Analysis Of Semiochemicals For Dastarcus Helophoroides Newly-hatched Larvae Locating Anoplophora Glabripennis

Anoplophora glabripennis,with a wide geographical distribution and broad host range,have caused serious damage to Populus gansuensis,an important tree species for windbreak and sand fixation in HeXi Corridor,and the damage situation of A.glabripennis is on the rise year by year with the increase of artificial pure forest.Dastarcus helophoroides is the main parasitoid natural enemy of the A.glabripennis,and its newly-hatched larvae with three pairs of baenopoda could locate and parasitic A.glabripennis.The volatile semiochemicals that D.helophoroides newly-hatched larvae uses for locating the host are mainly from the host habitat,the host itself and excreta,the plant by host da maging and the compound of all.The semiochemicals of D.helophoroides newly-hatched larvae usd for locating A.glabripennis were studied from the chemical ecology of insects in this article,which provided a theoretical basis for studying the chemical mechanism of the phenomenon that D.helophoroides seeks for its host,using D.helophoroides to control longicorn and optimizing artificial propagation technology of D.helophoroides.The main research content and results are as follows:1.Odor source materials were collected while having an attractive effect on D.helophoroides newly-hatched larvae,such as the uninfested barks,uninfested xylem,bark with larval gallerys,wood with larval gallerys,larvae frass,wood dust,host mature larvae and host pupa.We use a four-wall olfactometer to perform a one-way bioassay test on the odor source materials.The results showed that D.helophoroides newly-hatched larvae had obvious selection behaviors on wood with larval gallerys,larvae frass and wood dust,host mature larvae,host pupa,and had no obvious tendency to respond to the uninfested barks and uninfested xylem and the healthy xylem of P.gansuensis.2.The volatiles from odor source materials were qualitatively analyzed by means of different adsorption methods,for instance,Tenax sampling method,solid-phase microextraction and headspace sampling method,combining them with gas chromatography-tandem mass spectrometry.Also,the study compared the adsorption effects of different adsorption methods.The results showed that Tenax sampling method is more comprehensive in collecting substances and the response value of gas chromatography is larger;solid-phase microextraction is better for the collection of alkanes and aldehydes;headspace sampling method is better for collecting olefins and aldehydes.The volatile substances was analyzed from odor source materials mainly include alkanes,olefins,alcohols,aldehydes,aromatic hydrocarbons and esters.The characteristics of volatile substances in different odor source materials were summarized.It could be found that there existed more olefins and their relative percentage in volatile substances of the wood with larval gallerys,larvae frass and wood dust,host mature larvae and pupa,and the R-(+)-limonene was only detected in the volatile substances of the uninfested xylem,larvae frass and wood dust,host mature larvae ang pupa;α-pinene was widely found in the volatiles of all odor source materials,but the relative content of the volatiles was significantly higher in the wood with larval gallerys,larvae frass and wood dust,host mature larvae ang pupa.The release of aldehydes,green leaf volatiles,from the infected trees increased.Hexanal exists not only in the volatiles of plant materials,but also in volatiles of host mature larvae ang pupa.3.Through qualitative results of odor source material and the first part of comprehensive comparison of experimental results,four compounds were selected,such as R-(+)-limonene,α-pinene,hexanal and heptanal.We used a four-wall olfactometer to perform a one-way bioassay test on a single chemical.The results showed that R-(+)-Limonene,α-Pinene and Hexanal had attractive effects on D.helophoroides newly-hatched larvae,and the order of action intensity from large to small was α-Pinene,hexanal and R-(+)– Limonene,while heptanal having no obvious attractive effect on the D.helophoroides newly-hatched larvae.