P2.90 Monday, Jan. 5 The sublethal effects of multiple acute cold exposure: lessons from Drosophila MARSHALL, K.E.*; SINCLAIR, B.J.; University of Western Ontario; University of Western Ontario firstname.lastname@example.org
Changes in snow cover and temperature with projected climate change will influence not only the mean temperatures that overwintering insects are exposed to, but also the frequency of freeze-thaw cycles. However, the majority of insect cold tolerance studies have focused on the effects of a single cold exposure, and the consequences of multiple cold exposure in insects have remained poorly elucidated. Two competing hypotheses are proposed: either chill injury is cumulative with increasing cold exposure regardless of intervals between exposures, or individuals are able to repair damage incurred during exposure allowing greater survival with repeated versus sustained cold exposure. We employed a Drosophila model system to gain a better understanding of the impacts of multiple cold exposure on metabolic fuels and fecundity. Adult virgin female flies were exposed to either a sustained (single ten hour) or multiple (five exposures, two hours each separated by 24 h) cold treatment at -0.5 degrees Celsius. Controls included treatments that examined the interaction between age and cold tolerance. Treated flies were assayed for total lipid, protein, and carbohydrate content. Total male and female offspring from treated females were also counted, allowing examination of sex ratio, fecundity, generation time, and intrinsic rate of increase. Initial results support the hypothesis that multiple cold is less deleterious than sustained cold.