Meeting Abstract
Physiological changes during development cause dynamic shifts in energy and macronutrient demands. Using a wing polymorphic cricket (Gryllus lineaticeps), we tested the hypotheses that diet composition differentially impacts performance according to nutrient demands set by ontogenetic stage, and that nutrient preferences shift along with nutrient demands. Morphs of G. lineaticeps specialize in dispersal or reproduction. We predicted that dispersal morphs require more protein than reproductive morphs during the last juvenile life-stage (instar) for flight muscle development, but more carbohydrates (carbs) during early adulthood to support flight fuel synthesis. During the last instar or early adulthood, crickets were assigned to one of three ad libitum isocaloric diets: 1) choice between protein-biased and carb-biased diets, 2) protein-biased diet (2P:1C), or 3) carb-biased diet (1P:4C). When provided a choice, crickets modulated feeding to optimize nutrient intake. Dispersal and reproductive morphs did not differ in preferred intake. However, preferences shifted throughout ontogeny: juveniles selected a slightly carb-biased diet (Female 4P:5C; Male 7P:10C), while adults preferred a higher protein diet (Female 1P:1C; Male 4P:5C). When fed a carb-biased diet (1P:4C), development time to adulthood was extended and female morph determination was biased to the reproductive morph. Regardless of diet, juvenile dispersal morphs consumed more food than reproductive morphs. Results from this experiment indicate that bulk nutrient intake varies with life history strategy, and that macronutrient composition preferences change during ontogeny. Further experiments will focus on physiological performance consequences of these dietary shifts.
