落叶松鞘蛾防治指标的研究

根据害虫发生量预测模式来测害虫未来种群数量,就成为制定防治计划和措施的依据。在森林害虫管理中,把经济损失的最低发生量视为“经济受害允许水平”。为了防治落叶松鞘蛾为害造成的经济损失而进行防治时,事先要衡量害虫造成的损失价值与防治经费之间的得失关系,如有所获得时,才要进行防治,这种与“经济受害允许水平”相应的阈值就是防治指标。在确定害虫防治指标前,首先确定害虫为害指标,就是有多少头落叶松鞘蛾幼虫食多少落叶松计叶而导致对树木生长有明显影响。从模拟摘叶试验中得出结论,摘叶量达到1/2时,对落叶松生长量有明显影响,所以当落叶松鞘蛾幼虫为害达到此标准时的虫口密度定为为害指标。试验证明,当落叶松鞘蛾幼虫发生量控制在9头/株以下时,可以获得较大的经济效益,超过此发生量,一定要进行防治,所以当鞘蛾虫口密度超过9头/株,针叶量损失1/2时定为防治指标。

STUDY ON THE CONTROL INDEX OF LARCH CASEBEARER

It is basis for working out the plan and meas(?)re of prevention to predict the quantity of future population according to pest occuring amount model. In the management of forest insect pests, the least economic losses is regarded as the allowable level of economic damage, the losses value caused by in ect pest, the preventing and controlling expense must be judged. If there is some economic effect, prevention and control should be conducted. This allowable level of economic damage is the index of prevention and control. The index of pests do harm is how many larvae of larch casebearer eat how many coniferous leaves of larch result in obvious impact on the trees growth. The conclusion from the simulated test of picking leaves identified that: when the leaves were picked off 1/2, there is obvious impact on the growth, the density of insect pests is decided to be the index of pests do harm. When the occurring amount is controlled under 9 larvae/branch, greater economic benifit can be obtained. So, the larva density of larch casebearer exceeding 9 larvae/branch, and the quantity of coniferous leaves damaged up to 1/2 is decided to be the index of prevention and control.