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Although it can fly, the sweet potato whitefly is not actually a fly, rather, it is a hemipteran which congregates on the undersides of leaves to mate, lay eggs and feed, using piercing and sucking mouthparts to extract juices from its host plant. More than 500 species in 74 families are described as plant hosts for the polyphagous Bemisia tabaci. The small size of the sweet potato whitefly, its ability to fly and disperse long distances and its rapid reproduction predispose this species to explosive population growth. Bemisia tabaci is destructive in multiple ways. Areas of plants fed on by whiteflies whither and lose leaves. In addition to directly damaging plants by eating them, the whitefly larvae produce a sugary honeydew, which builds up on leaf surfaces and supports growth of sooty black and other molds. This mold residue reduces the plants’ ability to photosynthesize and thus also reduces the health of the plant, and on crop plants requires expensive washing to remove mold before they can be marketed. The sweet potato whitefly is also devastating in its role as a vector for over 100 plant viruses, especially Begomoviruses, which are responsible for a significant amount of crop damage and loss world-wide.
Bemisia is difficult to control with insecticides because it is difficult to reach the underside of leaves where the pests infect the plants, and also because it has rapidly developed resistance to every group of insecticide developed for its control. There is hope in limiting damage due to Bemisia through developing virus-resistant host plant strains as well as plant strains that discourage these pests (e.g. smooth, rather than hairy leaves and less waxy leaf coats are less attractive for whitefly oviposition). Biocontrol methods taking advantage of natural predators, parasitoids and pathogens of Bemisia are the leading long term solutions. Insect growth regulators specific to whitefly larvae can also be used help control the pest without indiscriminately killing beneficial species.
(McAuslane 2009; Wikipedia 2011, 2011; CABI 2001; Fasulo et al. 1995)