Multiple P450 genes: Identification, tissue-specific expression and their responses to insecticide treatments in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidea)

• The study presents cloning and characterization of 12 P450 genes from Bactrocera dorsalis.
• Several P450 genes could be significantly up-regulated by the tested insecticides at LD50 dose.
• P450 genes exhibited differential expression in different tissues and organs.

The oriental fruit fly Bactrocera dorsalis is an economically important pest, yet little research has focused on the mechanisms underlying the increasing insecticide resistance of this species. In this study, 12 cytochrome P450 genes were isolated from B. dorsalis, and alignments of the deduced amino acid sequences confirmed that they contained the conserved motifs of the P450 superfamily. Phylogenetic analyses indicated relationships with CYP3, CYP4, and mitochondrial cytochrome P450 gene families. Expression profiles of the P450 genes were compared between control and insecticide-treated adult flies using real-time quantitative PCR (RT-qPCR) methods. Results showed that five, four, and seven P450s were up-regulated following exposure to LD50 doses of malathion, abamectin, and beta-cypermethrin, respectively, and that transcriptional levels reached a maximum at 36 h post-exposure. In addition, several genes did not show significant changes in expression, and several down-regulated genes were also noted. Most of the P450s (except CYP28F1) in untreated adults showed higher levels of transcription in the midgut, fat body, and/or Malpighian tubule than in the head. Taken together, these findings showed that multiple P450s are up-regulated in response to insecticide exposure and have various levels in different tissues. Further studies are needed to determine their possible role in the insecticide metabolism.

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