Geographical distribution and damage degree of Monochamus alternatus in Yunnan Province.

The long-horn beetle Monochamus alternatus is the main vector insect of the pine wood nematode Bursaphelenchus xylophilus.In order to prevent the pine wilt disease,the geographical distribution and damage extent of Monochamus alternatus in Yunnan Province were surveyed through methods of route survey,trace identification and sample plot investigation.The results showed that among the 129 counties in Yunnan Province,M.alternatus has been found in 116 counties(accounts for 89.9% of the total counties) and has not yet been found in 13 counties(accounts for 10.1%).The beetle has caused slight damage in 85 counties(accounts for 65.9% of the total counties),medium damage in 16 counties(12.4%),and severe damage in 15 counties(11.6%).The study showed that the vertical distribution of M.alternatus ranged between 649 m and 3 255 m,and the altitude difference was 2 606 m.The host tree species of M.alternatus are Pinus yunnanensis,P.kesiya var.langbianensis,P.densata,P.massoniana,and P.armandi.