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

Abstract

Summary1. 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.

Controlling the impact of the managed honeybee on wild bees in protected areas

“…A growing body of literature reports examples of massively introduced honeybees having detrimental effects on the abundance and diversity of local wild bees 4 , 7 , 8 . However, the findings are often inconsistent between different studies because the underlying ecological processes are not well understood and obviously depend on the local situation, including region 9 , habitat type and season 5 , 10 – 12 , or the degree of dietary specialisation in the wild bee population 13 . In the absence of clear evidence of the underlying ecological processes, and without specific guideline or legislation on this issue, protected land managers remain unaware of the potential threat high-density beekeeping poses to their nature conservation efforts.…”

Plant–pollinator interactions and threats to pollination: perspectives from the flower to the landscape

“…Honeybees, and more recently bumblebees, have been extensively transported around the world for crop pollination purposes and have also become invasive. Christian Pirk and colleagues in this issue (Pirk, Crewe & Moritz 2017) take a fresh look at the interactions between wild and managed bees. Such interactions are usually assumed to be negative, as when pathogens are transmitted to native bees or between wild or feral colonies and managed populations (F€ urst et al 2014;Schmid-Hempel et al 2014).…”

“…Such interactions are usually assumed to be negative, as when pathogens are transmitted to native bees or between wild or feral colonies and managed populations (F€ urst et al 2014;Schmid-Hempel et al 2014). The association between the parasitic mite Varroa and the pathogenic DWV virus has been disastrous for beekeeping when coupled with the anthropogenic spread of honeybees (Wilfert et al 2016), and in their review Pirk, Crewe & Moritz (2017) present several scenarios for past and future introductions of the Varroa mite. However, they also point out positive interactions between wild and managed bee populations: for example, resilience to Varroa in Africa and the Americas is due to the high ratio of wild to managed honeybee colonies.…”

Reproductive parasitism by worker honey bees suppressed by queens through regulation of worker mandibular secretions

“…This strict colony organisation, of which honey bees are an example, is maintained by use of chemical communication, with caste-related tasks and reproductive development mostly controlled by means of pheromones produced by the queen and brood 1 , 2 . While the reproductive role of the queen in most honey bee colonies is firmly maintained, especially in European subspecies of the Western honey bee ( Apis mellifera L.), it is more complex in others, such as the African subspecies where the majority of the colonies are not kept in apiaries 3 . Workers are, in principle, able to activate their ovaries and lay unfertilised eggs that normally become drones 4 .…”