Högskolan i Skövde

Honeybees (Apis mellifera) are one of the most important pollinators in the ecosystem and agriculture, insect pollination helps with more than 35% of the global food supply. Their health is directly linked to a stable gut microbiota, supporting digestion, immune system, and protection against pathogens.

Melissococcus plutonius, is a pathogen that can cause a bacterial disease that threatens honeybee colony health globally called European Foulbrood (EFB). The aim of this study is to identify the bacterial flora associated with A. mellifera gut through sequencing the 16s rRNA gene and comparing the bacterial composition between samples with and without M. plutonius. 48 specimens collected from two hives in Uddevalla, Sweden, were dissected and analysed using 16S rRNA and ITS amplicon sequencing on the Oxford Nanopore MinION, followed by RT-qPCR for targeted pathogen detection. The 16S sequencing produced consistent high classification rates. It showed that Bartonella was the dominant genus in all groups, likely due to seasonal changes. A reduction in Bifidobacterium in the infected bees shows that M. plutonius infection is linked with general disruption of the microbial community. Database limitation has led to unsuccessful classification of the fungal community. The study findings suggested that RT-qPCR is more sensitive than 16S sequencing for pathogen detection and could successfully differentiate between infected and non-infected samples.

Future studies are recommended to use other ITS bioinformatics tools, use appropriate internal controls in qPCR assays, and expand sample sizes to further investigate the relationship between M. plutonius infection and gut microbiota composition in A. mellifera.