An improved method for the detection and presumptive identification of Paenibacillus larvae subsp. larvae spores in honey

SUMMARY

One of the most important diseases that attacks honey bees (Apis spp.) in the larval stage is American foulbrood (AFB), for which Paenibacillus larvae subsp. larvae is the causative agent. American foulbrood is considered an exotic bee disease in Brazil because it has not yet been detected in the country. Feeding honey containing spores of P. I. larvae to bee larvae can transmit AFB, hence imported honey could spread this disease to Brazil. Since the disease is widely spread in some Latin American countries, including one bordering Brazil, the Brazilian authorities, and beekeepers, are concerned about the risk of introduction of AFB to Brazil. Accordingly, an improved method of detecting spores of P. I. larvae in honey has been developed. The method is based on concentrating spores by centrifugation, inactivating vegetative cells and then inoculating onto a newly developed selective solid medium: Paenibacillus larvae subsp. larvae agar (PLA). Suspect colonies are then selected and cultures are confirmed by biochemical identification. The method was able to detect less than 10 viable spores of P. I. larvae per 1 ml of honey.

Keywords:

• American foulbrood
• Paenibacillus larvae larvae
• brood diseases
• diagnosis
• culture techniques
• spores
• Brazil
• honey