Bombus fervidus

Bombus fervidus
Conservation status
Vulnerable  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Apidae
Genus:	Bombus
Subgenus:	Thoracobombus
Species:	B. fervidus
Binomial name
Bombus fervidus (Fabricius, 1798)
Bombus fervidus distribution map

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 Texas, Alaska, and the northern parts of Canada. It is common in cities and farmland, with populations concentrated in the North Eastern part of the United States. It is similar in color and range to the American bumblebee (Bombus pensylvanicus). It has complex behavioral traits, which include a communication system that involves dancing and a coordinated nest defense to ward off predators. B. fervidus is an important pollinator, so recent population decline is a particular concern.

Taxonomy and phylogeny

Danish zoologist Johan Christian Fabricius first identified Bombus fervidus, also known as the yellow bumblebee or golden northern bumblebee, in 1798. B. fervidus is a member of the order Hymenoptera, which comprises wasps, ants, bees, and sawflies. Bombus is the Latin word for “buzzing.” It is also in the Apidae, which is a diverse family of bees including honeybees, orchid bees, bumble bees, stingless bees, cuckoo bees, and carpenter bees.

Description and identification

Bombus fervidus is on average 13–16 mm long^[2] However, there are slight differences in morphology between queens, workers, and drones (see table below).^[3] The first four abdominal tergites are yellow.^[4] The occiput and face are black, and have yellow pleurae extending to or nearly to the bases of the legs. A black strip runs along the abdomen between the wings. The wings are dark to dark grey colored. The rest of the body is yellow, giving it the common name golden bumblebee. The hairs are thick. B. fervidus is long-tongued and therefore specializes on flowers with long corollas.^[5] B. fervidus use long tongues to extract nectar and pollen from longer flowers.^[6] Males have slightly more yellow on their abdomen that fades into the thorax. Males have a wingspan of 22 mm while female workers have a wingspan of 40 mm.^[7] The sexes are colored or patterned differently; the male is more colorful.^[7]

It is similar in color and range to the American bumblebee (Bombus pensylvanicus).^[8]

Distribution and habitat

Bombus fervidus is commonly found in northern New England.^[2] Populations can also be found throughout northern portions of Arkansas, Alabama, Georgia and North Carolina, as well as the northern part of the United States.^[6][8] Its nests are not easily found, and are often formed inside the open space of abandoned wild beehives.^[2] B. fervidus are native to Canada, Mexico and continental United States.^[9]

The species prefers temperate savanna, grassland and tall grass biomes, and readily coexists with suburban or agricultural developments. It is common in grazing farmlands.^[10][11]

Nest

The nest of B. fervidus is a loose mass of soft, lightly entangled grass mixed with goose or other feces that are most likely carried in and arranged by the bees themselves.^[2] B. fervidus generally nest in grassy, open areas, which includes forests and along roadsides.^[6] Nests can be located both above and below ground, but the latter is more common.^[2] Nests are typically within 50 meters of a food source sufficient to feed the entire growing colony.^[12]

Colony cycle

Bombus fervidus queens lay eggs individually in cells within the nest that she builds herself.^[6] She first lays 8-10 eggs, one in each cell. When these eggs hatch, the larvae emerge and feed on honey for growth.^[6] The queen makes the honey for the larvae until they are ready to pupate, which is when the larva create cocoons for themselves where they stay to metamorphose into adults.^[6] Metamorphosis typically takes 16 to 25 days.^[7] Once the adults bees emerge from the cocoon, they are adult workers.^[7] This first generation of the brood that becomes workers are responsible for feeding the next generation of developing larvae and the queen. This ensures that the queen can focus on laying more eggs.^[6] Thus, each generation of B. fervidus is larger than the one before it.^[6][7]

Nest population

A typical nest contains four eggs, fifteen larvae, forty-two pupae and seventeen adults.^[2] Ten of the adults are worker adults, containing small undeveloped ovaries with no eggs, while the remaining adults are males with mature sperm.^[2] The pupae are 37 males, 5 future workers and only one queen.^[2] The larvae fall into three groups – large (nearly full grown), small or indeterminate.^[2] Workers typically live on average for 34.1 days.^[13]

