Bt与硫丹、氟铃脲对棉铃虫的联合作用

通过室内和田间试验，研究了Bt与硫丹、氟铃脲对棉铃虫的联合作用。结果表明：(1)Bt与硫丹无论以何种比例相混，对敏感品系和氰戌菊脂中抗品系均增效。(2)Bt与氟铃脲只有以1:60相混才明显增效；Bt中加入少量氟铃脲和氟铃脲中加入少量Bt则明显拮抗。（3）Bt与硫丹和氟铃脲混用，明显加快了2龄幼虫的死亡速度，混剂在处理后第3d，死亡率便明显高于Bt，而与硫丹或氟铃脲单用接近。（4）田间试验中，Bt和硫丹的混剂显著增效，Bt与氟铃脲的混剂在药后4d表现出一定的增效作用，但药后7d明显拮抗。

TOXICTTY AND FIELD EFFECT OF MIXTURES OF BACILLUS THURINGIENSIS WITH ENDOSULFAN AND HEXAFLUMURON TO THE COTTON BOLLWORM HELICOVERPA ARMIGERA

In the laboratory, mixtures of Bt and endosulfan at three different ratios increased the toxicity to 2nd instar larvae of Helwoverpa armigera. Moreover, the combination of Bt and hexaflu-muron at the ratio 60: 1 also enhanced the toxicity. Both kinds of mixtures accelerated larvae' s death. But increased toxicity was not observed when low concentration of Bt combined with hexaflu-muron and low concentration of hexaflumuron with Bt. The results of field trails showed that the control effect of mixture of Bt and endosulfan against the 4th generation cotton bollworm was better than that of Bt or endosulfan alone. However, the control effect of Bt/hexaflumuron combination varied. This combination exhibited synergistic effect 4 day after treated, but showed counter effect 7 day after sprayed.