Bacillus thuringiensis (Bt) is one of the most commonly used microbial pesticides, and currently represents the largest share of the biopesticides market (~ 67%). Bt is highly active against insects such as caterpillars, mosquito larvae, or blackflies that transfer river blindness in Africa. During the sporulation of Bt, crystal aggregates of proteins are produced, which along with its spores are responsible for its high insecticidal activity. However, Bt lacks long term activity in the field, due to sensitivity of the spores to UV, and lack of persistence of the crystal proteins on plant leaves due to rain. In this study, we present the development of materials providing rainfastness and UV resistance to Bt superior to currently available commercial benchmarks for both liquid and dry flowable Bt formulations. The high rainfastness performance observed was maintained after spray-drying of liquid Bt formulations containing our rainfastness agents and re-dispersion in water of the dry products obtained. In addition, we present a newly developed method that enabled the measurement of the concentration of phenolic groups present in the different UV protectants tested. Based on this method we were able to correlate the performance of an additive as a UV protectant for Bt to its concentration of phenolic groups.

Enhanced microbial pesticides via rainfastness and UV resistance improvement

2019 Fall National Meeting

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