Behavioral Responses And Mechanism Of Anoplophora Glabripennis (Motschulsky) To Host Volatile Compounds

Anoplophora glabripennis Motshulsky (Coleoptera: Cerambycidae) is one of the most destructive insect borers of poplar trees in China. In recent years millions of poplar trees were damaged to death or near death in "Three-North Area", which caused heavy losses economically, ecologically and socially. Through the study on host selecting behaviors and behavioral responses to plant volatiles of A. glabripennis adult, this dissertation is to confirm the mechanism of hosts selection of A. glabripennis and plant volatile's effect, which can be taken as a theoretical support on the selection of suitable trees to establish well-arranged forest resistant to A. glabripennis with multiple tree species. By means of setting a certain number of host trees and models, or host trees covered with green or black cloth, or models in field under artificial control, host selecting behavior of A. glabripennis adult were observed and studied. The results showed that olfaction played an important role in the host finding of A. glabripennis when there were various factors of stress and limitation of green quantity of host trees and models in field, while vision did a subsidiary one in the deed of direction to host trees. The function of olfaction worked even more obviously when host trees are closer to A. glabripennis. The research of ability of arresting of host trees and moulds to A. glabripennis showed that there was a recognition process involving feeling, gustation and olfaction after the beetle landed on host trees or models, then the beetle made its choice to accept or reject host trees after comprehensive recognition. It was possible that A. glabripennis owned contact pheromone that may conduce to communicate each other by way of feeling organs such as antenna not in the distance, but at close quarters. From preferred host tree ash-leaf maple Acer negundo Linn., susceptible host tree Populus opera, P. simonii Carr, Salix matsudana Koidz, and resistant host tree, P. alba L. var. pyramidalis Bunge , P. tomentosa, Elaeagnus angustifolia Linn, and nonhost tree Ailanthus altissima (Mill.) Swingle and Fraxinus chinensis Roxb., volatile compounds were collected by adsorbent at headspace, and examined by adsorption-thermodesorption and GC-MS identification. The experiment results showed that the volatile of ash-leaf maple consists of 31 compounds, which are classified into alcohols, aldehydes, acids, esters, ketones, terpenes and others. There were different diurnal rhythms of volatile released from maple in July and in August. After suffering from drought stress and artificial damage, releasing of most volatiles from maple was greatly enhanced. Especially when ash-leaf maple was artificially damaged, lots of terpenes such as α-farnesene,(E)-β-ocimene,γ-terpinene and camphor were released. Among other host trees of A. glabripennis, there were higher contents of esters and terpenes in susceptible host trees and higher contents of aldehydes and alcohols in resistant host trees and nonhost trees. Different genus of trees also had different chemical components of volatiles. Lots of terpenes were released and the releasing of aldehydes and alcohols were also enhanced when those trees were damaged, but the releasing of esters decreased. Electroantennograms (EAG) activities of A. glabripennis to host volatile compounds were recorded. The result showed that there were no differences between EAG reactions of the antennas of female and male. It was also concluded that the top antenna of A. glabripennis was the sensitive part to volatile, and ethanol had some EAG responses to A. glabripennis. Among 11 volatiles that were used in experiments, aliphatic compounds such as hexanol, trans-2-Hexen-1-ol, cis-3-Hexen-1-ol and trans-2-Hexen-1-al elicited the largest EAG values. Aromatic derivatives elicited lowest EAG values, while others elicited moderate EAG values. When trans-2-Hexen-1-al was mixed with butyl acetate, furfural and 5-methy-furfural, the EAG activities are obviously enhanced. Gas chromatographic (GC) analysis of volatiles electroantennographic detector (EAD) revealed 2-pentanol and 1-pentanol gave the strongest antennal response, followed by 1-hexenol, cis-3-hexen-1-ol and 1-butanol. The behavioral responses of A. glabripennis to plant volatiles were tested in a four-armed olfactometer. It was found that different substances and concentrations of volatiles influenced behavior reaction to A. glabripennis. cis-3-hexen-1-ol, butyl acetate, ethyl butyrate, hexanal, trans-2-Hexen-1-al, propyl propionate that consists of green leaf volatiles and cymene were the most attractive compounds. The mixture from butyl acetate and propyl propionate was the most attractive to A. glabripennis in the olfactometer when these volatiles were mixed each other.