五种杀虫剂现场灭蚊幼效果观察

Efficacy of Five Mosquito Larvicides Against Mosquito Larvae in Field

目的了解几种不同作用机制的化学杀虫剂在灭蚊幼中的效果及持效期,为今后防治蚊幼工作提供可靠的依据。方法选择污水沟和苇塘后测量水体体积,分别施药(毒死蜱、10%高效氯氰菊酯有效成份:1 g/m3;50%马拉硫磷有效成份:1、2 g/m3;苏云金杆菌:40ml/m3,天蟾:10ml/m3),并在施药前后用勺捕法进行密度测定,施药后70d内评价效果。结果苏云金杆菌以40ml/m3施于污水沟内,1～7 d密度下降率为39.97%～100%;于苇塘施药后1～38 d达79.66%～100%;天蟾杀蚊幼虫悬浮剂在施药后1～d、6～14 d、24 d密度下降率分别为99.53%,100%,93.01%。毒死蜱、马拉硫磷、高效氯氰菊酯施药量为1 g/m3,对蚊幼毒性高低及持效期的长短依次为:毒死蜱>高效氯氰菊酯>马拉硫磷,毒死蜱在施药后68 d密度下降率仍达95.34%。结论毒死蜱、天蟾杀蚊幼虫悬浮剂杀蚊幼效果及持效期较长,值得推广应用,在实际现场灭蚊幼中可根据环境、特点、水体污染状况等选择适宜的杀虫药剂和使用剂量。

Objective To observe the efficacy of 5 kinds of mosquito larvicides against mosquito larvae of C. pipiens pallens in field and provide the scientific data for controlling mosquito larvae in future. Methods The experimental site （include treatment and control area） were selected and the volume of water body were measured, then insecticides were sprayed respectively into the experiment spot. The density assessment was carried out periodically with the ladle catches method in the treatment and control area before and after treatment. Results Applied Bti （dosage 40 ml/m^3） for controlling mosquito larvae in sewage type and in clear water type （reed pond）. After treatment for 1-7d , the decrease rate of larvae density was from 39.97% to 100% in sewage type water and after treatment for 1-38 d, it was from 99.71% so 100% in the clear water. Applied the mixture of Bti and Bs-10 （10 ml/m^3） for controlling mosquito larvae in reed pond, after ld, 6-14 d, 24 d, the decrease rate of larvae density were 99.53%, 100% and 93.01% respectively. When the application dosage was lg a.i./m^3, chlopyrifos, malathion, beta-eypemethrin were tested for controlling mosquito larvae in field, the efficacy ranked as chlopyrifos〉 beta-eypemethrin〉 malathion. 68 days after chlopyrifos was sprayed, the decrease rate of larvae density was still 95.34%.Conclusion The efficacy and persistent activity of chlopyrifos and the mixture of Bti and Bs-10 against mosquito larvae was better than the others. To control mosquito larvae in field, the suitable larvicides and application dosages should be applied according to the environment, characteristics, the pollute condition of water body etc.