Navon, A., Department of Entomology, ARO, Volcani Center, Bet Dagan 50250, Israel

Bacillus thuringiensis (Bt) has been the leading biopesticide against lepidopterous pests since 1959. In the 1990s the following developments contributed to increased rational uses of Bt: (1) natural and recombinant Bt products were developed to broaden the insect host range in pest management programs; (2) new formulations based on conventional or genetically engineered encapsulation of the toxins and/or feeding stimulants to increase ingestion and, in turn, the efficacy of the microbe; (3) screening of the interactions of Bt with insect herbivores and plant allelochemicals or natural enemies of the pests, to aid the formulation of biological control strategies; and (4) knowledge and management of insect resistance to Bt. The prospects for Bt insecticides will be described and discussed. (C) 2000 Elsevier Science Ltd.