Passive laboratory surveillance in Spain: pathogens as risk factors for honey bee colony collapse

Many European and North American countries have reported losses in honey bee populations over recent years. Although multiple factors appear to be involved in this decline, the influence of pathogens may be particularly important. In the present study, we analyzed the presence of the major honey bee pathogens and neonicotinoid insecticides in ten professional apiaries (five affected by high honey bee colony mortality and five asymptomatic apiaries). Our results confirm that Nosema ceranae and trypanosomatids are very prevalent in the apiaries affected by depopulation and high colony loss. By contrast, and while they have been demonstrated to be highly toxic to bees, neonicotinoid insecticides do not seem to play an important role in colony mortality in these apiaries. This kind of passive surveillance system is important to collect information about pathogen incidence, particularly when supplemented with a strong system of active disease surveillance that enables emergent diseases to be detected.