Genome Analysis of Cytochrome in Dinotefuran-Treated Apolygus lucorum (Meyer-Dür)

Resistance to dinotefuran in Bemisia tabaci in China: status and characteristics

BACKGROUND

Bemisia tabaci (Gennadius) is a serious agricultural pest worldwide. Neonicotinoids are the most important new class of synthetic insecticides used in the management of B. tabaci. However, B. tabaci populations have developed resistance to various active ingredients in neonicotinoids following long-term and widespread application.

RESULTS

Dinotefuran exhibited high toxicity against most B. tabaci field populations. One population (Din-R) with a high level of resistance to dinotefuran (255.6-fold) was first identified in the field. The Din-R population exhibited medium to high levels of resistance to all the tested neonicotinoid insecticides and a high level of resistance to spinetoram. Genetic inheritance analysis revealed that resistance to dinotefuran was incompletely recessive and polygenic. The synergist piperonyl butoxide significantly increased the toxicity of dinotefuran to Din-R. P450 activity in the Din-R population was 2.19-fold higher than in the susceptible population. RNA-sequencing analysis showed that 12 P450 genes were significantly upregulated in the Din-R population, of which CYP6DW5, CYP6JM1 and CYP306A1 were found to exhibit more than 3.00-fold higher expression in Din-R when using a reverse transcription quantitative real-time polymerase chain reaction. Expression of eight P450 genes was obviously induced by dinotefuran, and CYP6DW5 showed the highest expression level. After knockdown of CYP6DW5 in Din-R, the toxicity of dinotefuran increased significantly.

CONCLUSION

P450 had a crucial role in dinotefuran resistance in B. tabaci, and CYP6DW5 was involved in the resistance. These results provide important information for the management of resistance in B. tabaci and improve our understanding of the resistance mechanism of dinotefuran. © 2022 Society of Chemical Industry.

Biochemical toxicity and transcriptome aberration induced by dinotefuran in Bombyx mori

Dinotefuran is a third-generation neonicotinoid pesticide and is increasingly used in agricultural production, which has adverse effects on nontarget organisms. However, the research on the impact of dinotefuran on nontarget organisms is still limited. Here the toxic effects of dinotefuran on an important economic species and a model lepidopteran insect, Bombyx mori, were investigated. Exposure to different doses of dinotefuran caused physiological disorders or death. Cytochrome P450, glutathione S-transferase, carboxylesterase, and UDP glycosyl-transferase activities were induced in the fat body at early stages after dinotefuran exposure. By contrast, only glutathione S-transferase activity was increased in the midgut. To overcome the lack of sensitivity of the biological assays at the individual organism level, RNA sequencing was performed to measure differential expressions of mRNA from silkworm larvae after dinotefuran exposure. Differential gene expression profiling revealed that various detoxification enzyme genes were significantly increased after dinotefuran exposure, which was consistent with the upregulation of the detoxifying enzyme. The global transcriptional pattern showed that the physiological responses induced by dinotefuran toxicity involved multiple cellular processes, including energy metabolism, oxidative stress, detoxification, and other fundamental physiological processes. Many metabolism processes, such as carbon metabolism, fatty acid biosynthesis, pyruvate metabolism, and the citrate cycle, were partially repressed in the midgut or fat body. Furthermore, dinotefuran significantly activated the MAPK/CREB, CncC/Keap1, PI3K/Akt, and Toll/IMD pathways. The links between physiological, biochemical toxicity and comparative transcriptomic analysis facilitated the systematic understanding of the integrated biological toxicity of dinotefuran. This study provides a holistic view of the toxicity and detoxification metabolism of dinotefuran in silkworm and other organisms.

The overexpression of three cytochrome P450 genes CYP6CY14, CYP6CY22 and CYP6UN1 contributed to metabolic resistance to dinotefuran in melon/cotton aphid, Aphis gossypii Glover

Dinotefuran, the third-generation neonicotinoid, has been applied against melon/cotton aphid Aphis gossypii Glover in China. The risk of resistance development, cross-resistance pattern and potential resistance mechanism of dinotefuran in A. gossypii were investigated. A dinotefuran-resistant strain of A. gossypii (DinR) with 74.7-fold resistance was established by continuous selection using dinotefuran. The DinR strain showed a medium level of cross resistance to thiamethoxam (15.2-fold), but no cross resistance to imidacloprid. The synergism assay indicated that piperonyl butoxide and triphenyl phosphate showed synergistic effects on dinotefuran toxicity to the DinR strain with a synergistic ratio of 8.3 and 2.5, respectively, while diethyl maleate showed no synergistic effect. The activities of cytochrome P450 monooxygenase and carboxylesterase were significantly higher in DinR strain than in susceptible strain (SS). Moreover, the gene expression results showed that CYP6CY14, CYP6CY22 and CYP6UN1 were significantly overexpressed in DinR strain compared with SS strain. The expression of CYP6CY14 was 5.8-fold higher in DinR strain than in SS strain. Additionally, the transcription of CYP6CY14, CYP6CY22 and CYP6UN1 in A. gossypii showed dose- and time-dependent responses to dinotefuran exposure. Furthermore, knockdown of CYP6CY14, CYP6CY22 and CYP6UN1 via RNA interference (RNAi) significantly increased mortality of A. gossypii, when A. gossypii was treated with dinotefuran. These results demonstrated the overexpression of CYP6CY14, CYP6CY22 and CYP6UN1 contributed to dinotefuran resistance in A. gossypii.