CRISPR-mediated mutagenesis of the odorant receptor co-receptor (Orco) gene disrupts olfaction-mediated behaviors in Bactrocera dorsalis.

Olfaction plays an essential role in insect behavior such as host location, foraging, mating, and oviposition. The odorant receptor co-receptor (Orco) is an obligatory odorant receptor and indispensable in odor perception. Here, we characterized the Orco gene from the oriental fruit fly, Bactrocera dorsalis (Hendel), a notorious agriculture pest. The olfactory deficiency mutants were generated by editing the BdorOrco gene using the CRISPR/Cas9 system. Electroantennograms (EAG) and olfactory preference assays confirmed that BdorOrco -/- mutant flies had reduced perception of methyl eugenol, β-caryophyllene, and ethyl acetate. Oviposition bioassays showed that the eggs laid by BdorOrco -/- females mediated by benzothiazole and 1-octen-3-ol were significantly decreased. In addition, BdorOrco -/- mutant flies took a significantly longer time to locate the food source compared with wild type (WT) flies. Altogether, our data indicated that Orco is essential for multiple physiological processes in B. dorsalis, and it expands our understanding of the function of insect Orco.