Transcriptomic responses to different doses of cycloxaprid involved in detoxification and stress response in the whitebacked planthopper, Sogatella furcifera

The whitebacked planthopper, Sogatella furcifera (Horvath) (Hemiptera: Delphacidae), an economically important rice pest, has developed resistance to many insecticides. Cycloxaprid, a novel cis-nitromethylene neonicotinoid insecticide, has good industrialization prospects because of its high efficiency against rice planthoppers, including imidacloprid-resistant populations. This study focused on the genes involved in xenobiotic detoxification and stress reaction after exposure to doses of cycloxaprid. Ten cytochrome P450 monooxygenase genes (one CYP3, three CYP4, and six CYP6), one microsomal glutathione S-transferase (GST) gene, and one acetylcholinesterase (AChE) gene were up-regulated in response to a high-dose treatment (HD, 85% mortality). Five P450 genes (one CYP4, two CYP6, and one CYP15), one delta-GST gene, and two carboxylesterase genes were up-regulated in response to a low-dose treatment (LD, 15% mortality). These findings were consistent with previous reports showing that CYP4, CYP6, and GSTd were associated with insecticide detoxification in insects and contributed significantly to insecticide resistance. Another interesting finding was that one Hsp70 and one small Hsp (sHsp) were up-regulated in response to HD treatment, whereas they were downregulated in response to LD treatment. In order to check the accuracy of transcriptome data, 10 unigenes were randomly selected to compare their expression between treatments. Regulations of related genes in response to cycloxaprid doses could contribute to explaining the quick responses to insecticide stress.