PRELIMINARY STUDIES ON THE BIONOMICS AND MANAGEMENT OF THE PINE BARK BEETLE (Conyza canadensis L.)IN KUNMING DISTRICT, CHINA

The pine bark beetle (B. piniperda L.) has become the most destructive pest in the stands of Pinus yunnanensis in Kunming district and other forest regions in Yunnan Province. This paper reports the primary results of studies on bionomics and management of the pest at both Haikou and Fangwang tree farms during 1983-1986. The insect completes one generation a year. It overwinters in the adult stage without apparent hibernation. A certain proportion of the overwintering adults make second attacks on the host trunk after reemergence, and therefore are capable of establishing sister broods, The life stages of the within-tree broods are rather overlaping. However, the peak period of the population abundance in the host occures during Feb. -April. This suggests the proper time for treating the infestation spots, including bark-peeling. The attacking behavior of the beetle and its gallery pattern are described in the text. Our work also reveals that the forest fire-injured stands are pro-minent among the causal factors identified as contributing to host susceptibility. An extraordinary low-temperature attack in spring may cause a mortality rate of above 60% to the larval brood within the host. An Ostomatid (Temnochila sp.) predator is of importance among the natural enemies of the pest. It is observed that 3-4 larvae of this beneficial beetle are capable of devouring 53.8% of the pest population in a gallery. In suggesting the bark beetle management, treatments a brief review of both the domestic and world informations on the bark beetle control is presented. The authors urgently emphasize the significance of silvicultural practices in reducing susceptibility of stands to beetle attacks. They also stress the importance of implementing frequent detection on the active infestation spots and prompt treatment to suppress the populatien under infestation level.