Abstract: To clarify the impact of Pinus massoniana forest structure on the bioecological characteristics of Monochamus alternatus adults, we analyzed the relationship between the proportion of P. massoniana and plant diversity with the eclosion quantity, eclosion rate, sex ratio, and body length of M. alternatus adults in forest plots with different proportions of Pinus massoniana and broad-leaved trees. The results showed that the peak of eclosion of M. alternatus occurred from late May to early June. The eclosion curve of M. alternatus adults presented a typical “steamed bread” type, as described by the linear model of y=18.5+21.9x-93x². The proportion of P. massoniana trees in the mixed forest exhibited a significant impact on the number of adults emerged from dead P. massoniana trees (P<0.001). The mean eclosion number of adults per tree increased with increasing proportion of P. massoniana trees. The eclosion rate of M. alternatus adults was not significantly correlated with plant diversity, but positively correlated with the proportion of P. massoniana trees (y=0.216+0.0525x, R²=0.88, P<0.001). There was no difference in the body length of the female adults among the forests with low, medium, and high proportion of P. massoniana trees. Body length of the male in the forests with medium proportion of P. massoniana trees was significantly longer than that in the forests with low and high proportion of P. massoniana trees. Our results indicated that the proportion of P. massoniana trees in the forests had a significant impact on the population dynamics and eclosion rate of M. alternatus. Our findings will help further understand the impact of tree species configuration and structure in mixed forests on the biological characteristics of herbivorous insects, providing important information for the prevention and control of pine wilt disease based on forest manipulation.

Key words: Monochamus alternatus, Pinus massoniana, eclosion rate, plant diversity, stand structure