title: Presence and impact of allelic variations of two alternative s-kdr mutations, M918T and M918L, in the voltage-gated sodium channel of the green peach aphid Myzus persicae.
abstract: BACKGROUND
  Pyrethroids have been widely employed in order to control several agricultural pests, including Myzus persicae. Target-site resistance is the main mechanism that confers insensitivity to this class of compounds, and the most common amino acid substitutions are kdr (L1014F) and s-kdr (M918T), but recently another mutation in the s-kdr locus (M918L) has been described in French and Korean populations of M. persicae.
  
  
  RESULTS
  Molecular analysis of several Italian populations of M. persicae by pyrosequencing revealed the presence of the new s-kdr mutation (M918L) in different forms. It was found in two different nucleotide polymorphisms (a/t or a/c substitution), in heterozygous or homozygous status, and also in combination with the classic kdr and s-kdr. Bioassays on populations carrying the M918L mutation show that it strongly affects pyrethroid efficacy, particularly of type II pyrethroids such as lambda-cyhalothrin, while it has no effect against DDT.
  
  
  CONCLUSIONS
  This work provides more information about the new s-kdr M918L mutation in M. persicae, describing a more complicated situation arising from the possible combination with the classic L1014F and M918T. Our data open new questions concerning the origin of these new genotypes with different combinations of target-site mutations, and also their possible influence on control strategies.
authors.affiliation: Department of Sustainable Crop Production, Section Sustainable Crop and Food Protection, Università Cattolica del Sacro Cuore, Piacenza, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Panini
authors.forename: Matteo
authors.initials: M
authors.lastname: Anaclerio
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Puggioni
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Stagnati
authors.forename: Ralf
authors.initials: R
authors.lastname: Nauen
authors.forename: Emanuele
authors.initials: E
authors.lastname: Mazzoni
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001042:Aphids / Q000187:drug effects / Q000235:genetics*; D003634:DDT / Q000494:pharmacology; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D011722:Pyrethrins / Q000494:pharmacology; D061566:Voltage-Gated Sodium Channels / Q000235:genetics*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D061566:Voltage-Gated Sodium Channels; D003634:DDT; C037304:cyhalothrin
keywords: M918L; Myzus persicae; kdr; knockdown resistance; pyrethroid resistance; target-site mutation