Microbial insecticides in forestry

Research has been conducted in Canada on bacteria, viruses, protozoa, fungi and nematodes for control of forest insect pests. Environmental concerns regarding the use of synthetic chemical pesticides have resulted in increased use of the only microbial control agent that is commercially available, the bacterium Bacillus thuringiensis (B.t.). There are currently 18 B.t. products registered for forestry use in Canada. The greatest use of B.t. has been for control of spruce budworm, Choristoneura Jumiferana, although it has been extensively used on several other species of defoliating lepidopterous pests.The use of other microbial control agents is insignificant compared to B.t. Three viral insecticides containing baculoviruses are registered in Canada, two for control of Douglas-fir tussock moth and one for control of redheaded pine sawfly. Registration petitions have been submitted for viral insecticides to control European pine sawfly and gypsy moth.The advent of recombinant DNA technology has opened the door to limitless possibilities for the genetic manipulation of microbial insecticides. Genetic engineering of B.t. toxin genes into other microorganisms and into plants has been accomplished. Foreign genes have been expressed in baculoviruses; most of these products have pharmaceutical applications unrelated to insect control, but this technology can be used to engineer viral insecticides for enhanced activity.