Molecular detection of honeybee pathogens in honey from a UK citizen science program

Fruits, legumes, oilseeds and nuts have a high dependency on insect pollination, of which the honey bee (Apis mellifera L.) is a critical contributor. However, declines in wild insect pollinators and managed honey bees have been widely reported. An increase in the prevalence of diseases is likely to be directly or indirectly contributing to these declines. In the United Kingdom, the fungal chalkbrood, the microsporidian Nosema, and the bacterial European Foulbrood (EFB), represent three major non-viral diseases of honey bees. Many of these diseases are economically important to honey bees and have the potential to cross over to wild bee species. Rapid large-scale monitoring of these pathogens provides advantages in controlling these diseases through pre-emptive mitigation measures. The UK National Honey Monitoring Scheme provides this kind of monitoring, and this study assesses the efficacy of molecular methods to detect these diseases within honey samples obtained through this citizen science scheme. The study used quantitative polymerase chain reaction (qPCR) from DNA extracted from 150 honey samples, which revealed chalkbrood (13%) and Nosema (11%) as the most abundant pathogens, whereas the legally notifiable EFB was discovered in less than 2% of colonies. Asymptomatic infections, including that of the high-risk EFB, were common. There is evidence to suggest that both asymptomatic and symptomatic disease expression become more prevalent throughout the year. Monitoring for these diseases is recognised as being vital in the control and containment of these pathogens. The application of low-cost, non-invasive methods with a large-scale monitoring scheme, could support mitigation as well as identify currently asymptomatic but highly contagious or notifiable diseases prior to outbreaks.