Seasonal change in metabolic rate of Drosophila simulans.

1. Second-generation descendents of wild-caught female Drosophila simulans Sturtevant collected at different seasons from Gainesville, Florida, USA, were reared under a constant temperature and food level but with seasonally variable photoperiods. 2. Body weight and metabolic rate, after adjustment to a common body weight, were higher in descendents of flies collected in fall and winter. 3. Temperature sensitivity (Q10) of metabolic rate was also related to season: higher Q10 values were associated with seasons of increasing temperatures and lower Q10 values were associated with seasons of decreasing temperatures. 4. These metabolic characteristics may be adaptive in enhancing activity at lower temperatures and conserving energy at higher temperatures.