Western honey bee
The western honey bee or European honey bee (Apis mellifera) is the most common of the 7–12 species of honey bees worldwide.[3][4] The genus name Apis is Latin for "bee", and mellifera is the Latin for "honey-bearing" or "honey carrying", referring to the species' production of honey.[5]
Like all honey bee species, the western honey bee is eusocial, creating colonies with a single fertile female (or "queen"), many normally non-reproductive females or "workers", and a small proportion of fertile males or "drones". Individual colonies can house tens of thousands of bees. Colony activities are organized by complex communication between individuals, through both pheromones and the dance language.
The western honey bee was one of the first domesticated insects, and it is the primary species maintained by beekeepers to this day for both its honey production and pollination activities. With human assistance, the western honey bee now occupies every continent except Antarctica. Western honey bees are threatened by pests and diseases, especially the Varroa mite and colony collapse disorder. There are indications that the species is rare, if not extinct in the wild in Europe and as of 2014, the western honey bee was assessed as "Data Deficient" on the IUCN Red List. Numerous studies indicate that the species has undergone significant declines in Europe; however, it is not clear if they refer to population reduction of wild or managed colonies. Further research is required to enable differentiation between wild and non-wild colonies in order to determine the conservation status of the species in the wild, meaning self sustaining, without treatments or management.[6]
Western honey bees are an important model organism in scientific studies, particularly in the fields of social evolution, learning, and memory; they are also used in studies of pesticide toxicity, especially via pollen, to assess non-target impacts of commercial pesticides.
Humans have been collecting honey from western honey bees for thousands of years, with evidence in the form of rock art found in France and Spain,[42] dating to around 7,000 BCE.[43] The western honey bee is one of the few invertebrate animals to have been domesticated. Bees were likely first domesticated in ancient Egypt, where tomb paintings depict beekeeping, before 2600 BC.[44] Europeans brought bees to North America in 1622.[45][46]
Beekeepers have selected western honey bees for several desirable features:[45]
These modifications, along with artificial change of location, have improved western honey bees from the point of view of the beekeeper, and simultaneously made them more dependent on beekeepers for their survival. In Europe, cold weather survival was likely selected for, consciously or not, while in Africa, selection probably favoured the ability to survive heat, drought, and heavy rain.[45]
Authors do not agree on whether this degree of artificial selection constitutes genuine domestication. In 1603, John Guillim wrote "The Bee I may well reckon a domestic insect, being so pliable to the benefit of the keeper."[47] More recently, many biologists working on pollination take the domesticated status of western honey bees for granted.[48][49] For example, Rachael Winfree and colleagues write "We used crop pollination as a model system, and investigated whether the loss of a domesticated pollinator (the honey bee) could be compensated for by native, wild bee species."[50] Similarly, Brian Dennis and William Kemp write: "Although the domestication of the honey bee is closely connected to the evolution of food-based socio-economic systems in many cultures throughout the world, in current economic terms, and in the U.S. alone, the estimated wholesale value of honey, more than $317 million dollars in 2013, pales in comparison to aggregate estimated annual value of pollination services, variously valued at $11–15 billion."[51]
On the other hand, P. R. Oxley and B. P. Oldroyd (2010) consider the domestication of western honey bees, at best, partial.[52] Oldroyd observes that the lack of full domestication is somewhat surprising, given that people have kept bees for at least 7,000 years. Instead, beekeepers have found ways to manage bees using hives, while the bees remain "largely unchanged from their wild cousins".[53]
Leslie Bailey and B. V. Ball, in their book Honey Bee Pathology, call western honey bees "feral insects", in contrast to the domestic silk moth (Bombyx mori) which they call "the only insect that has been domesticated", and refer to the "popular belief among many biologists as well as beekeepers that bees are domesticated". They argue that western honey bees are able to survive without human help, and in fact require to "be left at liberty" to survive. Further, they argue that even if bees could be raised away from the wild, they would still have to fly freely to gather nectar and pollinate plants. Therefore, they argue, beekeeping is "the exploitation of colonies of a wild insect", with little more than the provision of a weatherproof cavity for them to nest in.[54] Likewise, Pilar de la Rua and colleagues argue that western honey bees are not fully domesticated, because "endemic subspecies-specific genetic footprints can still be identified in Europe and Africa", making conservation of wild bee diversity important. Further, they argue that the difficulty of controlling drones for mating is a serious handicap and a sign that domestication is not complete, in particular as "extensive gene flow usually occurs between wild/feral and managed honeybee populations".[55]
Immune mechanisms[edit]
Innate immune mechanisms[edit]
Humoral and cellular immune mechanisms of western honey bees are similar to those of other insects. Trans-generational immune priming (TGIP) is an approach that insects use to pass specific immunity from one generation to the next. The offspring are more likely to overcome pathogens that their parents have encountered. TGIP resembles adaptive immune responses but with different underlying mechanisms. TGIP against Paenibacillus larvae, which causes American foulbrood, has been demonstrated. The egg-yolk protein Vitellogenin (Vg) plays an important role in TGIP in honey bees, as it participates in the information transmitted between queen and offspring.[5] Immune elicitors such as fragments or microbes are considered pathogen-associated molecular patterns (PAMPs). Vg can bind and deliver PAMPs to offspring and thereafter lead to the induction of immunity-related genes.[7] In laboratory experiments, injecting heat-killed P. larvae into honey bee queens can prevent 26% of death in their offspring.[10] Offspring produced by queens orally vaccinated in this way were 30%-50% more likely to survive infection. Immune priming in queens triples differentiated hemocytes in their offspring.[11]
Close relatives[edit]
Apart from Apis mellifera, there are six other species in the genus Apis. These are Apis andreniformis, Apis cerana, Apis dorsata, Apis florea, Apis koschevnikovi, and Apis nigrocincta.[100] These species all originated in southern and southeastern Asia. Only Apis mellifera is thought to have originated in Europe, Asia, and Africa.[101]