Among various pathogens and parasites of mosquitoes, bacterial agents such as B. thuringiensis and Bacillus sphaericus, which produce mosquitocidal crystal toxins, are very potential to use as bio control agents. They produce mosquitocidal protoxin crystals during sporulation and are highly toxic to susceptible species of mosquito larvae that ingest them in the aquatic environment. The protoxins get solubilized in the alkaline pH of the larval midgut and are proteolytically activated and bind to specific receptors located in the brush border epithelial cell membranes. Several mechanisms lyse the cells, and the larva stops feeding and dies. B. sphaericus and B. thuringiensis are very effective against various Culex, Anopheles, and Aedes mosquito species and are very safe to non-target organisms. B. sphaericus has been used successfully for the control of Culex quinquefasciatus and Culex pipiens, whereas B. thuringiensis, although helpful against Culex sp. mosquitoes, is the strain of choice for controlling Aedes aegypti. Both B. sphaericus and B. thuringiensis are toxic to Anopheles, and the effect is variable in the field. The mode of action of B. thuringiensis and B. sphaericus on mosquito larvae are well known.
Author(s) Details:
B. Usharani,
Department of Biomedical Genetics, Institute of Basic Medical Sciences, University of Madras, Tamil Nadu, India.
R. Venkateswari,
Department of Medical Microbiology, Institute of Basic Medical Sciences, University of Madras, Tamil Nadu, India.
P. Suganthi,
Department of Medical Biochemistry, Institute of Basic Medical Sciences, University of Madras, Tamil Nadu, India.
M. Muthuraj,
State TB Training and Demonstration Centre, Intermediate Reference Laboratory, Government Hospital for Chest Diseases, Puducherry, India.
