title: Knockdown of the ionotropic γ-aminobutyric acid receptor (GABAR) RDL gene decreases fipronil susceptibility of the small brown planthopper, Laodelphax striatellus (Hemiptera: Delphacidae).
abstract: Insect γ-aminobutyric acid receptors (GABARs) are important molecular targets of cyclodiene and phenylpyrazole insecticides. Previously GABARs encoding rdl (resistant to dieldrin) genes responsible for dieldrin and fipronil resistance were identified in various economically important insect pests. In this study, we cloned the open reading frame cDNA sequence of rdl gene from fipronil-susceptible and fipronil-resistant strains of Laodelphax striatellus (Lsrdl). Sequence analysis confirmed the presence of a previously identified resistance-conferring mutation. Different alternative splicing variants of Lsrdl were noted. Injection of dsLsrdl reduced the mRNA abundance of Lsrdl by 27-82%, and greatly decreased fipronil-induced mortality of individuals from both susceptible and resistant strains. These data indicate that Lsrdl encodes a functional RDL subunit that mediates susceptibility to fipronil. Additionally, temporal and spatial expression analysis showed that Lsrdl was expressed at higher levels in eggs, fifth-instar nymphs, and female adults than in third-instar and fourth-instar nymphs. Lsrdl was predominantly expressed in the heads of 2-day-old female adults. All these results provide useful background knowledge for better understanding of fipronil resistance related ionotropic GABA receptor rdl gene expressed variants and potential functional differences in insects.
authors: State and Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Pesticide Sciences, College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors: Qi
authors: Q
authors: Wei
authors: Shun-Fan
authors: SF
authors: Wu
authors: Chun-Dong
authors: CD
authors: Niu
authors: Hua-Yang
authors: HY
authors: Yu
authors: Yao-Xue
authors: YX
authors: Dong
authors: Cong-Fen
authors: CF
authors: Gao
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D005260:Female; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D006430:Hemiptera / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D007305:Insecticide Resistance; D007306:Insecticides; D008297:Male; D009154:Mutation; D011720:Pyrazoles; D018079:Receptors, GABA / Q000235:genetics / Q000378:metabolism*
chemical_list: D007306:Insecticides; D011720:Pyrazoles; D018079:Receptors, GABA; C082360:fipronil
keywords: Laodelphax striatellus; RNAi; alternative splice; fipronil; insecticide resistance