Bombus ternarius | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Hymenoptera |
Family: | Apidae |
Genus: | Bombus |
Subgenus: | Pyrobombus |
Species: | B. ternarius |
Binomial name | |
Bombus ternarius | |
Bombus ternarius, commonly known as the orange-belted bumblebee or tricolored bumblebee, [2] is a yellow, orange and black bumblebee. It is a ground-nesting social insect whose colony cycle lasts only one season, common throughout the northeastern United States and much of Canada. [3] The orange-belted bumblebee forages on Rubus , goldenrods, Vaccinium , and milkweeds found throughout the colony's range. Like many other members of the genus, Bombus ternarius exhibits complex social structure with a reproductive queen caste and a multitude of sister workers with labor such as foraging, nursing, and nest maintenance divided among the subordinates.
B. ternarius is a small, fairly slender bumblebee. The queen is 17–19 mm (0.67–0.75 in) long and the breadth of the abdomen is 8.5–9 mm (0.33–0.35 in). The workers are 8–13 mm (0.31–0.51 in), and the drones are 9.5–13 mm (0.37–0.51 in) in length. Both the worker and the drone have abdomens about 4.5–5.5 mm (0.18–0.22 in) in breadth. [4]
The queen and workers have black heads, with a few pale yellow hairs. The anterior and posterior thorax and the first and fourth abdominal segments are yellow, abdominal segments 2 to 3 are orange, and the terminal segments are black. The queen and the workers are close in resemblance, and the most striking difference between them is in the size [4] [5] of their fat deposits. Workers have very little fat, particularly in their abdomen, leaving plenty of room for the honey stomach, an enlargement of the oesophagus in which nectar can be stored on foraging trips. In contrast, in young queens, the abdomen is largely full of fat. This leads to queens being heavier for their size than workers. [5] [6]
The drone has a yellow head with a few black hairs. The coloration of the thorax and abdomen is similar to that of the females, with the exception that the last abdominal segments are yellow on the sides. The fur of the drone is longer than that of the females. [4]
B. huntii, another species of bumblebee common throughout the western United States, is nearly identical in coloration to B. ternarius, though it has primarily yellow facial hairs rather than black. [7]
B. ternarius mainly ranges in the northern parts of the US and much of Canada. Their range extends from the Yukon to Newfoundland and Labrador and British Columbia. Their United States territory extends from New York and Pennsylvania to Michigan, Washington, Wyoming, Utah and Montana. [8] The bumblebees are most successful in the northern, temperate climate, but they can rarely be found farther south. [8] [9]
B. ternarius, like most members of its genus, are seasonal, meaning the queen comes out of hibernation in late April to start a new colony. The bumblebee workers fly from May to October when the entire colony dies (except hibernating queens) to start the cycle again. [7] [9]
In late April, the queen comes out of hibernation from under a few inches of loose soil or leaf litter, and begins to search for a nesting site. Bombus ternarius prefer to nest underground in small and shallow cavities like rodent burrows or natural crevices. [9] She flies low to the ground, stopping often to investigate holes in the earth, and once a satisfactory nest site is found, she forages for pollen and nectar to support her future offspring. [10] Next, the queen secretes a protective waxy coating and builds a grove where she lays fertilized eggs destined to be the first of the new workers. The queen straddles the eggs, allowing for close contact between the ventral surface of her abdomen and thorax and the eggs. This close contact allows the queen to incubate her brood with the heat she generates by pulsing contractions in her abdomen. [11]
These eggs progress through four lifecycle stages starting as an egg, then larva, pupa, and after about a month after laying the egg, the adult workers emerge. [12] Considering that the entire lifecycle of a colony is only about a season long, incubation is necessary because it hastens the development of the first workers. However, the generation of such vast amounts of heat is incredibly costly for the queen. The queen uses an estimated 600 mg of sugar per day to incubate her brood. To obtain this amount of energy, she may need to visit as many as 6,000 flowers. Naturally, during her absence, the brood cools rapidly, so the availability of plentiful and rewarding flowers near the nest site is vital. [13]
The newly hatched workers take over the duty of foraging and expanding the nest. The workers also assist in incubation of the eggs and larvae. [14] B. ternarius nests rarely exceed more than 200 individuals. [9]
In late summer, the queen switches to laying unfertilized eggs, which develop into male drones that are meant for reproduction. Towards the end of her life, the queen reverts to laying fertilized eggs. These eggs give rise to new female queens. [14] The new adult queens forage for food. They use the nest for shelter, but the new queens do not contribute to the nests food reserves. During this time, the new queens mate with roaming male drones, build up reserves of body fat, and fill their nectar crop with honey to survive winter hibernation. [15] The rest of the colony, including the old queen, dies in mid-autumn.
