Attractiveness of three cucurbit plants to the silverleaf whitefly, Bemisia argentifolii (Homoptera: Aleyrodidae), and their potential as a trap crop for whitefly management on poinsettia

Trap cropping makes use of a highly preferred host plant to draw insect pests away from a less preferred main crop. Three cucurbit plants, cantaloupe (Cucumis melo), cucumber (C. sativus), and squash (Cucurbita pepo), were tested as a trap crop for the silverleaf whitefly (Bemisia argentifolii) on greenhouse poinsettia (Euphorbia pulcherrima). The tests were conducted with two whitefly populations that had been reared for more than 1 year each on bean (B-population) or poinsettia (P-population). Adult whiteflies were released in cages and their preference for one of the cucurbit plants and poinsettia was measured. In all cases, a greater proportion of adult whiteflies were observed on the cucurbit plant compared to the poinsettia: For the B-population, the proportions of the adults on cantaloupe, cucumber, and squash were 85, 78, and 83% after 3 days, respectively; for the P-population, the proportions were 77, 85, and 77%. A second cage experiment was conducted to determine the extent to which cucumber could draw adult whiteflies away from poinsettia when poinsettia was initially infested with whiteflies. A greater proportion of adult whiteflies were always observed on the pre-infested poinsettia than the cucumber: For the B-population, the proportion of the adults on cucumber increased up to 16% after 3 days; for the P-population, the proportion increased up to 26%. The result suggests that cucumber has a limited potential as a trap crop for management of the silverleaf whitefly on poinsettia.