华北棉区二代棉铃虫和叶螨为害棉花的动态复合防治指标研究

1993年在河南省郑州市进行二代棉铃虫和叶螨对棉花的复合为害和动态防治指标田间开放式小区试验。按“206”回归最优设计布置处理,以肩然感虫结合人工接虫形成棉铃虫量和螨害指数梯度组合,用协方差分析排除黄萎病干扰,以订正后的皮棉损失率为试验结果。主成分分析证明棉铃虫和叶螨的一次及二次型数值,尤其是二者的交互作用与皮棉损失率都呈显著正相关,得出二者复合为害二次曲线方程为: y=-0.13903 0.16901x_1-2.535×10~(-4)x_1~2 1.0502x_2-0.01185x_2~2 3.614×10~(-4)x_1x_2±0.63 由此推导出3％允许皮棉损失率的棉铃虫单独为害防治指标为29.5头3龄幼虫/百株,叶螨单独为害防治指标为3.11％螨害指数,以及一系列动态复合防治指标。

ON THE DYNAMIC COMPOUND ACTION THRESHOLDS OF SECOND GENERATION COTTON BOLL WORM AND SPIDER MITES DAMAGED TO COTTON IN NORTHERN CHINA COTTON AREA

In 1993, an uncaged field experiment on the compound damage and dynamic action thresholds of second generation cotton bollworm Helicoverpa armigera (Hubner) and spider mites (mixed population of Tetranychus cinnabarinus (Boisduval) and T. trunca-tus Ehara) to cotton was carried out in Zhengzhou City, Henan Province. The treatments were arranged according to "206" optimum regression design, the gradient combinations of larvae number of cotton bollworm and damage index of spider mites were formed by inoculation on natural population,and the lint loss rates, after the disturbance of Verticillium wilt disease was removed by co-variance analysis, were adopted as the experimental results. The principal pomponent analysis indicated that there were significant positive correlations among the linear and quodratic values of cotton boll-worm and spider mites, especially their interactions, and the lint loss rates of cotton. A quodratic camber equation dealt with the compound damage of the two pests to cotton lint loss rate was developed as follows:Under the 3% tolerant lint loss rate, 29. 5 3rd instar larvae/100 plants of cotton boll-worm alone, 3.11% damage index of spider mites alone, and a series of dynamic compound action thresholds of the two pests were derived from this equation.