Olive fly transcriptomics analysis implicates energy metabolism genes in spinosad resistance

Efthimia Sagri, Martin Reczko, Maria-Eleni Gregoriou, Konstantina T Tsoumani, Nikolaos E Zygouridis, Klelia D Salpea, Frank G Zalom, Jiannis Ragoussis, Kostas D Mathiopoulos

The olive fly, Bactrocera oleae, is the most devastating pest of cultivated olives. Its control has been traditionally based on insecticides, mainly organophosphates and pyrethroids. In recent years, the naturalyte spinosad is used against the olive fly. As with other insecticides, spinosad is subject to selection pressures that have led to resistance development. Mutations in the alpha6-subunit of the nicotinic acetylcholine receptor (nAChR) have been implicated in spinosad resistance in several species (e.g., Drosophila melanogaster) but excluded in others (e.g., Musca domestica). Yet, additional 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 searched for mutations in the alpha6-subunit of the nAChR and for up-regulated genes in the entire transcriptome of spinosad resistant olive flies.