Detection of the S431F mutation associated with resistance to organophosphate/carbamate insecticides in Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae) distributed in Türkiye

The green peach aphid Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae) is a globally significant agricultural pest responsible for extensive crop damage through direct feeding and virus transmission. Long-term exposure to organophosphate (OP) and carbamate (CB) insecticides has led to the evolution of resistance mechanisms, particularly mutations in the acetylcholinesterase gene (ace-2). Among these, the S431F substitution, known as the Modified Acetylcholinesterase (MACE) mutation, confers reduced sensitivity to dimethylcarbamate insecticides, such as pirimicarb. This study, conducted between April 2024 and July 2025, aimed to detect and quantify the frequency of the S431F mutation in M. persicae populations collected from nine major peach-growing provinces of Türkiye using the PCR-RFLP technique. A total of 360 individuals were genotyped, revealing 15 homozygous resistant (RR), 131 heterozygous resistant (RS), and 214 homozygous susceptible (SS) individuals. The overall resistant allele frequency was 22.36%, with the highest rates observed in Niğde (17%), İzmir (15%), and Aydın (5%). Regionally, the Mediterranean, Aegean, and Marmara Regions exhibited similar resistance frequencies (22.8%, 22.5%, and 21.3%, respectively). These results indicate that resistance to OP/CB insecticides may be in its early stage of development, or that previously high resistance levels may have decreased. Continued molecular surveillance and region-specific IPM programs should be applied to delay the spread of resistance.