For the purpose of developing a microbial insecticide utilizing Bacillus thuringiensis Berliner, research was done and the following results were obtained.
1) As the freeze-dried matter of the cocoon-cooked water discarded from the filature contains much crude protein(51.825%) and a lot of inorganic salts, it can make a good nutrition source for the culture cf B. thuringiensis Berliner.
2) Based on the suspensibility, formula F-5 turned out to be the most suitable for insecticidal use. Its composition includes 0.2 g of the cell-spore-crystal mixture, 25 g of 200-mesh kaolin, 2.5 g of New Kalgen-NX-150, and 2.5 g of glycerine admixed with 8 ㎖ of distilled water and granulated in 80-mesh size.
3) All the components of F-5, F-6 and F-7 are identical except that the amounts of cell-spore-crystal mixture of F-5, F-6, and F-7 are 0.2 g, 0.4 g, and 0.6 g, respectively. Accordingly, their physical properties are almost all the same.
4) Formulas F-5, F-6, and F-7 exhibited an excellent toxicity to Anomis mesogona Walker, Dendrolimus spectabilis Butler, and Margaronia perspectalis Walker at the concentration of 5%.
5) Formulas F-8 and F-9 which contain NaHCO₃ as one of their components showed a remarkably reduced toxicity to Anomis mesogona Walker and Dendrolimus spectabilis Butler than F-6 which does not contain NaHCO₃.
6) A maximum of 2.97×10^9 spores per ㎖ was obtained by incubating B. thuringiensis in M-3 which has a pH of 7.05 and comprises 0.2% of ammonium sulphate and 0.8% of glucose dissolved in the cocoon-cooked water, with aeration for 96 hours.
7) Formula F-6 exhibited a somewhat reduced toxicity to Anomis mesogona Walker and Dendrolimus spectabilis Butler, when stored at room temperature for 70 days after formulation and it is desirable to keep it in a dark and cold place.
8) In held applications, formula F-6 showed a good activity in controlling Monema flavescens Walker. Margaronia perspectalis Walker, and Macrosiphum ibarae Matsumura.
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