Characteristics of insect community and the spread of parasitic insects under environmental gradients in cut slash affected by pine wilt disease.

This research presented the relationship among parasitic insects, pine wilt disease and environmental factors in 10 Masson pine forestland sample plots, which were natural recovery secondary communities and damaged by pine wilt disease in Zhoushan Island,Zhejiang Province of eastern China. The structure of insect communities and functional groups were investigated through application of window traps. Results indicated that the dominant insect populations in sample plots were Hymenoptera (17 families,47 species,1 178 individuals), Coleoptra (24 families, 41 species,520 individuals) and Diptera (18 families,32 species,616 individuals). The proportion of parasitic insect groups in cut slash affected by pine wilt disease was apparently larger than that of other conifer forest types. With the decrease of conifer forests爷proportion, the number of parasitic insects increased (5 conifer 5 broadleaf 3 conifer 7 broadleaf 1 conifer 9 broadleaf). Meanwhile, the damage degree performed reserved trend (1 conifer 9 broadleaf 3 conifer 7 broadleaf 5 conifer 5 broadleaf ), indicating that in order to enhance the resistance of forestlands to pine wood nematodes爷invasion, the ratio of broadleaf need to be increased so as to increase the proportion of parasitic insects. Furthermore, the redundancy analysis (RDA) showed that soil moisture was the major environmental factor affecting the distribution of parasitic insect groups in cut slash affected by pine wilt disease.