2000 Volume 44 Issue 3 Pages 177-182
In order to use an entomopathogenic fungus, Beauveria bassiana, as a microbial control agent for the diamondback moth, Plutella xylostella, the mortality patterns at various temperatures and the conidial invasion time after inoculation were investigated. When larvae were inoculated with a suspension of the B. bassiana strain MG-Bb-1 (1×107 conidia/ml), mortalities of >95% were obtained regardless of the incubation temperature. However, the longevities of infected larvae were prolonged as temperature decreased. The mean longevity±S.D. were 2.1±0.2, 2.0±0.2, 2.0±0.2, 2.8±0.4, 3.9±0.4, 5.1±0.6, 9.9±1.0, and 13.9±1.6 days at 30, 27, 25, 20, 18, 15, 11 and 7°C, respectively. The mortality patterns in larvae exposed to cycles of 25°C (12 h) and 15°C (12 h) was very similar to that in larvae reared at a constant temperature of 20°C. These results indicate that the speed of killing depends on a thermal constant. The conidial invasion into the host began approximately 7 h post-inoculation and was completed in 15 h.
