De novo assembly of two colletid genomes reveals detection of Apicystis bombi

The advent of new genome sequencing technology, improved bioinformatics pipelines, and reduced monetary costs are rapidly advancing our capacity to sequence the genomes of all biodiversity. In addition to achieving high data quality genomes of the target species, genome sequencing can also capture associated pathogens, parasites, and dietary items. In this study, we report on the detection of the bee pathogen Apicystis bombi (Arthrogregarida, Apicomplexa) in the yellow-faced bee Hylaeus volcanicus (Hymenoptera: Colletidae) endemic to the Hawaiian archipelago. Apicystis bombi is a gregarine parasite that can cause fat body hypertrophism in bees. While A. bombi has been documented in eusocial bees (Apidae), the parasite has also been documented in solitary bees including the genera Osmia (Megachilidae), Heriades (Megachilidae), and Andrena (Andrenidae). However, to our knowledge, the discovery of A. bombi in H. volcanicus is the first report of the pathogen documented in the bee family Colletidae. Furthermore, an assessment of 30 Hylaeus spp. specimens found 73% of individuals to be infected with A. bombi from a population on Hawai‘i Island. Our study of this single population underscores the prevalence of the pathogen in endemic Hawaiian bees, warranting continued investigation of the prevalence and pathology of A. bombi infection in this unique bee fauna. Finally, genome sequencing of the Hylaeus bees demonstrates the value of additional knowledge that can be gained in generating genomes for all biodiversity.