INVESTIGATION ON THE USE OF A BIOLOGICAL INSECTICIDE BASED ON METARHIZIUM FLAVOVIRIDE FOR THE CONTROL OF GRASSHOPPERS IN MALI

Metarhizium flavoviride Gams & Rozsypal (Deuteromycotinae; Hyphomycete s) was produced in diphasic culture, firstly in a sucrose-yeast medium , with sporulation on rice. Spores were extracted in kerosene or sieve d and dried. For application, the spores were formulated with a mixtur e of peanut oil and kerosene. The spore formulation was applied with s pinning disk sprayers at Ultra-Low Volume. From 1992 to 1994 several s pecies of grasshoppers were treated with this formulation containing M . flavoviride conidia. Field applications resulted in mortality rates of 92% for Oedaleus senegalensis (Orth., Acrididae) (Krauss) treated w ith the Niger strain (IMI 330189) kept in field cages in 1992. In 1993 , experiments compared two strains of M. flavoviride, the Niger strain (IMI 330189) and one from Mall (I92-794). Mortality rates obtained fo r samples incubated in cages were between 31% and 93%, respectively, f or IMI 330189 (Day 0) and I92-794 (Day 3) for Kravsella amabile (Orth. , Acrididae) (Krauss). Field applications in 1994 resulted in cage mor tality rates between 50% and 99% for O. senegalensis and K. amabile, r espectively when treated with IMI 330189 and I92-794, with between 26% and 83% of dead insects showing external sporulation. Field counts in the 1994 experiment showed a population reduction of 85%.