Olive fly transcriptomics analysis implicates energy metabolism genes in spinosad resistance

Area of Science:

• Entomology
• Pest Management
• Molecular Biology

Background:

• The olive fly (Bactrocera oleae) is a major pest of olives, with control relying on insecticides like spinosad.
• Spinosad resistance can develop through mutations or enhanced metabolism, with nAChR-α6 subunit mutations implicated in some species.
• Understanding spinosad resistance mechanisms in olive flies is crucial for effective pest control strategies.

Purpose of the Study:

• To investigate mutations in the nAChR-α6 subunit and identify differentially expressed genes in spinosad-resistant olive flies.
• To elucidate the molecular mechanisms underlying spinosad resistance in Bactrocera oleae.

Main Methods:

• Cloning of the nAChR-α6 subunit from sensitive and resistant olive fly strains.
• Whole transcriptome analysis to compare gene expression profiles between resistant and sensitive strains.
• Functional analysis of selected over-expressed and under-expressed genes.

Main Results:

• No significant mutations were found in the nAChR-α6 subunit of resistant olive flies.
• Transcriptome analysis revealed nine over-expressed and approximately 40 under-expressed genes in resistant flies.
• Four over-expressed loci (Yolk protein 2, ATP Synthase FO subunit 6, Low affinity cationic amino acid transporter 2, Serine protease 6) and two under-expressed loci (HexL1, Lsp1, Hsp70, Hsp23) were consistently identified.

Conclusions:

• Nicotinic acetylcholine receptor (nAChR)-α6 subunit mutations do not appear to be the primary driver of spinosad resistance in olive flies.
• Transcriptome data suggests that enhanced detoxification processes, potentially involving immune system loci and elevated energy demands, contribute to spinosad resistance.