This winter survival is an absolutely critical phase. Most insects cannot survive through the winter unless they go into a dormant state, Denlinger said. So were trying to understand how this dormant state is regulated. There is a chance it could be manipulated and the mosquito wouldnt be able to survive the winter. Right now, were focused on the mechanism at the physiological and molecular level. But it does have that kind of potential for application in the future.
The two genes under study are the insulin receptor, which binds to insulin to initiate its action, and a gene known as FOXO, or forkhead transcription factor, which is typically suppressed in the presence of insulin. The hormone insulin regulates blood sugar and body fat storage.
In this species, only females survive the winter. Males and females mate before the onset of winter. Females refuse to take a blood meal, and instead feed only on sugar. Their ovaries stop working, so their eggs will not mature. And they accumulate plenty of fat to sustain them over the winter.
Denlingers lab is raising colonies of this species of mosquito in two different artificial day-length environments to either impose a dormancy cycle or to prevent their shift to diapause. Some mosquitoes are reared under short-day conditions, with 12 hours of light and 12 hours of darkness, and others are reared with long days 15 hours of light and nine hours of darkness.
Denlinger and study co-author Cheolho Sim, a postdoctoral researcher in entomology, used the two populations to test the insulin signaling pathway genes effects on diapause.
In mosquitoes living under long daylight conditions, which were prepared to deposit mature eggs, the scientists used a technique to disrupt the insulin receptor gene from completing its function. This disruption halted reproductive activity in the mosquitoes and caused them to enter a state resembling diapau
|Contact: David Denlinger|
Ohio State University