Chromosomal location of the amplified esterase genes conferring resistance to insecticides in Myzus persicae (Homoptera: Aphididae)

A genomic probe encompassing most of an esterase gene (E4) that is amplified in insecticide-resistant Myzus persicae was hybridized in situ to mitotic and meiotic chromosome preparations of aphid clones of known esterase type and resistance level. Binding, which was detected using the biotin-avidin system located both known types of amplified esterase sequences (E4 and FE4). All except one of the E4-producing clones had a single amplified site, on autosome 3 near the break-point of an autosomal 1,3 translocation which previous work had shown to be genetically linked to insecticide resistance. The exceptional clone had two other E4-encoding sites. The most resistant FE4-producing clone (800F) had amplified sequences at five sites (three loci: two homozygous and one heterozygous). Altogether, amplified E4 and/or FE4 sequences were found on four of the five autosome pairs of M. persicae. Possible origins of these multiple loci are discussed.