Breeding and lifespan

Male bumblebees, also known as drones, have a purely reproductive purpose.^[6] In the fall, males and newly hatched queens mate before the weather cools. Each future queen mates only once and stores the sperm for the remainder of her life, using it to produce all the subsequent female progeny. After mating, young queens hibernate underground until the spring while all the other bees will die. The queens then emerge from hibernation and feed on pollen and nectar until they can lay their first brood of 8 to 10 eggs.^[7] Before laying the eggs, they build a nest out of grass and deposit honey into a wax honey pot that she made.^[6][7] They make and deposit honey in the honey pot after collecting enough pollen.^[11] Breeding occurs in the summer months.^[6] Most workers live for a brief period of time due to the intensity of their work, while queens live for 12 months on average.^[7] B. fervidus workers are responsible for making the honey that the queen and developing brood eat.^[6] The workers chew pollen and mix it with their saliva to make the honey. Since they need ample pollen for honey, workers spend a lot of time foraging for nectar and pollen, simultaneously pollinating flowers. When a worker emerges from its cocoon, it will devote most of its time toward developing the brood and consequently building a larger nest out of grass to accommodate the growing colony.^[6] If the colony grows too big, then new queens are sometimes killed before it is time for them to mate. Males have a purely reproductive purpose in the nest.^[7]

Breeding interval: Single queen lives for one season and produces offspring throughout.^[11]

Breeding season: occurs in the summer months.^[11]

Average age at reproductive maturity for queen: 1 year^[11]

Average lifespan: 12 months^[11]

Most B. fervidus do not live for more than a few months due to the toll hard work takes on the body and harsh winter weather. Only queens live approximately one year.^[7]

Behavior

Bombus fervidus make honey to feed the queen and developing brood by chewing/mixing pollen and saliva. In order to have enough food to feed the developing brood and queen, B. fervidus spend a lot of time foraging for pollen and nectar, pollinating other flowers in the process.^[6] This gives them an important role in the ecosystem. When a new worker bumblebee emerges from its cocoon, it takes care of the queen and her eggs. While the queen started the colony on her own, new workers will accommodate the growing colony by adding dead grass to the nest. If the population grows too big, newly emerged queens may arise that must leave the nest early or even be killed by other workers before they mate.^[6]

Because males have a purely reproductive process in the nest, they will often leave the nest. They live independently until the fall when they mate and then die.^[11]

Worker-queen conflict

The conflict arises because while workers never mate, they are able to lay unfertilized eggs, which, develop into males (drones).^[14] Like other hymenoptera, this species is haplodiploid, with haploid males arising from unfertilized eggs and diploid females. The relatedness asymmetries between workers and the queen cause a potential for worker queen conflict, but since this species is singly mated, workers as a whole agree with the queen that the queen's sons (workers' brothers) should be reared over other workers' sons (nephews), though each worker would prefer their own sons to be reared. See the section on worker policing for this logic.

Foraging

Bombus fervidus typically search for food in the afternoon, which is often the hottest part of the day.^[6] An individual can visit as many as forty-four flowers per minute, with each visit bringing 0.05 mg of sugar if another insect had not foraged at the site before. Therefore, B. fervidus can extract around 2.2 mg of sugar per minute. The bees' foraging behavior includes building stores or caches of foods such as nectar and pollen. These are used to feed and expand the colony.^[6] B. fervidus are expert foragers - sometimes to their own detriment. They sometimes work for too long at a rapid pace abnormal to their species and have been known to die of exhaustion.^[6]

Diet

Bombus fervidus is a nectavore, meaning it mostly acquires nutrients from the sugar-rich nectar of flowering plants.^[6] Brood are fed on pollen. Deriving food from flowers pollinates them, so this bee is part of a bee-plant mutualism. The long tongues of B. fervidus enables them to reach into long flowers, extracting the nectar before another competitor does.^[6] This suggests an evolutionary selective pressure for long tongues in B. fervidus. These bees are also very effective workers, and their quickness can sometimes be harmful to their health. B. fervidus sometimes work for so long at such a rapid pace that is normal for them that they die due to exhaustion.^[6] Additionally, adult bees chew pollen and mix it with their saliva to produce honey. This enriched honey is then used to feed the larvae and the queen. The efficiency of B. fervidus lends to its ability to grow to very large populations.^[6]

