Bombus occidentalis

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Bombus occidentalis
Bombus occidentalis.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Apidae
Genus: Bombus
Subgenus: Bombus
Species:
B. occidentalis
Binomial name
Bombus occidentalis
(Greene, 1858)
Bombus occidentalis distribution.svg
The range of Bombus occidentalis. (Dashed line indicates former range within the contiguous United States (not Canada).)

Bombus occidentalis, the western bumble bee, is one of around 30 bumble bee species present in the western United States and western Canada. [1] A recent review of all of its close relatives worldwide appears to have confirmed its status as a separate species. [2]

Contents

Description

Western bumble bee workers have three main color variations. [3] The first color variation is found from northern California, north to British Columbia, and east to southwest Saskatchewan and Montana. [3] B. occidentalis in these areas have yellow hair on front part of thorax. They are also marked by black hair segments on the basal section of the fourth abdominal segments have black hair and whitish lower edge of the fourth and fifth abdominal segments. In addition, they also have sparse whitish hairs that may appear black on the sixth abdominal segment, and an entirely black head.

The second color variation is found along the central coast in California. [3] It has yellow hair on the sides of the second abdominal segment and all of the third abdominal segment and a reddish-brown hair on fifth abdominal segment.

The third color variation is found from the Rocky Mountains to Alaska. [3] It has yellow hair on the thorax behind the wings and on the rear of the second and all of the third abdominal segments.

Identification

All insects have three main body parts; the head, thorax, and abdomen. [3] Bumble bee species identification tends to refer to colorations on the abdominal segments. The abdominal segments are numbered from T1 to T6 (T7 if male) starting from the abdominal segment closest to the thorax and then working ventrally.

Sex determination

A few ways are used to determine the sex of the western bumble bee. [1] The males (drones) have seven abdominal segments, while the females (queens and workers) have only six. [1] The drones' antennae have 13 segments, while the females have only 12. [1] Drones have no stingers. Additionally, the hind legs of the females tend to be wider and fatter with a pollen basket often visible. [1] Drones have thinner hind legs that do not have pollen baskets. [1] Another clue to sexual identity among B. occidentalis species is when they are being observed. Queens are the first to appear in the spring and then the workers appear after. All females can then be seen throughout the summer and into early fall. The drones only appear in the late summer and early fall.

Taxonomy and phylogeny

Female Bombus occidentalis, F, Face, Utah Co., Utah 2014-01-10-15.22.23 ZS PMax (12250840435).jpg
Female

This species is of class Insecta, order Hymenoptera, and family Apidae. Although closely related to Bombus terricola , DNA evidence supports that they are a distinct species. Evidence of a subspecies divide is found through examination of the COI-barcode of the bees, suggesting that Bombus occidentalis can be divided between the northern and southern population. The supposed subspecies each have specific haplotype groups, which is reflected by the differences in hair length between the populations. The southern B. occidentalis seem to have notably shorter hair compared to the northern B. occidentalis. [4]

Distribution and population

Bombus occidentalis was once one of the most common bee species in the North West America. [4] They have been found from the Mediterranean California all the way up to the Tundra regions of Alaska, making them one of the bees with the widest range geographic range. [4] However, recently there has been a noticeable decline in population. [5] In the past decade, the population of B. occidentalis has dropped by around 40.32%. The disappearance of these bees have been especially significant in California, western Oregon, and western Washington. [4] The range and persistence of B. occidentalis has also gone down by around 20%. Some scientists point to the rise of Nosema , a parasite, as the reason for the decline in population. Others say that the population decline could have come because of the invasion of European honey bees. [6] A recent study in 2016 suggests that the Western bumble bee population is rebounding, possibly due to evolutionary development of resistance to Nosema. [7]

