似士维螨对西洋参的经济危害水平和经济阈值
Economic-injury Level and Economic Threshold of Schwiebea similis(Acari: Acaridae) on American Ginseng

为了提高西洋参苗期病虫害治理效果，采用播前化防技术（吡虫啉和咯菌腈混合液拌种+辛硫磷颗粒剂处理土壤）、种植2种农产品、保留2级参苗密度等4项组合为条件，测算并确定西洋参新害虫似士维螨的经济危害水平（EIL）和经济阈值（ET）。因培育2 a生种苗和4 a生鲜根而采用这种播前化防技术，以成虫当量（AE）表示，似士维螨的EIL值为3 314和4 726 AE/m或20.7和52.5 AE/株；为阻止似士维螨密度达其EIL值而提前1代施药防治其越冬种群，以雌螨当量（AFE）表示，相应的ET值为96和137 AFE/m或0.6和1.5 AFE/粒催芽籽。上述EIL和ET值反映经济危害水平，将其应用于似士维螨化防领域的结果用于指导生产实践，将有助于优化其防治策略、促进西洋参种植业蓬勃发展。
In order to improve effects of pest management on American ginseng in seedling stage, the author estimated and determined economic-injury levels (EIL) and economic thresholds(ET) for the root mite Schwiebea similis Manson (Acari: Acaridae), a new pest of the medicinal plant, under the condition of 4 combinations such as applying the chemical control technique before sowing (that is, dressing seeds with mixed liquids of imdacloprid and fludioxonil plus treating soils with phoxim granules), growing 2 kinds of produces, and reserving 2 densities of seedlings. To grow both 2-year-old seedlings and 4-year-old fresh roots, when applying the technique and expressed in adult equivalent (AE), the EIL for the mite were estimated at 3 314 and 4 726 AE/m or 20.7 and 52.5 AE per plant; when applying the pesticides one generation in advance to control of overwintered population so as to prevent its density from reaching the EIL, expressed in adult female equivalent (AFE), corresponding ET were 96 and 137 AFE/m or 0.6 and 1.5 AFE per geminating seed. The mean values of EIL and ET mentioned above reflect the results of the EIL concept’s application in the field of chemical control of the mite. Directing productive practices with them will be helpful to optimize control strategy of the mite, and promote development of American ginseng plantations.