杀蚊幼剂对外环境水体蚊幼杀灭效果研究

目的了解不同杀蚊幼剂对蚊幼的杀灭效果，为今后防治蚊幼提供科学依据。方法选择水体，随机分为试验组和对照组，于试验前后一定间隔分别测定幼虫密度，并计算出密度指数、相关密度指数（PRI）和杀灭率。试验时分别将试验药剂施放于水体中（施药剂量：毒死蜱0．5、1ga．i／m^3；双硫磷1ga．i／m^3；马拉硫磷2ga．i／m^3）。结果2种剂量毒死蜱投药后1d对蚊幼虫杀灭率均为100％，前者持效66d，后者为69d；施药剂量为1ga．i／m^3双硫磷施药后1d仅发现1只蚊蛹，杀灭率达99．76％，2d达100％，投药后65d时仍达80．56％；2ga．i／m^3马拉硫磷施药后7d杀灭率为100％，12d时为85．59％，14d降至55．18％。结论结果表明，对幼虫杀灭效果及持效期优劣依次为：毒死蜱〉双硫磷〉马拉硫磷。建议今后水体灭蚊幼时，在条件允许的情况下，推荐使用前者.

Efficacy of mosquito larvicides against mosquito larvae in field

Objective To study on efficacy of different larvicides against mosquito larvae and provide scientific data for controlling the mosquito larvae in future. Methods The different water bodys were selected to randomized into the experimental spot and control spot. Assessment of pretreatment density and post-treatment were carried out separately at a time interval in treatment and control area. To calculate the density index, the population related index （PRI） and the killing rate of mosquito larvae to evaluate the efficacy of the larvicides against mosquito larvae. At the beginning of the test, three kinds of larvicides were put into the water body respectively. The dosage of larvicides were chlorpyrios at 0. 5 and 1 g a. i/m^3 , temephos at 1 g a. i/m^3 and malathion at 2 g a. i/m^3. Results The killing rates for mosquito larvae of two dosages of chlorpyrios were 100% equally at the first day after treatment, the effective durations lasted for 66 days and 69 days respectively. At the first day with emepbos treatment, a mosquito pupa was found in the water body and the killing rate was 99. 76% ; the killing rate were 100% at the second day and 80. 56% at the sixty-fifth day respectively. The killing rate of malathion were 100% , 85.59% and 55.18% at the seventh day, the twelfth day and the fourteenth day respectively ＇after treatment. Conclusion The results show that they are chlorpyrios 〉 temephos 〉 malathion respectively on the base of their efficacy and residual activity against mosquito larvae one by one in order. It indicates that cblurpyrios is recommended for killing mosquito larvae in water body in future if the condition is allowed.