MAINTENANCE AND MASS REARING OF PHYTOSEIID PREDATORS OF THE CASSAVA GREEN MITE

The cassava green mite Mononychellus tanajoa (Bondar), accidentally in troduced from South America into Africa, has spread across the cassava belt and is causing severe yield losses to cassava. Biological contro l was recognized as the most promising and sustainable strategy agains t this pest. Among the different stages of a biological control progra m, mass rearing of beneficials is often a major bottleneck. The differ ent rearing systems used by the International Institute of Tropical Ag riculture are described. A mother culture system maintains pure and hi gh quality colonies and provides inoculum to start mass production. Tw enty biotypes are maintained separately and no contamination has been found in the cultures. Oligophagous species are reared in the insectar y on artificial substrate, using alternative prey as a food source. Fo r phytoseiid species specific to M. tanajoa , an ''on plant'' system i s used in a greenhouse. Advantages and disadvantages of the two differ ent systems are discussed as well as general requirements and constrai nts in rearing phytoseiids.