Effects of Environmental Factors on Circadian Activity in the Flesh Fly, Sarcophaga Crassipalpis

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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.