Potential of Margosan-O, an azadirachtin-containing formulation from neem seed extract, as a control agent for spruce budworm, Choristoneura fumiferana

The effects on spruce budworm larvae, Choristoneura fumiferana (Clem.), produced by ingestion of Margosan-O, a commercially available neem seed extract formulation containing 0.3% azadirachtin, were investigated. Bioassays with the test material were conducted using various instars of spruce budworm larvae, with either artificial diet, cut branches of balsam fir, Abies balsamea (L.) Mill., or small growing balsam fir trees as substrates. The dose-response data on feeding reduction, developmental retardation, and mortality (LC50, LC95, and LD50) suggest that Margosan-O has promise as a control agent for spruce budworm in an integrated pest management program.