The research programme against the white grub Hoplochelus margínalis (Col: Melolonthinae) in the Reunion Island is an exemplary model of IPM strategy, particularly from an industrial and commercial point of view, against a soil insect pest. Following the accidental introduction of this species to the island, probably in the early 70s, significant damage has been caused since 1981 and 1989, chemical control was encouraged. From onwards full antagonists wer introduced without success. The following outlines the development of this biological control programme using a Beauveria brongniartii strain: - Discovery of the strain in its country of origin, Madagascar (CIRAD-INRA, 1987). - Purification of a monospore strain (Bt 96) and laboratory bioassays to check the virulence of the fungus strain (INRA-CIRAD, 1988). - Production of a registered product (BETELR): a)Field trials with Bt 96 mass produced on rice (CIRAD) and on clay granules produced in prototype pilot (INRA-CALLIOPE 1989-1993). b)Toxicological files (1993). - Setting up an efficient molecular test to monitor a characteristic pattern for Bt 96 (INRA, 1993). - Scaling up of industrial production (NPP 1993 - 1996), in order to offer large scale biological control, i.e. a single mixed treatment with a reduced rate of SusconR (6 kg/ha instead of 28 kg/ha) and BetelR biocide (50 kg clay granule formulation containing 0.2 x 109 spores/g dry weight) at the same price of the treatments using chemical insecticides alone. The ecological balance remains satisfactory for both the spores produced by saprophytic development and those produced by pathogenic development in adult insects.