How do mosquitoes predict winter’s arrival?

We are interested in determining how females of the Northern house mosquito, Culex pipiens, are able to predict the arrival of winter and enter a hibernation-like diapause. Although researchers have long known that this mosquito and other temperate insects rely on the short days of late summer and early fall to predict the coming winter, we do not know how mosquitoes are able to measure these cues. However, mosquitoes have circadian clock genes that tell them what time of day it is, and our earlier work demonstrates that clock genes are involved in initiating the overwinering diapause in this species. We are now working to determine how, precisely, the circadian clock is connected to the hormonal and signaling pathways that regulate diapause in female Northern House mosquitoes.

Do male mosquitoes contribute to female overwintering and reproductive success?

Another area of research focuses on male mosquitoes. Although males of Cx. pipiens do not survive the winter, it is possible that males might also respond to changes in daylength by altering the composition of their accessory gland proteins. We predict that under long day, summer-like conditions males pass accessory gland proteins to female mosquitoes during mating that encourage them mosquitoes to bite us and rapidly develop their eggs. In contrast, we predict that under short day, winter-like conditions, males increase the number and type of accessory gland proteins that help the female to store and protect their sperm for the 3-6 months when the females are in diapause.

Can understanding the seasonal ecology of mosquitoes lead to better control and reduced disease transmission?

Mosquito abundance and disease transmission is not distributed evenly through space or time. Members of the lab are determining the seasonal cues that put mosquitoes into diapause (light and temperature), and which cues break them out of diapause and how these vary among different latitudes. Additionally, we are interested in how aspects of the urban environment, such as artificial light at night and increasted temperatures in urban heat islands, influence seasonal responses. Our long-term goal with these projects is to develop a predictive model that will allow us to determine when and where mosquitoes will be abundant so we can better target our control efforts.

What genes and pathways are involved in the evolution of non-biting mosquitoes?

Female mosquitoes are reviled because their bites leave us with itchy welts and, sometimes, a pathogen that can make us sick or even kill us. However, blood feeding is a risky endeavor for female mosquitoes, requiring energy to find a host, anesthetics to extract blood without being detected, high-functioning excretory systems to quickly eliminate excess water and salts from the blood, and protective enzymes, antioxidants to protect themselves from toxic heme molecules that are released when the blood is digested. Not surprisingly, several mosquitoes evolved the capacity to produce eggs without blood feeding, and thereby avoid all of these risks. We are highly interested in the evolution of non-biting behavior in mosquitoes given the crucial role that blood feeding plays in disease transmission. In collaboration with researchers at Georgetown University and The University of Oregon, we are identifying differentially regulated genes between biting and non-biting mosquitoes belonging to 3 different species.