Observations on the termination of diapause in eggs of the wheat bnlb fly (Delia coarctata (Fall.)) and soil temperature

Abstract

SUMMARYThe temperature of the soil 15 cm deep was recorded before, during and after hatching of wheat bulb fly eggs at several sites in eastern Scotland during 1976 and 1978–80 inclusive. Eggs were extracted from soil cores and examined microscopically to monitor the progress of hatching. In 1976, 1978 and 1979, the difference between the minimum and maximum soil temperatures was small just before the start of hatching and large at or immediately afterwards. The termination of diapause and initiation of hatching of wheat bulb fly eggs in Scotland appeared to be associated with diurnal fluctuations of more than 5°C between the minimum and maximum soil temperatures.