Abstract
The ectoparasitic mite Varroa destructoris Anderson and Trueman is considered a destructive pest of honey bee Apis mellifera. Potentiality of using the entomopathogenic fungi Beauveria bassiana (Balsamo) as mycoacaricide against V. destructor was evaluated. Considerable effect of B. bassiana on Varroa mite numbers was recorded in treated colonies compared to the control. There were significant differences in mean numbers of mite mortality rates between treated and untreated colonies. Results indicated that conidial concentration of 5x10(6) spores/g caused higher mortality rate compared to the other tested concentrations. Results showed that B. bassiana had a good potential on V. destructor when was dusted more than one time (0, 6 and 10day). Scanning electronic microscopy examination of infected mite showed abundant hyphal growth and sporulation on treated mite cuticle. The results indicated that dusting of colonies with fungal conidiospores caused a reduction in the mite population reached 47.68, 33.44, 70.00 and 46.38%, 13 days after applications at concentrations of 1 x 10(6) conidia/g, 2.5 x 10(6) conidia/g, 5 x10(6)conidia/g, and 7.5 x10(6)conidia/g, respectively. The results showed also that the impact of fungus on workers bees was very low. Obtained results can suggest using B. bassiana as a potential effective bioacaricide against V. destructor in honey bee colonies.