Drones have one function in life: reproduction. They fly in a circuit and deposit a pheromone on prominent places such as tree trunks, rocks, posts, etc., to attract the newly hatched queens. A new queen follows the pheromone trail and mates with the male. [14]
Mating among B. ternarius typically occurs on the ground or in vegetation. The male mounts the female by grabbing her thorax, the queen then extends her stinger and the male inserts his genital capsule. Mating time varies widely from about 10 to 80 minutes, with the sperm being transferred within the first two minutes of copulation. While mating, both the male and female are vulnerable to predators. After the transfer of sperm is complete, the male secretes a sticky substance that hardens into a plug that blocks new sperm for about three days. [10] This prevents other males from impregnating the same queen and competing to fertilize eggs. The plug helps reduce competition and increases the first male's evolutionary success. [14]
Individual colonies have slightly different reproductive strategies. About half of the queens adopt an early switching strategy that produces mostly male drones, and the other half adopt a late switching strategy, giving rise to mostly new queens. [16] Because of this, bumblebee female to male sex ratio differs from the standard Hymenoptera three to one ratio as proposed by the haplodiploidy hypothesis, and sits closer to an even sex ratio. [17] One hypothesis proposes that the reason why bumblebee's sex ratio differ from the characteristic hymenopteran ratio is because of the queen's decision-making. She can decide to adopt an early switching, male-producing strategy, or a late switching, queen-producing strategy. The worker bees have no choice but to go along with the queen's choice. Normally, the workers would work to shift the ratio towards female prevalence, but in the case of B. ternarius, this would disfavor the workers' evolutionary success. [16]
For all hymenopterans, sex is determined by the number of chromosomes an individual possesses. [18] Fertilized eggs get two sets of chromosomes, one from each parent, and so larva develop into diploid females, while unfertilized eggs only contain one set from the mother, so develop into haploid males or drones. The act of fertilization is under the voluntary control of the egg-laying queen. [19] This phenomenon is called haplodiploidy.
However, the actual genetic mechanism of haplodiploid sex determination in bumblebees is more complex than simple chromosome number. In bumblebees, sex is actually determined by a single gene locus with many alleles. [20] Haploids at that locus are male and diploids are female, but occasionally a diploid will be homozygous at the sex locus and develop as a male instead. This is especially likely to occur in an individual whose parents were siblings or other close relatives. Diploid males are known to be produced by inbreeding in many ant, bee, and wasp species. Diploid biparental males are usually sterile. [21]
One consequence of haplodiploidy is that females have more genes in common with their sisters than they do with their own daughters. Because of this, cooperation among kindred females may be unusually advantageous, and has been hypothesized to contribute to the multiple origins of eusociality within bumblebees and other hymenopterans. In many colonies of bees, ants, and wasps, worker females remove eggs laid by other workers due to increased relatedness to direct siblings, a phenomenon known as worker policing. [22]
All fertilized eggs are capable of developing into members of either caste, whether the larva will turn into a worker or a queen, regardless of when they are laid during colony development. [23] Some evidence suggests bumblebees can determine the caste of a larva by feeding it a special diet. Larvae are fed a mixture of pollen and nectar combined with proteins secreted by adult bees. These proteins are mainly invertase and amylase produced in the hypopharyngeal gland. This mixture is regurgitated and presented to the larvae in droplets. [24] Future queens may receive additional glandular secretions, but in terms of total protein, pollen, and carbohydrates in the food mixture, larvae of all castes receive the same proportions. [24] Nurse bees have been observed to feed queen, worker, and male larvae using the contents of the same crop, so it seems unlikely a significant difference exists in the food consumed by larvae of different castes. [25]
By experimentally starving larvae, Pereboom et al. were able to demonstrate larvae produce a cue that stimulates workers to feed them. This suggests the rate at which larvae are fed might at least be partially controlled by the larvae. [26] If feeding had a role in caste determination, this would mean the larvae have a partial say in determining their future caste. Larvae, then, may have to make an economic decision as to whether becoming a worker or a queen is more beneficial.
