Evaluation of the efficacy of azadirachtin and imidacloprid trunk injections for control of the emerald ash borer in green ash trees

This thesis is an investigation of the efficacy of two trunk-injected insecticides, azadirachtin and imidacloprid, as control agents of larvae and adult Emerald Ash Borer (Agrilus planipennis, Fairmaire; EAB) in green ash (Fraxinus pennsylvanicus) trees. The EAB is an invasive wood-boring beetle that originated from northeast Asia and has recently caused the death or decline of over 15 million ash trees across selected parts of North America. Azadirachtin trunk injections effectively controlled the larvae, but did not cause lethal effects in the adult EAB. Doses ≥0.014 g a.i.(cm dbh)-1 stopped EAB larvae from developing beyond the second instar within the stem tissue of treated trees. Imidacloprid injections provided control of both the larvae and adult EAB. Doses≥0.02 g a.i.(cm dbh)-1 controlled 94.0% (s.d.=7.87) of adult EAB, while injections ≥0.014 g a.i.(cm dbh)-1 completely stopped all new colonizing EAB larvae from creating galleries in the treated trees.