"Whiteflies, Hemiptera: Aleyrodidae, Bemisia tabaci, a complex of morphologically indistinguishable species ... , are vectors of many plant viruses. Several genera of these whitefly-transmitted plant viruses (Begomovirus, Carlavirus, Crinivirus, Ipomovirus, Torradovirus) include several hundred species of emerging and economically significant pathogens of important food and fiber crops ... These viruses do not replicate in their vector but nevertheless are moved readily from plant to plant by the adult whitefly by various means ... For most of these viruses whitefly feeding is required for acquisition and inoculation, while for others only probing is required. Many of these viruses ... cannot be easily transmitted by other means."