A more promising explanation of caste determination involves a pheromone excreted by the current queen. The queen excrete a pheromone to which larvae are sensitive between two and five days after emerging from the egg. The presence of the pheromone forces a larva to enter an irreversible pathway towards development as a worker. The absence of this pheromone causes the larva to become a queen. [24] [27] The pheromone has not yet been identified, but the evidence for its existence is convincing. Evidence suggests the pheromone is not airborne, but is transmitted directly by contact from bee to bee and from adults to larvae. [28] Larvae separated from the queen by a fine mesh developed into queens, but if workers were regularly moved from the queen's side to the side the larvae were on, then the larvae developed as workers. [29]
Major plants visited include Rubus , goldenrods, Vaccinium , and milkweeds. [4] B. ternarius eats and collects both nectar and pollen. The nectar is stored in a special internal pouch called the crop, while pollen collects on the hairs on the bumblebee body. The bumblebee pushes the grains of pollen towards its hind legs, where the pollen is pushed into the pollen basket. At the nest, the contents of the nectar crop is regurgitated, where it is mixed with enzymes and allowed to air dry. As the nectar and enzyme mixture dries, honey is created. Pollen is mixed with the nectar and honey to create a protein-rich larval food. [9] [30]
Before the introduction of western honey bees, bumblebees were the only honey-producing bees in North America; however, only small quantities are produced. [30]
Queen and worker bumblebees can sting. Unlike honey bee stingers, a bumblebee's stinger lacks harpoon-like barbs on the end of the stinger, so B. ternarius can sting repeatedly without risk of disemboweling itself and dying. [31] [32] B. ternarius is not normally aggressive, but will sting in defense of its nest or when threatened or provoked. [9]
B. ternarius, as well as other members of the genus Bombus, live in eusocial colonies in which the individuals in the group act as a single multiorganismal superorganism. Eusociality may have evolved in the bumblebee ancestor as a result of offspring remaining in the nest as adults to help rear their mother's young. The evolution of eusociality can be explained by Hamilton's inclusive fitness theory. [30] The mostly sterile workers forage for food and take care of the colony's needs, while the queen is in charge of reproducing and creating new generations of workers. [14] Toward the end of the colony lifecycle, workers jostle the queen, eat her eggs, and attempt to lay eggs of their own. The workers are not completely sterile, despite their inability to mate, since they have ovaries. Worker eggs always develop into males. The queen usually retaliates by acting aggressively toward the workers and trying to eat the workers’ eggs. However, the queen's retaliation proves insufficient in some cases and the aggressive reproductive bumblebee workers kill her. [30]
Flight for bumblebees is energy costly. Estimates put bumblebee metabolic rate at extremes surpassing even hummingbird metabolic rates, so efficient foraging and good decision-making is paramount or the workers risk a net loss of energy. [14] Pollen is rich in protein necessary to sustain flight, but is more difficult to collect than nectar. Bumblebees exhibit individual learning. New pollen foragers tend to return lighter from about the first 10 foraging trips, allowing foraging efficiency to increase, until it plateaus at about 30 trips. Furthermore, bumblebees tend to collect pollen when conditions are dry and humidity is lower, presumably because pollen clumps are drier then, making foraging easier. [33] For this reason, more experienced and older workers tend to collect pollen. [23] [34] This approach means inexperienced foragers waste less energy and more pollen is returned to the nest, maximizing the colonies' evolutionary success.
Little is known about its precise foraging range, but bumblebees' range is, on average, up to 6 km (3.7 mi) which can be extended to far away as 20 km (12 mi) when resources are scarce. [14] One would predict that food patches nearest to the nest would be most visited, so would offer the least uncollected nectar and pollen. A trade-off occurs between energy expenditure in flight and the competition between workers. This effect pushes workers to explore further away from the nest to forage. [35] Some propose that bumblebees venture out farther past their nest because foraging near the nest could bring unwanted attention from predators and consequently risk the success of the colony. This predator hypothesis, however, is often dismissed as showing little effect on bumblebee foraging range. [36]
A bumblebees often does not fill its nectar crop to full capacity when foraging. This phenomenon is best explained by the marginal value theorem. The weight of nectar in the nectar crop adds an additional energetic cost to flight, so a heavily loaded bumblebee expends significantly more energy to the point of diminishing returns. Depending on the flight distance, a fully filled crop may cause a bumblebee to burn more energy than a partially filled crop would bring back. [37]
The queen's primary role is to reproduce and ensure the colony has a steady supply of new workers. The worker bumblebees are responsible for most of the other chores, such as foraging, nest maintenance, and tending to the larvae. Younger workers typically start life as a worker where most of their time is devoted to working in the nest. Wax in bumblebees is secreted from the underside of the abdomen of the worker. An individual bumblebee's ability to produce wax starts at about the second day of adult life, but starts to decline after the first week. Since wax is only required within the nest, young workers are predisposed towards within-nest work such as nest maintenance. [38] As bumblebees mature, they are more likely to switch over from within-nest duty to foraging. Furthermore, newer foragers generally collect nectar and tend to switch over to collecting pollen as they age. [23] Long ago, foragers of a range of different bumblebee species were noticed to tend to be larger, on average, than bees that performed within-nest work. This trend can best be explained by the observation that larger-sized workers tend to switch from within-nest work to foraging earlier than smaller workers. The very smallest workers never switch to foraging and remain within-nest workers their entire lives. [39]
Bombus ternarius was first named by Thomas Say in 1837. [4] Bombus is Latin for buzzing, and refers to the sound the insects make. The specific name ternarius refers to the number three, which refers to the bumblebees' three colors. [7]
A bumblebee is any of over 250 species in the genus Bombus, part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related genera are known from fossils. They are found primarily in higher altitudes or latitudes in the Northern Hemisphere, although they are also found in South America, where a few lowland tropical species have been identified. European bumblebees have also been introduced to New Zealand and Tasmania. Female bumblebees can sting repeatedly, but generally ignore humans and other animals.
