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

LoryOBP29 and LoryOBP40 were cloned from Lissorhoptrus oryzophilus. Tissue expression analysis showed that both LoryOBP29 and LoryOBP40 were highly expressed in antennae and heads. Ligand binding assays revealed that the two LoryOBPs could bind to beta-ionone, diisobutyl phthalate, and 4-methylbenzophenone. The electroantennography (EAG) results showed that all three volatiles could elicit electrophysiological responses in the antennae of adult L. oryzophilus. Behavioral experiments indicated that adults were strongly attracted to beta-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 beta-ionone and diisobutyl phthalate, while those treated with dsLoryOBP40 lost their response to beta-ionone. In summary, our findings suggest that LoryOBP29 and LoryOBP40 may play a role in host plant location by L. oryzophilus adults.