A sodium channel point mutation is associated with resistance to DDT and pyrethroid insecticides in the peach‐potato aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae)

Abstract

The voltage-gated sodium channel is the primary target site of DDT and pyrethroid insecticides, and point mutations in the domain II region of the channel protein have been implicated in the knockdown resistant (kdr ) phenotype of several insect species. Here, we report that one of these mutations, a leucine-to-phenylalanine replacement in transmembrane segment IIS6, is also found in certain insecticide-resistant clones of the peach-potato aphid, Myzus persicae. The mutation was present in four clones with amplified E4 esterase genes, but was absent from both susceptible clones and those with amplified FE4 genes. The inferred presence of kdr-type resistance in the four E4 clones was subsequently confirmed by bioassays that showed this to be the primary mechanism of resistance to deltamethrin and DDT, although the esterase-based mechanism also contributes to the overall level of deltamethrin resistance. The kdr mutation on its own conferred 35-fold resistance to deltamethrin and this was enhanced up to 540-fold when it was present in a high (E4) esterase background. The esterase (FE4) mechanism was far less effective without the kdr mutation, conferring just 3-4-fold resistance to deltamethrin. These findings, and the linkage disequilibrium of the kdr mutation within clones overproducing the E4 esterase, have important implications for the evolution of resistance in this insect and for the use of pyrethroid sprays in the management of M. persicae populations in the field.

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

“…In M. persicae, kdr is caused by a single-point mutation (L1014P) in the para-type sodium channel gene. The genotypes of individual clones were determined by DNA sequencing of PCR-amplified para gene fragments as described previously (Martinez-Torres et al, 1999). Genotypes were scored as either susceptible homozygote (kdr-SS), heterozygote (kdr-SR), or resistant homozygote (kdr-RR) with the latter two being associated with resistance to pyrethroids and DDT (Martinez-Torres et al, 1999).…”

“…The genotypes of individual clones were determined by DNA sequencing of PCR-amplified para gene fragments as described previously (Martinez-Torres et al, 1999). Genotypes were scored as either susceptible homozygote (kdr-SS), heterozygote (kdr-SR), or resistant homozygote (kdr-RR) with the latter two being associated with resistance to pyrethroids and DDT (Martinez-Torres et al, 1999). Esterase levels, representing increasing levels of resistance (S, R 1 , R 2 , and R 3 ) to OPs and carbamates (Devonshire et al, 1982(Devonshire et al, , 1986 were based on the relative activities of immunocaptured E4 or FE4 carboxylesterases, the enzyme responsible for esterase-based insecticide resistance (Devonshire et al, 1986).…”

“…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). This latter mutation is common to many pyrethroid-resistant insect species, including Musca domestica (Diptera: Muscidae) (Vais et al, 2001).…”

Synergistic interaction between two cockroach sodium channel mutations and a tobacco budworm sodium channel mutation in reducing channel sensitivity to a pyrethroid insecticide

“…1) in segment 6 of domain II (IIS6) is associated with kdr and kdr-type resistance (Miyazaki et al, 1996;Williamson et al, 1996;Dong, 1997). Subsequently, the same mutation was found in other important insect pests, including diamondback moth, Plutella xylostella (Martinez-Torres et al, 1997), horn fly, Haematobia irritans (Guerrero et al, 1997), mosquitoes, Anopheles gambiae and Culex pipiens (Martinez-Torres et al, 1998), aphids, Myzus persicae (Martinez-Torres et al, 1999), and Colorado potato beetle, Leptinotarsa decemlineata (Lee et al, 1999a). Conversely, in pyrethroid-resistant tobacco budworm (Heliothis virescens), an L1029H mutation in IIS6 is associated with pyrethroid resistance .…”

Identification of ion channel genes in the Acyrthosiphon pisum genome

“…There are relatively few chemical classes of insecticide available for use against aphids, the main ones being neonicotinoids, which target nicotinic acetylcholine (nACh) receptors, and pyrethroids, which target voltage-gated sodium channels. Aphids resistant to these classes of chemical are increasing, as seen with the spread of kdr (knockdown resistance) to pyrethroids (Martinez-Torres et al, 1999), leading to an urgent need to develop new insecticides with differing modes of action. Recently, a new class of insecticides was launched, targeting ryanodine receptors of lepidopteran and sucking pests.…”