53.
The mode of action, extent of use, and the current knowledge on environmental fate and toxicity of three biological insecticides [
Bacillus thuringiensis (B.t.), nucleopolyhedrosis virus (NPV), and pheromones] are reviewed. Data gaps, environmental uncertainties in any large-scale use, and proposed registration guidelines which may lead to more extensive use are discussed.
B.t. disappears rapidly from plant foliage on exposure to sunlight and/or moisture, although it may persist in dry soil for several months or years. Foliar-applied NPVs are also inactivated by sunlight; the halflife on cotton leaves is 20–25 h. In the soil, NPVs may remain active for several years. Pheromones volatilize readily and do not persist in plant or in soil. Limited available data indicate that
B.t. and pheromones do not persist in aquatic environments; quantitative data are unavailable for NPVs. Based on bioassay data, the three insecticides exhibit undetectable to low toxicity to nontarget organisms; there are also no reports of human disease or injury due to exposure to these pesticides and no bioaccumulation is expected with normal application. Except for
B.t. which has been used in a limited large-scale applications, pest control uses of NPVs and pheromones are still in experimental stages. Areas of uncertainties requiring research and development include potential adverse health and ecological impacts in any large-scale and widespread use and efficacy and cost relative to synthetic chemical pesticides.
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