Olfactory responses of Endoclita signifer Walker larvae to volatiles of eucalyptus trunks and shallow soil under eucalyptus forest

【Objective】By comparing composition and content of volatiles from healthy and Endoclita signifer Walkerdamaged eucalyptus trunks and shallow soil under eucalyptus forest, to study transfer mechanism on how terrestrial E. signifer larvae caused arboreal harm, so as to provide a theoretical basis prevention and control for ecological prevention and control.【Method】Volatiles from the healthy and E. signifier-infected eucalyptus trunk and shallow soil of eucalyptus forest were extracted by dynamic headspace adsorption method. Components and contents of volatiles were determined through gas chromatography-mass spectrometry(GC-MS). Through random forest analysis, five volatiles were selected to determine the olfactory behavior of E. signifer larvae.【Result】Seventeen, forty-seven and twenty-three volatiles were identified in healthy trunk, ill trunks and shallow soil. Results of random forest analysis showed that:(-) -β-pinene, 3, 3-dimethyl-6-methylenecyclohexene and(-) -α-pinene were more important seen from comparison between volatiles from healthy and ill trunks; (-) -β-pinene, camphene, eucalyptol, o-cymene, 3, 3-dimethyl-6-methylenecyclohexene and(-) -α- pinene were more important seen from comparison of volatiles in eucalyptus trunks(healthy and ill) and shallow soil. Results of behavioral measurement showed that camphene and o-cymene(concentration of 10 mg/mL) had significant (P<0.05) and extremely significant(P<0.01) attraction to the 3^rd instar larvae of E. signifer.【Conclusion】Both o-cymene and camphene in the volatiles of eucalyptus trunks can significantly attract the 3^rd instar larvae of E. signifer, and their contents were both higher in the volatiles of ill eucalyptus trunks. It is speculated that the 2 components can regulate the host plant-seeking behavior of E. signifer larvae.