以烟粉虱为供试昆虫,采用不同处理方法对噻虫嗪活性进行了综合评价。3种处理方法对烟粉虱若虫毒力测定的结果显示,正面施药法、叶柄包药棉法和浸叶法的最高浓度(125 mg/L,2 000倍液)对1、2龄若虫的校正死亡率均达到90％以上,浸叶法和叶柄包药棉法的效果优于正面施药法。噻虫嗪对烟粉虱成虫同样具有较高活性,内吸作用效果最好,其次为浸叶法,正面施药法最低。灌根和喷雾施药方法对烟粉虱的田间防效显著高于单叶施药和涂茎方法,药后1 d、3 d的防效均达到95％以上,灌根方法持效期可达14 d以上。上述结果表明,噻虫嗪的内吸传导作用最强,其次为触杀活性,并有一定的渗透性,在田间持效期长,在生产中可以根据需要选择使用不同的施药方式,以达到最佳防治效果。
The toxicity and efficacy of thiamethoxam to tobacco whitefly, Bemisia tabaci were examined through laboratory bioassay and field trial. Results showed that thiamethoxam had good activity to the 1st and 2nd instar nymphs, and the adjusted mortalities were over 90% at the highest concentration of 125 mg/L. The efficacy of leaf-dipping method and wrapping the leafstalk with thiamethoxam (treated cotton) were better than that treating upside of the leaf only. Meanwhile high effectiveness of thiamethoxam was also observed to adult of the whitefly. Efficacy of the systematic action was the highest,the next was leaf-dipping method, and the last was the method treating upside of the leaf only. In the field trial, drench application and spraying had good effect, the control efficiency reached about 95% after 1 and 3 days treatment, and the efficacy could sustain for over 14 days with drench application. These results indicated that thiamethoxam has excellent systematic efficacy and contact activity, strong penetrating effect and long-lasting residual activity, which provide farmers selectable application methods to obtain best control results.