抄録
The effects of the culture medium of Bacillus thuringiensis serovar japonensis Buibui on the insecticidal activities of B. thuringiensis formulations were investigated by a diet incorporation method using four lepidopterous insects, Spodoptera litura, Mamestra brassicae, Plutella xylostella and Adoxophyes honmai. Although the culture medium alone was not lethal to lepidopterous insects, its combination with δ-endotoxins from B. thuringiensis serovar kurstaki and aizawai, which were lethal only to lepidopterans, increased the toxicity higher than those by δ-endotoxins alone. The synergistic levels by the addition of culture medium reached a maximum of 42 fold based on a comparison of LC50, but the rates differed among species of insects tested and the kinds of δ-endotoxins used.
