Research on the fruit fly, Drosophila melanogaster, has revealed that Seminal Fluid Proteins (SFPs) from males trigger Post-Mating Responses (PMRs) in females, impacting everything from egg production and lifespan to circadian activity. The Male Accessory Gland (MAG) produces these SFPs, with Sex Peptide (SP) being a key initiator of PMRs, produced in the Main Cells (MCs) of the MAG. However, Secondary Cells (SCs) within the MAG are crucial for maintaining these responses by binding SP to sperm, allowing for extended triggering of the PMRs.

My research explored the evolution of PMRs across the Drosophilidae family. We observed that Sophophora species, including D. melanogaster, have smaller MAGs with fewer SCs compared to other species, suggesting an evolutionary divergence. We also developed DrosoVAM, a new video-based monitoring system, to study fly behavior, particularly circadian activity changes after mating.

Focusing on D. hydei, a species lacking SP but with many SCs, we found significantly different PMRs. Unlike D. melanogaster, mating in D. hydei doesn't reduce female receptivity and only causes a temporary burst in egg-laying. Interestingly, we identified a novel long-term PMR in D. hydei. Mated females show a striking reduction in nighttime activity, restricted to areas near food. These findings challenge the general assumption that the reproductive strategy of D. melanogaster is a general truth by exposing the radically different reproductive strategy used by D. hydei, and highlighting the importance of SCs in their reproductive biology.