Characterisation of a Malawian isolate of Beauveria bassiana, a potential control agent of coffee stem borer, Monochamus leuconotus.

The radial growth, sporulation and viability of a Beauveria bassiana isolate were assessed at three temperatures (23, 28, 33 degrees C) under light and dark conditions. Optimum radial growth and sporulation occurred at 23 degrees C regardless of photoperiod with the highest spore concentration being attained after incubating for 28 days. Loss of viability was highest at 33 degrees C and there was no significant loss in viability at 23 degrees C for up to five weeks. It would appear that 33 degrees C is too hot for the sporulation, growth and viability of this insect fungus. Photoperiod effects were insignificant for all the parameters evaluated. The infectivity on white coffee stem borers at 2.5 x 10(8) spores ml(-1) was high with 100% of the test larvae immobilised and not feeding within 24 h and dying within two to twelve days.