Risks and benefits of the biological interface between managed and wild bee pollinators

1. Increasing global human populations and climate change not only increase the demand for food but require it to be supplied in sustainable quantities. One crucial aspect for sustainability is to ensure pollinator services for crop production and ecosystem services. 2. The global distribution of universal bee pollinators and the different degrees of intensity of bee-keeping have resulted in a high variability of impacts. It is therefore essential to separate the different pollinator populations, in particular the cases of honeybees and bumblebees, into wild/feral and managed populations, which can and will interact. 3. Such interactions can be either beneficial or deleterious. A deleterious interaction between wild/feral colonies and the managed populations may result in disease and pest transmission. 4. However, a wild/feral population could easily buffer the effects of newly introduced pathogens increasing the resistance of the population as a whole. Varroa mites that caused the loss of the wild population of Apis mellifera in Europe have recently been established in South Africa. Studies of the mite's introduction into South Africa suggest that African honeybee populations are less affected by the mite and can deal with and survive parasite loads which would kill colonies in the Northern Hemisphere. 5. This observed resilience in Africa and Americas is most likely based on the interactions between wild and managed bees, since a large proportion of the total honeybee population is wild in these regions and therefore not influenced by humans. This allows the wild population to adapt to new parasites/pathogens, without human interference, with the large numbers of wild colonies ensuring that resilience is high. A high ratio of wild to managed colonies could also ensure that beneficial adaptations in the wild population filter through to the managed population. 6. Whether a similar situation prevails in bumblebees with wild and managed populations needs to be more carefully examined, particularly in the context of the global trade in colonies of these bees. Our current understanding of the interaction between wild/feral and managed populations suggests that transporting of species out of their endemic range should be done with great caution.