SUPPRESSION OF OSTRINIA-NUBILALIS (HUBNER) (LEPIDOPTERA, PYRALIDAE) BY ENDOPHYTIC BEAUVERIA-BASSIANA (BALSAMO) VUILLEMIN

The ubiquitous entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin was applied to whorl-stage corn plants, Zea mays L., by foliar application of a granular formulation of conidia and by injection of a conidial suspension. Plants were analyzed at harvest for presence of B. bassiana and for the amount of tunneling by laboratory-reared European corn borer larvae, Ostrinia nubilalis (Hubner). In 1989, 98.3% of the foliarly treated plants, 95.0% of the injected plants, and 33.3% of the nontreated plants were colonized by B. bassiana at harvest. In 1988, there were no significant differences between treatment effects on O. nubilalis tunneling in plants. In 1989, when environmental conditions were more conducive to fungal growth, tunneling was significantly greater in the control plants, followed by the injected and foliarly treated plants. When applied to foliage, B. bassiana provided the greatest amount of O. nubilalis suppression. The entomopathogenic fungus colonized the corn plant at whorl stage, moved within the plant, and persisted to provide season-long suppression of O. nubilalis.