草地贪夜蛾对不同生育期玉米产量的影响及防治指标

为明确草地贪夜蛾Spodoptera frugiperda对我国玉米产量造成的损失，并制订相应的防治指标，在玉米不同生育期分别接入不同数量的草地贪夜蛾3龄幼虫，研究其为害玉米后对产量和其他相关指标造成的影响，建立不同生育期产量损失与不同为害率之间的回归方程。结果显示，大喇叭口期接虫对玉米成株期株高有显著影响，玉米各生长时期接入不同数量草地贪夜蛾后对产量损失均有显著影响。根据防治成本及玉米产量等指标计算出国内玉米的经济危害允许水平为5.56%。利用回归方程计算出玉米小喇叭口期、大喇叭口期以及吐丝期的防治指标分别是为害率达8.72%、7.99%和6.17%。

Effects of fall armyworm Spodoptera frugiperda on corn yield at different growth stages and the control threshold

To clarify the corn yield loss caused by fall armyworm Spodoptera frugiperda in China and calculate the control threshold, the 3rd-instar larvae of S. frugiperda were introduced at different growth stages of corn to study the effects of its damage on yield and other related indexes. The regression equations between yield loss and damage rates at different growth stages were established. The results showed that the plant height of corn was significantly affected by insect infestation at late whorl stage, and the yield loss was significantly affected by different damage rates of S. frugiperda at all growth stage of corn. According to the control cost and corn yield index, the economic injury level of corn in China was 5.56%. The regression equations were then used to calculate the control thresholds at early whorl stage, late whorl stage, and silk stage, which were 8.72%, 7.99%, and 6.17%, respectively.