DIFFERENTIATION OF BEMISIA-TABACI (GENN) (HEM, ALEYRODIDAE) POPULATIONS IN COLOMBIA

We obtained evidence for genetic differentiation (detected by electrop horesis) of geographical populations of the whitefly, Bemisia tabaci ( Genn.), in Colombia. The differences are undetectable by conventional taxonomic characters bur are expressed at an esterase marker locus. Th ere was no indication of host-race formation. The present data on geog raphic differentiation of B. tabaci in Colombia, provide support to ea rlier reports that B. tabaci population in different parts of the worl d - in particular in South America - are biologically heterogeneous. T he recent outbreaks of B. tabaci in Florida and the Caribbean, and the colonization of previously uninfested host plants, may be due to the spread of rare or new genetic variants. We have shown in the first pan of this study (WOOL et al. 1993) that frequencies of electrophoretic variants at an Esterase locus in Israel are not the same in commercial , insecticide-treated fields as in samples from unsprayed sites. That result, coupled with the present data, indicates that subtle genetic v ariation exists in B. tabaci also in traits which are important for ag riculture.