Sex peptide receptor is not required for refractoriness to remating or induction of egg laying in Aedes aegypti

Across diverse insect taxa, the behavior and physiology of females dramatically changes after mating - processes largely triggered by the transfer of seminal proteins from their mates. In the vinegar fly Drosophila melanogaster, the seminal protein sex peptide (SP) decreases the likelihood of female flies remating and causes additional behavioral and physiological changes that promote fertility including increasing egg production. Although SP is only found in the Drosophila genus, its receptor, sex peptide receptor (SPR), is the widely-conserved myoinhibitory peptide (MIP) receptor. To test the functional role of SPR in mediating post-mating responses in a non-Drosophila dipteran, we generated two independent Spr-knockout alleles in the yellow fever mosquito Aedes aegypti. Although SPR is needed for post-mating responses in Drosophila and the cotton bollworm Helicoverpa armigera, Spr mutant Ae. aegypti show completely normal post-mating decreases in remating propensity and increases in egg laying. In addition, injection of synthetic SP or accessory gland homogenate from D. melanogaster into virgin female mosquitoes did not elicit these post-mating responses. Our results indicate that Spr is not required for these canonical post-mating responses in Ae. aegypti, indicating that unknown signaling pathways are likely responsible for these behavioral switches in this disease vector.