The diel locomotor activity patterns of wandering larvae in the flesh fly, Sarcophaga crassipalpis Macquart (Diptera: Sarcophagidae), were examined using a novel apparatus and shown to be primarily diurnal, but with a minority (37%) showing nocturnal activity. In response to the environmental stress of heat shock, a significantly larger proportion (72%) of the larvae became nocturnal. In comparison, adult circadian activity also was predominantly diurnal, but not correlated with the larval activity patterns. In addition, adult patterns showed age-related changes in entrainment and free running period. Finally, the phase of circadian-gated adult eclosion was shown to be entrained by a 3-day exposure to light-dark cycles delivered prior to pupariation, with the phase maintained throughout pupal-adult metamorphosis under constant dark conditions. These results demonstrate that environmental changes may have profound effects on the expression of 24-h activity patterns and circadian rhythms during different life stages throughout development.

The biogenic amines serotonin (5HT), dopamine (DA), and octopamine (OA) have been indicated in the regulation of behaviors, including aggression. The flesh fly, Sarcophaga crassipalpis, was used to investigate ontogenetic and circadian changes in amines and aggression. Heads of male flies were analyzed for amine content using high performance liquid chromatography with electrochemical detection (HPLC-ECD) at 3 time points on each of 4 consecutive days in 2 light cycles, 12:12 LD and 15:9 LD. Both DA and OA levels decreased with age. Light-cycle dependent differences were observed for all amines in overall levels and patterns of change throughout the day. A behavioral assay quantified interactive and aggressive behaviors at three time points in the light period for 2 age groups. The daily changes in behavioral profiles differed dependent on age. Correlations from these data can be made between changes in amine levels and time of day, photoperiod, age, and aggressive state.

1