Abstract: Insect cold hardening processing is related with the activity of some enzymes of intermediary metabolism, including enzymes of glycolysis, hexose monophosphate shunt and cryoprotectant synthesis. In this study, overwintering larvae of pine needle gall midge, Thecodiplosis japonensis, were sampled at various dates over 1998～1999 winter and the profile of enzymic activity of intermediary metabolism was studied. The increased glycogen phosphorylase during overwintering ensured the required flow of carbon into the synthesis of trehalose. Enzymes of glycolysis (hexokinase, lactate dehydrogenase, aldolase) showed low activities during overwintering when more carbon flowing into trehalose synthesis. The glucose-6-phosphate dehydrogenase increased during overwintering, indicating that reduced condition of cell might keep the cell in proper function even in cold temperature, and also for cryoprotectant synthesis. The changes in trehalase activity showed that low activity was for keeping higher trehalose content and high activity for removing it in the spring.

Key words: Thecodiplosis japonensis, intermediary metabolism, enzyme activity, freezeavoiding insect, overwintering insect