Roles

Like most bumble bees, B. occidentalis colonies are made up of one queen, some female workers, and other reproductive members of the colony when the end of a season is near. [4] The queen's job, after the start of the colony is to lay eggs. Bumble bee workers remain with the queen and help with the production of additional workers and male and female reproductive members. It is their job to feed the larvae. The female workers also have other roles such as foraging for nectar and pollen and defending the colony against predators and parasites. [4]

Only the female reproductive members, otherwise known as the gynes, survive the winter so that they can go through the colony cycle once again. Gynes have the potential to become queens, and it is their responsibility to find a space for hibernation during the winter so that they can start a colony again next season. [4]

Colony cycle

A new colony typically starts in the early spring by a solitary queen. First, the queen finds a suitable nest site. Like other bumble bees, B. occidentalis nests underground in cavities or random burrows left behind by rodents or other animals. The queen must then construct a wax structure and collect pollen to create a mass to lay eggs on. [4]

When the first brood of female workers have become adults, they take over the jobs of foraging for nectar and pollen, defending the colony, and feeding larvae. The queen's only job at this stage is to lay more eggs. A colony of B. occidentalis can have up to around 1,600 workers, which is large compared to that of other bumble bee species. [4] From early February to late November, the colony enters a flight period. Then, around the beginning of the fall, the reproductive individuals of the colony are produced. When winter starts, the old queen, workers, and males all die, leaving the gynes to search for a site to spend the winter hibernating. [4]

Behavior

Western bumble bees are generalist foragers. [8] Because they do not depend on any one flower type, they are considered to be excellent pollinators. bumble bees are also able to fly in cooler temperatures and lower flight levels than many other bees. [9] Additionally, bumble bees perform "buzz pollination". This behavior is displayed when a bumble bee grabs the pollen-producing structure of the flower in her jaws and vibrates her wing musculature, causing vibrations that dislodge pollen that would have otherwise remained trapped in the flower's anthers. [9] Tomatoes, peppers, and cranberries are some of the plants that require this type of pollination. [8] For these reasons, bumble bees are considered to be more effective pollinators than honey bees. Bombus occidentalis has been commercially reared to pollinate crops such as alfalfa, avocados, apples, cherries, blackberries, cranberries, and blueberries. [9]

Workers collect nectar and regurgitate it in the nest. Pollen is collected and put into "pollen baskets" located on the hind legs. Nectar provides carbohydrates while pollen provides protein.

Female Bombus occidentalis, F, Side, Utah Co., Utah 2014-01-10-15.27.00 ZS PMax (12250805893).jpg
Female

Foraging behavior

B. occidentalis are social bees, and successful foragers returning to the nest can stimulate their nestmates to forage, [10] although presumably like other bumble bees, they cannot communicate the actual location of resources. [11] This phenomenon is often referred to as 'foraging activation'. The amount of recruitment a returning forager is able to garner depends on the quality (i.e. concentration) of the nectar (or sucrose) that it has found. [10] The mechanism by which foraging activation occurs is not well understood, but it is possible that the returning forager, which before unloading its cargo will spend some time running around the nest and interacting with its nestmates, [11] releases a pheromone that induces foraging behaviour. [12] Furthermore, the sudden influx of high-quality nectar may itself stimulate foraging behaviour. [12]

Although bumble bees cannot apparently communicate resource location, it appears that foraging activation can communicate which floral species was particularly rewarding through scent, as the activated nestmates show preference for the odour brought home by the returning forager. [11]

Nectar robbing behavior

The "nectar robbing" behavior is exhibited when the organism obtains the nectar of the flowers without getting in contact with sexual parts of the flowers. B. occidentalis can be seen displaying this behavior due to the shortness of their tongues. Instead of going through the normal route, B. occidentalis use their mandibles to make holes to circumvent the process. The mandibles of B. occidentalis are thus understandably more toothed than that of other bumble species to help them cut into the flowers. [13]

