On the other end of the diapause spectrum, the scientists disrupted the function of the FOXO gene in mosquitoes that already had entered a dormant state. Within four days, these mosquitoes stopped retaining accumulated fat, killing more than 80 percent of them within three weeks.
Diapause is critical to the survival of the species, as these mosquitoes hold onto their immature eggs through the winter and wait until spring to develop them to maturity and deposit them. Similarly, the West Nile virus appears to be carried within the female from one season to another. Though newly infected birds also could be responsible for the viruss emergence in a given year, it appears that propagation of the virus may be dependent on these mosquitoes survival, Denlinger said.
Though there is limited evidence so far, other research has suggested the insulin signaling pathway affects dormancy in the roundworm and fruit fly.
These are very different organisms with a very different evolutionary history yet theyre using this common pathway of insulin signaling to regulate their dormancy. So an important aspect of this is the suggestion that this might be a common pathway used by lots of organisms to regulate their dormancy period, Denlinger said.
Warmer temperatures are identified as the signal that brings mosquitoes out of their dormant state, he said. At this stage, they produce a hormone called juvenile hormone, which implies another shift in the insulin signaling pathway at the end of diapause that enables this hormone production.
|Contact: David Denlinger|
Ohio State University