How mosquitoes survive the winter.

• Position: West Nile Virus

Two genes that help insulin regulate mosquitoes' growth have been identified as key contributors to how the insects enter a dormant state to survive winter's cold. The research finding broadens the understanding of the mosquito life cycle and appears to shed some light on how other insects and invertebrate species weather the winter months.

The shorter days of autumn trigger certain species of mosquitoes into diapause, a hibernation-like state of arrested development that allows them to survive through the winter, but this new research has determined that a hormonal response is behind the mosquito's ability to store up extra fat and halt reproductive activity in preparation for its months-long dormancy, explains David Denlinger, professor of entomology at Ohio State University, Columbus.

Denlinger's lab is working with Culex pipiens, a common mosquito in the U.S. and the species that carries the West Nile virus in North America. While the point at this stage is understanding fully the intricacies of this life cycle, the findings someday could lead to methods to manipulate mosquito populations so they never emerge from their dormant cycles.

"This winter survival is an absolutely critical phase. Most insects cannot survive through the winter unless they go into a dormant state," Denlinger indicates. "So, we're trying to understand how...