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5、要考虑长期的影响一种措施不仅会短期杀伤有害生物种群,而且可能对其产生长期影响。另一方面,杀伤天敌的恶果短期内未必容易觉察,但我们总有一天会感到主要有害生物的复苏和次要有害生物上升的威胁。因此,不光要考虑以往的施药对当时的影响,也要考虑当时的施药对以后种群的长期影响。6、不同防治方法阈值也不同在实施某种措施的过程中建立一个阈值后,如改变防治手段或方法,该阈值即失去意义。有不少
5, to consider the long-term effects of a measure not only short-term killing of pest populations, and may have long-term effects. On the other hand, the consequences of killing natural enemies may not be readily apparent in the short term, but one day we may feel the threat of the recovery of the major pests and the rise of the secondary pests. Therefore, it is not only necessary to consider the impact of the previous pesticide application on the time, but also consider the long-term effects of the pesticide application on the future population. 6, different methods of control threshold is also different In the implementation of a measure of the process of establishing a threshold, such as changing the means or methods of prevention and control, the threshold is meaningless. There are many