The invasive whitefly Bemisia tabaci (Gennadius) is a worldwide pest of agricultural crops that feeds on a wide variety of host plants. Although host plant preference is known to vary among B. tabaci biotypes, far less is known about the potential for intraspecific divergence caused by long-term isolation on a single species of host plant. We tested the hypothesis that multigenerational isolation of B. tabaci B, a biotype that has been well-established in China for nearly two decades, on three different host plants would lead to population-level divergence in feeding behaviors. We used individuals from a cabbage-feeding (Brassica oleracea L.) population of B. tabaci B to create three populations reared exclusively on B. oleracea, cucumber (Cucumis sativus L.), or tomato (Lycopersicon esculentum Mill.) for >80 generations. We then used electrical penetration graph techniques to investigate the feeding behavior of the three B. tabaci populations on each of the three host plants (nine total treatments). Across all three host plants, the cabbage-specific population equaled or exceeded the performance of the cucumber-specific (CuSP) and tomato-specific (ToSP) populations. Strikingly, neither CuSP nor ToSP ever had the best feeding performance on their natal hosts. Our results support the hypothesis that feeding differentiation has occurred, but we found no evidence that these changes increased the feeding performance of either CuSP or ToSP. Although confirming that rapid interpopulation divergence is possible, our findings nonetheless suggest that this differentiation did not yield highly adapted populations that might pose problems for future efforts at pest management.