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The cytochrome P450 monooxygenases of insects play crucial roles in the metabolic detoxification of insecticides. Our previous finding showed that two cytochrome P450 genes, both CYP301B1 and CYP6AX1v2, in the BPH underwent overexpression due to β-asarone. In this study, we investigated the molecular characteristics, expression patterns and functions of these two cytochrome P450 genes. The results showed that CYP301B1 had the highest expression level in the eggs, while CYP6AX1v2 was expressed in macropterous female adults. Moreover, the expression level of CYP301B1 in the head was higher than that in the integument, fat body and gut. The expression level of CYP6AX1v2 in the fat body and gut was higher than that in head and integument. Importantly, silencing CYP301B1 and CYP6AX1v2 separately could increase the sensitivity, resulting in significant higher mortality of BPH following treatment with β-asarone. Our findings indicated that CYP301B1 and CYP6AX1v2 could contribute to the resistance of BPH to β-asarone, and these two genes may be involved in the detoxification metabolism of β-asarone in BPH.

Ecological engineering-based diversified farming systems contribute to the delivery of ecosystem services, which is critical for biological control of pests in agro-ecosystems. In paddy ecosystems, rice stem borers are the most destructive lepidopteran pests that have been studied in detail, but the effects of meteorological factors related to global change on these pests have been scarcely explored. Our 9-year data from Chongming Island of China indicated that there was an exponential decay each year in the numbers of adult pink stem borers and striped stem borers trapped in the lamp in ecological engineering-based diversified farming ecosystems. By stepwise regression analysis, we found that both average daily temperature and average daily wind velocity had significantly negative effects while sunshine duration had a significantly positive effect on the number of adult pink stem borers, and that average daily temperature significantly and positively affected while average daily wind significantly and negatively affected the number of adult striped stem borers. Our study reveals that global warming might promote the occurrence of striped stem borers but inhibit the occurrence of pink stem borers in the future.

Nine-year data were collected to analyze the occurrence of rice planthoppers in diversified farming on Chongming Eco-Island in China from 2006 to 2014, the most important pests of rice in agroecosystems. We found a significantly linear decrease in the average numbers of adult rice planthoppers trapped per light trap per day. Using quadratic regression polynomial analysis we concluded that four meteorological indicators (average daily temperature, daily rainfall, sunshine duration, and average daily wind velocity) had significant effects on the numbers of brown planthopper ( Nilaparvata lugens ) and white-backed planthopper ( Sogatella furcifera ) trapped in the lamp, and that average daily temperature had a significant effect on the number of small brown planthopper ( Laodelphax striatella ) trapped in the lamp. These findings suggest that increasing temperature related to climate change might promote the occurrence of rice planthoppers in diversified farming in the future.