title: Chemical residues and bioactivity of tebufenozide applied to apple foliage.
abstract: Tebufenozide, an insect growth regulator that acts as an ecdysone agonist, was applied at recommended label rate to apple trees in August 1997 and May 1998. Foliar residues were determined by high-performance liquid chromatography from samples collected 2, 24, 48 and 96 h post-spray, and at weekly intervals thereafter for 9 weeks in 1997 and 11 weeks in 1998. Foliage sampled at the same times was used in bioassays to determine residual toxicity to first-instar obliquebanded leafrollers, Choristoneura rosaceana (Harris). Residue decay followed first-order kinetics in both years, with residual half-life of 36.3 days in 1997 and 7.2 days in 1998. Estimates of the time needed to reduce bioactivity to 50% in bioassays were 18.7 days in 1997 and 36.3 days in 1998. The accuracy of equations describing decay of tebufenozide residues and bioactivity over time was not improved by using degree-day accumulations as the independent variable.
authors.affiliation: Agriculture & Agri-Food Canada, Pacific Agri-Food Research Centre, Summerland, BC VOH 1ZO, Canada. smirlem@agr.gc.ca
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Smirle
authors.forename: D Thomas
authors.initials: DT
authors.lastname: Lowery
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Zurowski
mesh_terms: D000818:Animals; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006207:Half-Life; D006834:Hydrazines / Q000493:pharmacokinetics / Q000494:pharmacology*; D007300:Insect Control / Q000379:methods; D007306:Insecticides / Q000493:pharmacokinetics / Q000494:pharmacology*; D007700:Kinetics; D007915:Lepidoptera / Q000187:drug effects* / Q000254:growth & development; D027845:Malus / Q000187:drug effects* / Q000378:metabolism; D010573:Pesticide Residues / Q000032:analysis*; D018515:Plant Leaves / Q000187:drug effects* / Q000378:metabolism
chemical_list: D006834:Hydrazines; D007306:Insecticides; D010573:Pesticide Residues; C082026:tebufenozide