Quantification of post-mating feeding behavior in Drosophila females. Jennifer Apger, Mariana Wolfner. Cornell University, Ithaca, NY.

   In Drosophila, seminal fluid proteins transferred from the male during mating elicit physiological and behavioral changes in the female that are important for fertility. One of these changes is an increase in feeding by mated females. A male seminal protein, sex peptide (SP), is known to induce the post-mating increase in feeding (Carvalho et al., 2006), in addition to other effects, such as decreasing receptivity to remating and increasing ovulation and egg-laying. Some of SPs effects are transient, but others, such as its effects on egg-laying and receptivity, persist for up to 2 weeks. Persistent SP effects are due to the peptides binding to, and slow release from, sperm in the female. It was unknown whether SPs effect on feeding also showed such long-term characteristics. To determine whether SP effects on feeding were part of its long-term response we assayed food intake by female flies, by an assay (Cognigni et al., 2011) that measures fecal output. We found that SP affects feeding over several days. By mating females to either males that dont produce sperm, or males that produce a form of SP that cannot be cleaved from sperm, we showed that the gradual cleavage of sperm-bound SP is necessary for the increase in feeding to persist for at least 72 hours after mating. Additionally, consistent with previous studies linking egg production and feeding behavior, we found that SP indirectly increases feeding behavior by increasing egg production over several days.