Meeting Abstract
Reduced temperatures have shown to increase the longevity of cold-tolerant insects. Insects that are not cold-tolerant experience elevated mortality when held at static reduced temperatures. A fluctuating thermal regime (FTR) has been shown to increase longevity and survivability in multiple insect species. During a fluctuating thermal regime insects are held at a reduced temperature with a one hour pulse of increased temperature each day. We measured the effect of FTR compared to constant temperature (CT) on the longevity and fecundity of Drosophila melanogaster held at CT-6°C, CT-22°C, and a FTR that oscillates between 6°C and 22°C. We demonstrate that a fluctuating thermal regime which oscillates between the cold and warm static temperatures greatly increases longevity with mean survival approximately seven times as long as other treatments and up to 241 days. We assessed the effects of FTR on male and female fecundity at 20-day intervals from 20 to 100 days and fecundity in the subsequent generation. Under the FTR treatment the fecundity of both JW and Oregon-R female flies declined steadily but after 60 days when no CT-6°C flies remained alive the fecundity of both strains remained at approximately 53% of control. Male flies of both strains exhibited an increase in fecundity under FTR peaking at 80 days before dropping significantly after 100 days. The reduction in female fecundity is likely a combination of the high cost of egg production and adult flies not consuming FTR culture media, while the increase in male fecundity remains unexplained. Offspring reared from each treatment group did not exhibit the patterns found in FTR parents.
