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甘兰夜蛾在宁夏引黄灌区连年发生,过去主要为害白菜、甘兰等蔬菜,80年代以来随着甜菜的发展,又成为甜菜的主要害虫.尤其是第二代幼虫在8月下旬对甜菜为害甚烈,严重时几天之内可将叶片食尽,仅留叶脉及叶柄,可使产量降低10~20%,糖度下降0.8~1.0度,对甜菜生产影响极大.为
Hyphantria cunea occurred year after year in Ningxia Yellow River Irrigation Area, the past major damage cabbage, cabbage and other vegetables, with the development of beet since the 1980s, has become the major pests of sugar beet, especially the second generation larvae in late August on the beet Very damaging, severe within a few days can be exhausted leaves, leaving only the veins and petiole, can reduce the production of 10 to 20%, 0.8 to 1.0 degrees sugar reduction, the great impact on the production of sugar beet