The B biotype of whitefly Bemisia tabaci has been regarded as an extreme generalist capable of causing heavy damage to many vegetables, ornamental plants and other crops. However, field and laboratory observations show that whitefly populations vary greatly in their performance on different host plants. A combination of factors including secondary chemicals, physical features and nutrition likely explain performance variations for herbivores feeding on different host plants, but the real situation might be even more complex than expected. In this study, the fecundity and survivorship of B biotype whitefly reared on 29 plant species were measured. Then fitness of whitefly on each host plants was estimated using two models that were designed to assess larval performance for herbivore populations. The fitness data for 23 plant species were analyzed by statistical methods that classified all hosts into 2 groups: preferred and acceptable. The preferred host group included only cucumber and cabbage on which whitefly performed very well with high fecundity and survivorship. In contrast, the acceptable host group included the remaining host plants where whitefly showed varied and modest nymphal performance. B biotype whitefly populations might depend on a hierarchy of niches as a means for adapting to host plants and exploiting new habitats. Whitefly are likely to occupy nuclear niches on several preferred plants that are important for population increase or shelter during unfavorable periods or in suboptimal environments. Meanwhile a wide range of acceptable hosts permit whitefly populations to spread and invade new areas around the world. It is still unclear why some whitefly biotypes (B and Q) were able to develop more successful niches than others. So future research should examine additional niche features such as structure and scale, source and sink potential, especially for generalist invasive species.