苏云金素与苏云金杆菌芽孢晶体混剂对小菜蛾的增效作用

THE SYNERGISM OF THURINGIENSIN IN THE MIXTURE WITH ENDOGENOUS Bt CRYSTAL ON DIAMOND-BACK MOTH

将苏云金素和苏云金杆菌的孢晶制剂分别作为单一制剂,用混和饲料感染法在室内测定苏云金素分别与苏云金杆菌HD—1、CT—43、81—6、WP—2等4个菌株孢晶制剂的混剂对小菜蛾幼虫的协同作用。按Sun—Johnson毒力指数法计算结果表明,苏云金素对所有供试菌的孢晶制剂都有增效作用,共毒系数从127.43至415.62不等。当混剂以芽孢晶体为主要活性组分时,苏云金素占全部活性组分的16.7％(w/w)情况下增效作用最强,共毒系数值235.31;当以苏云金素为混剂的主要活性组分时,苏云金素与芽孢晶体之比为100:10(w/w)情况下增效作用最强,共毒系数值可达1021.49。增效作用的大小因试虫感染毒物时间的长短而异。对于同是3龄的小菜蛾幼虫,苏云金素对3龄末期幼虫的增效作用最显著。

The synergism of thuringiensin, β-exotoxin of Bacillus thuringiensis (Bt), in the mixtures mixed separately with the endogenous crystal preparations of HD-1, CT-43, 81-6 and WP-2, on the larvae of diamond-back moth Plutella xylostella , were tested by diet infection method and analyzed by Sun-Johnson's toxicity index method. The results showed that thuringiensin was synergistic to all the Bt crystal preparations, the co-toxi-city coefficient (CTC) ranged from 127. 43 - 415. 62. As endogenous crystal was dominant in the mixture, the optimum synergism, CTC=235. 31, occurred at the percentage that thuringiensin occupied 16. 7%(w/w) of the whole active components; contrarily, as thuringiensin was dominant, the optimum synergism, CTC=1021. 49, occurred at 100/10 (w/w) of the ratio of thuringiensin to Bt crystal. The synergism increased with the infection time on larvae. The highest synergism of thuringiensin in 3rd instar occurred at the end of this instar.