title: A point mutation in the acetylcholinesterase-1 gene is associated with chlorpyrifos resistance in the plant bug Apolygus lucorum.
abstract: Control of Chinese Apolygus lucorum relies heavily on organophosphate insecticides. Here we describe resistance to the organophosphate chlorpyrifos in an A. lucorum strain, BZ-R, which was developed from a field-collected strain (BZ) by selection with chlorpyrifos in the laboratory. BZ-R showed 21-58 fold resistance to chlorpyrifos compared with the laboratory reference strain LSF and another susceptible strain, BZ-S, derived from BZ. BZ-R also showed several fold resistance to two other organophosphates and a carbamate. No synergism of chlorpyrifos by metabolic enzyme inhibitors nor any increase in detoxifying enzyme activities were observed in BZ-R. No sequence differences in acetylcholinesterase-2 were found to be associated with the resistance but the frequency of an alanine to serine substitution at position 216 of acetylcholinesterase-1 was 100% in BZ-R, ∼21-23% in SLF and BZ, and 0% in BZ-S. A single generation treatment of chlorpyrifos on the BZ strain also increased its frequency of the serine substitution to 64%. Recombinantly expressed acetylcholinesterase-1 carrying the serine substitution was about five fold less sensitive to inhibition by chlorpyrifos oxon than the wild-type enzyme. Quantitative real-time PCR found no differences in ace1 or ace2 expression levels among the strains tested. Thus the chlorpyrifos resistance is strongly associated with the serine substituted acetylcholinesterase-1. An equivalent substitution has been found to confer resistance to many organophosphate and carbamate insecticides in four other insect species.
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Wu
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Kairan
authors.initials: K
authors.lastname: Zuo
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Zhaokui
authors.initials: Z
authors.lastname: Kang
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yihua
authors.initials: Y
authors.lastname: Yang
authors.affiliation: CSIRO Land and Water Flagship, P.O. Box 1700, Canberra, ACT 2601, Australia.
authors.forename: John G
authors.initials: JG
authors.lastname: Oakeshott
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: wyd@njau.edu.cn.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000110:Acetylcholinesterase / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D002681:China; D004390:Chlorpyrifos / Q000031:analogs & derivatives* / Q000494:pharmacology; D020062:Heteroptera / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D017354:Point Mutation
chemical_list: D007306:Insecticides; C009618:O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphate; D000110:Acetylcholinesterase; D004390:Chlorpyrifos
keywords: Acetylcholinesterase; Apolygus lucorum; Insecticide resistance; Point mutation