Impact of Legislation on Antibiotic Use and Awareness of Beekeepers

Legislation plays a key role in regulating beekeeping practices and biosecurity measures, but different countries present conflicting legislative frameworks in terms of allowing antibiotic use. Currently the EU and the UK only permit antibiotics under the cascade principle, but while the UK considers the application in cases of European Foulbrood, the EU strongly discourages antibiotic use. In the US, antibiotics are registered for honeybees and their treatments are regularly authorised. This study relied on an international survey to assess the current use of antibiotics and general awareness among beekeepers, within the three legislative contexts. The results showed a similar use of antibiotics in all three geographical areas, regardless of the legislative context. General use and awareness indicated that the EU and US would likely benefit from national inspectors. Furthermore, even though beekeepers were somewhat aware of the various risks associated with improper antibiotic use, they would likely benefit from targeted training on the matter.

Melissococcus plutonius Can Be Effectively and Economically Detected Using Hive Debris and Conventional PCR

European foulbrood (EFB) is an infectious disease of honey bees caused by the bacterium Melissococcus plutonius. A method for DNA isolation and conventional PCR diagnosis was developed using hive debris, which was non-invasively collected on paper sheets placed on the bottom boards of hives. Field trials utilized 23 honey bee colonies with clinically positive symptoms and 21 colonies without symptoms. Bayes statistics were applied to calculate the comparable parameters for EFB diagnostics when using honey, hive debris, or samples of adult bees. The reliability of the conventional PCR was 100% at 6.7 × 103 Colony Forming Unit of M. plutonius in 1 g of debris. The sensitivity of the method for the sampled honey, hive debris, and adult bees was 0.867, 0.714, and 1.000, respectively. The specificity for the tested matrices was 0.842, 0.800, and 0.833. The predictive values for the positive tests from selected populations with 52% prevalence were 0.813, 0.833, and 0.842, and the real accuracies were 0.853, 0.750, and 0.912, for the honey, hive debris, and adult bees, respectively. It was concluded that hive debris can effectively be utilized to non-invasively monitor EFB in honey bee colonies.

Biofilm-forming lactic acid bacteria of honey bee origin intended for potential probiotic use

Scientists around the world are focusing their interest on the use of probiotics in honey bees as an alternative method of prophylaxis against causative agents of both American and European foulbrood. In our study we tested inhibitory activity against Paenibacillus larvae and the biofilm formation activity by various lactic acid bacteria isolated from honey bee guts or fresh pollen samples in the presence of different sugars added to the cultivation media. In addition, we tested the probiotic effect of a newly selected Apilactobacillus kunkeei V18 in an in situ experiment in bee colonies. We found antibacterial activity against P. larvae in four isolates. Biofilm formation activity of varying intensity was noted in six of the seven isolates in the presence of different sugars. The strongest biofilm formation (OD570 ≥ 1) was noted in A. kunkeei V18 in the presence of fructose; moreover, this isolate strongly inhibited the growth of P. larvae under laboratory conditions. Inhibition of P. larvae and Melissococcus plutonius by A. kunkeei V18 in situ was confirmed in a pilot study.

Pathogenesis, Epidemiology and Variants of Melissococcus plutonius (Ex White), the Causal Agent of European Foulbrood

The bacterium Melissococcus plutonius is the etiologic agent of the European foulbrood (EFB), one of the most harmful bacterial diseases that causes the larvae of bees to have an intestinal infection. Although EFB has been known for more than a century and is practically present in all countries where beekeeping is practiced, the disease has been little studied compared to American foulbrood. Recently, great advances have been made to understand the disease and the interaction between the pathogen and its host. This review summarizes the research and advances to understand the disease. First, the morphological characteristics of M. plutonius, the infection process and bacterial development in the gut of the larva are described. Also, the epidemiological distribution of EFB and factors that favor the development of the disease as well as the classification of M. plutonius according its genomic and phenotype characteristics are reported. Finally, the new molecular tools for the study of M. plutonius, possible virulence factors in its genome, the issue of current EFB control measures and possible alternatives to the use of antibiotics are addressed.

In Vitro Effects of Pesticides on European Foulbrood in Honeybee Larvae

Neonicotinoid and fungicide exposure has been linked to immunosuppression and increased susceptibility to disease in honeybees (Apis mellifera). European foulbrood, caused by the bacterium Melissococcus plutonius, is a disease of honeybee larvae which causes economic hardship for commercial beekeepers, in particular those whose colonies pollinate blueberries. We report for the first time in Canada, an atypical variant of M. plutonius isolated from a blueberry-pollinating colony. With this isolate, we used an in vitro larval infection system to study the effects of pesticide exposure on the development of European foulbrood disease. Pesticide doses tested were excessive (thiamethoxam and pyrimethanil) or maximal field-relevant (propiconazole and boscalid). We found that chronic exposure to the combination of thiamethoxam and propiconazole significantly decreased the survival of larvae infected with M. plutonius, while larvae chronically exposed to thiamethoxam and/or boscalid or pyrimethanil did not experience significant increases in mortality from M. plutonius infection in vitro. Based on these results, individual, calculated field-realistic residues of thiamethoxam and/or boscalid or pyrimethanil are unlikely to increase mortality from European foulbrood disease in honeybee worker brood, while the effects of field-relevant exposure to thiamethoxam and propiconazole on larval mortality from European foulbrood warrant further study.