title: Characterization of the voltage-gated sodium channel of the Asian citrus psyllid, Diaphorina citri.
abstract: The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an important insect pest of citrus. It is the vector of 'Candidatus' Liberibacter asiaticus, a phloem-limited bacterium that infects citrus, resulting in the disease Huanglongbing (HLB). Disease management relies heavily on suppression of D. citri populations with insecticides, including pyrethroids. In recent annual surveys to monitor insecticide resistance, reduced susceptibility to fenpropathrin was identified in several field populations of D. citri. The primary target of pyrethroids is the voltage-gated sodium channel (VGSC). The VGSC is prone to target-site insensitivity because of mutations that either reduce pyrethroid binding and/or alter gating kinetics. These mutations, known as knockdown resistance or kdr, have been reported in a wide diversity of arthropod species. Alternative splicing, in combination with kdr mutations, has been also associated with reduced pyrethroid efficacy. Here we report the molecular characterization of the VGSC in D. citri along with a survey of alternative splicing across developmental stages of this species. Previous studies demonstrated that D. citri has an exquisite enzymatic arsenal to detoxify insecticides resulting in reduced efficacy. The results from the current investigation demonstrate that target-site insensitivity is also a potential basis for insecticide resistance to pyrethroids in D. citri. The VGSC sequence and its molecular characterization should facilitate early elucidation of the underlying cause of an established case of resistance to pyrethroids. This is the first characterization of a VGSC from a hemipteran to this level of detail, with the majority of the previous studies on dipterans and lepidopterans.
authors.affiliation: Entomology and Nematology Department, Citrus Research and Education Center, University of Florida, Florida, USA.|Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Entomology and Nematology Department, Citrus Research and Education Center, University of Florida, Florida, USA.
authors.forename: Monique R
authors.initials: MR
authors.lastname: Coy
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
authors.forename: Jin-Jun
authors.initials: JJ
authors.lastname: Wang
authors.affiliation: Entomology and Nematology Department, Citrus Research and Education Center, University of Florida, Florida, USA.
authors.forename: Lukasz L
authors.initials: LL
authors.lastname: Stelinski
mesh_terms: D000818:Animals; D002957:Citrus / Q000469:parasitology; D006430:Hemiptera / Q000235:genetics* / Q000254:growth & development; D019476:Insect Proteins / Q000378:metabolism*; D007303:Insect Vectors; D007305:Insecticide Resistance; D007306:Insecticides; D009154:Mutation; D009758:Nymph; D011722:Pyrethrins; D061566:Voltage-Gated Sodium Channels / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D011722:Pyrethrins; D061566:Voltage-Gated Sodium Channels; C044267:fenpropathrin
keywords: citrus greening; disease management; knockdown resistance (kdr); target-site insensitivity