Development and Current Status of Bacillus thuringiensis for Control of Defoliating Forest Insects

Abstract

RCsumCBacillus thuringiensis (Bt) is a naturally occurring bacterium Bacillus thuringiensis (B. t.) est une bactkrie naturelle, aujourthat is now widely used for control of spruce budworm and d'hui largement utilisCe contre la tordeuse des bourgeons de several other defoliating forest insects in Canada. It took more 1'Cpinette et plusieurs autres dCfoliateurs des forCts du Canada. than 25 years of research and development to bring Bt from first Depuis son premier emploi expCrimental, au dCbut des annCes experimental use in the early 1960s into full operational use in 60, jusqu'a son utilisation en grand, dans le milieu des anntes the mid 1980s. Critical to this process was the adoption of HD-1 80, il s'est pass6 plus de 25 annCes de recherche-dCveloppement. for commercial use, the standardization of formulations based Une Ctape critique de cette Cvolution a Ct C l'adoption du HD-1 on international units, and the development of higher potency pour emploi industriel, la normalisation des prCparations grice products. An increase in product potency from 4 BIUIL in the B l'emploi des unitCs internationales ainsi que la mise au point early 1970s to 16.9 BIUIL in the mid 1980s, concomittant with de produits plus puissants. Ainsi, l'accroissement de la puisimprovements in formulation and application technology, sance, de 4 unitCs biologiques internationales au litre (UBIIL), reduced treatment costs while at the same time improving reliaau dCbut des annCes 70, B 16,9, au milieu des annCes 80, en bility of efficacy. A shift in political climate pushed Bt into operam&me temps que les amCliorations des techniques de prCparational use by 1985. Since then, Bt has been used in more than tion et d'application, ont permis de rtduire les coOts du traitehalf of all spruce budworm control programs. The use of highment tout en amCliorant la fiabilitC de l'efficacitk. Un nouveau potency formulations (12.7 to 16.9 BIUIL) applied undiluted climat politique a favoris6 l'emploi en grand de B.t. dks 1985. at 30 BIU in 2.4 Llha or less has significantly reduced but not Depuis, B.t. a servi dans plus de la moitiC de tous les eliminated initial constraints of high treatment costs and inconprogrammes antitordeuse. Le recours B des prkparations trks sistent efficacy. Current research is focussed on further reducing puissantes (de 12,7 B 16,9 UBIIL) appliquCes sans dilution B these constraints. In the short term, registration of formulations raison de 2,4 Llha a permis de rCduire considCrablement, sans containing 25 BIUIL or more is expected to permit application les Climiner complktement, les contraintes initiales posies par of reduced dosages in less than 1 Llha and to clear the way for les coDts ClevCs du traitement et I'efficacitC inconsta~te. La adoption of a split application scheme to increase reliability of recherche actuelle se propose de rMuire ces contraintes. A court efficacy. Selection and commercialization of more effective terme, I'homologation des prkparations renfermant 25 UBIIL strains and the enhancement of natural s...

Impact of biotechnology on forest ecosystems

“…The time required for the safe and economical development of many of the technologies (Table 1) will be at least one to three decades. This is consistent with the observation that over 30 years of research and development were necessary to make the use of B. thuringiensis feasible at the operational level (van Frankenhuyzen 1990). It is evident then, that much time and energy have yet to be invested before the potential of biotechnology can be realized.…”

“…Forest biotechnology involves a large number of activities (Charest and Michel 1991, Cheliak and Rogers 1990, Duchesne et al 1989b, Dunstan 1988, Hubbes 1987, Mantel1 et al 1985, Singh 1989, Van Frankenhuyzen 1990, von Arnold et al 1991 which can be divided into three major groups. The first group is comprised of tissue culture methodologies such as protoplast fusion, embryogenesis, organogenesis, and germplasm storage technologies and has in common the manipulation of tree cells in vitro.…”

Microbial insecticides in forestry

“…There are currently 18 B.t. products registered for forestry use in Canada by 8 different companies (van Frankenhuyzen 1990). Of these, 11 products are readily available and the remaining 7 have been replaced by improved formulations without cancellation of their registrations.…”

“…B.t. is now an operational alternative to synthetic chemical insecticides for control of spruce budworm (Srnirnoff and Morris 1982) and several other major forest defoliators (van Frankenhuyzen 1990).…”

Legislative and policy limits to successful integrated pest management in Canada's forests

“…Bt has proven to be an effective insecticide when applied to an appropriate population level, at the right stages of foliage and insect development, and when favorable weather is expected to follow application (van Frankenhuyzen 1990). Operational results have varied tremendously: although normally successful against spruce budworm, the 1988 Bt application in New Brunswick produced very unsatisfactory results (van Frankenhuyzen 1990). Our incomplete understanding of the population dynamics of forest pests limits fully effective deployment of control measures.…”