Assessment of Bacterial Pathogens Diversity and Beekeeping Constraints in Apis Mellifera Colonies of Embu County, Kenya

Abstract

Wild and managed honeybees (Apis mellifera) contribute towards economic gain as a source of income and food. Additionally, honeybees provide pollination services to numerous plants thus contributing greatly to food chains, ecosystem functions and world economy. Bee health is thus crucial in the attainment of these diverse roles. Over time persistent bee population decline has been reported globally due to biotic and abiotic stresses. Among the biotic factors are the honeybee diseases caused by bacteria, fungi and viruses. Among the bacterial pathogens, the most pernicious and with a world wide distribution is the American foulbrood (AFB) caused by Paenibacillus larvae. Additionally, the honeybee microbiome and its immediate hive environment is composed of various microbial symbionts that are involved in mutualistic, commensalistic or parasitic interactions, and which have significant impact on bee health. The objective of this study was to determine the diversity of bacteria and constrains associated with Apis mellifera keeping in Embu County, Kenya. Specifically, the study established constraints associated with Apis mellifera production, determined bacteria diversity within the honey and honeycombs using culture-dependent approach and metagenomic approach. Questionnaires were used to establish constraints associated with beekeeping. Samples of adult bees, honey, honeycombs, frame scrappings and bee larvae were collected randomly from bee farmers, and total DNA was extracted and genotyped using the 16S rRNA marker gene. Results showed that colony decline was associated with pests (42.3%), swarming (20.6) and hive abscondment (37.1%) across the traditional, transitional and frame hives. A total of 17 bacteria isolates were obtained using the culturedependent approach. Based on comparative analysis of their sequences with closest relatives from National Center for Biotechnology Information (NCBI) GenBank database, results revealed that these isolates were affliated with the phylum Firmicutes, Proteobacteria and Actinobacteria. They were represented by the genera Bacillus, Microbacterium, Micrococcus, Serratia, Staphylococcus, Klebsiella, Erwinia and Devosia. Key observation was the utilization of multiple carbon sources exhibited by bacterial isolates. This indicates the significance of bacteria degrading diverse polysaccharides in honeybee nutrition.Using metagenomics approach, 499,300 nucleotide sequence reads were obtained. These were represented by the phyla Firmicutes, Proteobacteria, Bacteriodetes, Actinobacteria and Cyanobacteria. The most abundant genera comprised of Fructobacillus, Lactobacillus, Gilliamela, Bombella, Frischella, Enterobacter, Lactococcus, Serratia, Leuconostoc and Bacillus. These were similar to the core honeybee gut bacteria signifying stability in honeybee metabolism and nutrition. The findings of this study showed that the bacterial community associated with honeybees derived from the host and the beehive environment play a crucial role in host nutrition and health modulation. The study recommends the prioritization of management strategies to reduce potential stressors that result in a hive absconding. Data generated from this study can be used in conservation and preservation of this important insect and ecosystem service provider.