宁南县是一个以农业为主的山区小县,为了发展畜牧业,县有关部门结合宁南实情,引进了紫花苜蓿、白眉草等优质牧草在宁南各乡镇示范种植。宁南得天独厚的光热资源为各种植物的生长提供了适宜的环境,但同样有利各种病虫草害发生、蔓延、为害。2005年全县紫花苜蓿田斜纹夜蛾大发生 Ningnan County is a mountainous small county dominated by agriculture. In order to develop livestock husbandry, the relevant departments of the county, in combination with the actual situation in southern Ningxia, introduced high-quality forage grass such as alfalfa and breed grass to plant demonstration in various towns and villages in southern Ningxia. Ningnan unique light and heat resources for the growth of a variety of plants provide an appropriate environment, but also beneficial to a variety of pests and diseases occur, spread, damage. In 2005 the county alfalfa field occurrence of Spodoptera major