Bdor\Orco is important for oviposition-deterring behavior induced by both the volatile and non-volatile repellents in Bactrocera dorsalis (Diptera: Tephritidae).

Several studies have shown that the selections of gravid females to potential oviposition sites from a distance were mediated by volatile signals, however, the means by which the sensory cues from non-volatile chemicals affected the insect behavior were still a controversial subject. Chemosensory in insect is a complex process, which is mediated by multigene families of chemoreceptors, including olfactory receptors, olfactory co-receptors, and odorant-binding proteins. To elucidate the chemoreception mechanism of volatile and non-volatile chemicals, the roles of Orco and OBP in oviposition-deterrent activities induced by citronellal and Rhodojaponin-III were investigated. Our results suggested that RNAi-mediated expression inhibition was successfully achieved by feeding dsRNA in Bactrocera dorsalis. High levels of Bdor\Orco expression were essential for recognizing two chemicals of different physical properties, whereas the expression of Bdor\OBP was only imperative in perception of volatile chemical. The results suggested that volatile and non-volatile chemicals may evoke distinct molecular basis for chemosensory in the flies, while Orco was essential in the perception of both chemicals. The study highlighted that the central role of Orco in chemical recognition, which enabled it to be the universally applied target of designing new botanical pesticide.