Mutations in the Sodium Channel Associated with Pyrethroid Resistance in the Greenhouse Whitefly, Trialeurodes Vaporariorum

Background: Trialeurodes vaporariorum Westwood is an important pest of protected crops in temperate regions of the world. Resistance to pyrethroid insecticides is long established in this species, but the molecular basis of the mechanism(s) responsible has not previously been disclosed.

Results: Mortality rates of three European strains of T. vaporariorum to the pyrethroid bifenthrin were calculated, and each possessed significant resistance (up to 662-fold) when compared with a susceptible reference strain. Direct sequencing revealed three amino acid substitutions in the para-type voltage-gated sodium channel (the pyrethroid and DDT target site) of bifenthrin-resistant T. vaporariorum at positions previously implicated with pyrethroid or DDT resistance (M918L, L925I and T929I) in other related species.

Conclusion: This study indicates that resistance to bifenthrin in T. vaporariorum is associated with target-site insensitivity, and that the specific mutations in the sodium channel causing resistance may differ between localities.