Rapid selection for resistance to diamide insecticides in Plutella xylostella via specific amino acid polymorphisms in the ryanodine receptor

- Baseline susceptibility of Plutella xylostella to diamide insecticides collated.
- Instances of diamide resistance in P. xylostella summarized.
- Diamide insecticide specificity for the insect ryanodine receptor highlighted.
- Efforts to isolate and characterize the P. xylostella ryanodine receptor described.
- Molecular mechanisms of diamide resistance in P. xylostella discussed.

Diamide insecticides, such as flubendiamide and chlorantraniliprole, are a new class of insecticide with a novel mode of action, selectively activating the insect ryanodine receptor (RyR). They are particularly active against lepidopteran pests of cruciferous vegetable crops, including the diamondback moth, Plutella xylostella. However, within a relatively short period following their commercialisation, a comparatively large number of control failures have been reported in the field. In this review we summarise the current body of knowledge regarding the molecular mechanisms of diamide resistance in P. xylostella. Resistant phenotypes collected from different countries can often be linked to specific target-site mutation(s) in the ryanodine receptors' transmembrane domain. Metabolic mechanisms of resistance have also been proposed. Rapid resistance development is probably a consequence of over-reliance on this one class of chemistry for diamondback moth control.

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