Species or Strain?

The March, 1994 issue of the Annals of the Entomological Society of America, Vol. 87, no. 2 (pp. 195 - 206), carried a description of Bemisia argentifolii Bellows & Perring, the silverleaf whitefly, for the first time. Before this there had been discusssion as to whether this insect was a separate species or simply "Strain B" of Bemisia tabaci (Gennadius), the sweetpotato whitefly. At this time, there are many who believe that the silverleaf whitefly is still just "Strain B." This is understandable in that scores, if not hundreds, of entomologists world-wide have spent considerable time studying this major insect pest and are interested in the speciation process. Some insects species (of the millions identified), when split into two or more, or even combined into one, species, provoke no such discussion simply because only a few entomologists spend time studying that group. At this point, the key question that should concern extension specialists and agents, crop consultants, and growers dealing with whiteflies is "which strain or species am I dealing with?" The answer could have a serious impact on your integrated pest management stratagies.