Importance of nectar

It is crucial for B. occidentalis to maintain high levels of nectar for their colony. Not only does the level of stored nectar affect the temperature of the colony, but deficiencies in nectar cause a significant change in behavior due to low energy of the bees. When energy abundant colonies are threatened by predators, they assume the natural defense behavior, moving about loudly to deter the predator. However, low energy colonies will remain still in their colonies. Although temporary low energy periods do not affect the survivability of the larvae, it increases the colonies' susceptibility to predators and increases the time of development for the larvae. [14]

Brood recognition of queens

The queens of B. occidentalis have the ability to recognize her own nest and brood. Upon arriving on a specific brood, the queen will behave differently depending on whether it is her own brood or foreign. Queens will spend significantly more time inspecting the surface of foreign brood clumps with their antennas if they are on a foreign brood. Upon recognizing the brood as not their own, the Queens will be more much likely to depart during this observation period. However, these queens will stay within the vicinity of the foreign brood, making short flights around the entrance of the nest before reentering it. Most queens will choose to adopt the new colony rather than to abandon it, and the workers of the foreign brood will start working for the new queen. In contrast, queens that return to their original nests will incubate their brood and lather honey pot on its brood much more quickly. [15]

Some scientists hypothesize that this ability could have come about as an evolutionary response to usurpation and parasitism. B. occidentalis suffer high rates of inter-specific and intra-specific usurpation. In addition, they also face invasion by the parasitic Psithyrus bees. It is possible that the recognition ability evolved in form of adaptions to them. Others argue that brood recognition ability is a byproduct of factors of B. occidentalis. For social wasps, like B. occidentalis, nestmate recognition is crucial. The queen might have just evolved to recognize unfamiliar odors, allowing them to also recognize foreign broods. [15]

Threats

Threats to this species include: [8]

Conservation

Due to their role as pollinators, loss of bumble bee populations can have far-ranging ecological impacts. [8] B. occidentalis once had a wide range that included northern California, Oregon, Washington, Alaska, Idaho, Montana, western Nebraska, western North Dakota, western South Dakota, Wyoming, Utah, Colorado, northern Arizona, and New Mexico. [8] Since 1998, it has been declining in population. [3] The areas of greatest decline have been reported in western and central California, western Oregon, western Washington, and British Columbia. From southern British Columbia to central California, the species has nearly disappeared. [3] However, the historic range was never systematically sampled. [3]

Agricultural and urban development has resulted in bumble bee habitat becoming increasingly fragmented. [8] All bumble bee species have small effective population sizes due to their breeding system, and are particularly vulnerable to inbreeding which reduces the genetic diversity within a population, [8] and theoretically can increase the risk of population decline. [8]

A parasite of genus Nosema Parasite140019-fig2 Nosema podocotyloidis - Hyperparasitic Microsporidia.tif
A parasite of genus Nosema

Between 1992 and 1994, B. occidentalis and B. impatiens were commercially reared for crop pollination, shipped to European rearing facilities and then shipped back. [3] Bumble bee expert Robbin Thorp has hypothesized that their decline is in part due to a disease acquired from a European bee while being reared in the same facility. [3] North American bumble bees would have had no prior resistance to this pathogen. Upon returning to North America, affected bumble bees interacted and spread the disease to wild populations. [3] B. occidentalis and B. franklini were affected in the western United States. [8] B. affinis and B. terricola were affected in the eastern United States. [8] All four species' populations have been declining since the 1990s. Additionally, these four bumble bee species are closely related and belong to the same subgenus; Bombus sensu stricto. [8] Dr. Thorp has also hypothesized that B. impatiens species may have been the carrier and that different bumble bee species may differ in their pathogen sensitivity. [8] In 2007, the National Research Council determined that the major cause of decline in native bumble bees appeared to be recently introduced non-native fungal and protozoan parasites, including Nosema bombi and Crithidia bombi . [8]

