Role of host plant volatile in the host-finding behavior of the strawberry leaf beetle, Galerucella vittaticollis Baly (Coleoptera: Chrysomelidae)

The strawberry leaf beetle, Galerucella vittaticollis Baly, is an oligophagous insect that feeds on strawberry and polygonaceous plants. Behavioral responses of G. vittaticollis to host and non-host plant volatiles were investigated. Beetles were attracted to the odors of their host, rosaceous plant, Fragaria ananassa Duchn., and polygonaceous plants, Rumex obtusifolius L., Fagopyrum esculentum Moench, Polygonum thunbergii Sieb. et Zucc., P. cuspidatum Sieb. et Zucc. and P. blumei Meisn. They were not attracted to non-host plants, Raphanus sativus L. (Brassicaceae), Lycium chinense Mill. (Solanaceae), Artemisia princeps Pampan. (Compositae) and Triticum aestivum L. (Gramineae). The main component of the headspace of all host plants tested was one of the green leaf volatiles, cis-3-hexenyl acetate. This compound was detected also in the non-host plants except T. aestivum. However, its relative content in A. princeps or L. chinense was different from that in host plants. The headspace of R. sativus contained one of the isothiocyanates, characteristic components of brassicaceous plants, in addition to cis-3-hexenyl acetate. The attractancy of cis-3-hexenyl acetate and two other typical green leaf volatiles, cis-3-hexen-1-ol and trans-2-hexenal, to the beetles was examined. The beetles were significantly attracted to only cis-3-hexenyl acetate. The findings suggest that G. vittaticollis uses cis-3-hexenyl acetate as an olfactory cue to find the host plants, strawberry and polygonaceous plants.