Attraction Of Scarab Beetles To Plant Volatiles

The scarab beetles of Holotrichia oblita Falderman, Holotrichia parallelaMotschulsky, Metabolus flavescens Brenske and Brahmina faldermanni Kraatz arecommon agricultural pests, which have important impact on economy. All of these beetlesbelong to the Melolonthidae family, the largest family of superfamily Scarabaeoidea. Theobjective of this research is to investigate preferences of the scarab beetles to theirhost-plants, to identifiy volatile odor components from host plants, and to futher developplant attractants for sustainable control of the scarab beetles. In this research, the abovefour scarab beetles and seven plants, including Ginkgo biloba, Lonicera maackii (Rupr.)Maxim, Ulmus pumila, Hibiscus moscheutos, Syringa oblate, Magnolia denudate,Diospyros kaki, were used. Electroantennography (EAG), gas chromatography-massspectrometry (GC-MS), gas chromatography-electroantennographic detection (GC-EAD)techniques were used in this study. And the results were as following:EAG responses of scarab beetles to the plant volatiles. Dynamic headspacesampling and solvent extraction were used to collect the plant volatiles for EAG tests. Thepresent study showed that the four scarab beetles had large EAG response to volatiles fromhost-plant U. pumila. Additionally, M. flavescens Brenske showed large EAG response tovolatiles from S. oblate. The scarab beetles had sex-related difference in EAG responses.Under the same treatments, the females of H. oblita Falderman had significant larger EAGamplitudes than the males to some plant volatiles. However, the EAG amplitudes from H.parallela Motschulsky females were slightly lower than males, but not significant. TheEAG response of M. flavescens Brenske females to the extract of H. moscheutos wassignificantly larger than males.GC-MS analyses of the plant volatiles. In this study, headspace volatiles from sevenplants including G. biloba, L. maackii (Rupr.) Maxim, U. pumila, H. moscheutos, S. oblate,M. denudate, D. kaki were analysed by GC-MS technique. Respectively, we identified13compounds,16compounds,12compounds,27compounds,19compounds,6compoundsand5compounds. Several compounds were shared by two or more of these plants, such asNonanal,3,7-Dimethyl-1,3,6-octatriene,(Z)-3-Hexenyl acetate,(Z)-3-Hexen-1-ol.GC-EAD responses of Metabolus flavescens Brenske to the plant volatiles.GC-EAD technique was used to analyse responses of M. flavescens Brenske to headspacevolatiles from U. pumila and S. oblate. Nine compounds were identified in inducingGC-EAD responses of M. flavescens Brenske, containing (Z)-3-Hexenyl acetate,(Z)-3-Hexen-1-ol, Nonanal,[1,1’-Bicyclopentyl]-2-one,-Farnesene,(E)-6,10-Dimethyl-5,9-undecadien-2-one, pentadecane, caryophyllene and1-(4-ethylphenyl)-ethanone. Among these compounds,(Z)-3-Hexenyl acetate, Nonanal andα-Farnesene were shared by the two host plant volatiles.