title: Cross-resistance to three phenylpyrazole insecticides and A2'N mutation detection of GABA receptor subunit in fipronil-resistant Laodelphax striatellus (Hemiptera: Delphacidae).
abstract: BACKGROUND
  Laodelphax striatellus (Fallén) is an important pest of crops in East Asia. Over the past decade, phenylpyrazole insecticides, which target the insect GABA receptor, have increasingly been used as alternatives against rice planthoppers.
  
  
  RESULTS
  Cross-resistance to ethiprole and butene-fipronil was detected in a laboratory-selected fipronil-resistant strain of L. striatellus (LsFR). Compared with a fipronil-susceptible strain (LsFS), LsFR had obtained a high-level resistance to fipronil (112.1-fold) and moderate resistance to ethiprole (24.5-fold) and butene-fipronil (14.7-fold). For the resistance of field populations, LC50values of ethiprole were remarkably higher than the other two analogues in Gaochun and Yancheng populations in 2016. Significant correlations were demonstrated between the LC50values of three phenylpyrazole insecticides (R = 0.944-0.998, P = 0.007-0.016). Additionally, an AS-PCR assay was developed to detect the A2'N mutant GABA receptor in L. striatellus strains or populations. It was noteworthy that mutation frequencies of 19.2 and 3.6% appeared in Lujiang and Gaochun populations in 2016, respectively. Furthermore, there was an extremely significant difference in genomic expression of Lsrdl between the LsFS and LsFR individuals (1.85-fold, F = 26.8, P = 0.0008).
  
  
  CONCLUSIONS
  This study could help us better understand the cross-resistance mechanisms in L. striatellus, and be beneficial for proposing effective pest management strategies of phenylpyrazole resistance. © 2016 Society of Chemical Industry.
authors.affiliation: Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Nanjing, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wei
authors.affiliation: Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Nanjing, China.
authors.forename: Xi-Chao
authors.initials: XC
authors.lastname: Mu
authors.affiliation: Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Nanjing, China.
authors.forename: Shun-Fan
authors.initials: SF
authors.lastname: Wu
authors.affiliation: Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Nanjing, China.
authors.forename: Li-Xiang
authors.initials: LX
authors.lastname: Wang
authors.affiliation: Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, State and Local Joint Engineering Research Centre of Green Pesticide Invention and Application, Nanjing, China.
authors.forename: Cong-Fen
authors.initials: CF
authors.lastname: Gao
mesh_terms: D000818:Animals; D020440:Gene Duplication; D017344:Genes, Insect / Q000235:genetics; D006430:Hemiptera / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides; D009154:Mutation; D011720:Pyrazoles; D011963:Receptors, GABA-A / Q000235:genetics*
chemical_list: D007306:Insecticides; D011720:Pyrazoles; D011963:Receptors, GABA-A; C082360:fipronil
keywords: Laodelphax striatellus; RDL GABA receptor; cross-resistance; gene duplication; mutation detection; phenylpyrazole insecticide