BACILLUS-THURINGIENSIS - PRODUCT STANDARDIZATION

At present, all accepted methods for standardisation are based on bioassay against living insects. These methods are slow, expensive and require a large number of 'standard' insects. Potency is expressed in terms of International Units per gram or per milligram. However, it must be recognised that there is only one International Standard and the standardised assay applies only to Trichoplusia ni as the target. Many other methods have been described but none are acceptable. Bt producing companies are at present attempting to come to agreement over standards and procedures to be used in the future.