Abstract
Mycelial growth and germination rates of Beauveria bassiana F-263 at various temperatures were investigated to determine efficient culture conditions and tolerance of this strain to higher temperatures. Mycelial growth was quantified by measuring colony diameters at constant temperatures and occurred from 6 to 33°C, with maximal growth at 30°C. The fungus could recover and grow when transferred to 25°C after exposure to higher temperatures, even if the fungus did not grow during high temperature exposures. The longest high temperature periods after which this fungus survived were 8 d at 35°C and 4 d at 36°C when initiated with hyphal bodies and more than 14 d at 35°C and 7 d at 36°C when initiated with conidia. At 25 to 30°C, the conidial germination rate rose to almost 100% within 20 h. At 34°C, germination was very low within 20 h, but almost 100% over 48 h. At 35°C, germination was only 4.6% even more than 4 d after inoculation, although most conidia inflated within 24 h. No germination was observed at 36°C, although most conidia inflated within 24 h. Growth rates of germ tubes from conidia were slower at temperatures higher than 33°C.
