title: Susceptibility of Adult Cat Fleas (Siphonaptera: Pulicidae) to Insecticides and Status of Insecticide Resistance Mutations at the Rdl and Knockdown Resistance Loci.
abstract: The susceptibility of 12 field-collected isolates and 4 laboratory strains of cat fleas, Ctenocephalides felis was determined by topical application of some of the insecticides used as on-animal therapies to control them. In the tested field-collected flea isolates the LD50 values for fipronil and imidacloprid ranged from 0.09 to 0.35 ng/flea and 0.02 to 0.19 ng/flea, respectively, and were consistent with baseline figures published previously. The extent of variation in response to four pyrethroid insecticides differed between compounds with the LD50 values for deltamethrin ranging from 2.3 to 28.2 ng/flea, etofenprox ranging from 26.7 to 86.7 ng/flea, permethrin ranging from 17.5 to 85.6 ng/flea, and d-phenothrin ranging from 14.5 to 130 ng/flea. A comparison with earlier data for permethrin and deltamethrin implied a level of pyrethroid resistance in all isolates and strains. LD50 values for tetrachlorvinphos ranged from 20.0 to 420.0 ng/flea. The rdl mutation (conferring target-site resistance to cyclodiene insecticides) was present in most field-collected and laboratory strains, but had no discernible effect on responses to fipronil, which acts on the same receptor protein as cyclodienes. The kdr and skdr mutations conferring target-site resistance to pyrethroids but segregated in opposition to one another, precluding the formation of genotypes homozygous for both mutations.
authors.affiliation: Department of Entomology, University of California, Riverside, Riverside, CA, 92521, USA, michael.rust@ucr.edu.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Rust
authors.forename: Richard
authors.initials: R
authors.lastname: Vetter
authors.forename: Ian
authors.initials: I
authors.lastname: Denholm
authors.forename: Byron
authors.initials: B
authors.lastname: Blagburn
authors.forename: Martin S
authors.initials: MS
authors.lastname: Williamson
authors.forename: Steven
authors.initials: S
authors.lastname: Kopp
authors.forename: Glen
authors.initials: G
authors.lastname: Coleman
authors.forename: Joe
authors.initials: J
authors.lastname: Hostetler
authors.forename: Wendell
authors.initials: W
authors.lastname: Davis
authors.forename: Norbert
authors.initials: N
authors.lastname: Mencke
authors.forename: Robert
authors.initials: R
authors.lastname: Rees
authors.forename: Sabrina
authors.initials: S
authors.lastname: Foit
authors.forename: Claudia
authors.initials: C
authors.lastname: Böhm
authors.forename: Kathrin
authors.initials: K
authors.lastname: Tetzner
mesh_terms: D000818:Animals; D058251:Ctenocephalides / Q000187:drug effects* / Q000235:genetics*; D005786:Gene Expression Regulation; D005838:Genotype; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D009154:Mutation; D005423:Siphonaptera / Q000235:genetics
chemical_list: D007306:Insecticides