华南稻田农田害鼠复合防治指标的理论研究

Theory model of the multiple-species economic threshold of farmland rodents in rice fields, South China

依据对华南地区稻田 3种主要害鼠黄毛鼠、板齿鼠和小家鼠的田间捕获率调查 ,以及对害鼠造成的相应水稻产量损失率 ( y)研究 ,建立了水稻产量损失率与鼠密度关系的多元线性回归方程。确定板齿鼠作为本项研究的标准鼠种 ,利用 3种主要农田害鼠的捕获率在回归方程中对应的系数 ,计算出农田害鼠的标准当量损害指标。结果显示 ,每个标准鼠单位造成的水稻产量损失率分别相当于 4.0 84个黄毛鼠当量单位 ,或 31 .5 93个小家鼠当量单位。进一步 ,对原始调查数据进行二次处理 ,建立了标准当量 ( x)与 ( y)的相互关系数学模型 ;文中配合 EIL计算公式 ,求出了在不同水稻产量和不同灭鼠效果等条件下的华南农田害鼠的复合防治指标。

This paper deals with the theory model construction of the multiple-species economic threshold of farmland rodents in rice fields, South China. Three rodent species including Rattus rattoides Hodgson, Bandicota indica Bechstein and Mus musculus, were studied. The sampling sites were selected in Dongguan City and Boluo City of the Pearl River Delta; where characterizes with alluvial plain and few hills or low mountains. Two multiple linear regression models were constructed by analyzing the relations between the yield losses rate of rice (y) and the capture rates of the three main species of rats. The concept of equivalent density of rodent was proposed. Equivalent density could be used to define the standard quality damage and to calculate the total damage caused by the three main rodents in the farmland. B. indica was determined as the basic species of rodent. By comparing and computing the coefficients of two multiple linear regression equations, the results showed that the damage ability of one B. indica (x 2) equals to that of 4.084 individuals of Rattus ratoides(x 1) and 31.593 individuals of Mus musculus(x 3). The quantity of total density of mixed population (x) belongs to the area [2.480,5.870]. Models were made to simulate the relationship between x and the rate of yield losses of rice (y). The simulation results showed that the mean arithmetical error to the rate of yield losses of rice (y) is smaller than 7.79%. To formulate a policy for farmland rodent controlling, it was considered that the best opportunity for rodent controlling is at the period when the rate of yield losses of rice increases slowly and the density of mixed population is also lower, so that the cost of controlling should be lower too. Based on the models (14)～(16), a basic principle to draft the multiple-species economic threshold (MET) should be that: MET<x 0=1.3404. By using the calculating equation for economic permitted injury level (EIL), the multiple-species economic threshold was calculated (see table 5) under local different conditions such as rice yield, price of rice and effectiveness rate of killing rodents.