No evidence of an increased prevalence of knockdown resistance in the English grain aphid Sitobion avenae following the EU ban on neonicotinoids in Ireland

Abstract

The English grain aphid Sitobion avenae is a major pest of cereals in Europe, with control hindered by pyrethroid resistance in a single clonal lineage (SA3) due to a mutation in the voltage-gated sodium channel gene (knockdown resistance or kdr). In 2018, the European Union banned neonicotinoid seed treatments for outdoor use, leaving pyrethroids as the only chemical control. We hypothesised that this ban and reliance on pyrethroids would increase the prevalence of S. avenae with kdr. A 3-yr survey of 155 winter barley crops was conducted to assess if the prevalence of S. avenae with kdr had increased following the neonicotinoid ban. Our survey showed that the percentage of kdr-carrying S. avenae was lower than in surveys before the neonicotinoid ban. Notably, no S. avenae homozygous for the kdr mutation were found. We conclude there is currently no evidence of an increase in S. avenae carrying kdr following the neonicotinoid ban.