Ligand Binding Characteristics and Functional Analysis of Odorant-Binding Proteins in Rice Water Weevil <i>Lissorhoptrus oryzophilus</i> (Coleoptera: Curculionidae)

<i>LoryOBP29</i> and <i>LoryOBP40</i> were cloned from <i>Lissorhoptrus oryzophilus</i>. Tissue expression analysis showed that both <i>LoryOBP29</i> and <i>LoryOBP40</i> were highly expressed in antennae and heads. Ligand binding assays revealed that the two LoryOBPs could bind to <i>beta</i>-ionone, diisobutyl phthalate, and 4-methylbenzophenone. The electroantennography (EAG) results showed that all three volatiles could elicit electrophysiological responses in the antennae of adult <i>L. oryzophilus</i>. Behavioral experiments indicated that adults were strongly attracted to <i>beta</i>-ionone (100, 10, and 1 μg/μL), diisobutyl phthalate (10 and 1 μg/μL), and 4-methylbenzophenone (1 μg/μL). However, higher concentrations of 4-methylbenzophenone (100 and 10 μg/μL) exhibited significant repellent effects on adults. RNA interference results demonstrated that adults treated with dsLoryOBP29 lost their response to <i>beta</i>-ionone and diisobutyl phthalate, while those treated with dsLoryOBP40 lost their response to <i>beta</i>-ionone. In summary, our findings suggest that LoryOBP29 and LoryOBP40 may play a role in host plant location by <i>L. oryzophilus</i> adults.