Flight And Responses Of Dendroctonus Armandi (Coleoptera: Curculionidae: Scolytinae) To Volatiles Of Chinese White Pine

Chinese white pine bark beetle (Dendroctonus armandi Tsai and Li, Coleoptera: Scolytidae) is arguable the most destructive insect in Qingling Mountains, which primarily attacks healthy Chinese white pine (Pinus armandi Franch) aged over 30 years and causes widespread tree mortality. It severely damage environmental and economic benefits of the Qingling Mountains forest ecosystems. The volatiles of P. armandi are the critical factor in the migration proliferation and invasion process of host of D. armandi. It is of great significance to the theory and practice for providing invasion and proliferation mechanism of D. armandi and ways of biological control in forest ecosystems.In this research, approach-avoidance-behavior response and flight performance of laboratory adults of D.armandi was tested to the 11 major monoterpenes and the volatile oil from phloem of P. armandi by using a Y-tube olfactometer and flight mill system. The results are as follows:1. All the monoterpene tested includingα-phellandrene, (S)-(-)-β-pinene, (R)-(+)-α-pinene, (S)-(-)-α-pinene, (+)-camphene, (-)-camphene, (R)-(+)-limonene, (S)-(-)-limonene, 3-carene,β-myrcene, and bornyl acetate, could evoke approach-avoidance-behavior response of the male and female D. armandi at at different concentrations. Besides (S)-(-)-β-pinene, all those monoterpenes were showed positive approach response.2. Volatile oils from phloem of P. armandi were showed significant positive approach response to the male and female of D. armandi. Concentration contributes significant influence in approach avoidance behavior of D. armandi. In the low concentration stimulus, onlyα-phellandrene attracted the male and female of D. armandi. significantly; with the concentration reached 100μg/μL, the most positive approach responsive monoterpene was added into (S)-(-)-α-pinene,α-phellandrene, (-)-camphene in female andα-phellandrene, (R)-(+)-α-pinene and 3-carene in males.3. Male adults are more sensitive to change of the host volatiles concentration, which are significantly different trends in the test sample concentration 100μg/μL. When the concentration of the volatiles oil was 100μg/μL, there is a significant difference between the host volatiles (H/I) and other monoterpenes, exceptα-phellandrene. And the positive approach response ofα-phellandrene was higher than the response of (R)-(+)-α-pinene, (S)-(-)-α-pinene, (-)-camphene and 3-carene in female;α-phellandrene and (R)-(+)-α-pinene could evoke significant higher approach response than (S)-(-)-α-pinene, (-)-camphene and 3-carene in male.4.?There's sexual dimorphism available in approach-avoidance-behavior response of the D. armandi to volatiles of Chinese white pine. The behavior responses of female adults to (-)-camphene and volatile oil of H-phloem in P. armandi were significant higher the males. There were no significant differences between females and males in other monoterpenes and volatile oil from phloem of P. armandi.5. Chinese white pine beetles in female under 3-carene and (R)-(+)-α-pinene condition showed improved flight performance compared with those that under the control condition, (S)-(-)-α-pinene had a significant effect on invigorating flight activity of males. Total flight time of males in (S)-(-)-α-pinene, moreover, was significantly higher than females. Apart from that, there were no significant differences in flight performance between other monoterpenes and volatile oil from phloem of P. armandi, and also between the sexes.