Bombus terrestris, the buff-tailed bumblebee or large earth bumblebee, is one of the most numerous bumblebee species in Europe. It is one of the main species used in greenhouse pollination, and so can be found in many countries and areas where it is not native, such as Tasmania. Moreover, it is a eusocial insect with an overlap of generations, a division of labour, and cooperative brood care. The queen is monogamous which means she mates with only one male. B. terrestris workers learn flower colours and forage efficiently.
The early bumblebee or early-nesting bumblebee is a small bumblebee with a wide distribution in most of Europe and parts of Asia. It is very commonly found in the UK and emerges to begin its colony cycle as soon as February which is earlier than most other species, hence its common name. There is even some evidence that the early bumblebee may be able to go through two colony cycles in a year. Like other bumblebees, Bombus pratorum lives in colonies with queen and worker castes. Bombus pratorum queens use aggressive behavior rather than pheromones to maintain dominance over the workers.
The tree bumblebee or new garden bumblebee is a species of bumblebee common in the European continent and parts of Asia. Since the start of the twenty-first century, it has spread to Great Britain. These bumblebees prefer habitats that others do not, allowing them to pollinate flowers in areas that many other species do not get to.
Bombus lapidarius is a species of bumblebee in the subgenus Melanobombus. Commonly known as the red-tailed bumblebee, B. lapidarius can be found throughout much of Central Europe. Known for its distinctive black and red body, this social bee is important in pollination.
Bombus polaris is a common Arctic bumblebee species. B. polaris is one of two bumblebees that live above the Arctic Circle. The other is its social parasite Bombus hyperboreus. B. polaris is a social bee that can survive at near freezing temperatures. It has developed multiple adaptations to live in such cold temperatures. B. polaris has a thicker coat of hair than most bees, utilizes thermoregulation, and makes insulated nests.
Bombus hyperboreus is a species of Arctic bumblebee with a circumpolar distribution. The species is primarily found in the arctic areas of Greenland, northern Scandinavia, and Russia. In 2015 the nearctic species, Bombus natvigi, was separated from this species, based on genetic analysis. Accordingly, Bombus hyperboreus is limited to the Palaearctic, despite older literature listing this species as occurring in the Nearctic.
Bombus vestalis, the vestal cuckoo bumblebee, is a species of cuckoo bumblebee that lives in most of Europe, as well as North Africa and western Asia. It is a brood parasite that takes over the nests of other bee species. Its primary host is Bombus terrestris. After its initial classification as Psithyrus vestalis, this bumblebee recently was reclassified into the genus Bombus, subgenus Psithyrus.
Bombus bohemicus, also known as the gypsy's cuckoo bumblebee, is a species of socially parasitic cuckoo bumblebee found in most of Europe with the exception of the southern Iberian Peninsula and Iceland. B. bohemicus practices inquilinism, or brood parasitism, of other bumblebee species. B. bohemicus is a generalist parasite, successfully invading several species from genus Bombus. The invading queen mimics the host nest's chemical signals, allowing her to assume a reproductively dominant role as well as manipulation of host worker fertility and behavior.
Bombus lucorum, the white-tailed bumblebee, is a species of bumblebee, widespread and common throughout Europe. This name has been widely used for a range of nearly identical-looking or cryptic species of bumblebees. In 1983, Scholl and Obrecht even coined the term Bombus lucorum complex to explain the three taxa that cannot be easily differentiated from one another by their appearances. A recent review of all of these species worldwide has helped to clarify its distribution in Europe and northern Asia, almost to the Pacific. B. lucorum reaches the Barents Sea in the North. However, in southern Europe, although found in Greece it is an upland species with its distribution never quite reaching the Mediterranean.
