Much remains unknown about how food choice and nutritional quality affects the virulence of pathogens in phytophagous insects. In the current study we investigated these issues using the generalist caterpillar Spodoptera littoralis and its nucleopolyhedrovirus. Two experiments, both designed within the context of the 'geometric framework', were conducted. In the first no-choice experiment, final stadium caterpillars were infected with NPV and fed one of five synthetic foods that differed in their protein:carbohydrate ratio (p35:c7, p28:c14, p21:c21, p14:c28 or p7:c35). Survival was greatest on the most protein-biased food (p35:c7) and decreased as the nutrient content of the food became more carbohydrate-biased. Results also showed that nutrient utilization varied between i) infected and uninfected caterpillars and ii) the different food treatments. In the second experiment, infected and uninfected caterpillars were given one of two food pairings (p21:c21 w/ p35:c7 and p17:c17 w/ p28:c6). Uninfected caterpillars selected an intake target that was consistent with earlier studies (ca. 60% protein to 40% carbohydrate). However, among the infected caterpillars, differences in food selection behavior were observed between those caterpillars that completed larval development and those that succumbed to NPV infection. Infected caterpillars that survived and completed development had significantly lower carbohydrate intake and selected a higher protein to carbohydrate ratio compared to infected caterpillars that failed to complete development. We discuss the ecological and behavioural implications of our findings.
Species 1: Lepidoptera Noctuidae Spodoptera littoralis (cotton leaf worm)
Keywords: nutrient-virus interaction, food selection
Back to Student Competition Display Presentations, Subsection Cd. Behavior and Ecology
Back to Student Competition Poster
Back to The 2002 ESA Annual Meeting and Exhibition