Meeting Abstract
A large body size is important for many reasons, including increases in viable eggs, decrease risk of cannibalism, and increased success in male-male combat. However, building a large body is costly and may require particular amounts and ratios of nutrients. For many animals, especially carnivores on which less is known of their nutritional ecology, the balance of nutrients at which animals maximize growth and body size remains unknown. We manipulated the quantity and nutrient content of flies as prey to test how the lipid and protein content of prey affected the growth of spiders. We measured the body size of 420 F1 jumping spiders, Phidippus audax, raised on 21 different diet treatments ranging from high protein to high lipid across several prey quantities. The ratio of lipid to protein in prey had the largest effect on spider growth in the high prey abundance treatments. Overall, spiders weighed more and had larger body size on diets that were more lipid-biased. Our results suggest that spiders require lipid rich prey for maximal growth. Previous work indicates most prey in nature are lipid poor. Spiders should then either select lipid rich prey over lipid poor prey or find alternative energy sources, like extra floral nectar.
