Composition of the volatiles from intact and tea aphid‐damaged tea shoots and their allurement to several natural enemies of the tea aphid

Abstract

Abstract: The comparison between the composition of the volatiles from intact tea shoots (ITS) and that from tea aphid‐damaged tea shoots (TADTS) was accomplished, and the difference of both volatiles in attraction to natural enemies of the tea aphid, Toxoptera aurantii, i.e the ladybug, Leis axyridis (Pallas), the aphid parasite, Aphidius sp., and the lacewing, Chrysopa septempunctata Wesmeal, was investigated in the current paper. Volatile components from ITS, obtained by air entrainment, were identified by their mass spectra and retention times and comfirmed by comparison with authentic samples. They are E‐2‐hexenal, ocimene, Z‐3‐hexenyl acetate, Z‐3‐hexen‐1‐ol, butanoic acid‐3‐hexenyl ester, linalool, 1‐octanol, geraniol and indole. Volatiles from TADTS have been identified as E‐2‐hexenal, ocimene, Z‐3‐hexenyl acetate, Z‐3‐hexen‐1‐ol, linalool, geraniol, indole, benzaldehyde and E‐2‐hexenoic acid. Z‐3‐hexen‐1‐ol is the main component in the two kinds of volatiles, whilst benzaldehyde is the another main component in TADTS volatiles. The air entrainment extracts of TADTS and benzaldehyde elicit the stronger electroantennogram (EAG) responses, and the stronger upwind flight and arresting behaviour from each natural enemy in wind tunnel. EAG responses from Leis axyridis and Chrysopa septempunctata were bigger than those from Aphidius sp., whereas Leis axyridis responds to these odours slightly less than Aphidius sp. and Chrysopa septempunctata in wind tunnel bioassay. So TADTS emits volatile synomones, in which the amount of benzaldehyde is ample and its allurement is the strongest.