Bombus terricola

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Bombus terricola
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Apidae
Genus: Bombus
Subgenus:
Bombus
Species:
B. terricola
Binomial name
Bombus terricola
Kirby, 1837
Specimen

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.[2]

Taxonomy and phylogeny

B. terricola belongs to the order

Bombus occidentalis has been speculated to be a subspecies of B. terricola, but most experts now agree that it is its own distinct species.[3] B. terricola is also closely related to B. affinis both phylogenetically and in terms of pheromone signalling. Oftentimes, the B. terricola is so similar to B. affinis that members of B. affinis can invade and dominate entire B. terricola nests without the hosts knowing.[4]

Description

The yellow-banded bumblebee is black and yellowish-tan, and has a characteristic fringe of short yellow-brown hairs on its fifth abdominal segment.[2] The queen is about 18 mm (0.7 in) long. The front half of the thorax is yellowish-brown, as are segments 2, 3 and 4 and the sides of segment 6 of the abdomen. The other parts of the thorax and abdomen are black. The worker is similar in appearance to the queen but smaller at a length of 9 to 14 mm (0.35 to 0.55 in). The male is intermediate in size, being 13 to 17 mm (0.5 to 0.7 in) long. In the male, abdominal segments 2, 3, and 7 are yellowish-brown as are usually the sides of abdominal segment 6.[5]

Distribution and habitat

Bombus terricola occupies the eastern and Midwestern parts of the United States as well as southern Canada. They are known to occupy a wide range of habitats including urban areas, meadows, grasslands, wetlands, woodlands, and farmlands. They can also occupy alpine meadows to lowland tropical forests.[6]

Colony cycle

In B. terricola, there are three phases of colony development. The first phase, known as colony initiation, begins when a solitary queen starts to produce her first workers by laying

haploid eggs to produce male bees.[7] During the third phase, the workers exhibit overt aggression towards each other and towards the queen. The beginning of the third phase is known as the competition point. Reciprocal oophagy also occurs during this third stage.[7]

Behavior

Reproduction

In Bombus terricola, there are female-biased investment ratios. The workers of the colony try to bias the sex ratios to be 3:1, in favor of the worker bees, which are female.[8] The workers attempt to bias the sex ratios so that they can benefit for their own gene propagation; however, the queen tries to bring the sex ratio back to a favorable 1:1 of males and females for her own benefit as well. This process is referred to conflict between kin and is commonly seen in bees. B. terricola queens usually have a single mating opportunity in one mating flight with multiple males; the queen then stores all of the sperm in a spermatheca, from which only one sperm will get to fertilize her egg.[9]

Orphaning

Sometimes, some B. terricola colonies become orphaned.[8] If there are feeble and weak queens, the queen has a decreased ability to fertilize eggs or cannot fertilize them at all. With declining queen vigor, worker-laid male eggs became more common.[8] Furthermore, the highest proportion of worker-laid male eggs was observed in smaller colonies.[8] Due to the absence of a strong queen leader, these male-dominated colonies attempt to get young, strong queens back because that would be in the best interest and benefit for the colony.

Foraging

Bombus terricola congregate in nectar rich areas. They can discern which flowers have been previously visited by other bees or are depleted of resources such as nectar or pollen.[10] They usually visit consecutive flowers in one direction and do not return to previous flowers. They tend to go to areas that are rich in resources and usually do not visit these areas again once the bees deplete the resources.[10] Instead, it has been found that B. terricola expend energy to fly to new locations of food sources. Although the flight costs energy, they expend it for future profit in finding areas abundant in resources.[10] The mechanism of their foraging beyond this information is currently unknown; it is also unknown whether they do not return to previously visited sites due to memory of the flowers or memory of landmarks (such as a nearby tree).

