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刘女士为自己购买的养老保险产品的内涵报酬率是()。
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目前投资于开放式基金需要缴纳的税收政策主要是()。
封闭式基金相对开放式基金会的特有投资风险是()。
保险合同的解释原则中不包括()。
Agricultural pests are winning the battle against the poisonous chemicals in pesticides. As each new chemical pesticide is used, the insects or rodents gradually become used to it. The pests change themselves so that they are not killed by the poison. Therefore, farmers, scientists, and food planners are trying a new method to control the pests that attack their crops, This method is called Integrated Pest Management or IPM.
Integrated Pest Management is a plan that combines several different methods to destroy insects and rodents. These methods are specifically developed for individual areas and crops. The control methods include using the pests' natural enemies, controlling the pests' breeding environment, and developing stronger varieties of seeds. Chemical poisons are used only when necessary. The IPM method accepts the fact that it is useless to try to destroy pests completely with chemical poisons. Its aim is to control pest populations so that crops can still grow well.
Cotton farmers in Texas have been using the IPM method; The farmers find the best combination of control methods for their needs. In this way, they can produce crops without using too many chemical poisons. In 1977, three quarters of Texas cotton fields received no insecticides at all. That year's cotton crop was better than average. The IPM methods showed the farmers a better way to control the pests in their fields.
The United Nations Environment Program(UNEP)has been studying agricultural pests and chemicals. It has found that 223 pests are resistant to, or not affected by, insecticides. Rodents, including rats, are also gaining resistance to poisons. In 1965, another UN organization, the UN Food and Agricutural Organization, listed 182 resistant types of pests. Three years later, there were 228 species on the resistant list. The 1977 survey raised the number to 364 species. Because so many pests are becoming resistant to chemical poisons, it is necessary to find another method of control. By using Integrated Pest Management, farmers can still control and limit pests without depending on chemical poisons.
Agricultural pests are______.
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