvae of Spodoptera litura (Lepidoptera: Noctuidae)

“…Caballero et al (1991) reported that Apanteles telengai (Hymenoptera: Braconidae), Aleiodes gasteratus (Hymenoptera: Braconidae), and Campoletis annulata (Hymenoptera: Ichneumonidae) parasitized significantly more healthy than the granulovirus-infected larvae of Agrotis segetum (Lepidoptera: Noctuidae). Beegle and Oatman (1975) observed that female Hyposoter exiguae (Hymenoptera: Ichneumonidae) laid as many eggs in NPV-infected Trichoplusia ni (Lepidoptera: Noctuidae) larvae as in non-infected larvae.…”

“…The transmission of viruses by parasitoids can be categorized into two means: mechanical vectors in the translocation of viruses as a result of contaminated body parts contacting host food sources (Irabagon and Brooks, 1974;Beegle and Oatman, 1975;Raimo et al, 1977;Young and Yearian, 1990;Sait et al, 1996), and biological vectors in the translocation of viruses as a result of the direct inoculation of the host via a virus-contaminated ovipositor (Beegle and Oatman, 1975;Levin et al, 1983;Hamm et al, 1985;Caballero et al, 1991). In this study, we examined the possibility of M. pulchricornis wasps as mechanical and biological vectors of SpltNPV, but no parasitoid females transmitted an effective dose of SpltNPV to other hosts.…”

The parasitoid factor in the virulence and spread of lepidopteran baculoviruses

“…Consequently, an earlier general conclusion among researchers that postponing the exposure of parasitized larvae to a host baculovirus increased the percentage of successful parasitoid development, may be a function of more than just enabling the parasitoid sufficient time to develop and emerge from infected tissue before imminent virus-induced host mortality (3, 5, 14, 30).As a baculoviral host infection can decrease the survival of a parasitoid, it is apparent that it would be in the parasitoid' s best interest to avoid infected hosts in the field. Research to date has shown that many, although not all, hymenopteran parasitoids are able to discriminate to varying degrees, between infected and non-infected hosts(8,16,17,35). For example, both Venturia canescens and Meteorus gyrator females were shown to reduce the number of eggs that they inserted into betabaculovirus-infected Indian meal moth, Plodia interpunctella and Lacanobia oleracea larvae, respectively, based on the level of the host=s infection(38,45).…”

Effect of nucleopolyhedrovirus infection ofSpodoptera lituralarvae on host discrimination byMicroplitis pallidipes

“…However, our field experiment was conducted at a high-virus concentration (1.6 × 10 8 OB·ml A 1), and whether host discrimination by M. pallidipes would be the same at a lower virus concentration remains to be determined. In addition, our results can be viewed in the context of the parasitoid-pathogen interspecific competition hypothesis (Caballero, Vargas-Osuna, & Santiago-Alvarez, 1991;Hochberg, 1991), which postulates that M. pallidipes and SlNPV would compete for the host resources in dually attacked hosts (infected and parasitized), with negative consequences to the reproduction of both parasitoid and virus, leading M. pallidipes to increase its fitness by avoiding parasitizing NPV-infected larvae.…”