TELANG, A.*; CHAPMAN, R.F.; WHEELER, D.E.: Sexual differences in protein and carbohydrate utilization by larval tobacco budworm, Heliothis virescens (F.).

Female Lepidoptera are often heavier than males, presumably due to greater food consumption. Our previous studies indicated that female Heliothis virescens caterpillars use both feeding and post-ingestive processing as mechanisms to meet nutrient needs. Our present report focuses on the latter mechanism. Post-ingestive responses to four different diets containing protein and carbohydrate at various concentrations were analyzed for fifth stadium Heliothis virescens caterpillars of both sexes. Amounts eaten, excreted and used toward growth were measured across the fifth stadium. Both female and male larvae differentially utilized ingested protein and carbohydrate with females achieving greater mean relative growth rate and protein-derived growth on all four diets. Results suggests that females are capable of more efficiently utilizing ingested protein toward such growth. Chemical analyses of frass nitrogen content suggest that ammonia excretion may be employed by caterpillars under high protein, low carbohydrate diet conditions.