:''This article is about the flying
insect. For other uses see
Bumblebee (disambiguation) or
Bombus (disambiguation).''
'Bumblebees' (also spelled 'bumble bee', also known as 'humblebee') are flying
insects of the
genus ''Bombus'' in the family
Apidae.
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] 'In contrary to popular belief one does not get a burning sensation when mating with a bumblebee. See the ancient greek fable of the rabbit and the bumblebee for more information.' Another obvious (but not unique) characteristic is the soft nature of the long, branched
setae, called pile, that covers their entire body, making them appear and feel fuzzy. They are best distinguished from similarly large, fuzzy bees by the form of the female hind leg, which is modified to form a
corbicula; a shiny concave surface that is bare but surrounding by a fringe of hairs, used to transport
pollen (in similar bees, the hind leg is completely hairy, and pollen grains are wedged into the hairs for transport). 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] Bumblebee species are non-aggressive, but will sting in defense of their nest, or if harmed.
Like their relatives the honey bees, bumblebees feed on
nectar and gather pollen to feed their young.
Biology
A bumblebee is covered in pollen
White Tailed Bumblebee
Drone fertilizes bumblebee, early September, southern Ontario, Canada
Anatomy
The blood or
hemolymph, as in other
arthropods, is carried in an
open circulatory system. The body organs, heart, muscles, etc. are surrounded in a reservoir of blood. The heart does pulse blood through its long tube, though, so there is a circulation of sorts.
In fertilised queens the ovaries are activated and when the queen lays her egg it passes along the
oviduct to the vagina. In the vagina there is a container called the
spermatheca. This is where the queen stored sperm from her mating. Before she lays the egg she will decide whether to use sperm from the spermatheca to fertilise it or not. Non-fertilised eggs grow into male bumblebees, and only fertilised eggs grow into females and queens.
As in all animals
hormones play a big role in the growth and development of the bumblebee. The hormones that stimulate the development of the ovaries are suppressed in the other female worker bees while the queen remains dominant. Salivary glands in the head secrete saliva which is mixed with the nectar and pollen. Saliva is also mixed into the nest materials to soften them.
The bumblebee tongue is specialised to suck up nectar via capillary action. At rest or when flying the tongue is kept inside a sheath and folded under the head and thorax. The
abdomen is covered with dorsal
tergites and ventral
sternites. Wax is secreted between these plates.
The brightly-coloured
pile of the bumble bee is a form of
aposematic signal. Depending on the species and
morph, these colours can range from entirely black, to bright yellow, red, orange, white, and pink. Thick pile can also act as insulation to keep the bee warm in cold weather. Further, when flying a bee builds up an electrostatic charge, and as flowers are usually well grounded, pollen is attracted to the bee's pile when it lands. When a pollen covered bee enters a flower, the charged pollen is preferentially attracted to the
stigma because it is better grounded than the other parts of the flower.
A bumblebee does not have ears, and it is not known whether or how a bumblebee can hear sound waves passing through the air, however they can feel the vibrations of sounds through wood and other materials.
The heart, like that in most other insects, runs down the entire length of the body.
The fat body is a nutritional store. Before hibernation queens eat as much as they can to enlarge their fat body. The fat in the cells is used up during hibernation.
Habitat
Bumblebees are typically found in higher
latitudes and/or high
altitudes, though exceptions exist (there are a few lowland
tropical species). A few species (''
Bombus polaris'' and ''
B. arcticus'') range into very 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.
[Heinrich, B. (1981) ''Insect Thermoregulation'']
Nests
Bumblebees form
colonies. However, their colonies are usually much less extensive than those of honey bees, 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
tussock grass. Bumblebees sometimes construct a wax canopy ("involucrum") over top of their nest for protection and insulation. 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.
Colony cycle
Bumblebee nests are first constructed by over-wintered queens in the spring (in temperate areas). Upon emerging from
hibernation, the queen collects pollen and nectar from flowers and searches for a suitable nest site. The characteristics of the nest site vary amoung bumble bee species, with some species prefering to nest in underground holes and others in tussock grass or directly on the ground. Once the queen has found a site, she prepares wax pots to store food and wax cells into which eggs are laid. These eggs then hatch into
larvae, which cause the wax cells to expand isometrically into a clump of brood cells.
