Phenotypic plasticity and susceptibility to pathogens in Anticarsia gemmatalis (Lepidoptera: Noctuidae)

• Ano de defesa: 2010
• Autor(a) principal: Silva, Farley William Souza
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; BR; Ciência entomológica; Tecnologia entomológica; Mestrado em Entomologia; UFV
• Palavras-chave em Português: Prophylaxis; Pathogens; Caterpillar soybean; Profilaxia; Patógenos; Lagarta-da-soja; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::ENTOMOLOGIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/3911

Prophylactic investment in defense from parasites and pathogens involves a high cost. Thus, it is expected that organisms use this only when required, for example, when at high population densities, where the risk of parasite or pathogen transmission may be increased. If the infection risk for individuals increases with host density, it is expected that hosts subject to high densities evolve mechanisms of resistance, as proposed by the "density-dependent prophylaxis" (DDP) hypothesis. Tests of these predictions have been conducted in a wide range of insects, both in comparative studies, where species live at different densities and in experimental studies, where the host density is manipulated. In the latter case, however, tests have mostly been restricted to gregarious insects that present density-dependent phase polyphenism. For this reason, we chose to test these predictions in a solitary species, Anticarsia gemmatalis (Lepidoptera: Noctuidae), that presents features of gregarious insects. We showed a prophylactic response to increased conspecific densities in A. gemmatalis larvae. When at increased larval density, with the accompanying phenotypic change, there is a greater degree of encapsulation of the nylon filament, higher hemocyte numbers, but lower melanization. We showed that this response was a function, not only the density per se, but also of the contact among conspecifics. Thus, we showed that DDP is a more common phenomenon thatpreviously thought, occurring even in a species known as being solitary. Furthermore, the prophylactic responses in this species are not only densitydependent, but are more specifically contact- dependent. This may provide a new context to the DDP hypothesis; in which even solitary species may present plastic prophylactic responses at crowded moments.