Bioassay with Insects for Bacillus thuringiensis Products-Factors Affecting the Results.

Bacillus thuringiensis has been used widely as one of representative microbial insecticides against variety of pest. Since the insecticidal principles produced by B. thuringiensis are complex with variety of toxins of different spectrum, spores and soluble substances affecting the biological activity of toxins, the bioassay with insects is requisite and important for comparing the activity among different formulations of B. thuringiensis. However there are several factors affecting the results in the bioassay. Author reviewed and discussed those factors affecting the results in the bioassay with insects using B. thuringiensis formulations at standpoints of species and stage of test insects, procedure for application, test temperatures, kinds of diet used, feeding periods and scoring time, methods for evaluating the biological activity and so on.