Current Status of Bacillus thuringiensis for Spruce Budworm Control

Abstract

Research and development over many years have now established that Bacillus thuringiensis Berliner (B.t.) can be a safe and effective biological insecticide for spruce budworm. B.t. must be ingested before it can kill the insect and good results are thus obtained when the B.t. spray is applied at the correct time and covers the foliage so that most larvae consume a lethal dose of B.t. within 1 or 2 days of application. Under these conditions, B.t. treatments can save as much foliage as chemical insecticide treatments. However, the cost of materials and application for a B.t. treatment is higher than for a chemical treatment. In recent years emphasis in B.t. research has thus been to reduce cost by obtaining better distribution of the material on foliage, by reducing the volume of liquid carrier, and by looking for strains and fermentations of B.t. that provide an even more potent product against spruce budworm.