EFFECTIVENESS OF THE ENTOMOPATHOGENIC FUNGUS BEAUVERIA-BASSIANA (BALS) VUILL FOR CONTROL OF THE STEM BORER CHILO-PARTELLUS (SWINHOE) IN MAIZE IN KENYA

The fungus Beauveria bassiana (Bals.) Vuill. and insecticide trichlorfon were compared for the control of stem borer, Chilo partellus (Swinhoe) in field experiments at different times of infestation. Egg masses of C. partellus at the blackhead stage were pinned to the undersurface of the maize leaves. Two fungal formulations, conidial aqueous suspensions and a granular formulation, were applied. Compared with the untreated checks, the numbers of surviving C. partellus larvae were significantly reduced in treatments where B. bassiana was applied at a concentration of 10(13) conidia ha-1 as granules and as two aqueous spray formulations. No significant difference in numbers of stem borer larvae was found between trichlorfon and the untreated check. Fungus granules persisted longer in the field than did one spray of the fungus inoculum at the same concentration, or trichlorfon. A major increase in grain yield was obtained with two fungal sprays and with fungus granules both applied at a concentration of 10(13) conidia ha-1. A granular formulation of B. bassiana should be considered for the control of the stem borer C. partellus.