Effects of some insect pathogens on the Africanized honey bee, <i>Apis mellifera</i> L. (Hym., Apidae)

Abstract

Abstract: Young bees were treated either per os or topically with an iridovirus, a granulosis virus, a nuclear polyhedrosis virus, and the fungi Nomuraea rileyi, Beauveria bassiana and Metarhizium anisopliae , and maintained in cages mounted into a brood frame of Langstroth hives. Infection was only confirmed in bees treated with B. bassiana or with M. anisopliae and no effect of other pathogens was observed. Beauveria bassiana and M. anisopliae conidia (l g) were also applied to field hives containing 20 000–25 000 bees. These fungi caused low mortality and infection of bees in treated hives but no noticeable effect on bee behaviour, larval development or colony characteristics. In the laboratory, bees fed a diet containing B. bassiana conidia had significantly higher mortality than control bees maintained at 35°C. Bees maintained at 26°C had high mortality independent of the treatment received. The results suggest that B. bassiana and M. anisopliae may be incapable of causing epizootic in field hives and most likely will not cause bee mortality following field applications for pest control.