CYP6B Subtype Expression Fluctuates in the Great Mormon, Papilio memnon, with Changes in the Components of the Host Plants

Cytochrome P-450 (CYP) is one of the metabolic enzymes which is conserved among organisms to metabolise xenobiotics. The metabolic role and transcriptomic profiles of the CYP6B subfamily have been studied in some Papilionidae insects. However, the role of <i>CYP6B</i>s expressed in Rutaceae plant-fed swallowtails has yet to be fully examined. Here, the expression profile of <i>CYP6B</i> in the Great Mormon (<i>Papilio memnon</i>) larvae, which prefer Citrus plants to the Rutaceae plant, was investigated by RNA sequencing analysis and real-time quantitative PCR when feeding different kinds of Citrus plants. We found that six kinds of <i>CYP6B</i> subtype transcripts were expressed in the larval fat body and midgut. Then, we focused on <i>CYP6B2</i>, <i>CYP6B5</i>, and <i>CYP6B6</i> transcripts and examined their mRNA expression in the larvae fed on different plants. These <i>CYP6B</i> mRNA expressions were changed in the larval fat body and the midgut by changing the host plants. The presence of chemicals specific to each host plant was confirmed when the host plant components were examined by database, literature, and thin-layer chromatography. Our study suggests that phytochemicals in the host plant affect <i>CYP6B</i> subtypes mRNA expression in <i>P. memnon</i> larval fat body and midgut, and CYP6B subtypes may relate to metabolise the phytochemicals in the host plants.