Bombus pensylvanicus, the American bumblebee, is a threatened species of bumblebee native to North America. It occurs in eastern Canada, throughout much of the Eastern United States, and much of Mexico.
Bombus vosnesenskii, the yellow-faced bumblebee, is a species of bumblebee native to the west coast of North America, where it is distributed from British Columbia to Baja California. It is the most abundant species of bee in this range, and can be found in both urban and agricultural areas. Additionally, B. vosnesenskii is utilized as an important pollinator in commercial agriculture, especially for greenhouse tomatoes. Though the species is not currently experiencing population decline, urbanization has affected its nesting densities, and early emergence of the B. vosnesenskii has been implicated in the increasing lack of bee diversity on the West coast.
Bombus occidentalis, the western bumblebee, is one of around 30 bumblebee species present in the western United States and western Canada. A recent review of all of its close relatives worldwide appears to have confirmed its status as a separate species.
Bombus fervidus, the golden northern bumble bee or yellow bumblebee, is a species of bumblebee native to North America. It has a yellow-colored abdomen and thorax. Its range includes the North American continent, excluding much of the southern United States, Alaska, and the northern parts of Canada. It is common in cities and farmland, with populations concentrated in the Northeastern part of the United States. It is similar in color and range to its sibling species, Bombus californicus, though sometimes also confused with the American bumblebee or black and gold bumblebee. It has complex behavioral traits, which includes a coordinated nest defense to ward off predators. B. fervidus is an important pollinator, so recent population decline is a particular concern.
Bumblebees, like the honeybee collect nectar and pollen from flowers and store them for food. Many individuals must be recruited to forage for food to provide for the hive. Some bee species have highly developed ways of communicating with each other about the location and quality of food resources ranging from physical to chemical displays.
Bombus affinis, commonly known as the rusty patched bumble bee, is a species of bumblebee endemic to North America. Its historical range in North America has been throughout the east and upper Midwest of the United States, north to Ontario, Canada, where it is considered a "species at risk", east to Quebec, south to Georgia, and west to the Dakotas. Its numbers have declined in 87% of its historical habitat range. On January 10, 2017, the United States Fish and Wildlife Service placed B. affinis on the list of endangered species, making the rusty patched bumblebee the first bee to be added to the list in the continental United States.
Bombus terricola, the yellow-banded bumblebee, is a species of bee in the genus Bombus. It is native to southern Canada and the east and midwest of the United States. It possesses complex behavioral traits, such as the ability to adapt to a queenless nest, choose which flower to visit, and regulate its temperature to fly during cold weather. It was at one time a common species, but has declined in numbers since the late 1990s, likely due to urban development and parasite infection. It is a good pollinator of wild flowers and crops such as alfalfa, potatoes, raspberries, and cranberries.
Bombus pauloensis is a neotropical bumblebee, formerly known as Bombus atratus, that is found throughout regions of South America, including Colombia, Ecuador, Brazil, and Argentina. It lives in social colonies that include a founder queen/queens, workers and brood. B. pauloensis is somewhat unusual because of its potential to oscillate between polygynous and monogynous nesting cycles. Bombus pauloensis was the first species in the genus Bombus that was discovered to display such polygynous nesting patterns. The polygynous nesting cycles lead to certain specific types of behavior including queen-queen aggression. Nests can also be perennial, which is a characteristic rarely found in other bumblebees. B. pauloensis can be helpful to agricultural because of their ability to pollinate different species of plants. B. pauloensis has been found to occupy a range of geographic areas and climates throughout South America. Colonies have the ability to thermoregulate nests and keep them a little bit warmer than the outside environment. Foraging workers use muscle contractions to maintain stable temperatures and coupe with seasonal and daily fluctuations in temperature.
Bombus ignitus is a species of bumblebee in the family Apidae. It is mainly distributed in Eastern Asia, commonly found in China, Japan and Korea. It is used in China and Japan commercially as a pollinator. B. ignitus is a eusocial insect with a queen that is monandrous: mating with only one male in the late summer before hibernating until the following spring. It builds its nest out of a mass of pollen and lays its eggs after completion. Due to numerous conflicts between queens and fertile workers, some surviving queens are badly injured, described by some as living corpses.
Bombus hypocrita, also known as the short-tongued bumblebee, is a Japanese bumblebee commonly used in commercial pollination. These short-tongued bumblebees have a proboscis about 7-9mm long, which is folded under their head when flying. Bumblebees are a small fuzzy insect with yellow and black banding along their abdomen. They are round and covered in pile, the hair-like structures that give them their distinct fuzzy appearance.
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