The spread of Paenibacillus larvae subsp larvae infections in an apiary

SUMMARY

The culture of Paenibacillus larvae subsp. larvae from adult honey bees was used to trace the spread of P. I. larvae from colony to colony in a 20-colony apiary in which five had artificially induced American foulbrood (AFB). P. I. larvae quickly spread to the uninoculated colonies but no other colonies developed AFB. All colonies at some stage of the 24-week experimental period had P. I. larvae infected adult bees. The peak number of subclinically infected colonies was detected in week 12 when 12 colonies had P. I. larvae infected adult bees without showing clinical evidence of AFB. The prevalence of subclinical infections rapidly decreased after the removal of diseased colonies in week 19 to the point where no subclinical infections were detected in week 22. This work provides further evidence that AFB is not easily spread by drifting bees.

Keywords:

• Paenibacillus larvae subsp. larvae
• American foulbrood
• honey bees
• transmission
• drifting