DEVELOPMENT OF BIORATIONAL PEST-CONTROL FORMULATION AGAINST LONGICORNBEETLES USING A FUNGUS, BEAUVERIA-BRONGNIARTII (SACC.) PETCH

Some basic experiments were performed in order to develop a biocidal f ormulation which is lethal to certain species of longicorn beetle. The entomopathogenic filamentous fungus, Beauveria brongniartii could be grown aerobically in the presence of 4% corn steep liquor and 2% gluco se at 25 degrees C with a minimum doubling time of 7 h. Depletion of g lucose and the onset of the stationary phase occurred within 48 h. App lication of a diluted aliquot of this culture to a nonwoven pulp fabri c sheet resulted in the growth of B, brongniartii on the surface of th e fabric, The conditions for the growth of cultures on fabric sheets w ere optimized and large-scale cultivation of the cultures on fabric wa s achieved in a specially designed chamber. The cultures covered with conidia could be stored sealed in polyethylene bags for more than 400 d at 5 degrees C without loss of infectivity, while. storage at room t emperature resulted in a gradual decrease in the number of viable cell s, Infectivity was lost when the population of cells decreased below 1 0(7) cells/cm(2), However, when water was added to dried cultures whic h had been stored at 25 degrees C for an extended period of time, the number of viable cells recovered and the infectivity of the cultures c ould be restored. Under field conditions, periodic rainfall which mois tens the sheet cultures may help to sustain the infectivity of this ag ent. When the effects of this biocide were probed in field tests using tangerine crops, it was observed that the use of this agent prevented the proliferation Of beetles, in addition to killing adult insects.