[Effects of environmental temperature on Dendrolimus punctatus development and survival]

In a simulation test, three treatments of low, normal and high temperature were designed to examine the effects of environmental fluctuant temperature on the development and survival of second generation Dendrolimus punctatus larvae. The results showed that under different temperature but same light and dark cycle, the mortality of lst to approximately 3rd instar was apparently different. Under long photophase, the larval mortality of 1st to approximately 3rd instar was 25.55%, 55.13% and 58.23% at low, normal and high temperature, while under short photophase, the mortality was 32.67%, 64.67% and 94.32%, respectively. High temperature resulted in the diapause of larvae. Under the same short photophase, the larvae exposed to high temperature could develop to 5th instar by 40%, while those exposed to normal and low temperature kept diapause, and could not develop to 5th instar after 20 days. After 48 days, the larvae exposed to high temperature became cocoons, while those exposed to normal and low temperature still diapaused. It was suggested that if the second generation larvae of D. punctatus encountered consecutive high temperature, most of them could develop to third generation.