Effects of Male Accessory Gland Proteins on Female Reproductive Physiology in the Northern House Mosquito, Culex pipiens

Joseph Urso
Undergraduate (Entomology)
Dr. Megan Meuti

During the summer females of the Northern House Mosquito, Culex pipiens, transmit West Nile virus to humans, while during the winter females stop biting humans and enter a dormant state. Male mosquitoes produce proteins in their accessory glands (MAGs) that are transferred to females during copulation. MAG proteins and other components of the ejaculate alter female behavior and physiology by increasing biting propensity and bloodmeal digestion, enhancing fecundity and facilitating sperm survival in the female reproductive tract, all of which contribute to female reproductive success and disease transmission. Our earlier work shows that males of Cx. pipiens differentially regulate several genes in their MAGs in response to seasonal cues. Specifically, Cathepsin- B-like thiol protease (CapB) and Trypsin-1 precursor (Tryp1) are upregulated in the MAGs of long day-reared males, and we hypothesize that this increases female biting propensity and fecundity. In contrast Glutathione-S-transferase (GST) is upregulated in the MAGs of short day-reared males, and we hypothesize that this may increase sperm survival in overwintering females. To test our hypotheses, we used RNA interference (RNAi) to knock down these genes of interest in males, then allowed them to mate with virgin females and observed effects. We anticipate that knocking down CapB and Tryp1 in males will decrease the likelihood that mated females will take a blood meal and that these females will produce fewer offspring. In contrast, we predict that knocking down GST in males will result in lower sperm survival in overwintering females. Our results, if confirmed, could serve as the foundation for novel mosquito control measures that could prevent females from biting and/or successfully reproducing and thereby reduce disease transmission.