几种植物的杀虫活性初探

首次报道黄连（根）和菟丝子（种子）的杀虫活性。用1％浓度的甲醇提取物处理试虫后，所筛选的植物巾菟丝子种子和李叶绣线菊茎的甲醇提取物对家蝇48h的毒杀作用强，分别为100．00％和75．86％，单面针叶和阔叶十大功劳茎叶也有较好的毒杀作用，分别为58．62％和67．86％。黄连根甲醇提取物24h和大叶醉鱼草茎叶甲醇提取物48h对亚洲玉米螟3龄幼虫的拒食率分别为76．48％和76．50％，且出现虫体细且短小、头部宽大、与腹部极不对称和化蛹延迟现象，大黄和阔叶十大功劳也表现出一定的毒杀或拒食或抑制生长发育现象。所筛选的特有植物对赤拟谷盗种群的毒杀作用和繁殖抑制作用较低。毒杀作用最强的为大叶醉鱼草茎叶，处理后30d，赤拟谷盗的死亡率为40．16％，繁殖抑制率最强的为黄连根，处理后60d，繁殖抑制率为46．38％。以甲醇冷浸提取法对所采集的植物材料进行冷浸提取时，提取率分布在1．41％～7．06％之间。

Preliminary investigations on insecticidal activity of several plant species

Previously unreported insecticidal activities of Coptis chinensis roots and Cuscuta chinensis stems were determined. Among all plant material screened, 1% methanol extracts of Cuscuta chinensis seeds and Spiraea prunifolin stems provided 100.00 and 75.86% control, respectively, of house fly adults 48 h after treatment. Zanthoxylum planispium leaves and Mahonia bealei stems and leaves also exhibited toxicity against house fly adults, with 58.62 and 67.86% mortality, respectively. Antifeedant rates of methanol extracts of Coptis chinensis roots (24 h after treatment) and Buddleja davidii stems and leaves (48 h after treatment) against third instar larvae of Ostrinia furnacalis were 76.48 and 76.50%, respectively, while the bodies of test insects became very small and short with enlarged heads and pupation was delayed. In addition, Rheum officinale and Mahonia bealei showed a degree of toxicity or antifeedant activity or growth inhibition activity against the third instar of O. furnacalis. All tested plants showed weak poisoning activity and reproduction inhibition activity against adults of Tribolium castaneum, with the highest mortality being 40.2% caused by Buddleja davidii stems and leaves 30 d after treatment and the highest reproduction inhibition rate being 46.4% caused by Coptis chinensis roots 60 d after treatment. Methanol extraction rates of these plants varied from 1.41 to 7.06% by a cold soaking method.