The objective of this research was to evaluate the behavior of the whitefly, Bemisia tabaci (Gennadius, 1889) biotype B (Hemiptera: Aleyrodidae), in an isolated and mixed planting design with sesame, Sesamus indicum L., and cowpea, Vigna unguiculata (L.) Walp. The experiment was set in two arenas into cages where four situations were possible: Arena 1; preference of whiteflies for sesame (central position) when associated with cowpea on outside position. (Treatment 1); whitefly preference for cowpea in presence of sesame considered potentially as an attractive plant (Treatment 2); Arena 2: cowpea in central position with the same species around to evaluate the whitefly infestation with the absence of the alternative harborer. (Treatment 3); and cowpea in an external circle to verify the insect preference in this special distribution (Treatment 4). Treatments were composed by those four situations replicated 10 times in a period of three months. The attractiveness of the plants to whiteflies was evaluated by counting all nymphs in a 2 cm2 circular area taken from the two oldest leaves of the plants. It was observed, by counting nymphs, that the whitefly, Bemisia tabaci (Gennadius) byotipo B prefer sesame seed, Sesamum indicum L., instead of cowpea, Vigna unguiculata (L.) Walp. Cowpea leaves showed a low number of nymphs even when the adults had no choice. The flat distribution pattern of the cowpea plants in the arena didn’t interfere in the preference of the ovipositor.
