Virus diseases that have emerged in the past two decades affected the production of important vegetable crops in tropical, subtropical, and temperate regions worldwide. Whiteflies (Aleyrodidae: Hemiptera) are serious sucking pests of crops that are found in all warmer parts of the world as well as greenhouses in temperate areas. Direct crop damage occurs when whiteflies feed on plant phloem, remove plant sap and reduce plant vigor. Whiteflies also excrete honeydew, which promotes sooty mold that interferes with photosynthesis and may lower harvest quality, from a phytopathological perspective, however, the main concern about whiteflies is their ability to transmit viruses. Though there are about 1,500 species of whiteflies recorded, only a few have been shown to transmit plant viruses as vectors. Whitefly-transmitted diseases were recognized based on symptoms like mosaic type, leaf curl type, and yellowing type. The etiology of these diseases was based on relatively little information, and it was even unclear whether particular diseases were caused by whitefly transmitted viruses, mycoplasma-like organisms, or viroids. Though whitefly-transmitted viruses are said to be mainly begomoviruses (family Geminiviridae), but also vectors of criniviruses, ipomoviruses, torradoviruses and some carlaviruses. Although most of the information available on the influence of whitefly populations on virus emergence comes from studies with Bemisia tabaci and begomoviruses, emerging diseases caused by criniviruses may also be affected by shifts in whitefly populations. Factors driving the emergence and establishment of whitefly-transmitted diseases include genetic changes in the virus through mutation and recombination, changes in the vector populations coupled with polyphagy of the vector and long distance traffic of plant material or vector insects due to trade of vegetables and ornamental plants. In addition weeds also act as reservoirs that can play an important role in the emergence of virus diseases affecting the crops. The role of humans in increasing the emergence of virus diseases is obvious, and the effect that climate change may have in the future is unclear (Jones, 2009). Important emerging diseases affecting vegetable crops include tomato yellow leaf curl disease, African cassava mosaic disease, ipomovirus diseases of cucurbits, tomato chlorosis caused by criniviruses, and the torrado-like diseases of tomato. Control is currently based on integrated disease management (IDM), i.e., on the coordinated use of multiple tactics to assure crop production and to maintain virus damage below the economic injury level while minimizing hazards to humans and the environment.