A scientific note on the prevalence of Nosema spp in honey bee colonies in relation to the proximity of mining regions and levels of heavy metal contamination

Due to its detrimental effects on bee health and overall hive output, various pests and pathogens, including Nosema spp microsporidians, have become a major problem for beekeepers worldwide. Understanding the prevalence of nosemosis and potential risk-factors for its occurrence is essential to safeguard honey bee populations. We examined apiaries 5 km, 2.5 km away and within the mining region in the Ngororero region of Rwanda’s Western Province. We found lead (Pb) in all examined apiaries at a high contamination level from 0.01 to 0.06 mgg−1 mean concentration. Pb variable (p < 0.001) and proximity to the mining region (p = 0.031) were significantly associated with Nosema spp spore presence. Nosema spp spore presence among the worker honey bees within the mining region was significantly higher statistically than that 5 km away from the mining region. The study suggests that the increased prevalence of Nosema spp near mining regions may be due to delayed exposure of worker bees and colonies to environmental stressors released from the mining region, such as Pb.