Exposure of the wild bee Osmia bicornis to the honey bee pathogen Nosema ceranae

Abstract

Abstract Wild bees are important pollinators for agricultural crops and solitary species such as Osmia bicornis are particularly suitable for pollination management. Wild bees share floral resources with managed honey bees and may be exposed to emerging infectious diseases. Although studies have explored the prevalence of pathogens in solitary wild bee species, data regarding the impact of pathogens on solitary bee health are lacking. We carried out experiments examining whether the solitary bee species O. bicornis is susceptible to infection with the emerging pathogen Nosema ceranae and recorded the impact of exposure on survival. The results obtained indicate that N. ceranae may be able to infect O. bicornis but its impact on host fitness is negligible: survival rates did not differ between control and inoculated bees, although male survival was marginally lower after infection. To explore the possible field‐relevance of our findings, we collected wild bees near an infected and a non‐infected hive and showed that N. ceranae was shared between managed and wild bees, although only the in presence of infected honey bees. The findings of the present study show that O. bicornis is susceptible to pathogen spillover and could act as a potential reservoir host for N. ceranae in pollinator networks. Additional studies on this species incorporating sublethal effects, multiple infections and other interacting stressors are warranted.