A petition was submitted by the Xerces society, Defenders of Wildlife, and the Center for Food Safety to the California Fish and Game Commission in October 2018 to list Bombus occidentalis and three others as endangered under the California Endangered Species Act. [16] [17] The California Department of Fish and Wildlife evaluated this petition in a report for The California Fish and Game Commission completed in April 2019. [17] On June 12, 2019 the California Fish and Game Commission voted to add the four bumble bees, including Bombus occidentalis, to the list of protected species under the California Endangered Species Act. [18] A subsequent legal challenge of the CESA's definition of a fish as "a wild fish, mollusk, crustacean, invertebrate, amphibian, or part, spawn, or ovum of any of those animals" [18] was eventually overruled, because the explicit intent was for all invertebrates (therefore including insects) to be qualified for protection under this legal definition. [19]

Human importance

As mentioned before, B. occidentalis has been previously used to help in greenhouses. They have been used for a variety of crops, but have played an especially important role with tomatoes. [4] A problem with the use of these bumble bees was the drifting effect. Due to the close aggregation of colonies within the greenhouse habitats, they found that some bees developed a behavior of drifting into foreign colonies. These drifting bees were essentially social parasites, as they give up their roles in their colonies and introduce their mature ovaries to foreign colonies. [20]

Furthermore, due to careless regulation between states in America and Europe, Nosema parasitism became prevalent within the B. occidentalis population. Now they are no longer bred or sold commercially because of the threateningly low number, and B. impatiens have been used in their place. [6]

Related Research Articles

<span class="mw-page-title-main">Bumblebee</span> Genus of insect

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.

<i>Bombus terrestris</i> Species of bee

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.

<i>Bombus ternarius</i> Species of insect

Bombus ternarius, commonly known as the orange-belted bumblebee or tricolored bumblebee, 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. 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.

<i>Bombus polaris</i> Species of bee

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.

<i>Bombus hortorum</i> Species of bee

Bombus hortorum, the garden bumblebee or small garden bumblebee, is a species of bumblebee found in most of Europe north to 70°N, as well as parts of Asia and New Zealand. It is distinguished from most other bumblebees by its long tongue used for feeding on pollen in deep-flowered plants. Accordingly, this bumblebee mainly visits flowers with deep corollae, such as deadnettles, ground ivy, vetches, clovers, comfrey, foxglove, and thistles. They have a good visual memory, which aids them in navigating the territory close to their habitat and seeking out food sources.

<i>Bombus suckleyi</i> Species of bee

Bombus suckleyi is a species of bumblebee known commonly as Suckley's cuckoo bumblebee, named after biologist George Suckley. Suckley's bumble bee is a generalist pollinator and represents a rare group of obligate, parasitic bumble bees. Suckley's bumble bee is a social-parasite because it invades the nests of the host bumble bees, including the western bumble bee, and relies on host species workers to provision its larvae. It is native to northwestern North America, including Alaska and parts of western and central Canada and the western United States.

<i>Bombus pensylvanicus</i> Species of bee

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.

Two-spotted bumble bee Species of bee

The two-spotted bumble bee is a species of social bumble bee found in the eastern half of the United States and the adjacent south-eastern part of Canada. In older literature this bee is often referred to as Bremus bimaculatus, Bremus being a synonym for Bombus. The bee's common name comes from the two yellow spots on its abdomen. Unlike many of the other species of bee in the genus Bombus,B. bimaculatus is not on the decline, but instead is very stable. They are abundant pollinators that forage at a variety of plants.

<i>Bombus vosnesenskii</i> Species of bee

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.

<i>Bombus fervidus</i> Species of bee

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.

<i>Bombus impatiens</i> Species of insect

Bombus impatiens, the common eastern bumblebee, is the most commonly encountered bumblebee across much of eastern North America. They can be found in the Eastern temperate forest region of the eastern United States, southern Canada, and the eastern Great Plains. Because of their great adaptability, they can live in country, suburbs, and even urban cities. This adaptability makes them a great pollinator species, leading to an increase in their commercial use by the greenhouse industry. This increase consequently led to their farther spread outside their previous distribution range. They are considered one of the most important species of pollinator bees in North America.

