Study On The Role Of Host Volatiles Form Five Rosaceae Trees Ii Chemical Communication Of Scolytus Seulensis Murayama

Scolytus seulensis is an important boring insect and a major threat to five kinds of Rosaceae trees:Amygdalus communi, Prunus salicina, Malus pumila, Amygdalus persica, Prunus armeniaca. Recently it has severely occurred in Xinjiang Province in China, causing a large number of one kind of its host tree-Prunus armeniaca to death. And it has posed a grave threat to the local apricot resources. This study is to determine the semiochemicals that are effective on host selection of this beetle by analysis of host tree volatiles profile, while provide a basis for the comprehensive management of Scolytus seulensis.In behavioral test, we monitored the preference of the beetles to whether the healthy Prunus armeniaca or weak trees. The result showed that sticky cards installed in weak Prunus armeniaca have attracted more beetles than healthy trees, revealed that Scolytus seulensis were more easier to be attracted by weak Prunus armeniaca.The volatiles of Prunus armeniaca (both healthy trees and weak trees)were collected by headspace absorption method in natural environment and analyzed by thermal desorption combined with GC-MS from April to May in Luntai county, Xinjiang province. Eighteen compounds have been identified in healthy plants, while twenty four compounds in weak plants. Among them, aldehydes is the highest concentrations of the volatiles. The ratio of green leaf aldehydes like Nonyl aldehyde, Octyl aldehyde, Decanal are almost the same in both healthy and weak trees. While alpha-pinene is only identified in weak trees.The volatiles from five important host plant trees (Amygdalus communi, Prunus salicina, Malus pumila, Amygdalus persica, Prunus armeniaca) were analyzed using ATD-GC-MS. In total,18different compounds were identify in the Amygdalus communis,12were present in Prunus salicina,17in Malus pumila,22in Amygdalus persica,24in Prunus armeniaca. They were divided into five categories:alkenes, aldehydes, alcohols, Ketones and esters, the major volatile components of these five plants was alkenes. Volatiles of each tree species is different in type and content, but volatiles of the five kinds of plants have a common characteristic, they all have highest concentrations of aldehydes. These substances may constitute a specific chemical fingerprint of the Rosaceae trees. Importantly,9of the volatile components were common to all five plants. They were:3-Methylbutyraldehyde, Hexanal, Heptaldehyde, alpha-pinene, Benzaldehyde, methyl heptenone, Octylaldehyde, Nonylaldehyde, Decenol. These9kinds of components will be selected for other experiments.The beetle response to the9compounds in different concentration are tested with Electroantennogram(EAG). The beetles showed different responses to different compounds. For green leaf aldehydes it shows a trend that with concentration gradually increase, the response also gradually enhanced. While for alpha-pinene, the highest response was detected at a low concentration (volumetric concentration is1/100, using n-hexane as solvent). The beetles reacted strongly to Heptaldehyd, Benzaldehyde, Octyl aldehyde, Nonyl aldehyde, alpha-pinene. In olfactory test,3-Methylbutyraldehyde, Hexana, Nonyl aldehyde, alpha-pinene, Decenol have attracted some bettles, but compare to controlled trial, it shows no significant difference.In the field, Hexana, Nonyl aldehyde, alpha-pinene, Heptaldehyd showed certain attractant effect, but the results are not obvious.