Bacillus thuringiensis (Bt) has been extensively used for four decades in biopesticidal formulations due to its safe environmental and human health records. The widespread use of Bt is often challenged by production as well as formulation costs. Various alternative local media have successfully replaced costly synthetic media, but the actual constraint is embedded in harvesting and formulation costs. Harvesting efficacy governs the marketability of a product by affecting potency and aiding in further processing during formulation development. Formulation is a crucial link between production and application and dictates economy, longer shelf life. ease of application and enhanced field efficacy. There are various environmental factors like ultraviolet radiation. rain, pH, temperature and foliage physiology which impede efficacy of Bt formulations. There have been developments of various formulations depending on application target and feasibility - solid and liquid - to overcome the adverse environmental effects. Conventional formulations have been substituted by advanced versions like microencapsulations and microgranules to enhance residual entomotoxicity. This article reviews recent advances in downstream processing and formulations of Bt based biopesticides incorporating effect of different environmental parameters. In addition. probable inclusion of alternative Bt formulations from fermented wastewater (WW) and wastewater sludge (WWS) in the future also has been included with inputs on their advantages with some salient results. (c) 2005 Elsevier Ltd. All rights reserved.