title: Characterization of resistance to clofentezine in populations of European red mite from orchards in Ontario.
abstract: Resistance to clofentezine was identified in four populations of the European red mite, Panonychus ulmi (Koch), from apple orchards in Ontario after ca. 5 years use. Resistance was expressed at high levels (> 2000-fold at the LC 50) to clofentezine in a population selected in the laboratory. This population was resistant to hexythiazox and to the organotin compounds cyhexatin and fenbutatin-oxide. However, a population selected with fenbutatin-oxide did not show cross resistance to clofentezine. The clofentezine-resistant population was not resistant to pyridaben, propargite or dicofol. The synergists, piperonyl butoxide and DEF, were ineffective in overcoming the resistance. Resistance to clofentezine declined rapidly in a mixed population (most resistance was lost in fewer than three generations). There were several fitness factors (fewer eggs/female, longer egg stage, longer development time for males) associated with the resistant population which may have contributed to the loss of resistant phenotypes. However, in a second test in which selection was removed from a resistant population, resistance persisted for at least 10 generations. Observations on field populations indicated that resistance persisted for at least two seasons.
authors.affiliation: Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, Vineland Station, Ontario L0R 2E0, Canada. preed@agr.gc.ca
authors.forename: D J
authors.initials: DJ
authors.lastname: Pree
authors.forename: L A
authors.initials: LA
authors.lastname: Bittner
authors.forename: K J
authors.initials: KJ
authors.lastname: Whitty
mesh_terms: D000818:Animals; D002722:Chlorobenzenes / Q000494:pharmacology*; D007305:Insecticide Resistance; D008925:Mites / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D009864:Ontario; D010574:Pesticide Synergists / Q000494:pharmacology; D010575:Pesticides / Q000494:pharmacology*; D012641:Selection, Genetic
chemical_list: D002722:Chlorobenzenes; D010574:Pesticide Synergists; D010575:Pesticides; C062106:clofentezine