几种药剂对褐稻虱种群数量控制的研究

本研究应用昆虫生命表及种群趋势控制指数方法,探讨几种药剂对揭稻虱种群数量的控制作。同时研究这几种药剂对稻田天敌密度的作用,并通过杀虫剂的毒力测定,验证主要的两种天敌对几种杀虫剂的反应。 试验结果表明:喹硫磷由于严重杀伤稻田天敌,因而增大了下代的种群趋势,控制指数(14.36)甚低于对照区(28.43)。叶蝉散区的控制指数(29.40)仅略高于对照区,在天敌作用比较明显的环境下(对照区的种群趋势指数为1.8793),防治效果不明显。优乐得(App-laud)区的控制指数最高(65.96),种群趋势指数最低(0.7523),这种药剂属于主要对同翅目昆虫起作用的生长调节剂,不但抑制褐稻虱的种群数量,同时也相对地助长其天敌的作用,因而防治效果较好。 在昆虫生命表的基础上,通过种群趋势控制指数的分析,有助于杀虫剂和天敌协调作用的综合评价。

STUDIES ON THE EFFICACY OF SEVERAL INSECTICIDES IN COTROLLING RICE BROWN PLANTHOPPER, NILAPARVATA WGENS POPULATION

In this paper,the life tables and indices of population control(IPC)were applied at the methods to evaluate the effect of several insecticides on the population dynamics of the rice-brown planthopper,Nilaparvata lugens Stao1.At the same time,the population dynamics of natural enemies in rice fields were also studied,and the response of two major natural enemies to several insecticides was examined by toxicity tests.The experimental results showed that the IPC of area spraying Quinaphos(14.36)was much lower than that of the control(28.43)(the population trend of next generation was upward),while control effect was unsatisfactory,because of having killed a proportion of natural enemies in the paddy field.The IPC of MIPC was only a little higher than that of the control(29.40).The IPC of Applaud was highest(65.96)and its index of pepulation trend was lowest(.7523),this insecticide being an insect regulator with high activity on Homop-tera,killed mainly rice plant hoppers and favoured most of natural enemies in rice fields.Therefore,it not only decreased the abundance of the rice planthoppers,but also increased omparatively the effect of natural enemies.As a result,the population of the brown planthopper was controlled effectively.The life table and the index of population control(IPC)are helpful in evaluating the efficacy of insecticides harmonic to natural enemies.