title: The A2'N mutation of the RDL gamma-aminobutyric acid receptor conferring fipronil resistance in Laodelphax striatellus (Hemiptera: Delphacidae).
abstract: The planthopper Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) is a serious insect pest of rice, Oryza sativa L., and has developed resistance to fipronil in Japan. Sequence analysis of L. striatellus RDL gamma-aminobutyric acid (GABA) receptor subunit (LS-RDL) genes from a fipronil-resistant population and a fipronil-susceptible strain identified the A2'N mutation (index number for M2 membrane-spanning region), that was previously implicated in fipronil resistance in the planthopper Sogatella furcifera (Horváth) (Hemiptera: Delphacidae). Nineteen of 21 fipronil-resistant L. striatellus individuals were genotyped as heterozygous for the A2'N mutation, suggesting that this mutation is associated with fipronil resistance and that most fipronil-resistant L. striatellus express wild-type and A2'N mutant LS-RDL simultaneously. To confirm the role of the A2'N mutation of LS-RDL, Drosophila Mel-2 cells were transfected with wild-type and A2'N mutant LS-RDL genes, either individually or together. A membrane potential assay showed that fipronil had no inhibitory effect at 10 microM on cells transfected with the A2'N mutant LS-RDL gene with or without the wild-type LS-RDL gene. By contrast, the IC50 value of fipronil for wild-type LS-RDL homomers was 14 nM. These results suggest that the A2'N mutation of the RDL GABA receptor subunit confers fipronil resistance in L. striatellus as well as S. furcifera.
authors.affiliation: Agrochemical Research Center, Mitsui Chemicals Agro, Inc., Mobara, Chiba 297-0017, Japan. toshifumi.nakao@mitsui-chem.co.jp
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Nakao
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kawase
authors.forename: Ayako
authors.initials: A
authors.lastname: Kinoshita
authors.forename: Reiko
authors.initials: R
authors.lastname: Abe
authors.forename: Masako
authors.initials: M
authors.lastname: Hama
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kawahara
authors.forename: Kangetsu
authors.initials: K
authors.lastname: Hirase
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics; D006430:Hemiptera / Q000187:drug effects / Q000235:genetics*; D019476:Insect Proteins / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D009154:Mutation; D011720:Pyrazoles / Q000494:pharmacology*; D018079:Receptors, GABA / Q000235:genetics*; D011963:Receptors, GABA-A / Q000235:genetics; D014162:Transfection
chemical_list: D029721:Drosophila Proteins; D019476:Insect Proteins; D007306:Insecticides; D011720:Pyrazoles; C082030:Rdl protein, Drosophila; D018079:Receptors, GABA; D011963:Receptors, GABA-A; C082360:fipronil