Oleson James D, Park Yong-Lak, Nowatzki Timothy M, Tollefson Jon J
Department of Entomology, Iowa State University, Ames, IA 50011-3140, USA.
J Econ Entomol. 2005 Feb;98(1):1-8. doi: 10.1093/jee/98.1.1.
Corn rootworm larval feeding on corn roots can significantly reduce grain yield by interfering with photosynthetic rates, limiting the uptake of water and nutrients, and by increasing the plant's susceptibility to lodging. Of the techniques developed to measure the efficacy of corn rootworm larval control tactics, root damage ratings have generally been adopted as the standard because sampling roots is relatively efficient. Historically, the primary scales used for scoring root injury from corn rootworm larval feeding have been the 1-6 and 1-9 scales. A critical deficiency of those scales, however, is that each increase in a root-rating score does not reflect a linear increase in the actual amount of injury to the root system. This results in injury scores that are expressed qualitatively. We developed the node-injury scale to more accurately quantify corn rootworm larval injury based on the proportion of nodal roots that contain feeding injury. With the node-injury scale, the relationship between the numerical scale and the amount of root injury is linear and intuitive. In this article, we describe the node-injury scale, discuss sampling issues to consider when using the scale, and suggest the minimum node-injury score that causes economic damage under varying degrees of environmental stress.
玉米根萤叶甲幼虫取食玉米根系会干扰光合速率、限制水分和养分吸收，并增加植株倒伏易感性，从而显著降低谷物产量。在已开发的用于衡量玉米根萤叶甲幼虫防治策略效果的技术中，由于对根系取样相对高效，根损伤评级通常被用作标准。从历史上看，用于评估玉米根萤叶甲幼虫取食造成的根系损伤的主要尺度是1 - 6级和1 - 9级。然而，这些尺度的一个关键缺陷是，根系评级分数每增加一级，并不反映根系实际损伤量的线性增加。这导致损伤分数是定性表达的。我们开发了节点损伤尺度，以便根据含有取食损伤的节根比例更准确地量化玉米根萤叶甲幼虫造成的损伤。使用节点损伤尺度时，数值尺度与根系损伤量之间的关系是线性且直观的。在本文中，我们描述了节点损伤尺度，讨论了使用该尺度时要考虑的取样问题，并提出了在不同程度的环境胁迫下造成经济损害的最小节点损伤分数。
