Studies On The Biological Characteristics And Integrated Management Techniques Of Leptinotarsa Decemlineata(Say), In Xinjiang, China

The distribution, dispersal, damage, life cycle, field population dynamics and integrated managementmethods of Colorado Potato Beetle, Leptinotarsa decemlineata (Say), an exotic pest insect of potatocrops, were studied in Xinjiang Uyghur Autonomous Region. Conclusions of these studies were drawnas follows:(1) Field investigations showed that Colorado Potato Beetle (CPB) has now spread throughout all35counties of8prefectures around Junggar Basin, which is located in the north of Tianshan Mountain. Thedistribution of CPB covered about260000km2in northern Xinjiang. Flight of the adult is the maindispersal form of this pest. The larvae and adults of CPB feed on the leaves of potato crops, and causedthe damage of30%~50%of the yield, or even over90%when the crops were heavily infested.(2)The results of the studies on life history, field population dynamics and host plant range showed thatCPB can finish1~3, but mostly2generations per year in northern Xinjiang, and the.generations oftenoverlap with each other. CPB possess the habits of high capacity of reproduction, diapause andmigration in this region.(3)Cultural practices such as fall plowing, winter irrigation and crop rotation, and chemical insecticidescan suppress CPB effectively. Fall plowing caused mortality of overwintered adult by33.3%~76.36%.Crop rotation caused29.4%~84.3%reduction in overwintered adult population and also postponedoccurrence of overwintered adults by4~7d. In the field CPB were controlled by many natural enemies,especially the predacious arthropods, and89.2%of these predacious arthropods prey on the larvae ofCPB.14kinds of environment-sound insecticides were selected to control CPB in the field, and thecontrol efficacy of these insecticides were over90%in the20thday after applying. The economicthresholds for chemical control were established as24overwintered adults or106first instar larvae per100potato plants. The combination of rational fertilization, plastic film mulches and drip irrigationtechniques can enhance the tolerance of potato plants to CPB, and can increase10.5%~24.8%morepotato yield.