Bemisia tabaci (MEAM1) (silverleaf whitefly).

Abstract The exact origin of the MEAM1 species of Bemisia tabaci, and the reasons why it became such an important pest are still not fully known. MEAM1 was first identified in the mid 1980s when it invaded the southern states of North America. Vast numbers of whiteflies were found to be infesting winter vegetable crops and consequently caused an estimated $500 million loss to the 1991 winter harvest in California. Investigations led to the assumption that the B biotype had spread to the USA on ornamental plants that were being transported around the world. Species such as poinsettia and gerbera were highlighted as probable hosts. During the 1990s MEAM1 was reported on every continent. Biological traits of MEAM1 implied that it had evolved within intensive agricultural regions with exposure to pesticides and modern cultural practices. These included an ability to feed and develop on a wide range of plant and crop species, a high level of fecundity and a predisposition to develop resistance to a wide range of pesticides. MEAM1 is also an effective vector of many different plant viruses which, in conjunction with its high level of polyphagy, make it extremely problematic within agricultural regions where crops may be susceptible to viruses acquired from indigenous plants. Despite B. tabaci being a tropical/sub-tropical whitefly species, MEAM1 is often transported on plant species to temperate regions of the world. Within these cooler regions, MEAM1 can survive within a protected environment and could feasibly spread virus diseases to new locations. It is for this reason that B. tabaci and members of its species complex, including MEAM1, are on EPPO A2 Alert list.