Bt与乙酰甲胺磷混配药效之时间动力强度

Time-dynamic Intensity of the Mixture-toxicity of Bt and Acephate

组建了Bt和乙酰甲胺磷两类不同性质、不同LT50剂量母液配对的类群A和B（以下简称A群和B群），其配对母液LT50的大小，前者均为“乙酰甲胺磷〈Bt”，后者均为“乙酰甲胺磷〉Bt”。以小菜蛾Plutella xylostella Linnaeus为试虫对两类群的系列体积混配组合逐一进行室内毒力测定，按同一死亡率观察时段范围，计算每一LT-p线所涉及的梯形面积，并将该面积定义为药效，亦即药剂致死作用的时间动力强度；以该面积的大小作为量化指标，再引申出计算动力增强系数Ⅰ和Ⅱ，运用于试验结果的药效分析。同时与其他不同药效量化评价方法进行了比较。结果表明：①在配对性质不同的类群A和B中，不同配对系列混配组合筛选出的“优良配比”数目不同。如A群有关配对的9个混配组合中，属于“优良配比”的一般仅在2个以下，而在B群内一般可达4～7个，表明B群的配对优于A群。②配对的优越性与母液间LT50值的合理搭配有关。如配对67．3／792．5和43．6／473．1，其LT50的差异明显较大，致使动力增强系数Ⅱ较小，仅为73．5和90．4；而LT50差异明显较小、或较适宜的配对80．57／90．36和23．76／45．31，其动力增强系数Ⅱ则较大，分别达110．3和101．8。

Bioassay of the time-dynamic intensity （TDI） of toxicity and the dynamic strengthen coefficient （DSC） were carded on under laboratory condition. DSC Ⅰ and Ⅱ of Bacillus thuringiensis （Bt） and acephate and their mixtures to larvae of diamond back moth （Plutella xylostella Linnaeus） were obtained. TDI values were all calculated as the basis of respective ladder-shaped area by LT-p line. The results showed that ： （1）The number of good mixture ratios for mother solution pairs （MSP） of two insecticides varied with pairs A and B. According to LT50 of MSP, the pairs A showed acephate was weaker than Bt,in contrast, stronger than Bt in the pairs B. There were less 2 good mixture from pair A and 4 -7 good mixture from pair B among 9 mixture combinations, that means pair B is better than pair A. （2）Good mixture in various combinations was related to the pairing of ＂LT50 to LT50＂ of MSP. For example ,the pairs of 67.3/792.5 and 43.6/473.1 with small average value of DSC Ⅱ ,being 73.5 and 90.4, respectively. In contrast, the pairs of 80. 57/90. 36 and 23. 76/45.31 showed larger average values,110.3 and 101.8.