Sublethal and transgenerational effects of pyridaben exposure on the fitness and gene expression of Panonychus citri.

Background: Panonychus citri is a globally dominant citrus plant pest mite. Pesticide-induced population resurgence is a concern for mite control. Exposure to sublethal concentrations of pesticides has stimulated reproduction and outbreak risks in many pests. Pyridaben, a mitochondrial electron transport inhibitor, has been frequently used worldwide in mite control. In the study, sublethal and transgenerational effects of pyridaben exposure on Pyr_Rs (resistant) and Pyr_Control (susceptible) strains were systematically investigated in both exposed parental generation (F ) and unexposed offspring generations (F and F ) by evaluating life-table and physiological parameters.

Results: After exposure to pyridaben, the fecundity of both strains was significantly reduced in F generation while significantly induced in F generation. Interestingly, these effects also stimulated the fecundity of the F generation in Pyr_Control strain while no significant effects occurred for Pyr_Rs strain. The intrinsic rate of increase (r) and finite rate of increase (λ) were significantly decreased only in F generation of Pyr_Control strain after exposure treatment. Meanwhile, the population projection indicated a smaller population size in F generation of Pyr_Control strain while a population increase for Pyr_Rs strain after sublethal treatment. Subsequent detoxification enzyme assays indicated that only P450 activities in F generation were significantly activated by LC exposure to pyridaben in both strains. Significant downregulation of reproduction-related (Pc_Vg) genes was observed in the F generations of both strains. Significant upregulation of P450 (CYP4CL2) and Pc_Vg of the F generation in both strains suggested the presence of delayed hormesis effects on the reproduction and developed tolerance to pyridaben, although the effects did not last over a longer period (F generation).

Conclusion: These results provide evidence for transgenerational hormesis effects of low concentrations of pyridaben exposure that may lead to population increase and resurgence risks of resistant-mites in natural settings by stimulating reproduction. © 2023 Society of Chemical Industry.