Expression and functional characterization of odorant-binding protein 2 in the predatory mite Neoseiulus barkeri.

Olfactory plays a crucial role for arthropods in foraging, mating and oviposition. Odorant-binding protein gene (OBP) was considered one of the most important olfactory genes. However, little is known about its functions in predatory mites. Here, we used Neoseiulus barkeri, an important commercialized natural enemy, to explore its chemosensory characteristics. In this study, N. barkeri was attracted by methyl salicylate (MeSA) and showed higher crawling speed under MeSA treatment. Then, we identified and cloned an OBP gene named Nbarobp2 and analyzed its expression profiles in the predatory mite. The Nbarobp2 was 663 bp, highly expressed in larval and nymphal stages, and was significantly up-regulated in N. barkeri under MeSA treatment. Nbarobp2 encoded 202 amino acid residues with a molecular weight of 23 kDa (After removing the signal peptide). Sequence comparisons revealed the OBPs in Arachnida shared six conserved cysteine sites, but was distinguishable from OBPs of Insecta on the phylogenetic tree. RNA interference, Western-blotting and binding affinity assays further proved that Nbarobp2 involved in volatiles perception of predatory mites. This study shed light on the functional characteristics of OBPs in predatory mites, providing a new insight for better biological control. This article is protected by copyright. All rights reserved.