Olive fly transcriptomics analysis unveils mechanisms of spinosad resistance

The olive fly, Bactrocera oleae, is the most devastating pest of the olive tree. Its control has been traditionally based on insecticides, mainly organophosphates and pyrethroides. In recent years, the naturalyte spinosad has been added in the arsenal against the olive fly. Inevitably, the use of chemicals for insect management and control leads to the development of resistance. Mutations in the a6 subunit of the nicotinic acetylcholine receptor (nAChR) have been implicated in spinosad resistance in several insect species (e.g., Drosophila melanogaster) but excluded in others (e.g., in the house fly Musca domestica). Yet, more mechanisms involving enhanced metabolism of detoxification enzymes (such as P450 monooxygenases or mixed function oxidases) have also been reported. In order to clarify the spinosad resistance mechanisms in the olive fly we both searched for mutations in the a6 subunit of the nAChR, as well as looked for up-regulated genes in the entire transcriptome of spinosad resistant olive flies.