Tesis Maestría en Ciencias en Recursos Naturales y Desarrollo Rural El Colegio de la Frontera Sur 2002

Bibliografía: hojas 25-31

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The extremely high infectivlty of invertebrate iridescent viruses (IIVs) by injection has lead to the suggestion that insect parasitoids could transmit IIVs during the act of oviposition. An IIV was isolated from Spodoptera frugiperdai}. E. Smith) larvae in Chiapas State, Mexico. We examined the interaction between this virus and the solitary ichneumonid endoparasitoid Eiphosoma vitticoHe Cressou. In simultaneous choice tests, parasitoids examined and stung significantly more virus infected than healthy larvae, apparently due to a lack of defense reaction in virus infected hosts. There was no significant difference in the mean interval between exposure and attack by parasitoids. All of the female parasitoids that stung a virus infected host transmitted the virus to healthy larvae. Each female parasitoid transmitted the virus to an average (± SE) of 3.7 ± 0.3 larvae immediately after stinging a patently infected larva. This number fell markedly at 1 day and 2 days after stinging the infected larva. Parasitoid survival to adulthood was completely eliminated in hosts infected by IIV at 1 and 3 days postparasitsm (due to premature death of the host) and was severely reduced in host inoculated at 7 and 11 days postparasitism. Most parasitoids that developed in patently infected hosts themselves developed a patent infection and died prior to emergence. Parasitoids that successfully developed in virus inoculated hosts did not differ in pupal weight or wing length compared to controls. Female parasitoids that emerged from virus inoculated hosts did not transmit the virus to healthy larvae. Two experiments performed using healthy and virus infected larvae on maize plants in field cages with and without parasitoids indicated that virus transmission to healthy larvae only occurred in cages containing infected hosts (as inoculum) and parasitoids (as vectors). We suggest that the polyphagous habits of many noctuld parasitoids combined with the catholic host range of most IIVs may represent a mechanism for the transmission of IIVs between different host species in the field. Inglés

Entomología Tropical