First Reports in the Uk of Strong Resistance to Neonicotinoid Insecticides in the Aphid Crop Pest, Myzus Persicae

Long-term work by Rothamsted Research has included peach-potato aphid (Myzus persicae) testing for neonicotinoid insecticide resistance. Until mid-2023, no evidence arose for the strong resistance ('Neonic', R81T target site-based mechanism) present in mainland Europe. However, in late-2023, the first UK record of Neonic resistance was discovered, initially in bioassays applying neonicotinoids to live aphid samples collected from oilseed rape in Suffolk. Follow-up molecular tests confirmed these aphids carried the R81T mutation. Further micro-satellite tests, performed at the James Hutton Institute, suggested a DNA genotype not recorded in the UK previously. It is therefore likely, given Suffolk-European proximity and mainland Europe R81T-resistant M. persicae prevalence, that this first report arose from an aphid population incursion. Co-evolution cannot be discounted, and more studies on a larger population are required to substantiate their origin. Subsequent 2024 testing of live M. persicae samples and preserved specimens collected from Rothamsted Insect Survey suction traps revealed more R81T-Neonic occurrences, indicating that these highly resistant forms have a UK foothold. Consequently, neonicotinoid sprays and seed treatments, where approved, may not prove effective. The significance of our findings is discussed in context of the future risk posed to crop protection and legislation banning UK neonicotinoid seed treatments. The wider distribution of R81T-resistant population(s) in the UK must be established, thus continued monitoring for these and other insecticide resistances remains essential if we are to gain an up-to-date picture of their presence, temporal and geographical spread, facilitating the development of effective integrated pest management solutions.