63.6 Jan. 7 Resource allocation to testes in the walnut fly, Rhagoletis juglandis CARSTEN-CONNER, L.D.*; O\'BRIEN, D.M.; University of Arizona; University of Alaska, Fairbanks firstname.lastname@example.org
Testes size often predicts whether a male will win during episodes of sperm competition. However, little is known about the source of nutrients allocated to testes development. Among holometabolous insects, metabolic resources can be derived from the larval or the adult diet, which often differ substantially in nutritional quality. Distinguishing the source of nutrients allocated to testes can shed light on life history factors that shape the evolution of male reproductive strategies. For instance, if allocated resources are derived mostly from larval reserves, then maternal influences such as oviposition decisions may ultimately determine male reproductive success. Conversely, if allocated resources are mostly derived from adult stores, then male reproductive success may rely more on the foraging ability of that individual. Here we used an experimental approach to assess resource allocation to testes development in walnut flies (Rhagoletis juglandis) from differing nutritional backgrounds. We fed adult male walnut flies on yeast diets that contrasted with the larval diet in carbon and nitrogen stable isotope ratios. This design allowed us to assess the dietary source of testes carbon and nitrogen and its change over time under differing adult nutritional regimes. We discuss our findings and the evolutionary implications.