EAG and behavioral responses of the wingless tea aphid Toxoptera aurantii(Homoptera:Aphididae) to tea plant volatiles

Electrophysiological and behavioral responses of the apterous tea aphid,Toxoptera aurantii Boyer,to fourteen synthetic volatiles identified from tea shoots,and their partial(GLV mixture) and full(ACB) blends,as well as fresh young tea leaves,buds,tender stems,adult tea leaves and tea aphid-damaged young leaves(ADYL),were studied by using an electroantennography(EAG) and a four-arm olfactometer.The full blend elicited the largest EAG responses.Major volatile components from the tea shoots,Z-3-hexen-1-ol,E-2-hexenal,n-hexanol,methyl salicylate and benzylalcohol,were strongly EAG active.All the tea tissue materials tested also elicited significant EAG responses,with the young tea leaf being the strongest,followed by bud,tender stem and adult tea leaf.Surprisingly,ADYL elicited a weakly negative EAG response.In the olfactory assays,the fresh and tender tea leaves,as well as the individual major volatile components from the tender shoots(EAG-active),e.g.Z-3-hexenyl acetate,methyl salicylate,E-2-hexen-1-ol,Z-3-hexen-1-ol,etc.were all attractive.This result might indicate that the apteral tea aphids may use tea shoot volatiles as kairomone to find their optimal feeding sites,i.e.fresh tender tea shoots.