Molecular evidence that insecticide resistance in peach-potato aphids (Myzus persicae Sulz.) results from amplification of an esterase gene

Abstract

cDNA clones for the esterase (E4) responsible for broad insecticide resistance in peach-potato aphids (Myzus persicae Sulz.) were isolated and used to study the molecular basis of resistance. Increased esterase synthesis by resistant aphids was found to be associated with amplification of the structural gene for the esterase (E4 or its closely related variant, FE4), the degree of amplification being correlated with the activity of the esterase and the level of resistance. Hybridization of the cDNA clones to genomic Southern blots showed that only some of the esterase-related restriction fragments are amplified. Qualitative differences between restriction patterns in different clones of resistant aphids correlated with the presence or absence of a specific chromosome translocation and with production of E4 or FE4.

Purification and characterization of a carboxylesterase involved in malathion-specific resistance from Tribolium castaneum (Coleoptera: Tenebrionidae)

“…Their molecular weight is similar, ranging from 55 to 70 kDa for many esterases (Heymann, 1980). Esterases with similar molecular weights have been reported in Boophilus microplus (De Jersey et al, 1985), Myzus persicae (Field et al, 1988), Culex quinquefasciastus (Merryweather et al, 1990), Culex tarsalis (Whyard et al, 1994b) and Lucilia cupri-nia (Whyard et al, 1994a). However, the pI values of this protein were basic and differed significantly between the two strains.…”

“…The putative mechanism involves a gene amplification that results in an overproduction of an esterase in resistant insects (Mouches et al, 1986;Field et al, 1988). Kinetic properties of this esterase are similar in susceptible and resistant insects (Devonshire, 1977); the esterase hydrolyses insecticides very slowly, but in highly resistant strains the enzyme accounts for 12% of the total soluble protein (Mouches et al, 1986).…”

Inheritance of the amplified esterase genes responsible for insecticide resistance in Myzus persicae (Homoptera: Aphididae)

“…Two slightly different esterases are involved: E4, which is always found in aphids with an A1,3 chromosomal translocation, and FE4, an enzyme with a slightly higher *Correspondence. molecular weight which has only been found in aphids of apparently normal karyotype (Field et aL, 1988(Field et aL, , 1993.…”

Analogous pleiotropic effects of insecticide resistance genotypes in peach–potato aphids and houseflies

“…In the peach-potato aphid, Myzus persicae (Hemiptera: Aphididae), gene amplification leads to the overproduction of carboxylesterases that enhance the detoxification of insecticidal esters such as organophosphates (OPs) and carbamates (Devonshire and Moores, 1982;Field et al, 1988). In the same species, a point mutation of a voltagegated sodium channel gene confers cross-resistance to pyrethroids and DDT (knockdown resistance or kdr) (Martinez-Torres et al, 1999).…”