title: Resistance and cross-resistance in populations of the leafrollers, Choristoneura rosaceana and Pandemis pyrusana , in Washington apples.
abstract: Insecticide bioassays of the leafrollers, Choristoneura rosaceana (Harris), and Pandemis pyrusana Kearfott (Lepidoptera: Tortricidae), were used to investigate resistance and cross-resistance between azinphosmethyl and other insecticides. Comparisons of field-collected populations with susceptible laboratory colonies of both leafroller species were made in 1996-97, prior to registration and field introduction of several of insecticides, and were re-tested in 2000-2001 following several years of use in the field. Insecticides tested included azinphosmethyl, chlorpyrifos, methyl parathion, tebufenozide, methoxyfenozide, spinosad, indoxacarb, acetamiprid, Bacillus thuringiensis , and azadirachtin. Azinphosmethyl-susceptible laboratory colonies were used for comparison to field populations. Resistance to azinphosmethyl was found in all populations of C. rosaceana (5.2-26.8 fold) and P. pyrusana (8.4-24.9 fold) collected from commercial orchards. Cross-resistance between azinphosmethyl and the insect growth regulators tebufenozide and methoxyfenozide was found in all but one population of the two leafroller species. No cross-resistance was found to chlorpyrifos. Some of the populations tested were cross-resistant to spinosad and indoxacarb, but the responses to these materials were more variable.
authors.affiliation: Washington State University, Tree Fruit Research and Extension Center, Wenatchee, WA 98801, USA. dunleyj@wsu.edu
authors.forename: John E
authors.initials: JE
authors.lastname: Dunley
authors.forename: Jay F
authors.initials: JF
authors.lastname: Brunner
authors.forename: Michael D
authors.initials: MD
authors.lastname: Doerr
authors.forename: E H
authors.initials: EH
authors.lastname: Beers
mesh_terms: D000818:Animals; D007305:Insecticide Resistance; D007306:Insecticides; D007928:Lethal Dose 50; D027845:Malus / Q000469:parasitology*; D009036:Moths / Q000502:physiology; D014861:Washington
chemical_list: D007306:Insecticides