WANG, G.; HUEY, R. B.; RAINWATER, S.; Unv. of Washington, Seattle; Unv. of Washington, Seattle; Ingelmoor High School, Kenmore: Maximum Voluntary Temperature of Drosophila sp. Larvae

Temperature has a large effect on larval development time and ultimate adult size in Drosophila sp., and extreme temperatures can be damaging or even lethal. Thus the body temperatures selected by larvae are of critical selective importance; however, essentially nothing known about larval thermoregulatory behavior. One important parameter of behavioral thermoregulation is the maximum temperature tolerated before an escape response is initiated. We describe a new technique (adopted from studies with reptiles) for quantifying the maximum voluntary temperature tolerated in Drosophila sp. larvae, and employ it to determine the maximum voluntary temperature in Drosophila melanogaster and Drosophila subobscura. Eggs (40) are collected from a laboratory population and transferred to a 3mm thick disk of Drosophila medium in a small petri plate (1� diameter). While the larvae are in the first instar (48 hours), the plate is placed on a heating block under a dissecting scope. The block is connected to a temperature bath containing ice water which is set on constant heating. As the larvae leave the media they are removed, and the temperature of the medium at emergence is recorded. In addition, we explore whether maximum voluntary temperature varies with time of day or larval stage.