Potter喷雾法操作因子对杀虫剂毒力的影响

研究了Potter喷雾法操作因子对杀虫剂沉积量和毒力的影响，15，30，60，120s4种沉积时间对沉积量的影响很小，不影响乐斯本对斜纹夜蛾2龄幼虫毒力，但喷雾体积和喷雾压力对沉积量有显著影响，对乐斯本，灭多威和高效氯氰菊酯3种杀虫剂的毒力也有显著影响，喷雾压力对沉积量和毒力的影响要小于喷雾体积，这3种杀虫剂4mL处理的毒力（LC50）比0.5mL处理分别高11，3和5倍，而不同喷雾压力处理之间的毒力差异均在2倍以内，操作因子对毒力曲线的斜率的影响很小，因此影响Potter喷雾法毒力测定结果的操作因子主要是喷雾体积和压力，适宜的操作条件是：沉降时间30－60s，喷雾体积1－2mL，喷雾压力100kPa.

Studies on the Influence of Operational Factors on the Toxicities of Insecticides in Potter Tower Method

A series of laboratory bioassays was conducted to determine the effects of various operational factors on the deposition and the responses of 2nd instar larvae of tobacco cutworm, Spodoptera litura , to three insecticides, chlorpyrifos, methomyl and beta cypermethrin in the petri dish Potter tower method. Settling time could affect the deposition. Toxicities of chlorpyrifos on the tested insects were not significantly different between 15, 30, 60, 120 s settling times. The spray volume (0 5-4 0 mL) and pressure (25-200 kPa) significantly influenced the deposition and the responses of tobacco cutworm to insecticides. For the three insecticides, LC 50 of a 4 0 mL spray volume was 11, 3 and 5 fold more toxic than that of a 0.5 mL spray volume, respectively. However, the influences of pressure on the deposition and LC 50 were not so serious as volume, and the difference of between pressures was less than 2 fold. The optimal spray conditions in Potter tower method were suggested.