ABSTRACT
The Bacillus thuringiensis subspecies israelensis (Bti) produces proteinaceous parasporal crystals during sporulation. Introducing the Bti entomicidal toxin gene into a larval food source capable of replicating naturally would preclude repeated applications of the control agent. W. E. Thomas and D. J. Ellar showed that solubilized Bti crystals caused rapid lysis of insect and mammalian cells and, through further experimental analysis, assigned the mosquitocidal activity to the 26-kDa protein. L. Thorne et al. described the cloning of a fragment from the 75-MDa plasmid of Bti that encodes larvicidal activity. F. J. H. Fredeen has tested various bacteria found in natural blackfly larval habitats to determine their potential as larval food sources. He fed Simulidae larvae the alga Chlamydamonas, the Gram-positive bacterium B. subtilis, and Gram-negative bacteria Aerobacter aerogenes and E. coli. The ultimate insecticide for mosquito and blackfly control involves incorporating the gene encoding entomicidal activity into these insects' natural food source.
