title: A three amino acid deletion in the transmembrane domain of the nicotinic acetylcholine receptor α6 subunit confers high-level resistance to spinosad in Plutella xylostella.
abstract: Spinosad is a macrocyclic lactone insecticide that acts primarily at the nicotinic acetylcholine receptors (nAChRs) of target insects. Here we describe evidence that high levels of resistance to spinosad in the diamondback moth (Plutella xylostella) are associated with a three amino acid (3-aa) deletion in the fourth transmembrane domain (TM4) of the nAChR α6 subunit (Pxα6). Following laboratory selection with spinosad, the SZ-SpinR strain of P. xylostella exhibited 940-fold resistance to spinosad. In addition, the selected insect population had 1060-fold cross-resistance to spinetoram but, in contrast, no cross-resistance to abamectin was observed. Genetic analysis indicates that spinosad resistance in SZ-SpinR is inherited as a recessive and autosomal trait, and that the 3-aa deletion (IIA) in TM4 of Pxα6 is tightly linked to spinosad resistance. Because of well-established difficulties in functional expression of cloned insect nAChRs, the analogous resistance-associated deletion mutation was introduced into a prototype nAChR (the cloned human α7 subunit). Two-electrode voltage-clamp recording with wild-type and mutated nAChRs expressed in Xenopus laevis oocytes indicated that the mutation causes a complete loss of agonist activation. In addition, radioligand binding studies indicated that the 3-aa deletion resulted in significantly lower-affinity binding of the extracellular neurotransmitter-binding site. These findings are consistent with the 3-amino acid (IIA) deletion within the transmembrane domain of Pxα6 being responsible for target-site resistance to spinosad in the SZ-SpinR strain of P. xylostella.
authors: College of Plant Protection, Nanjing Agricultural University, Nanjing, China. Electronic address: wangjing610610@163.com.
authors: Jing
authors: J
authors: Wang
authors: College of Plant Protection, Nanjing Agricultural University, Nanjing, China. Electronic address: wxl@njau.edu.cn.
authors: Xingliang
authors: X
authors: Wang
authors: Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom. Electronic address: s.lansdell@ucl.ac.uk.
authors: Stuart J
authors: SJ
authors: Lansdell
authors: College of Plant Protection, Nanjing Agricultural University, Nanjing, China. Electronic address: 2013102103@njau.edu.cn.
authors: Jianheng
authors: J
authors: Zhang
authors: Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom. Electronic address: n.millar@ucl.ac.uk.
authors: Neil S
authors: NS
authors: Millar
authors: College of Plant Protection, Nanjing Agricultural University, Nanjing, China. Electronic address: wyd@njau.edu.cn.
authors: Yidong
authors: Y
authors: Wu
mesh_terms: D000818:Animals; D004338:Drug Combinations; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D018942:Macrolides / Q000494:pharmacology*; D009036:Moths / Q000737:chemistry / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion
chemical_list: D004338:Drug Combinations; D019476:Insect Proteins; D007306:Insecticides; D018942:Macrolides; D011978:Receptors, Nicotinic; C104518:nicotinic receptor alpha6; C415329:spinosad
keywords: Deletion; Insecticide resistance; Nicotinic acetylcholine receptor; Plutella xylostella; Spinosad