Bacillus thuringiensis (Bt) and Bs-based products are used worldwide as biological insecticides to control specific insect pests. A characteristic of Bt and Bs that distinguishes them from other Bacillus species is the production of one or more parasporal bodies during sporulation that consists primarily of crystalline proteinaceous materials (protoxins) which, when activated in a susceptible insect, cause disruption of the insect gut and eventual death. The activated toxins, called delta-endotoxins, are active on the immature stages of susceptible insects and do not cause mortality in adult insects.
The biology, ecology, and safety of Bt has been thoroughly reviewed by the WHO in their Environmental Health Criteria series of monographs #217 Bacillus thuringiensis (IPCS WHO 1999), by Glare and O’Callaghan (2000), and in various other publications: e.g., Bacillus thuringiensis: A Cornerstone of Modern Agriculture (Metz 2003). These reviews indicate that there are no significant environmental and health issues related to the use of Bt-based products.
Numerous laboratory and field tests against several invertebrate/non-target species confirm the specificity of Bs for mosquitoes and safety for the vast majority of non-targets, including a variety of mosquito predators and other species of Nematocera (Mulla et al. 1984; Aly and Mulla 1987; Karch et al. 1990; Lacey and Mulla 1990; Rodcharoen et al. 1991; Walton and Mulla 1991; Yousten et al. 1991, 1992; Lacey and Siegel 2000; Lacey and Merritt 2003; Brown et al. 2004). The specificity of Bs for mosquito larvae also completely eliminates its direct risk to vertebrates including fish, birds, and mammals (Shadduck et al. 1980; Saik et al. 1990; Siegel and Shadduck 1990b, 1990c; Lacey and Siegel 2000; Lacey and Merritt 2003). Few long-term effects of repeated applications of Bs on aquatic-community structure and diversity have been reported (Lacey 2007).
Minimizing the potential impact on humans, the environment, and other non-target organisms is a top priority for any sustainable insect-control program. Valent BioSciences is committed to providing our customers with products that achieve their insect-control objectives in a sustainable way.
Note: All referenced literature can be found in the References/White Papers section of this site.