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 freshweight (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., stronglymitigating the potential effects of non-target biota in soil or aquatic compartments.
CONCLUSION: The magnitude andduration of exposures observed in this field study were considered tobe 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.
Society of Chemical Industry – Pest Management Science (2001).
Susana Grimalt, Dean Thompson, Derek Chartrand, John McFarlane, Blair Helson, Barry Lyons, Joe Meating and Taylor Scarr.