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

BACKGROUNDPanonychus 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-0) and unexposed offspring generations (F-1 and F-2) by evaluating life-table and physiological parameters. RESULTSAfter exposure to pyridaben, the fecundity of both strains was significantly reduced in F-0 generation while significantly induced in F-1 generation. Interestingly, these effects also stimulated the fecundity of the F-2 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 (lambda) were significantly decreased only in F-1 generation of Pyr_Control strain after exposure treatment. Meanwhile, the population projection indicated a smaller population size in F-1 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-0 generation were significantly activated by LC30 exposure to pyridaben in both strains. Significant downregulation of reproduction-related (Pc_Vg) genes was observed in the F-0 generations of both strains. Significant upregulation of P450 (CYP4CL2) and Pc_Vg of the F-1 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-2 generation). CONCLUSIONThese 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. (c) 2023 Society of Chemical Industry.

Automated summary

The study systematically investigated the sublethal and transgenerational effects of pyridaben exposure on two strains of Panonychus citri mites. The results showed that pyridaben exposure reduced the fecundity of both strains in the parental generation, but increased it in the offspring generation. The population size decreased in the offspring generation of the susceptible strain, while it increased in the resistant strain. These findings suggest that low concentrations of pyridaben exposure can have transgenerational hormesis effects on mite population dynamics.