水稻食叶类害虫等量损害系统与复合防治指标

INJURY EQUIVALENCE SYSTEM OF LEAF-MASS CONSUMING INSECT GUILD ON RICE AND THE MULTIPLE-SPECIES ECONOMIC THRESHOLD

稻纵卷叶螟Cnaphalocrocis.medinalis Guenèe中华稻蝗Oxya chinensis (Thunberg)稻苞虫Parnara guttatus (Bremer et Grey)是江苏地区水稻的主要食叶类害虫,取食水稻叶片,导致光合叶面积减少。剪叶模拟试验表明,水稻不同生育阶段叶面积损失率与产量损失率呈线性相关。其回归方程分蘖期、孕穗期、腊熟期分别为 D(I_t)=72.50759I_t^1.15906、D(I_t)=141.61737I_t^1.08002、D(I_t)=25.12434I_t^1.00569。在叶面积损失率相同的情况下,产量损失率孕穗期>分蘖期>腊熟期。试验通过三种害虫的各龄取食量,不同生育阶段水稻叶面积及为害与损失率之间的关系,建立了不同生育阶段的经济允许损害水平(EIL_t)。并根据各种害虫的相对潜在取食量,计算了校正等量损害系数,为制订复合防治指标提供了依据。实践证明:以等量损害为单位的复合防治指标有较大的实用价值,生态效益、经济效益、社会效益明显。

The rice leaf roller Cnaphalocrocis medinalis,Chinese rice grasshopper Oxya chinensis and rice skipper Parnra guttatus are chief leaf-mass consuming insects on rice in Jiangsu Province.Simulation tests by leaf-cut were carried out at different development stages of the hybrid rice-'Shan You 63'.The results are summarized as follows:There was significant correlation between the yield lossess D(It) and the total consumption percentages (It) of leaf area at different developmental stages of rice The yield loss followed the order:booting stage>tillering stage>wax-ripening stage.The damage function relating yield loss to injury were D(It)=72.50759I,1.15906;D(It)=141.6173It1.108002;and D(It)=25.12434It1.00569 respectively.It is proposed to use the multiple-species economic injury level at different development stages of rice on the basis of leaf-consuming area,total leaf area at each stage of rice and the damage function relating yield loss to injury.In the present paper the injury equvalency system (IES) and multiple-species economic threshold on the basis of relative consumption potential of each species and the actual data for the leaf-mass consuming guild and related sampling information to the EIL are presented.For example,if the rice leaf roller is used as the standard species,the multiple-species economic threshold would be 2.49 IE per hill at tilling stage;1.16 IE per hill at booting stage and 4.79 IE per hill at the wax-ripening stage re-spsctively.The results have also proved that the indices 'injury equvalency' to assessing the multiple-species economic threshold is useful in the integrated pest management in rice.