Abstract:

A biocontrol program was carried out by releasing the parasitoid Dastarcus helophoroides (Coleoptera: Bothrideridae) of the longhorn beetle Batocera horsfieldi (Coleoptera: Cerambycidae), an important stem-borer of ashes (Fraxinus velutina) in shandong, the Huanghe Yellow River Delta in the present study. Adults and eggs of D. helophoroides were released in fields in eight plots in Dongying and Binzhou City. Control effect was evaluated by two investigation indexes, i.e. , infested trees and the longhorn beetle larvae density. The biocontrol results showed that releasing eggs and adults of the parasitoid were able to effectively control B. horsfieldi. After the release of the parasitoid for two years, in the five plots of release the parasitoid eggs, the mean correction reducing rate of the longhorn beetle larvae was 73.16% per tree, and the mean correction reducing rate of infested trees was 72.36%. In three plots of releasing the parasitoid adults, mean correction reducing rate of the longhorn beetle larvae was 77.20% per tree, and the mean correction reducing rate of infested trees was 69.68%. It was showed that the control results by releasing adults of the parasitoid were a little better than releasing eggs, but the difference was not significant. Thus, the technique of releasing eggs of the parasitoid would be worth extending in the large area control of the pest for low cost of its eggs in mass rearing.

Key words: Fraxinus velutina, Batocera horsfieldi, biological control, parasitoid, Dastarcus helophoroides