EAG and behavioral responses of adults of Adoxophyes orana (Lepidoptera: Tortricidae) to volatiles of its major host plants LI Guang-Wei, CHEN Yu-Xin, YAN Rui, LEI Yi-Xue, CHEN Xiu-Lin, LI Bo-Liao
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【Aim】 Adoxophyes orana is an important insect pest endangering apple, peach, pear, jujube and other fruit trees. In recent years, the occurrence area of A. orana in the apple and jujube orchards of Shaanxi has increased by years, causing increasing harm to fruit production. The objective of this study is to clarify the roles of host-plant volatiles in the olfactory communication of A. orana adults, so as to provide basic data for the development of botanical attractants for A. orana. 【Methods】 The electroantennogram (EAG) responses of the 2-day-old unmatched female and male adults of A. orana to 51 host-plant volatile compounds were determined using EAG apparatus, and the behavioral responses of A. orana adults to 15 volatile compounds with strong EAG amplitude were measured with the device developed by our laboratory for testing the olfactory behavior of tiny moths. 【Results】 The EAG test results showed that there were significant differences in the relative EAG response values of A. orana adults to the tested 51 hostplant volatile compounds. Both sexes showed strong EAG responses towards cis-3-hexen-1-ol, trans-2-hexen-1-ol, 1-hexanol, 1-heptanol, hexanal, ( E) -2-hexenal, heptanal, octanal, nonanal, butyl acetate, isopentyl acetate and cis-3-hexenyl acetate. In addition, male adults also displayed strong EAG responses to 3 -methyl-1-butanol, 1-penten-3-ol, benzaldehyde, butyl butyrate, ethyl acetate, ethyl trimethylcrotonate, ethyl hexanoate, butyl propionate, cis-3-hexenyl isovalerate, benzonitrile and lemonile. Obvious differences existed in the EAG response values towards 29 compounds of the tested 51 volatile compounds between the females and the males, and female adults showed significantly higher EAG responses to (-)-α-phellandrene and camphene than males, while male adults exhibited significantly higher EAG responses to the other 27 volatile compounds than females. When the doses of volatile compounds ranged from 0.02 μg to 20 μg, the relative EAG response values did not increase significantly, however, when the doses of volatile compounds increased from 20 μg to 200 μg, the relative EAG values in both female and male adults significantly increased. The olfactory behavioral tests revealed that the female adults showed obvious preference to hexanal, heptanal, octanal and cis-3-hexenyl acetate, with the selection rates to them all exceeding 58%, while the males showed obvious preferences to 1-hexanol, heptanal, isopentyl acetate and benzonitrile. 【Conclusion】 The unmated male adults of A. orana show higher sensitivities towards host-plant volatiles in the EAG responses than the unmated females. 1-Hexanol, hexanal, heptanal, octanal, cis-3-hexenyl acetate, isopentyl acetate and benzonitrile have obvious attractancy to female or male adults of A. orana and can be applied in developing botanical attractants for this pest.