Published online by Cambridge University Press: 31 May 2012
An understanding of all environmental effects resulting from control actions is important in the selection of a method of managing insect populations. Effects may extend beyond the year of treatment and can modify management decisions. In 1978, a nuclear polyhedrosis virus (NPV) and Bacillus thuringiensis Berliner (B.t.) were tested as aerial spray applications against the western spruce budworm, Choristoneura occidentalis Freeman, on Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, near Cache Creek, British Columbia. The impact on population densities and on the incidence of NPV was measured in the treated and non-treated areas for 2 vears following the year of application, and is reported here.