Characterization of Six Diamide Insecticides on Ryanodine Receptor: Resistance and Species Selectivity

Ryanodine receptor (RyR) has been used as an insecticidetargetto control many destructive agricultural pests. The effectivenessof these insecticides has been limited by the spread of resistancemutations identified in pest RyRs, but the detailed molecular impactsof the individual mutations on the activity of different diamide compoundshave not been fully explored. We created five HEK293 cell lines stablyexpressing wild type rabbit RyR1, wild type Spodopterafrugiperda RyR (Sf RyR), or Sf RyR carrying different resistance mutations, includingG4891E, G4891E/I4734M, and Y4867F, respectively. R-CEPIA1er, a geneticallyencoded fluorescent protein, was also introduced in these cell linesto report the Ca2+ concentration in the endoplasmic reticulum.We systematically characterized the activities of six commercial diamideinsecticides against different RyRs using the time-lapse fluorescenceassay. Among them, cyantraniliprole (CYAN) displayed the highest activityagainst all three resistant Sf RyRs. The good performanceof CYAN was confirmed by the toxicity assay using gene-edited Drosophila expressing the mutant RyRs, in which CYANshowed the lowest LD50 value for the double resistant mutant.In addition, we compared their acitivty between mammalian and insectRyRs and found that flubendiamide has the best insect-selectivity.The mechanism of the anti-resistance property and selectivity of thecompounds was proposed based on the structural models generated byhomology modeling and molecular docking. Our findings provide insightsinto the mechanism of insect resistance and guidance for developingeffective RyR agonists that can selectively target resistant pests.

Automated summary

Ryanodine receptor (RyR) is used as a target for insecticides, but resistance mutations have limited their effectiveness. This study investigated the activity of diamide insecticides against resistant RyRs in insects and mammals, and identified effective insecticides against resistant pests.