Bacterial research

Last changed: 11 July 2023

A substantial part of our research on bacteria associated with honeybees focus on the devastating bacterial honeybee brood disease American foulbrood (AFB) caused by the bacterium Paenibacillus larvae.

We were part of a project that led to a re-classification of this bacterium in the mid-2000s, but our current work on American foulbrood is mostly applied. Effective sampling and proper diagnosis should reflect the current disease status of the honeybee colony and are essential if the goal is to give practical advice to beekeepers. We have been investigating and published data on detection and sanitation as well as improved management practices to mitigate the disease.

Methods for tracing disease outbreaks

Epidemiology and contact tracing is highly important as a basis for disease prevention. We have successfully used new DNA-based sequencing techniques previously used for tracing bacterial diseases in man and animals to trace disease outbreaks of American foulbrood in Sweden.

This was done in collaboration with the Swedish National Veterinary Institute (SVA) and led to further projects and a recent publication presenting a stable and evaluated core genome multilocus typing (cgMLST) scheme for the causative agent of American foulbrood. This typing method was produced in collaboration with the European Reference Laboratory (EURL) for bee health. The cgMLST allowed not only for fine-scale differentiation between samples that had the same profile using traditional MLST, but was also successfully used to identify and trace a localised Swedish outbreak, where a cluster of isolates was linked to a country-wide beekeeping operation. This stable cgMLST provides standardised typing capabilities and allows fast and comparable results between laboratories.

The method is at the moment used in an extensive nationwide study of the genetic variation and relatedness of P. larvae isolates from AFB outbreaks in the Sweden.

Probiotics for honeybees?

The pathogenesis of disease-causing bacteria and interactions between different microorganisms for disease development in the honeybee gut is poorly understood. Our research on honeybee-specific lactic acid bacteria (hbs-LAB) and their potential as probiotics for honeybees has shown that observed positive effects on individuals does not necessarily translate into an effect on a honeybee colony with thousands of bees.

Further research will allow us to investigate microbial interactions on both levels in more detail.


Eva Forsgren, Senior Lecturer and External Collaboration Specialist
Department of Ecology, SLU 18-67 20 83