These larvae need to be fed both nectar for
carbohydrates and pollen for
protein in order to develop. Bumblebees feed larvae nectar by chewing a small hole in the brood cell into which nectar is regurgitated. Larvae are fed pollen in two ways, depending on the bumblebee species. So called "pocket-maker" bumblebees create pockets of pollen at the base of the brood cell clump from which the larvae can feed themselves. Conversely, "pollen-storer" store pollen in separate wax pots and feed it to the larva in the same fashion as nectar.
[ Evans, Elaine et al. Befriending Bumble Bees. University of Minnesota Press. 2007. ] Bumble bees are incapable of
trophallaxis.
With proper care, the larvae progress through four
instars, becoming successively larger with each molt. At the end of the fourth instar the larvae spin a silk cocoon under the wax covering the brood cell, changing it into a pupal cell. The larvae then undergo an intense period of cellular growth and differentiation and become
pupae. These pupae then develop into adult bees, who chew their way out of the silk cocoon. When adult bumble bees first emerge from their cocoons, the hairs on their body are not yet fully pigmented and are a greyish-white colour. The bees are referred to as "callow" during this time, and they will not leave the colony for at least 24 hours. The entire process from egg to adult bee can take as long as five weeks, depending on the species and the environmental conditions.
After the emergence of the first or second group of workers, workers take over the task of foraging and the queen spends most of her time laying eggs and caring for larvae. The colony grows progressively larger and at some point will begin to produce males and new queens. The point at which this occurs varies among species and is heavily dependant on resource availability and environmental factors. Unlike the workers of more advanced
social insects, bumble bee workers are not physically reproductively sterile and are able to lay
haploid eggs that develop into viable male bumble bees. Only fertilized queens can lay
diploid eggs that mature into workers and new queens.
Early in the colony cycle, the queen bumble bee compensates for potential reproductive competition from workers by suppressing their egg-laying by way of physical aggression and pheromonal signals.
[ Van Honk C.G.J., Velthuis H.H.W., Röseler P.-F.,Malotaux M.E. (1980) The mandibular glands of Bombus terrestris queens as a source of queen pheromones, Entomol. Exp. Appl. 28, 191–198. ] Thus, the queen will usually be the mother of all of the first males laid. Workers eventually begin to lay males later in the season when the queen's ability to suppress their reproduction diminishes.
[ Fletcher D.J.C., Ross K. (1985) Regulation of reproduction in eusocial Hymenoptera, Annu. Rev. Entomol. 30, 319–343.] The reproductive
competition between workers and the queen is one reason that bumble bees are considered "primitively
eusocial".
New queens and males leave the colony after maturation. Males in particular are forcibly driven out by the workers. Away from the colony, the new queens and males live off nectar and pollen and spend the night on flowers or in holes. The queens are eventually mated (often more than once) and search a for suitable location for
diapause.
Foraging behavior
Bumblebees generally visit flowers exhibiting the bee
pollination syndrome. They can visit patches of flowers up to 1-2 kilometres from their colony.
[Walther-Hellwig K, Frankl R (2000). Foraging distances of Bombus muscorum, Bombus lapidarius, and Bombus terrestris (Hymenoptera, Apidae). Journal of Insect Behavior, 13, 239–246.] Bumblebees will also tend to visit the same patches of flowers every day, as long as nectar and pollen continue to be available.
[Dramstad WE, Fry GLA, Schaffer MJ (2003) Bumblebee foraging —is closer really better? Agriculture, Ecosystems and Environment, 95, 349–357.]
When bumblebees arrive at a flower, they extract nectar using their long tongue ("
glossa") and store it in their
crop. Some species (e.g., ''B. occidentalis'') of bumblebee also exhibit what is known as "nectar robbing": instead of inserting the mouthparts into the flower normally, these bees bite directly through the base of the
corolla to extract nectar, avoiding pollen transfer.
