Abstract |
The olive fruit fly Bactrocera oleae has a unique ability to cope with olive flesh, and is the most destructive pest of olives worldwide. Its control has been largely based on the use of chemical insecticides, however, the selection of insecticide resistance against several insecticides has evolved. The study of detoxification mechanisms, which allow the olive fruit fly to defend against insecticides, and/or phytotoxins possibly present in the mesocarp, has been hampered by the lack of genomic information in this species. In this study, the efficacy of alpha-cypermethrin via biochemical and molecular approaches was investigated. Selected strains, susceptible or resistant to pyrethroids (mainly a-cypermethrin), included: HYBRID & LAB (laboratory strains – susceptible), Kou (origin Kounoupidiana – resistant), Sa (origin Samos – susceptible), Pa (origin Panagia – moderate resistant). The biochemical analysis indicated a possible association between P450 activities and the resistance phenotype. However, further studies, involving insecticide selections and synergistic analysis with metabolic inhibitors, will clarify the role of P450s in the resistance of B. oleae to pyrethroids. The possible occurrence of target-site mutations within the domain II region of the B. oleae para-type sodium channel gene, which could be responsible for the pyrethroid resistance observed, was also investigated, but no target site mutations were revealed. Further work is required in order to elucidate the possible link between detoxification enzymes (such as cytochrome P450s) and pyrethroid resistance. The IIS4–IIS6 region of the B. oleae para-type sodium channel gene is the default area in which to look for resistance mutations if target-site resistance to pyrethroids arises in B. oleae field populations.
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