Bt与乙酰甲胺磷混配药效之时间动力强度

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。

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

Bioassay of the time-dynamic intensity (TDI) of toxicity and the dynamic strengthen coefficient (DSC) were carried on under laboratory condition.DSCⅠand 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: ①The 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.②Good 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 DSCⅡ,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.