447B Poster - 05. Reproduction and gametogenesis
Friday April 08, 2:00 PM - 4:00 PM

Authors:
Olayinka David; Kevin Sanchez; Anthony Bellantuono; Andre Costa-da-Silva; Matthew DeGennaro

Affiliation: Florida International University

Keywords:
h. sex-specific traits and molecules; b. segmentation

Mosquitoes are the deadliest animals to humans. They are responsible for over half a million deaths annually and get more than 200 million people around the world sick every year. Female mosquitoes of many species require vertebrate blood for egg development. A female mosquito undergoes multiple discrete rounds of reproductive cycles also known as gonotrophic cycles. A gonotrophic cycle spans the period from bloodmeal intake to the time the mature oocytes are deposited. Mosquitoes are capable of transmitting diseases to humans and other vertebrate hosts during bloodmeal intake. Transmission of mosquito-borne diseases to hosts typically occurs during the second round of blood ingestion, an event that often coincides with the start of the second gonotrophic cycle. Mosquitoes rely on odorant receptors (ORs) for detecting chemical molecules in their surroundings. This chemosensory potential is necessary for processes such as vertebrate host localization, nectar seeking, identifying suitable mates, and finding egg-laying sites. Odorant receptor co-receptor (orco) is an insect-specific obligate counterpart necessary for the function of tuning ORs. Studies have reported the expression of orco in ovaries and testes across different insect taxa. These receptors have been shown to activate both human and mosquito sperm. To determine the role of orco in Aedes aegypti reproduction, we employed individual mosquito fecundity and fertility assays to quantify the reproductive output of Aedes aegypti orco^-/- mosquitoes across two gonotrophic cycles. Surprisingly, we found that eggs produced by mutant mosquitoes have a significantly reduced hatch rate in the second reproductive cycle compared to controls. Histochemical assays revealed that the unhatched eggs were fertilized but the resulting embryos failed to attain full development. Additionally, using mixed genotype mating experiments, we found that the embryo developmental defect is a maternal effect, suggesting that orco is required in the female mosquito for optimum embryo viability. In control experiments, we quantified the amount of ingested blood, the number of sperm stored as well as the number of eggs laid per female mosquito and found no difference between wild-type and mutant mosquitoes. Lastly, when the ­orco gene was reconstituted into the orco^-/- background, the reproductive phenotype was reverted. Our findings inform a novel vector control approach that targets mosquito reproduction through halted embryo development.