CONIDIA PRODUCTION OF THE ENTOMOPATHOGENIC FUNGUS NOMURAEA-RILEYI AND ITS EVALUATION FOR CONTROL OF SPODOPTERA-LITURA (FAB) ON RICINUS-COMMUNIS

An addition of 1% yeast extract to crushed sorghum was found to be an ideal substrate for culturing the fungus Nomuraea rileyi and yielded a maximum of 1.4 x 10(9) conidia/g after 8-9 days at 25 degrees C. The efficacy of the fungus was tested against Spodoptera litura in a lab, net house, and field. A dose of 2 x 10(11) conidia/liter of spray solution was found to bring about effective control of late second to early third instar S. litura larvae on castor crop (Ricinus communis Var. VP.1). In the field, larval mortality of 52-60% was observed at 12 days after spraying with N. rileyi conidia. The highest cumulative mortality of 88-97% was observed by 19 days. (C) 1994 Academic Press, Inc.