The cyanobacteria are the oldest and widespread autotrophic eukaryotes on the planet earth. Some of their species are useful as biofertilizers in agriculture due to nitrogen fixing ability. Some of the cyanobacteria species are, however, known to produce toxins. Successful attempts have been made to use various marine and fresh-water terrestrial toxin producing cyanobacteria for production of useful chemicals and in pest control in agriculture and human health programmes.The results of these investigations prove that there is scope for finding nematicidal molecules including water soluble...