title: Amino acid substitutions of acetylcholinesterase associated with carbofuran resistance in Chilo suppressalis.
abstract: BACKGROUND
  Over 1000-fold carbofuran resistance has been observed in Chilo suppressalis (Walker) collected from the Changhua (CH) and Chiayi (CY) prefectures of Taiwan. An understanding of the pertinent mechanisms will benefit effective insecticide resistance management of C. suppressalis.
  
  
  RESULTS
  Among the five amino acid substitutions of acetylcholinesterase (AChE) identified in C. suppressalis, A314S and H668P had been reported and E101D, F402V and R667Q were novel. Substitution frequencies in AChE of CH and CY populations were much higher than in the susceptible Hsinchu (HC) population. Significantly negative correlations were observed between the frequencies of E101D, A314S and R667Q and the kinetic parameters of AChEs in these populations. AChE from the resistant CH population was less susceptible to the inhibition of carbofuran, with an I50 that was 3.6-fold higher than that of the susceptible HC population. Although Km and Vmax of AChE from the CH and CY populations were reduced to 72-87% of those from the HC population, the overall catalytic efficiency (Vmax /Km ) remained constant for all three populations.
  
  
  CONCLUSIONS
  Amino acid substitutions identified in the AChE of C. suppressalis are associated with changes in AChE kinetics and its insensitivity to carbofuran. These observations are helpful for rapid monitoring, prediction and management of OP and CB resistance in the field.
authors.affiliation: Biotechnology Centre, National Chung-Hsing University, Taichung, Taiwan, Republic of China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Chang
authors.forename: Xuan
authors.initials: X
authors.lastname: Cheng
authors.forename: Xin-Yi
authors.initials: XY
authors.lastname: Huang
authors.forename: Shu-Mei
authors.initials: SM
authors.lastname: Dai
mesh_terms: D000110:Acetylcholinesterase / Q000235:genetics*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002235:Carbofuran / Q000494:pharmacology*; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000201:enzymology; D009036:Moths / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics*; D059645:Mutation Rate; D017422:Sequence Analysis, DNA; D013624:Taiwan
chemical_list: D007306:Insecticides; D000110:Acetylcholinesterase; D002235:Carbofuran
keywords: Chilo suppressalis; acetylcholinesterase; amino acid substitution; carbofuran resistance