Primary Diet: herbivore (nectarivore)^[11]

Plant Foods: nectar, pollen^[11]

Foods Eaten: Aster, Black-eyed Susan, Common Milkweed, Queen Anne's Lace, Dandelions, Bull Thistle, Goldenrod, Jewelweed, Devil's Beggartick, Joe-pye Weed, Climbing Bittersweet, Black Willow, Yellow Poplar, American Holly, Ragweed, Greater Bladderwort, Blueberry, Jimsonweed, Honeysuckle, Rose Mallow^[6]

Communication

Bombus fervidus, like many bee species, communicates mainly by dancing.^[6] These dances communicate information such as the location of food or as a warning of nearby danger. They also communicate via regurgitation, in which bees present nectar to each other and it is either accepted or rejected by the colony based on the needs of the colony.^[6] This is an indirect form of communication.^[11]

Communication Channels: visual; tactile^[11]

Perception Channels: ultraviolet; tactile; chemical^[11]

Interaction With Other Species

Predation

Bombus fervidus use different means to protect themselves against predators.^[15] If an intruder enters the nest, then the bees cover the intruder with honey. If a bee has not developed enough to fly, and becomes slightly alarmed within the nest, it will lift up its middle legs. If the disturbance is elevated, the bee will lie on its back and place its legs and feet in a position that implies it is preparing itself for whatever may come next.^[15] The stinger is positioned in the air with the mandibles flaring.^[15] The mature adults will leave the nest to sting and bite the predator or attacker.^[6] Since bumblebees, unlike honeybees, do not lose their stingers or die after one sting, they can sting an attacker over and over again.^[6] This gives the bee a better chance of survival. B. fervidus are also known to defecate on an intruder or attacker.^[6] Workers vary the method of attack with the nature of the insect intruder.^[15] If stingless or comparatively weak, like the honey bee, the intruder is seized immediately and stung to death, while daubing is resorted to only if the intruder possesses strong fighting ability.^[15]

Known predators:^[11]

• Chinese mantis Tenodera aridifolia
• Goldenrod spider Misumena vatia
• Green darner Anax junius
• Least shrew NCryptotis parva
• Striped skunk Mephitis mephitis
• Great crested flycatcher Myiarchus crinitus
• American bullfrog Lithobates catesbeianus
• Eastern mole Scalopus aquaticus
• Southern leopard frog Lithobates sphenocephalus
• Bombus ashtoni

Parasites

One very successful parasite of all Bombus species is Bombus ashtoni.^[6] It lives within the nest and eats the eggs of its host. Consequently, the host workers care for the brood of the parasite instead of their own.^[6] The earlier this parasite enters the host nest, the longer it will wait before laying its eggs.^[16] Eggs are laid during the growth phase of workers in their colony cycle, which results in a reduced number of workers reared in the nest.^[16] This replacement of host eggs with parasite eggs is a gradual process as a strategy in which there is an overlap between the colony investment of both species.^[16]

Ecosystem roles

The greatest role of Bombus fervidus in the ecosystem is as a pollinator of many flowering plants.^[7] Thus, B. fervidus have a positive influence on humans as they help to pollinate many flowers including major plant crops harvested as food.^[6][7] One negative influence of B. fervidus on humans is that they sting humans immediately when they feel a threat as a defense mechanism.^[6]

Ecosystem Impact: pollinates^[11]

Positive Impacts: pollinates important crops^[11]

Negative Impacts: injures humans via bites or stings^[11]

Conservation status

Like most bumblebees, Bombus fervidus is in decline and in need of protection. Abundance declines have been observed across most of North America; the most apparent threat is the loss of its preferred grassland and tallgrass habitats to agricultural intensification. It is currently classified as vulnerable by the IUCN.^[1]

References