GOBP1 from the Variegated Cutworm Peridroma saucia (Hübner) (Lepidoptera: Noctuidae) Displays High Binding Affinities to the Behavioral Attractant (Z)-3-Hexenyl acetate

SIMPLE SUMMARY: The variegated cutworm Peridroma saucia (Hübner) is a polyphagous pest that originated in Europe and North America and has gradually become an important agricultural pest worldwide since the 1970s. In 2017, this pest experienced a serious outbreak in the suburbs of Luoyang, Henan Province, China. Odorant-binding proteins (OBPs) are small soluble proteins expressed in insect olfactory tissues and involved in the first step of odorant reception. Characterization of the function of P. saucia OBPs may contribute to identifying new attractants/repellents and assist in the development of more efficient and environmentally acceptable controlling strategies of this pest. In this study, we cloned an antennae-specific gene PsauGOBP1 which encodes for a general odorant-binding protein (GOBP) of P. saucia. We expressed PsauGOBP1 in bacteria and found that the purified recombinant PsauGOBP1 binds robustly to (Z)-3-hexenyl acetate. Electroantennogram tests demonstrate that (Z)-3-hexenyl acetate elicits strong responses from the antennae of both males and females of P. saucia. Y-tube olfactometer bioassays show that (Z)-3-hexenyl acetate is attractive to adult P. saucia of both sexes. This study increases our understanding of the olfactory mechanism of P. saucia and provides a theoretical basis for the design of attractants for the control of P. saucia. ABSTRACT: The variegated cutworm Peridroma saucia (Hübner) is a worldwide pest that causes serious damage to many crops. To recognize sex pheromones and host plant volatiles, insects depend on olfactory chemoreception involving general odorant-binding proteins (GOBPs). In this study, PsauGOBP1 was cloned from the adult antennae of P. saucia. RT-qPCR and Western-blot analysis showed that PsauGOBP1 was specifically and equally expressed in the adult antennae of both females and males. Fluorescence competitive-binding assays with sex pheromones and host plant volatiles demonstrated that PsauGOBP1 bound to six host plant volatiles: (Z)-3-hexenyl acetate (K(D) = 4.0 ± 0.1 μM), citral (K(D) = 5.6 ± 0.4 μM), farnesol (K(D) = 6.4 ± 0.6 μM), nonanal (K(D) = 6.8 ± 0.3 μM), (Z)-3-hexen-1-ol (K(D) = 8.5 ± 0.6 μM), and benzaldehyde (K(D) = 9.4 ± 0.5 μM). Electroantennogram recordings with the six host plant volatiles indicated that (Z)-3-hexenyl acetate elicited the strongest responses from both male and female antennae. Further bioassays using Y-tube olfactometers showed that (Z)-3-hexenyl acetate was attractive to adult P. saucia of both sexes. These results suggest that PsauGOBP1 might be involved in detecting host plant volatiles and that (Z)-3-hexenyl acetate might serve as a potential attractant for the biological control of P. saucia.