<i>Bombus ruderatus</i> Species of bee

Bombus ruderatus, the large garden bumblebee or ruderal bumblebee, is a species of long-tongued bumblebee found in Europe and in some parts of northern Africa. This species is the largest bumblebee in Britain and it uses its long face and tongue to pollinate hard-to-reach tubed flowers. Bumblebees are key pollinators in many agricultural ecosystems, which has led to B. ruderatus and other bumblebees being commercially bred and introduced into non-native countries, specifically New Zealand and Chile. Since its introduction in Chile, B. ruderatus has spread into Argentina as well. Population numbers have been declining and it has been placed on the Biodiversity Action Plan to help counteract these declines.

<i>Bombus frigidus</i> Species of bee

Bombus frigidus, the frigid bumblebee, is a rare species of bumblebee largely found in Canada and parts of the United States.

<i>Bombus dahlbomii</i> Species of bee

Bombus dahlbomii, also known as the moscardón, is a species of bumblebee endemic to southern South American temperate forests. B. dahlbomii is one of the largest bee species in the world, with matured queens growing up to 40 mm (1.6 in) long. Because of its size and furry appearance, the species has been described as "flying mice" colloquially, and "a monstrous fluffy ginger beast" by British ecologist David Goulson.

<i>Bombus affinis</i> Species of bee

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 bumble bee the first bee to be added to the list in the continental United States.

<i>Bombus terricola</i> Species of bee

Bombus terricola, the yellow-banded bumble bee, 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.

<i>Bombus pauloensis</i> Species of bee

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.

<i>Bombus morio</i> Species of insect

Bombus morio is one of the few bumblebee species found in South America. These bees reside mainly in the forests of Brazil, nesting on the surface of the ground. They are one of the biggest species of bumblebee and are important pollinators. They are one of the few species of bees that exhibit buzz pollination to collect pollen from the flowers.

<i>Bombus crotchii</i> North American bee species

Bombus crotchii, commonly called Crotch's bumble bee, is a species of bumblebee named after the entomologist George Robert Crotch. It is classified as endangered due to the impacts of pesticides, climate change, and human development.

<i>Bombus vancouverensis</i> Species of bee

Bombus vancouverensis, the Vancouver Island Bumblebee, is a common species of eusocial bumblebee of the subgenus Pyrobombus. B. vancouverensis inhabits mountainous regions of western North America, where it has long been considered as a synonym of Bombus bifarius, and essentially all of the literature on bifarius refers instead to vancouverensis. B. vancouverensis has been identified as one of the two species of bumblebee observed to use pheromones in kin recognition. The other is the frigid bumblebee, Bombus frigidus.

