title: Acaricide resistance in northern fowl mite (Ornithonyssus sylviarum) populations on caged layer operations in Southern California.
abstract: Southern California caged layer operations were visited over 3 yr. Northern fowl mites from 26 field populations were tested for acaricide resistance using a capillary pipette and glass dish bioassay. One was a susceptible field population with no pesticide exposure for over 30 yr (reference site for resistance ratio calculation). Technical and commercial formulations of malathion, carbaryl (Sevin), permethrin, and a commercial formulation of tetrachlorvinphos/dichlorvos (Ravap) were tested. Malathion did not have high activity for mites relative to other materials, but resistance to both technical and commercial formulations was low (< 5x). Resistance to other materials was moderate to extreme. Frequency of carbaryl resistance (> 10x) was higher with the commercial (88%) than the technical material (41%); 19% of the populations had resistance > 100x to commercial carbaryl. Frequency of Ravap resistance (> 10x) was 68%; 8% of populations had resistance > 100x. Frequency of permethrin resistance (> 10x) was 72% for the technical material and 88% for the commercial formulation. Extreme permethrin resistance (> 1,000x) was observed in 56 and 50% of mite populations assayed using the technical and commercial formulations, respectively. Among sites, resistance to permethrin was uncorrelated with resistance to other chemicals, suggesting a different resistance mechanism. Resistance to carbaryl and Ravap was highly correlated [r = 0.76 at the LC50 level (concentrations estimated to be lethal to 50% of the test population) and r = 0.99 at the LC95 level], suggesting a common resistance mechanism. Producers currently depend completely on pesticides to control mite infestations. Mite resistance to registered materials emphasizes the need for integrated control measures.
authors.affiliation: Department of Entomology, University of California Cooperative Extension, University of California, Riverside, California 92521, USA. mullens@mail.ucr.edu
authors.forename: B A
authors.initials: BA
authors.lastname: Mullens
authors.forename: R K
authors.initials: RK
authors.lastname: Velten
authors.forename: N C
authors.initials: NC
authors.lastname: Hinkle
authors.forename: D R
authors.initials: DR
authors.lastname: Kuney
authors.forename: C E
authors.initials: CE
authors.lastname: Szijj
mesh_terms: D000383:Agriculture / Q000379:methods; D000818:Animals; D012721:Carbaryl / Q000008:administration & dosage; D002645:Chickens; D004006:Dichlorvos / Q000008:administration & dosage; D007300:Insect Control / Q000379:methods; D007305:Insecticide Resistance; D008294:Malathion / Q000008:administration & dosage; D008925:Mites; D026023:Permethrin / Q000008:administration & dosage; D013751:Tetrachlorvinphos / Q000008:administration & dosage
chemical_list: D026023:Permethrin; D004006:Dichlorvos; D013751:Tetrachlorvinphos; D012721:Carbaryl; D008294:Malathion