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Bumblebee

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This article is about the flying insect. For other uses see Bumblebee (disambiguation).

Bombus
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Insecta
Order:
Hymenoptera
Family:
Apidae
Subfamily:
Apinae
Tribe:
Bombini
Genus:
Bombus

Latreille, 1802
Species

more than 250 species and subspecies in 37 subgenera

Bumblebees (also spelled bumble bee, also known as humblebee) are flying insects of the genus Bombus in the family Apidae. Like their relatives the honey bees, bumblebees feed on nectar and gather pollen to feed their young. These creatures are beneficial to humans and the plant world alike, and tend to be larger and more visibly furry than other types of bee. Most, but not all, bumblebee species are gentle. Bumblebees are social insects that are characterized by black and yellow body hairs, often in bands, a commonality among the majority of the species of Bombus; however, some species are known to have orange or even red on their bodies, or may be entirely black[1]. Another distinguishing characteristic is the soft nature of the long, branched setae, called pile, that covers their entire body, making them appear and feel fuzzy. Queen and worker bumblebees can sting, but the sting is not barbed like that of the honey bee, so they can sting more than once[2].

Importance

Bumblebee collecting pollen from a sunflower.

Bumblebees are important pollinators of both crops and wildflowers.

Agricultural Use

Bumblebees are increasingly cultured for agricultural use as pollinators because they can pollinate plant species that other pollinators cannot by using a technique known as buzz pollination. For example, bumblebee colonies are often emplaced in greenhouse tomato production, because the frequency of buzzing that a bumblebee exhibits effectively pollinate tomatoes[3].

The agricultural use of bumblebees is limited to pollination. Because bumblebees do not overwinter the entire colony, they are not obliged to stockpile honey, and are therefore not useful as honey producers.

Endangered Species

Bumblebees are in danger in many developed countries due to habitat destruction and collateral pesticide damage. In Britain, until relatively recently, 19 species of native true bumblebee were recognised along with six species of cuckoo bumblebees (bumblebees that trick other species into looking after their young). Of these, three have already become extinct[1] [2], eight are in serious decline and only six remain widespread. A decline in bumblebee numbers could cause large-scale sweeping changes to the countryside, due to inadequate pollination of certain plants. In response to this, a new organisation has recently been set up - The Bumblebee Conservation Trust aims to halt these declines through conservation and education (see links).

Life

Bumblebee on Sea Holly.
Drone fertilizes bumblebee, early September, southern Ontario, Canada

Habitat

Bumblebees are typically found in higher latitudes that range from warm to cold climates where other bees might not be found. One reason for this is that bumblebees can regulate their body temperature, via solar radiation, internal mechanisms of "shivering" and radiative cooling from the abdomen (called heterothermy). Other bees have similar physiology, but it has been best studied in bumblebees.[3]

Nests

Bumblebees form colonies, much like honeybees. However, their colonies are usually much less extensive than those of honeybees, because of the small physical size of the nest cavity, the fact that a single female is responsible for the initial construction, and the restriction to a single season (in most species). Often, mature bumblebee nests will hold fewer than 50 individuals, and may be within tunnels in the ground made by other animals, or in tussocky grass. Bumblebees mostly do not preserve their nests through the winter, though some tropical species live in their nests for several years (and their colonies can grow quite large, depending on the size of the nest cavity). The last generation of summer includes a number of queens who overwinter separately in protected spots. The queens can live up to one year, possibly longer in tropical species.

Food

Unlike honeybees, bumblebees only store a few days' worth of food and so are much more vulnerable to food shortages. However, because bumblebees are much more opportunistic feeders than honeybees, these shortages may have less profound effects.

Reproduction

In temperate zone species, in the autumn, young queens ("gynes") mate with males (drones) and diapause during the winter in a sheltered area, whether in the ground or in a man-made structure. In the early spring, the queen comes out of diapause and finds a suitable place to create her colony, and then builds wax cells in which to lay her fertilized eggs from the previous winter. The eggs that hatch develop into female workers, and in time the queen populates the colony, with workers feeding the young and performing other duties similar to honey bee workers. New reproductives are produced in the fall, and the queen and workers die, as do the males.

Sting

Queen and worker bumblebees sting, but only do so in self-defense or if their nest is disturbed. See Schmidt Sting Pain Index.

Bumblebee myths

File:Bumblebee in Flight.jpg
A bumblebee in flight

Flight

According to 20th century folklore, the laws of aerodynamics prove that the bumblebee should be incapable of flight, as it does not have the capacity (in terms of wing size or beat per second) to achieve flight with the degree of wing loading necessary. Not being aware of scientists proving it cannot fly, the bumblebee succeeds. The origin of this myth has been difficult to pin down with any certainty. John McMasters recounted an anecdote about an unnamed Swiss aerodynamicist at a dinner party who performed some rough calculations and concluded, presumably in jest, that according to the equations, bumblebees cannot fly.[4] In later years McMasters has backed away from this origin, suggesting that there could be multiple sources, and that the earliest he has found was a reference in the 1934 French book Le vol des insectes by M. Magnan. Magnan is reported to have written that he and a Mr. Saint-Lague had applied the equations of air resistance to insects and found that their flight was impossible, but that "One shouldn't be surprised that the results of the calculations don't square with reality".[5]

It is believed[citation needed] that the calculations which purported to show that bumblebees cannot fly are based upon a simplified linear treatment of oscillating aerofoils. The method assumes small amplitude oscillations without flow separation. This ignores the effect of dynamic stall, an airflow separation inducing a large vortex above the wing, which briefly produces several times the lift of the aerofoil in regular flight. More sophisticated aerodynamic analysis shows that the bumblebee can fly because its wings encounter dynamic stall in every oscillation cycle.

Buzz

One common, yet incorrect, assumption is that the buzzing sound of bees is caused by the beating of their wings. The sound is the result of the bee vibrating its flight muscles, and this can be done while the muscles are decoupled from the wings, a feature known in bees but not possessed by other insects. This is especially pronounced in bumblebees, as they must warm up their bodies considerably to get airborne at low ambient temperatures.[3]

Species

A Buff-Tailed bumblebee

Genus Bombus

Genus Psythirus

Associated Parasites

See also

Reference

  1. ^ Scientists Map The Flight Of The Bumblebee
  2. ^ Harman, Alan. "Bumblebee Shortage". Bee Culture, 59. July, 2003.
  3. ^ a b Heinrich, B. (1981) Insect Thermoregulation
  4. ^ McMasters, John H. "The flight of the bumblebee and related myths of entomological engineering." American Scientist 77 (March/April 1989): pp.146-169, cited in Ingram, Jay The Barmaid's Brain, Aurum Press, 2001, pp.91-92.
  5. ^ Ingram, Jay The Barmaid's Brain, Aurum Press, 2001, pp.91-92.

Further reading

  • "Bees." World Book Encyclopedia. 1998 ed.
  • Hasley, William D. "Bees." Collier's Encyclopedia. 1990 ed.
  • Abbott, Carl, and Bartlett, John. "Bumble Bees." Encarta Encyclopedia. 2004 ed.
  • Freeman, Scott. Biological Science. New Jersey: Upper Saddle River, 2002.
  • Macdonald, M. & Nisbet, G. 2006. "Highland Bumblebees: Distribution, Ecology and Conservation." HBRG, Inverness, www.hbrg.org.uk. ISBN 0-9552211-0-2.

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