European Foul Brood: a Disease of the Larval Honeybee (Apis mellifera L.) caused by a Combination of Streptococcus pluton (Bacillus pluton White) and Bacterium eurydice White

Abstract

RESULTS of preliminary experiments¹ have shown that European foul brood disease of the larval honeybee can be caused in bee colonies by spraying their brood with suspensions of Streptococcus pluton (Bacillus pluton White) and Bacterium eurydice White if the two organisms are grown together in mixed anaerobic culture ; fifth subcultures of a mixed culture were usually virulent, although virulence diminished rapidly after further sub-cultivation. It was not possible to cause the disease by simultaneous inoculation with separate cultures of the two organisms. As there is a tendency for colonies of S. pluton and B. eurydice to grow within, or upon, each other on agar in anaerobic cultures, the separate cultures of each organism were subcultured five times to try to ensure the exclusion of the other. The results of these experiments showed that virulence was maintained by one or both organisms in mixed culture, but the possibility remained that only one of the organisms was pathogenic; its virulence may have been maintained by the growth of the other which may, in vivo, be a secondary invader of the diseased larva.