Sublethal effects of lambda-cyhalothrin on the biological characteristics, detoxification enzymes, and genes of the papaya mealybug, Paracoccus marginatus

The papaya mealybug, Paracoccus marginatus, is an invasive pest that causes significant damage to various tropical fruits and ornamentals worldwide. Lambda-cyhalothrin, an effective insecticide in integrated pest management (IPM) strategies, can control P. marginatus. This study evaluated the sublethal effect of lambda-cyhalothrin on the life table parameters and the detoxification enzymes activities of P. marginatus. Furthermore, transcriptome sequencing analysis revealed the potential mechanisms of the detoxification-related genes associated with enzymes activities. The study reported that lambda-cyhalothrin showed high activity against P. marginatus, with LC₃₀ values of 8.98 mg/L. Two-sex life table results showed that the development duration of the second instar nymphs, preadults, and adult female longevity was significantly prolonged, and the fecundity was stimulated in the F₁-CY of P. marginatus when the parental generation was exposed to LC₃₀ lambda-cyhalothrin. Moreover, lambda-cyhalothrin treatment significantly increased the activities of Cytochrome P450 monooxygenases (P450) and glutathione-S-transferase (GST) enzymes. Additionally, significant expression levels of P450, GST, carboxylesterase, and esterase genes were observed in P. marginatus subjected to the sublethal lambda-cyhalothrin exposure. Our findings demonstrate that sublethal concentrations of lambda-cyhalothrin influenced the development and fecundity of P. marginatus, and changes in enzymes activities and differential expression of detoxifying genes might be involved in the response and detoxification metabolism of lambda-cyhalothrin in P. marginatus. These results could contribute to a comprehensive risk assessment and provide guidance for the scientific use of lambda-cyhalothrin in IPM strategies.