稠合杂环化合物唑虫酯对草地贪夜蛾的活性研究

The bioactivity of fused heterocyclic compounds of pyraquinil against Spodoptera frugiperda

【目的】草地贪夜蛾Spodoptera frugiperda原产于美洲,是一种对农作物造成严重危害的昆虫,被国际农业和生物科学中心CABI评为世界十大植物害虫。目前已入侵我国14个省区,对我国玉米等种植业造成严重威胁,为做好草地贪夜蛾的防控工作,及时控制其为害。【方法】采用浸叶法测定了唑虫酯对草地贪夜蛾幼虫的室内毒力,并进行了田间药效试验。【结果】唑虫酯对草地贪夜蛾幼虫具有优异的活性,处理后1、2、3d,对2龄幼虫的LC50值分别为5.51、1.95、0.91mg/L;对3龄幼虫的LC50值分别为7.50、3.92、1.94mg/L;对4龄幼虫的LC50值分别为13.79、10.30、8.78mg/L。田间药效结果表明,玉米喇叭口期,喷雾处理后3d,唑虫酯对1-3龄幼虫的防效达到90%以上,对4-6龄幼虫的防效在50%以下。药液喇叭口点施处理后3 d,唑虫酯对草地贪夜蛾的防效在93.65%以上,施药后7 d,防效在98.78%以上。【结论】药剂对低龄幼虫杀灭效果好,高龄幼虫具有钻进性,不容易防控。应结合虫情监测和田间监测情况,把握住1-3龄幼虫防控关键时期。

[Objectives] Spodoptera frugiperda, an insect native to the Americas, causes significant damage to crops worldwide and has been rated one of the world’s top ten plant pests by the international center for agriculture and biological sciences(CABI). S. frugiperda has now invaded more than 14 provinces in China's Mainland where it poses a major threat to corn and other crops. [Methods] We used the leaf immersion method and field trials to investigate the biological activity of pyraquinil against S. frugiperda larvae. [Results] The LC50 of pyraquinil after one two and three days was 5.51、1.95 and 0.91 mg/L, respectively for 2 nd instar larvae, 7.50, 3.92 and 1.94 mg/L, respectively for 3 rd instar larvae, and 13.79, 10.30 and 8.78 mg/L, respectively for 4 th instar larvae. At the corn trumpet stage, field trial results show that by 3 d after spray treatment pyraquinil had reduced the numbers of 1 st to 3 rd instars by > 90%, but the reduction in numbers of 4 th to 6 th instar larvae was < 50%. At the corn trumpet stage, control was over 93.65% after 3 days and over 98.78% after 7 days of trumpet point treatment. [Conclusion] Pyraquinil is effective on the younger larvae of S. frugiperda, but older larvae are less susceptible because they are able to burrow into corn plants. The key window for the prevention of S. frugiperda is therefore the 1 st to 3 rd instar period. Pesticide application should be combined with plant and field monitoring.