Target‐site mutations and phenotypic failure in <scp> <i>Myzus persicae</i> </scp> against pyrethroids and carbamates in central Europe

BACKGROUND The green peach aphid, Myzus persicae, is a major pest and virus vector in central European agriculture. Following the neonicotinoid seed treatment ban and under climate warming, its populations have increased, raising concerns about insecticide resistance. RESULTS This study assessed the phenotypic resistance and underlying target-site mutations in Czech populations of M. persicae from oilseed rape between 2022 and 2024. Bioassays with cypermethrin, pirimicarb, and acetamiprid revealed extreme and increasing pyrethroid resistance, whereas susceptibility to pirimicarb and acetamiprid remained high or improved compared to earlier periods. Molecular screening of 140 field-collected aphids identified four sodium channel mutations (L1014F, M918L, M918T, L932F) and the ace2 mutation S431F. Survival under insecticide selection strongly highlighted the functional role of specific mutations: the M918L mutation was the most prevalent among cypermethrin survivors (68.75%), confirming it as the primary mechanism of pyrethroid target-site resistance in these populations. Conversely, the S431F mutation reached complete fixation (100%) in pirimicarb survivors, serving as a definitive marker for carbamate resistance and indicating a high risk of rapid resistance development upon intensive use. Significant negative correlations between M918L and L1014F/L932F suggest divergent resistance lineages. CONCLUSION No clear geographical patterns were observed, indicating that resistance is driven by agricultural practices rather than regional factors. These findings highlight the rapid evolution of pyrethroid resistance and underscore the need for integrated pest management, including molecular monitoring and careful insecticide rotation, to sustain control of M. persicae in Czechia. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.