阿维菌素B2海藻酸钠-壳聚糖包埋颗粒剂的制备及性能研究

为了提高阿维菌素B2的农药利用率,以海藻酸钠与壳聚糖为复合载体,采用复凝聚法制备了阿维菌素B2海藻酸钠-壳聚糖包埋颗粒剂,并研究了其理化性质及其在土壤中的释放性能。通过单因素试验筛选出对包埋颗粒剂包埋率影响较大的因素,并进行正交试验,以获得优化制备配方;用红外光谱表征包埋颗粒剂的化学结构,用扫描电子显微镜（SEM）观察其物理形态。采用土壤包埋法研究了其模拟释放性能。结果显示:制备阿维菌素B2海藻酸钠-壳聚糖包埋颗粒剂的优选配方为海藻酸钠质量分数1.5%,壳聚糖质量分数1%,Tween-20质量分数0.75%,投药量m（阿维菌素B2）: m（海藻酸钠）= 1 : 2,油水比[m（油相）: m（水相）] = 1 : 20;所制备的包埋颗粒剂的载药量为22.38% ± 0.25%,包埋率为95.26% ± 0.61%。SEM图像显示,包埋颗粒剂形状不规则;红外光谱数据显示,阿维菌素B2被成功包埋于载体中。土壤中的释放性能试验结果表明:包埋颗粒剂在土壤中突释明显,在前30 d,阿维菌素B2的释放量占80 d总释放量的60%以上;小粒径颗粒剂具有更快的释放速率。粒径150~300 μm和 > 300 μm的包埋颗粒剂释放符合一级动力学方程,粒径150~300 μm和 < 150 μm的包埋颗粒剂亦符合Higuchi方程。     

阿维·乙螨唑11%乳油高效液相色谱分析

本文采用高效液相色谱法,以甲醇+乙腈+水溶液为流动相,使用Nova-pak C184μm为填料的不锈钢柱和紫外波长检测器,检测波长245nm,对阿维·乙螨唑11%乳油进行的定量分析。结果表明,方法的标准偏差分别为0.055、0.046,变异系数为1.068%、0.744%,平均回收率为99.77%、99.32%,线性相关系数为0.999、0.999。     

Lack of fitness cost and inheritance of resistance to abamectin based on the establishment of a near-isogenic strain of Tetranychus urticae

Many populations of the two-spotted spider mite, Tetranychus urticae Koch, have developed high levels of resistance to the pesticide abamectin in China and other countries. This study developed a near-isogenic line to understand better the inheritance, cross-resistance, and fitness costs associated with abamectin resistance in the field population of T. urticae in China. We introduced the trait that confers extremely high abamectin resistance in a field-collected population of T. urticae into a susceptible laboratory strain (IPP-SS) to generate an abamectin-resistant near-isogenic line (NIL-Aba). This process was carried out through multiple backcrossing to IPP-SS and via parthenogenesis and abamectin screening. Compared with IPP-SS, the NIL-Aba strain had a 25 147-fold resistance to abamectin and a high level of cross-resistance to bifenthrin (288.17-fold), an intermediate level to emamectin benzoate (42.57-fold), and low levels to bifenazate, chlorfenapyr, cyflumetofen, cyenopyrafen, and cyetpyrafen with resistance ranging from 3.18- to 9.31-fold. But it had no cross-resistance to profenofos. The resistance to abamectin in NIL-Aba was autosomal, incompletely dominant, and polygenic. Based on two sex life table parameters, no fitness cost was found in NIL-Aba. Establishing the NIL-Aba strain provides a reliable basis for an in-depth study of abamectin resistance in T. urticae. New information on toxicological characteristics and fitness cost should facilitate the management of abamectin resistance in field populations of T. urticae.