[Maloof, J.E. 2001. The Effects of a Bumble Bee Nectar Robber on Plant Reproductive Success and Pollinator Behavior. American Journal of Botany 88 (11) p. 1960-1965.] These bees obtain pollen from other species of flowers that they "legitimately" visit.
Pollen is removed from flowers deliberately or incidentally by bumblebees. Incidental removal occurs when bumblebees come in contact with the
anthers of a flower while collecting nectar. The bumblebee's body hairs receive a dusting of pollen from the anthers which is then groomed into the
corbiculae ("pollen baskets"). Bumblebees are also capable of
buzz pollination.
Once a bumblebee has visited a flower, it leaves a scent mark on the flower. This scent mark deters visitation of the flower by other bumblebees until the scent degrades.
[Goulson D, Hawson SA, Stout JC (1998) Foraging bumblebees avoid flowers already visited by conspecifics or by other bumblebee species. Animal Behaviour, 55, 199–206.]
Once they have collected nectar and pollen, bumblebees return to the nest and deposit the harvested nectar and pollen into brood cells, or into
wax cells for storage. Unlike honey bees, 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 honey bees, these shortages may have less profound effects. Nectar is stored essentially in the form it was collected, rather than being processed into
honey as is done in
honey bees; it is therefore very dilute and watery, and is rarely consumed by humans.
"Cuckoo" bumblebees
Bumblebees of the subgenus ''
Psithyrus'' (known as '
cuckoo bumblebees', and formerly considered a separate genus) are a lineage which has lost the ability to collect pollen, and are instead
cleptoparasitic in the colonies of other bumblebees. Before finding and invading a host colony, a ''Psithyrus'' female (there is no caste system in these species) will feed directly from flowers. Once she has infiltrated a host colony, the ''Psithyrus'' female will kill or subdue the queen of that colony and forcibly (using
pheromones and/or physical attacks) "enslave" the workers of that colony to feed her and her young.
[ Zimma BO, Ayasse M, Tengo J, Ibarra F, Schulz C, Francke W. (2003) Do social parasitic bumblebees use chemical weapons? (Hymenoptera, Apidae). Journal of Comparative Physiology A-Neuroethology Sensory Neural and Behavioral Physiology 189 (10): 769-775. ] The female ''Psithyrus'' also has a number of morphological adaptations, such as larger mandibles and a larger venom sac that increase her chances of taking over a nest.
[Fisher, RM, Sampson, BJ. (1992) Morphological specialization of the bumble bee social parasite ''Psithyrus ashtoni'' (Cresson) (Hymenoptera, Apidae). Canadian Entomologist 124 (1): 69-77.] Upon hatching, the male and female ''Psithyrus'' disperse and mate. Like non-parasitic bumblebee queens, female ''Psithyrus'' find suitable locations to spend the winter and enter diapause upon being mated.
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 autumn, 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. Female cuckoo bumblebees will aggressively attack host colony members, and sting the host queen, but will ignore other animals (including humans) unless disturbed. See
Schmidt Sting Pain Index.
Bumblebees do not have barbed stingers. They do not die when they sting and can sting multiple times.
Bumblebees and people
Bumblebees are important
pollinators of both
crops and
wildflowers.
Agricultural use
Main articles: List of plants pollinated by bees
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 releases tomato pollen.
[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 status
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. Of these, three have already become
extinct,
[4][5] 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).
In popular culture
★ ''
The Flight of the Bumblebee'' is a famous
orchestral
interlude written by
Nikolai Rimsky-Korsakov for his
opera ''
The Tale of Tsar Saltan'', composed in
1899-
1900.
★ The character
Bumblebee Man from
The Simpsons is a Mexican slapstick comedian who dresses in a bumblebee costume. He is based on
El Chapulín Colorado, a famous Mexican comedy character who dresses in a red
grasshopper costume.
★ In the north-east of
Scotland bumblebees are known as 'foggy bummers'.
[6]
★
Bumblebee of
Transformers
★
Buck Bumblebee was an Nintendo 64 starring the titular Bee in his battle against villainous bugs.
