Locomotor activity patterns are changed by gender, nutrition and age effects in the flesh fly, Sarcophaga crassipalpis

We have previously reported that male flesh flies (Sarcophaga crassipalpis) have a distinctly different spatial distribution during diurnal but not nocturnal conditions than do females and behavioral patterns of males also show an ontogeny of aggressive behaviors as they become sexually mature. We examine the influence of endogenous circadian rhythms on the initiation of aggressive (territorial) and reproductive behavior in these flies. Under photo-entrainment and constant dark conditions, there are significant gender and nutritional differences in entrainment patterns that changed with age. As expected, males are predominately diurnal, with higher activity in non-liver fed males and the greatest activity occurring in late photophase. Females show higher overall activity than males but also a surprising nocturnal activity occurring in the first half of the scotophase. This nocturnal activity developed earlier in females fed liver than in females not fed liver. Locomotor activity under constant dark conditions (DD) was also recorded. In DD conditions, both sexes showed free-running rhythms, with females exhibiting higher overall levels of activity. Both sexes displayed spontaneous changes in free-running period, suggesting a multi-oscillator circadian system. The nocturnal activity seen during LD entrainment in females did not persist during the subsequent DD free-run. Future work will focus on the physiological processes underlying these sex-, age- and nutrition-related changes.