Abstract: 【Objective】The objective of this study is to use the mechanism of insect olfactory recognition, making CSPs as potential targets, and interfering with the insect host location and mating behavior for integrate pest management (IPM). 【Method】 In the present study, a novel chemosensory protein Alin-CSP6 in lucerne plant bug Adelphocoris lineolatus (Goeze) was cloned and the recombinant protein was obtained. The binding characteristics of Alin-CSP6 with 113 volatile odors was explored by a fluorescent competitive binding experiment. 【Result】 Alin-CSP6 has a wide binding spectrum with odorant ligands, which can bind to alcohols, aldehydes, ketones, easters, aromatic and so on. The β-citronellol, trans -2 - hexene aldehyde, 6-methyl-5-heptene-2- ketone, 2-undecanone, butyl levulinate, myrcene, (1s)-(-)-β-pinene, nonane, 3,4 - dimethyl benzaldehyde, ethyl ether, ocimene, acetophenone and benzaldehyde have high binding affinities with Alin-CSP6. In order to verify the behavioral influence of the odors on A. lineolatus, Y-tube olfactometer tests were conducted to observe the response of the adult to odorants which exhibited high binding abilities to Alin-CSP6. It was found that trans-2-hexene aldehyde and acetophenone showed strong attraction to lucerne plant bug, whereas 6-methyl-5-heptene-2–ketone, (1s)-(-)-β-pinene and 4-ethylbenzaldehyde displaied strong repellent action. By homologous modeling analysis the 3D structure was predicted, and it was found that Alin-CSP6 is consists of six α-helices located between residues 13-18(α1), 20-32(α2), 39-52(α3), 59-76(α4), 78-88(α5) and 94-102(α6), two pairs of disulfide bridges Cys29-Cys3 and Cys55-Cys58 play an important role in holding the structural stability of the protein. It is speculated that Ile7 and Phe81 may participate in binding to oleic acid amide analogues.【Conclusion】Alin-CSP6 has a wide binding spectrum with odorant ligands which play an important role in olfaction of A. lineolatus.

Key words: Adelphocoris lineolatus, odor chemical, chemosensory proteins Alin-CSP6, fluorescent competitive binding, Y-tube olfactometer, 3D structure prediction