title: Foliar residue dynamics of azadirachtins following direct stem injection into white and green ash trees for control of emerald ash borer.
abstract: BACKGROUND
  Azadirachtins are natural insecticides derived from the neem tree. The emerald ash borer (EAB) is an exotic invasive insect pest that infests various ash tree species and has the potential for significant economic, aesthetic and ecological impacts throughout North America. The initial translocation and foliar residue dynamics of azadirachtins were examined following direct injection into white and green ash trees growing in urban scenarios as a potential control for EAB.
  
  
  RESULTS
  Substantial concentrations of azadirachtins A and B [mean maxima > 0.98 mg kg(-1) fresh weight (f.w.)] were observed within 2 days of injecting a specifically designed formulation of azadirachtins. Foliar residues declined exponentially through time, with half-life estimates ranging from 5.1 to 12.3 days. At the time of leaf senescence, foliar residue levels approximated 0.01 mg kg(-1) f.w., strongly mitigating the potential effects of non-target biota in soil or aquatic compartments.
  
  
  CONCLUSIONS
  The magnitude and duration of exposures observed in this field study were considered to be above the thresholds required for biological effectiveness against both larval and adult life stages of EAB. Results support the use of azadirachtins as an environmentally acceptable systemic insecticide for control of EAB and protection of high-value ash trees in urban environments.
authors.affiliation: Canadian Forest Service, Natural Resources Canada, Sault Ste. Marie, Ontario, Canada.
authors.forename: Susana
authors.initials: S
authors.lastname: Grimalt
authors.forename: Dean
authors.initials: D
authors.lastname: Thompson
authors.forename: Derek
authors.initials: D
authors.lastname: Chartrand
authors.forename: John
authors.initials: J
authors.lastname: McFarlane
authors.forename: Blair
authors.initials: B
authors.lastname: Helson
authors.forename: Barry
authors.initials: B
authors.lastname: Lyons
authors.forename: Joe
authors.initials: J
authors.lastname: Meating
authors.forename: Taylor
authors.initials: T
authors.lastname: Scarr
mesh_terms: D000818:Animals; D001517:Coleoptera; D031661:Fraxinus / Q000737:chemistry / Q000378:metabolism* / Q000469:parasitology; D007306:Insecticides / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D036701:Limonins / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D010573:Pesticide Residues / Q000032:analysis / Q000493:pharmacokinetics*; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D007306:Insecticides; D036701:Limonins; D010573:Pesticide Residues; C010329:azadirachtin; C476490:azadirachtin B