Tobacco caterpillar (Spodoptera litura (Fabricius)) and oriental tobacco budworm (Helicoverpa assulta (Guenée)) are important insect pests on tobacco which causing serious damage by defoliation. The niches and relationships of the two species were studied in this paper. The results indicated that the spatial niche breadth value and spatial niche overlap value of S.litura were higher than that of H.assulta, the spatial niche similarity between them was 0.0973. The temporal niche breadth values and temporal niche overlap values of S.litura and of H.assulta were very similar, and the temporal niche similarity between them was 0.9485. The coexistence ratios of S.litura and H.assulta on upper leaves, mid-leaves and underneath leaves of tobacco plants were only 6.11%, 3.23% and 0.51%, respectively. The results may suggest that the competition between S.litura and H.assulta is extremely improbable. The two species can occur and damage on the same tobacco plant at the same time because they incline to choose different spatial vertical resources.%斜纹夜蛾和烟青虫同是烟草上食叶类的重要害虫,对烟叶产量和品质均可构成严重的影响.研究两者在烟草上的生态位和种间关系,结果表明斜纹夜蛾的空间生态位宽度和空间生态位重叠指数均略大于烟青虫,两者空间生态位的比例相似性为0.0973,说明两种害虫在空间资源上几乎不存在竞争.斜纹夜蛾和烟青虫的时间生态位及时间生态位重叠指数很接近,时间生态位的比例相似性高达0.9485.斜纹夜蛾和烟青虫在烟草植株上、中、下部叶片共存的比例分别为6.11%、3.23%和0.51%.由于对空间垂直资源的不同选择,使它们可以同时在同株烟草上为害而互不干扰.
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