3.1.6.1. Investigating potential interactions between A. tumida and Paenibacillus larvae, the causative organism of American foulbrood

Brood combs with clinical American foulbrood (AFB) symptoms can be used to contaminate larval and adult SHB in the laboratory (Schäfer et al., 2010b). This contamination was shown to persist in pupae and newly emerged adults. Contaminated adult SHBs can be used to expose honey bee field colonies with P. larvae spores. The corresponding methods are outlined below:

  1. Take clinical combs with sealed and unsealed brood from infected AFB colonies and arranged into plastic containers with an equal amount of infected brood cells each.
  2. Collect adult SHBs from rearing programs or from infested field colonies and introduce into the containers (N= 20).
  3. Keep the containers in darkness at 30°C and high relative humidity (> 50%).
  4. After seven days, collect contaminated adult small hive beetles.
  5. Three days later, collect wandering larvae.
    Both adults and larvae can be used depending on the needs of the experiment. If needed, larvae can be moved into two sand containers placed in darkness in an incubator to allow further development.
  6. To quantify the number of P. larvae spores per specimen (see respective BEEBOOK paper by de Graaf et al., 2013), immediately freeze the samples after collection.
  7. To expose field colonies to contaminated adult SHB, introduce the collected beetles into the experimental field colonies, which should be free of P. larvae spores.

Note: Please always consider the biosafety risks when manipulating P. larvae for research! (see the BEEBOOK paper on American foulbrood by de Graaf et al., 2013). This method might also be practicable for European foulbrood and other brood diseases.