TEMPERATURE AND MOISTURE REQUIREMENTS FOR CONIDIAL GERMINATION OF AN ISOLATE OF BEAUVERIA-BASSIANA, PATHOGENIC TO RHODNIUS-PROLIXUS

The effects of temperature, relative humidity and water activity on ge rmination of conidia of an isolate of Beauveria bassiana (Bals.) Vuill . pathogenic to the triatomine vector of Chagas' disease, Rhodnius pro lixus Stal., were investigated in vitro. Germination occurred at tempe ratures between 15 degrees C and 35 degrees C under saturated atmosphe re and the optima ranged from 25 degrees C to 30 degrees C. At the ext reme temperatures tested (15 degrees C and 35 degrees C) the germinati on process was delayed, but germination rates reached more than 95%. G ermination of B. bassiana conidia was strongly affected by moisture co nditions. The availability of water, in both atmospheric and liquid co nditions, caused changes in germination times as well as in germinatio n rates. For example, at 25 degrees C + 0.5 degrees C, germination too k place within 20 h at 95.5% RH, whereas it needed 72 h of incubation at 90% RH. Germination times increased as the water activity declined from 0.96 a(W) to 0.92 a(W). Below 0.92 a(W), no germination was obser ved after a 72 h incubation time.