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 formulations, 1. a dry rice grain-based inoculum, 2. a soaked dry rice grain-based inoculum, and 3. an aqueous conidial suspension of Beauveria bassiana (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 formulations was applied as a single,treatment. The aqueous formulation and dry rice grain-based inoculum showed similar performance in reducing larval population of C. partellus, foliar damage, and stalk tunnel length. The grain yield was significantly higher in both of these treatments compared with the control. The dry rice grain-based inoculum, which is easy to apply, induced the highest fungal infection rates in the larval population 2 weeks after application. This formulation should be developed using other cheap, locally available raw materials.