Keywords: Apis mellifera, Greater wax moth, bioassay, fungus, Metarhizium anisopliae

Experiments were carried out to find out the effect of entomopathogenic fungus Metarhizium anisopliae (Metsch.) Sorokin on honeybee (Apis mellifera L.) and greater wax moth (Galleria mellonella L.) at the Institute of Agriculture and Animal Sciences, Rampur, Chitwan in 2004/05. Three virulent isolates M_1, M₆₅ and M₇₀ of M. anisopliae (Metsch.) Sorokin were tested on adult honeybees with the concentration of 10⁷ conidial spores per ml, gave positive results with no significant effect on mortality of honeybees. For the other experiment on greater wax moth, six fungus isolates, M₁, M₁₈, M₄₈, M₅₀, M₆₅ and M₇₀ of M. anisopliae were tested on greater wax moth larvae with the concentration of 10⁷ conidial spores per ml, which gave LT₅₀ value of 6, 8, 8, 7, 7 and 6 days, respectively. The isolate M₁ was found the most virulent killing 96.66% larvae ten day after treatment. Due to the most effective virulent isolate, again M₁ was tested on greater wax moth larvae at different concentrations of 10³, 10⁴, 10⁵, 10⁶, 10⁷and 10⁸ spores per ml. The mortality due to fungus occurred after three day of treatment and reached to maximum 96.66%, 93.33%, 90.00%, 86.66%, 83.33% and 80.00% death of greater wax moth larvae with 10⁸, 10⁷, 10⁶, 10⁵, 10⁴ and 10³ spores per ml, respectively, after ten days of treatment. Greater wax-moth larvae were again bioassayed with three methods as spraying, dipping and ingestion with the concentration of 10⁷ spores/ml of M₁ isolate and dipping gave the highest percent mortality (96.00%) with the lowest body weight (0.011g) compared to other two methods. These laboratory results indicated that the fungus is safe to honeybee but highly susceptible for greater wax moth. Therefore, its application to control greater wax moth in the infected beehive colony can be practiced safely for the benefits of beekeepers.