The researchers found 11 previously undiscovered genes that turn on heat-shock proteins during diapause. Until this study, they had only known of two such proteins.
Denlinger and his team also examined the expression of one of those previously discovered heat-shock proteins, Hsp70, in five additional insect species that aren't related to the flesh fly. Each insect is a fairly common agricultural pest: the gypsy moth, the European corn borer, the walnut husk maggot, the apple maggot and the tobacco hornworm. Collectively, these species cause millions of dollars of damage annually.
Hsp70 was active while all of the insects were in diapause.
When Denlinger's team knocked out the Hsp70 gene that makes the heat-shock protein, the insects were unable to survive at a low temperature (in this case, insects were exposed to -15C, or 5F.)
"This underscores the essential role of this gene for winter survival, suggesting that this particular heat-shock protein is a major contributor to cold tolerance in insects," Denlinger said. "It's highly likely that the other heat-shock proteins we found during diapause in the flesh fly are also important to an insect's ability to endure months of cold temperatures."
Denlinger has no plans to develop a method to get rid of heat-shock proteins in insect pests, but he says that it is important to understand how insects survive through the winter.
"There may be steps we can take to disrupt the diapause process and make an insect vulnerable to low temperatures," Denlinger said. "At this point, the findings broaden our palette of players that contribute to cold tolerance in insects."