References

  1. 1 2 3 4 5 6 Pocket Guide to Identifying The Western Bumble Bee Bombus occidentalis. The Xerces Society for Invertebrate Conservation.
  2. ↑ P. H. Williams; et al. (2012). "Unveiling cryptic species of the bumblebee subgenus Bombus s. str. world-wide with COI barcodes" (PDF). Systematics and Biodiversity. 10: 21–56. doi: 10.1080/14772000.2012.664574 . Retrieved May 30, 2012.
  3. 1 2 3 4 5 6 7 8 9 10 11 Bumble bees: western bumble bee (Bombus occidentalis). Archived 2010-01-23 at the Wayback Machine The Xerces Society for Invertebrate Conservation.
  4. 1 2 3 4 5 6 7 8 9 10 11 Hatfield, R., et al. 2015. Bombus occidentalis. The IUCN Red List of Threatened Species. Downloaded on 09 March 2016.
  5. ↑ Colla, S. R.; Ratti, C. M. (2010). "Evidence for the decline of the western bumble bee (Bombus occidentalis Greene) in British Columbia" (PDF). Pan-Pacific Entomologist. 86 (2): 32–34. doi:10.3956/2009-22.1. S2CID   85745028.
  6. 1 2 Sikes, D.; et al. (2015-01-01). "Bumble bees (Hymenoptera: Apidae: Bombus spp.) of Interior Alaska: Species composition, distribution, seasonal biology, and parasites". Biodiversity Data Journal. 3 (3): e5085. doi: 10.3897/bdj.3.e5085 . PMC   4426341 . PMID   25977613.
  7. ↑ Kobilinsky, D. (February 17, 2016). "Rare bumblebee makes comeback". The Wildlife Society. Retrieved 2016-02-28.
  8. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Evans, E., et al. Status review of three formerly common species of bumble bee in the subgenus Bombus. Archived 2016-03-04 at the Wayback Machine The Xerces Society for Invertebrate Conservation.
  9. 1 2 3 Jepsen, S. Invertebrate Conservation Fact Sheet - Bumble Bees in Decline. The Xerces Society for Invertebrate Conservation.
  10. 1 2 Nguyen, H.; Nieh, J. C. (2012). "Colony and individual forager responses to food quality in the New World bumble bee, Bombus occidentalis" (PDF). Journal of Insect Behavior. 25 (1): 60–69. doi:10.1007/s10905-011-9277-5. S2CID   254704107.
  11. 1 2 3 Dornhaus, A.; Chittka, L. (September 1999). "Evolutionary origins of bee dances". Nature. 401 (6748): 38. doi: 10.1038/43372 . ISSN   0028-0836.
  12. 1 2 Dornhaus, Anna; Chittka, Lars (2001-11-01). "Food alert in bumblebees (Bombus terrestris): possible mechanisms and evolutionary implications". Behavioral Ecology and Sociobiology. 50 (6): 570–576. doi:10.1007/s002650100395. ISSN   0340-5443. S2CID   46168842.
  13. ↑ Bentley, B.; Elias, T.s (1983). The Biology of Nectaries. Columbia University Press.
  14. ↑ Cartar, R. V.; Dill, L. M. (1991). "Costs of energy shortfall for bumble bee colonies: Predation, social parasitism, and brood development". The Canadian Entomologist. 123 (2): 283–293. CiteSeerX   10.1.1.379.6738 . doi:10.4039/Ent123283-2. S2CID   9453426.
  15. 1 2 Gamboa, G. J.; Foster, R. L.; Richards, K. W. (1987). "Intraspecific nest and brood recognition by queens of the bumble bee, Bombus occidentalis". Canadian Journal of Zoology. 65 (12): 2893–2897. doi:10.1139/z87-439.
  16. ↑ Hatfield R, Jepsen S, Jordan SF, Blackburn M and Code A. 2018. A Petition to the State of California Fish and Game Commission. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=161902&inline
  17. 1 2 California Department of Fish and Wildlife. 2019. EVALUATION OF THE PETITION FROM THE XERCES SOCIETY, DEFENDERS OF WILDLIFE, AND THE CENTER FOR FOOD SAFETY TO LIST FOUR SPECIES OF BUMBLE BEES AS ENDANGERED UNDER THE CALIFORNIA ENDANGERED SPECIES ACT. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=166804&inline
  18. 1 2 Weiland P. 2019. Fish and Game Commission Adds Four Bumble Bees to Candidate List. Endangered Species Law and Policy. https://www.endangeredspecieslawandpolicy.com/fish-and-game-commission-adds-four-bumble-bees-to-candidate-list
  19. ↑ "ALMOND ALLIANCE OF CALIFORNIA et al., v. FISH AND GAME COMMISSION et al" (PDF). May 31, 2022.
  20. ↑ Birmingham, A. L; et al. (2004-12-01). "Drifting bumble bee (Hymenoptera: Apidae) workers in commercial greenhouses may be social parasites". Canadian Journal of Zoology. 82 (12): 1843–1853. doi:10.1139/z04-181. ISSN   0008-4301.
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