HIGHLY MOSQUITOCIDAL ISOLATES OF BACILLUS-THURINGIENSIS SUBSPECIES KENYAE AND ENTOMOCIDUS FROM MEXICO

Isolates of Bacillus thuringiensis ssp. kenyae and B. thuringiensis ss p. entomocidus that produce highly mosquitocidal parasporal bodies sim ilar to those produced by B. thuringiensis ssp. israelensis have been obtained from, respectively, sorghum dust and soil samples in Mexico. The parasporal bodies of both isolates are spherical, contain several inclusions enveloped in a fibrous matrix, and are composed of proteins of 27, 65, 128 and 134 kDa which cross-react with polyclonal antisera made against the parasporal body of B. thuringiensis ssp. israelensis . Southern hybridization analyses of the plasmid complements of these new isolates using the cryIVD gene as a probe show that this gene is l ocated on a plasmid of about 110 kb, the same size as the plasmid that hears the cytA, cryIVA. cryIVB and cryIVD genes in B. thuringiensis s sp. israelensis. These results demonstrate that the 110 kb plasmid bea ring these insecticidal genes occurs in ecologically diverse habitats as well as in different subspecies of B. thuringiensis. Moreover, the latter finding in conjunction with previous studies shows further that the serotype/subspecies designation used to classify isolates of this bacterium is not a definitive indicator of the insecticidal spectrum of activity.