Juvenile hormone involvement in pupal diapause of the flesh fly Sarcophaga crassipalpis: regulation of infradian cycles of O2 consumption

A cyclic pattern of juvenile hormone (JH) activity is retained during pupal diapause in the flesh fly, Sarcophaga crassipalpis. Cycles of JH activity correlate with infradian cycles of O2 consumption. JH activity progressively increases during a 4-day cycle and appears to trigger the onset of an peak. During the first 2 days of an cycle, pupae are insensitive to an application of JH analogue, but when JH analogue is applied during the last 2 days of the cycle, rises and the cyclic pattern is destroyed. When JH analogue is applied to third instar larvae, O2 consumption is sustained at a steady, high rate throughout pupal diapause. The cycles persist in abdomen-ligated pupae but disappear following head ligation.