ALTERATION OF THE ECLOSION RHYTHM AND ECLOSION BEHAVIOR IN THE FLESH FLY, SARCOPHAGA-CRASSIPALPIS, BY LOW AND HIGH-TEMPERATURE STRESS

Heat shock (45 degrees C), cold shock (-10 degrees C), and indirect ch illing injury (a prolonged exposure to 2 degrees C) did not interfere with the continuation of pharate adult development in the flesh fly, S arcophaga crassipalpis, but such flies failed to eclose properly when the exposure was of sufficient duration. In all three forms of injury, development following the temperature treatments was also retarded. A mong flies that were less severely affected and still capable of emerg ing as adults, the circadian time of adult eclosion shifted from near dawn to near the middle of the photophase, thus suggesting that the ne urally-based clock is among the systems most vulnerable to heat-shock and cold-shock injury. Tensiometric records of ptilinum expansion reve aled important differences in the nature of the injury caused by the d ifferent temperature stresses. Heat-shocked flies and those subjected to indirect chilling injury displayed the two behavioral programs norm ally associated with adult eclosion, the program for obstacle removal (FOR) and the program for forward movement (PFM), but such flies faile d to eclose because the muscle contractions generated by these motor p atterns were insufficient for successful eclosion. In contrast, cold-s hocked flies retained the capacity for strong muscle contraction, but the centrally-generated FOR and PFM programs were altered. As the dura tion of cold shock increased, both patterns became more erratic; the P FM program was then lost completely, and in the most severe cases of c old-shock injury, flies lost the capacity to generate both programs. T his suggests that neuronal damage is the likely cause of injury inflic ted by cold shock.