Effect of experimentally-prolonged life span on flight performance of houseflies.

Reduction of metabolic rate by the elimination of flying activity extends the life span of male houseflies about two-fold as compared to those permitted to engage in flying activity. Flying performance of flies is known to undergo an age-associated decline. The objective of this study was to determine if such an age-related decline in flight performance is delayed by the reduction of metabolic rate. Flight performance was measured, by cross-sectional sampling at different ages, by the "stationary flight" method, as the total time spent in flight and the number and duration of individual flights and rest stops during a one hour observation period. Flies kept under conditions of low physical activity exhibited a superior flight performance at all ages as compared to those kept under high activity conditions. The decline in flight performance observed in old flies was delayed in the longer-lived low activity flies as compared to the shorter-lived high activity flies. Results support the concept that the rate of aging in houseflies is modified by variations in the level of physical activity.