EVALUATION OF 3 FORMULATIONS OF BEAUVERIA-BASSIANA (BALS) VUILL FOR CONTROL OF THE STEM BORER CHILO-PARTELLUS (SWINHOE) (LEP, PYRALIDAE)

Field experiments were conducted to evaluate the efficacy of 3 formula tions, 1. a dry rice grain-based inoculum, 2. a soaked dry rice grain- based inoculum, and 3. an aqueous conidial suspension of Beauveria bas siana (isolate ICIPE 35) against the stem borer Chilo partellus. Maize plants were artificially infested with an egg mass (blackhead-stage) placed into the whorl 2 weeks after plant emergence. Each of the 3 for mulations was applied as a single,treatment. The aqueous formulation a nd dry rice grain-based inoculum showed similar performance in reducin g larval population of C. partellus, foliar damage, and stalk tunnel l ength. The grain yield was significantly higher in both of these treat ments compared with the control. The dry rice grain-based inoculum, wh ich is easy to apply, induced the highest fungal infection rates in th e larval population 2 weeks after application. This formulation should be developed using other cheap, locally available raw materials.