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杀虫剂使用的最佳时间和最适浓度与很多因子有关,包括害虫种群动态、作物对为害的敏感性、作物单产和产品单价、杀虫剂药效降解速率和杀虫剂效率,以及气候条件等。运用边际分析方法,建立了确定杀虫剂使用的最佳时间和最适浓度的系统模型。此系统模型包括种群动态模型、产量损失预测模型、杀虫剂药效降解模型和杀虫剂效率模型。此外还引入了反映水稻对螟害敏感性程度的加权因子。通过求解一个函数的极大值问题,即可得到使得纯收益最大时的杀虫剂的使用时间和浓度。
The optimum time and optimum concentration of insecticide to use depends on a number of factors including the dynamics of the pest population, the susceptibility of the crop to the pest, crop yields and product prices, the rate of pesticide degradation and insecticide efficiency, and the climate Conditions and so on. Using the marginal analysis method, a systematic model for determining the optimal time and optimum concentration of pesticide use was established. The system model includes population dynamics model, yield loss prediction model, pesticide efficacy degradation model and pesticide efficiency model. In addition, weighting factors that reflect the sensitivity of rice to pest damage have also been introduced. By solving the maximum value of a function, the time and concentration of insecticide used to maximize net profit can be obtained.