Bumblebee myths
The flight of the bumblebee
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 under "the power of its own arrogance" (McFadden et. al. 2007). 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.
[7] 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".
[8]
It is believed 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.
[ This is how bumblebees can sometimes reach an internal thoracic temperature of 30 degrees Celsius.]
Selected species
Bumblebee of unknown species
For a complete list, see List of world bumblebee species.
★ ''Bombus affinis''
★ ''Bombus appositus''
★ ''Bombus ashtoni''
★ ''Bombus bifarius''
★ Two-spotted Bumblebee, ''Bombus bimaculatus''
★ ''Bombus borealis''
★ ''Bombus citrinus''
★ Cullum's bumblebee, ''Bombus cullumanus''
★ Great Yellow bumblebee, ''Bombus distinguendus''
★ Golden Northern Bumblebee, ''Bombus fervidus''
★ Yellow-faced bumblebee, ''Bombus flavifrons''
★ ''Bombus fraternus''
★ ''Bombus frigidus''
★ Grey-necked bumblebee, ''Bombus griseocollis''
★ Small Garden bumblebee, ''Bombus hortorum''
★ Frisky bumblebee ''Bombus impatiens''
★ ''Bombus insularis''
★ ''Bombus kirbyellus''
★ Red-tailed bumblebee, ''Bombus lapidarius''
★ ''Bombus lucorum''
★ Orange-rumped Bumblebee, ''Bombus melanopygus''
★ Blaeberry Bumblebee, ''Bombus monticola''[9][10]
★ ''Bombus occidentalis''
★ ''Bombus pascuorum''
★ ''Bombus pensylvanicus''
★ ''Bombus perplexus''
★ Northern bumblebee, ''Bombus polaris''
★ ''Bombus pratorum''
★ Large Garden bumblebee, ''Bombus ruderatus''
★ ''Bombus rufocinctus''
★ Short-haired bumblebee, ''Bombus subterraneus''
★ Shrill Carder bee, ''Bombus sylvarum''
★ ''Bombus sylvicola''
★ Orange-belted bumblebee ''Bombus ternarius''
★ Buff-Tailed bumblebee, or Large Earth Bumblebee, ''Bombus terrestris''
★ ''Bombus vagans''
Associated parasites
★ Tracheal mites - ''Locustacarus buchneri''
★ Protozoans- ''Crithidia bombi''
★ Microsporidia- ''Nosema bombi''
See also
★ Imidacloprid effects on bee population
★ Regent (insecticide)
★ Bees
★ Characteristics of common wasps and bees
References
1. Bumble Bees - Natural History Museum, London
2. Straight Dope Staff Report: Do bumblebees sting? Once or many times?
3. NRDC: OnEarth Magazine, Summer 2006 - The Vanishing
4. Scientists Map The Flight Of The Bumblebee
5. Harman, Alan. "Bumblebee Shortage". Bee Culture, 59. July, 2003.
6. University of Aberdeen - Elphinstone Institute collection Retrieved 17 June 2007.
7. 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.
8. Ingram, Jay ''The Barmaid's Brain'', Aurum Press, 2001, pp.91-92.
9. UK bumblebees face extinction Retrieved 17 June 2007.
10. 'Broadleaf' magazine No 68 (Spring 2007) ''The bee's knees''. Grantham. Woodland Trust.
Further reading
★ Michener, C.D. (2000). ''The Bees of the World''. Johns Hopkins University Press.
★ "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.
External links
★ Bumblebees of the world - find species by region, species groups, colour pattern
★ Distribution and decline of British bumblebees
★ The Bumblebee Conservation Trust
★ Buglife's Big Bumblebee Hunt in Essex, London and North Kent - Summer 2007
★ Bumble Bees - diagnostic photographs, Creative Commons
★ The Bumblebee Pages - Comprehensive Site
★ Alternative pollinators Also links to non-apis vendors.
★ Record UK Red-tailed Bumblebee sightings here - Springwatch 2006
العربية
中国
Français
Deutsch
Ελληνική
हिन्दी
Italiano
日本語
Português
Русский
Español.jpg)
