Biochemical and molecular diagnosis of insecticide resistance conferred by esterase, MACE, kdr and super-kdr based mechanisms in Italian strains of the peach potato aphid, Myzus persicae (Sulzer)

In this paper we analysed the basis of insecticide resistance in 59 Italian strains of the peach potato aphid Myzus persicae using both\r\nmolecular and biochemical assays. Our data as a whole clearly indicate that most M. persicae strains (76.3%) have high or extremely high\r\nproduction of an esterase enzyme which sequester and detoxify insecticides with esteric group. Kdr genotypes conferring resistance\r\ntowards pyrethoids are present in 57.7% of the analysed populations. Moreover, 26.5% of the kdr positive strains possess also the\r\nM918T mutation conferring super-kdr phenotype. Strains with modified AChE (MACE) are not so numerous (27.1%), although they\r\ncan be found almost everywhere in Italy. Considering all the strains analysed, both MACE and kdr phenotypes are associated with high\r\nlevels of esterase activity. In Central–Southern regions, kdr and MACE resistance mechanisms resulted in linkage disequilibrium. Bioassays\r\nperformed in order to evaluate the efficacy of a pyrethroid insecticide against a strain possessing a F979S mutation within its paratype\r\nsodium channel gene suggests that this amino acid substitution could affect the sodium channel responsivity to pyrethroids.