杨圆蚧严重威胁我国三北防护林。不少地方只进行化防,杀伤了天敌与污染环境,提高了防治费用。 到目前为止,此虫虫口密度达到多大是受害所不能允许的水平或虫口密度多大是在受害允许水平之下,这对综合管理杨圆蚧和制定科学防治指标具有重大的参考价值。如 Yang Kuwana serious threat to China’s Three North Shelterbelt. In many places, only chemical defense has been carried out, killing natural enemies and polluting the environment, raising the costs of prevention and treatment. So far, the population density of this insect is how much damage can not be allowed or how much the population density is under the allowable level of victimization, which is of great reference value for the comprehensive management of Yang Kuwana and the formulation of scientific control indicators. Such as