Flower pollination

B. terricola foragers are highly selective about the

pollinate. They can visit about 12–21 flowers per minute.[11] The amount, quality, and availability of nectar and pollen are the primary qualities that B. terricola use to determine which flowers to pollinate.[12] These bees can determine the quality of pollen grain from a distance, but the method as to how this is accomplished is still not yet known.[11] Individual foragers vary in their speed, flight, directionality, and erratic movements.[11] Some bees hover over flowers but never land on them. Flower visitation rates depend on the number of rewarding or non-rewarding flowers they encountered on their flights. Rewarding flowers are ones that contain much pollen or nectar. One study noted that B. terricola bypass flowers that they have previously visited and only foraged a small amount of pollen from them.[12] Finally, the bees release their pollen by emitting one to four sharp buzzing sounds of one second each. While buzzing, B. terricola also rotate clockwise or counterclockwise.[11]

Types of flowers

B. terricola have been known to forage on

fireweed (Epilobium angustifolium).[12] B. terricola exhibit consistent foraging behavior and tend to visit the same flowers repeatedly, especially if these flowers were rewarding in the past in terms of the amount of nectar and pollen they carried.[12]

Temperature regulation

thoracic temperature, these bees must expend a lot of energy. These bees can visit dispersed flowers within a short span of time at either high or low air temperatures. Sometimes at low temperatures, these bees do not have enough heat to maintain continuous flight. Consequently, landing on flowers warms them up so that their thoracic temperature remains high enough for flight.[13] Since they use up a lot of energy for this thermoregulation, they take a lot of nectar from flowers that are most readily available to use as energy storage.[13] By maintaining a high thoracic temperature, B. terricola can look for new sources of food and have the advantage to fly away quickly if they are at risk for predation.[14]

Interactions with other species

Parasites

There are a few

unicellular
parasite that is known to infect bumblebees. It may also be one of the factors that is leading to the decline in numbers of Bombus terricola. There is a high prevalence of this parasite specifically in Bombus terricola populations.

Population decline

Similar to other species of the Bombus

farming and urban development have taken away the natural landscapes and habitats that these bees would normally occupy. This decline in B. terricola corresponded with the huge growth in agriculture
and urban development. Furthermore, the Nosema bombi parasite may also contribute to the decline in populations of B. terricola as they particularly attack these bees.

Conservation status

Like several other

Bombus, the yellow-banded bumblebee has suffered sharp declines in numbers since the mid-1990s.The Xerces Society for Insect Conservation has placed Bombus terricola on their "Red List" of endangered bees.[16] The yellow-banded bumblebee has disappeared over large parts of its range, but is still present in Vermont, New Hampshire, and Maine, where the population appears to be stabilizing and in the Great Smoky Mountains, where the population seems to be expanding. It is not clear whether this is because it has developed some resistance to the parasite, Nosema bombi, or whether the parasite has not yet spread into these parts. The rusty-patched bumblebee (Bombus affinis) has suffered an even steeper decline. It will become clearer over time whether populations of these bees will remain viable or whether the species will become extinct.[17]

References

  1. doi:10.2305/IUCN.UK.2015-2.RLTS.T44937505A46440206.en
    . Retrieved 13 November 2021.
  2. ^ a b "Bumble bees: yellow-banded bumble bee (Bombus terricola)". The Xerces Society. Archived from the original on 2014-04-24. Retrieved 2015-02-13.
  3. doi:10.3956/2007-10.1
    .
  4. JSTOR 25009392
    .
  5. ^ "Bombus terricola Kirby, 1837". Discover Life. Retrieved 2015-02-13.
  6. doi:10.1111/j.1095-8312.2007.00784.x
    .
  7. ^
    doi:10.1163/156853988x00340
    .
  8. ^
    doi:10.1007/bf00300669
    .
  9. doi:10.1007/s00040-003-0641-0
    .
  10. ^
    PMID 28309608
    .
  11. ^
    JSTOR 25085442
    .
  12. ^
    doi:10.1007/bf00299738
    .
  13. ^
    doi:10.1007/bf00696519
    .
  14. JSTOR 30155879
    .
  15. doi:10.1080/03014223.1995.9518020
    .
  16. ^
    doi:10.1016/j.biocon.2008.09.027
    .
  17. ^ Schweitzer, D.F.; Capuano, N.A. (2011-10-07). "Bombus terricola - Kirby, 1837". NatureServe. Retrieved 2015-02-13.

External links

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