Increased expression of CSP and CYP genes in adult silkworm females exposed to avermectins.

We analyzed 20 chemosensory protein (CSP) genes of the silkworm Bombyx mori. We found a high number of retrotransposons inserted in introns. We then analyzed expression of the 20 BmorCSP genes across tissues using quantitative real-time polymerase chain reaction (PCR). Relatively low expression levels of BmorCSPs were found in the gut and fat body tissues. We thus tested the effects of endectocyte insecticide abamectin (B1a and B1b avermectins) on BmorCSP gene expression. Quantitative real-time PCR experiments showed that a single brief exposure to insecticide abamectin increased dramatically CSP expression not only in the antennae but in most tissues, including gut and fat body. Furthermore, our study showed coordinate expression of CSPs and metabolic cytochrome P450 enzymes in a tissue-dependent manner in response to the insecticide. The function of CSPs remains unknown. Based on our results, we suggest a role in detecting xenobiotics that are then detoxified by cytochrome P450 anti-xenobiotic enzymes.