Cytochrome P450 signatures in the emerald ash borer (Agrilus planipennis), an exotic invasive insect pest

The emerald ash borer (EAB, Agrilus planipennis) is an invasive insect pest in North America that has currently reached “high impact” status. Since its discovery in 2002, it has killed millions of ash trees (Fraxinus spp.). To date, there is little knowledge of the molecular biology of EAB. Therefore, we have undertaken a transcriptomic analysis of the EAB midgut (MG) and fatbody (FB), which are important physiological tissues involved in digestion and detoxification, to increase fundamental understanding of EAB biology, and to identify novel (susceptible) targets for management. We analyzed the transcriptomic data of larval EAB MG and FB using 454 pyrosequencing, which resulted in 25,173 and 37,661 ESTs, respectively. We are focusing particularly on cytochrome P450s (CYPs), which in other species mediate detoxification of various xenobiotics, including allelochemicals of host origin. Expression analysis of CYP genes in EAB was performed using quantitative real-time PCR. Members of the CYP gene families CYP6, CYP4, CYP9, CYP12, and CYP306 showed differential expression patterns in MG, FB, and cuticle, including at different developmental stages. CYP6 members revealed highest expression in actively feeding larvae, while CYP9 and CYP306 members showed high expression in cuticle and were expressed constitutively in all developmental stages. Results from this study will increase understanding of detoxification strategies in EAB larvae.