Application of Bacillus thuringiensis in forestry

Abstract

Current world-wide use of Bt subsp. kurstaki in forestry was preceded by its development for control of the spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae), a major defoliator of coniferous forests in North America. Since its widespread operational acceptance in the mid 1980s, Bt has been used on a cumulative total of about 8.5 million ha in Canada and 3 million ha in the United States. In Europe, Bt has been used for control of various defoliators on 1.7 million ha since 1990. In most forest protection programs, undiluted high-potency products containing 12.7–25.4 billion international units (BIU) per litre are applied in volumes of 1.2–2.5 litres per ha. Further optimisation of aerial forestry applications, currently in progress, uses a detailed process-oriented model that simulates the efficacy of Bt sprays against the spruce budworm.