Bombus pensylvanicus: Difference between revisions
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'''''Bombus pensylvanicus''''', also known as the American bumble bee,<ref name=Kaufman>Eaton ER, Kaufman K. (2007) Kaufman Field Guide to Insects of North America. New York: Houghton Mifflin. p. 344.</ref> is a species of bumblebee found in Eastern North America.<ref name = "identification">{{cite journal |author=Williams, Paul H. |title=Bumble Bees of North America : An Identification Guide|journal= |volume= |issue= |pages=208 |year=2014 |pmc= |pmid= |doi=}}</ref> Its name is derived from the former Latin name ''B. americanorum''.<ref name = "esa">{{ |
'''''Bombus pensylvanicus''''', also known as the American bumble bee,<ref name=Kaufman>Eaton ER, Kaufman K. (2007) Kaufman Field Guide to Insects of North America. New York: Houghton Mifflin. p. 344.</ref> is a species of bumblebee found in Eastern North America.<ref name = "identification">{{cite journal |author=Williams, Paul H. |title=Bumble Bees of North America : An Identification Guide|journal= |volume= |issue= |pages=208 |year=2014 |pmc= |pmid= |doi=}}</ref> Its name is derived from the former Latin name ''B. americanorum''.<ref name = "esa">{{cite journal |author= |title=ARTICLE TITLE |journal= Entomological Society of America |volume=29 |issue=11 |pages=8 |year=2006 |pmc= |pmid= |doi= }}</ref> Specifically, ''Bombus pensylvanicus'' ranges from the Eastern Great Plains to eastern and central US, southern Canada, Desert West, California, Oregon, and Mexico, but is not found in the Mountain West. ''Bombus pensylvanicus'' tends to live and nest in open farmland and fields. It feeds on food plants, favoring sunflowers, clovers, and other types of flowers. ''Bombus pensylvanicus'' was once the most prevalent species throughout the southern United States, but has recently decreased in number significantly.<ref name = "identification"/> Although its name suggests that the species is widespread, it is rarely seen in the northern portion of the noted range.<ref name= "bugguide">Bug Guide. [http://bugguide.net/node/view/65631]. 21 July 2006.</ref> |
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==Taxonomy and phylogenetics== |
==Taxonomy and phylogenetics== |
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==Colony cycle== |
==Colony cycle== |
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''Bombus pensylvanicus'' maintains a reproductive cycle that it similar to other species of bumblebee.<ref name="bioweb">Bombus pensylvanicus. [http://bioweb.uwlax.edu/bio210/s2013/netwal_meli/reproduction.htm]. 2013.</ref> Environmental factors, as well as accessibility of resources, affects the cyclic advancement of the colony. The cycle begins in February and ends around November or December.<ref name = "juan">{{ |
''Bombus pensylvanicus'' maintains a reproductive cycle that it similar to other species of bumblebee.<ref name="bioweb">Bombus pensylvanicus. [http://bioweb.uwlax.edu/bio210/s2013/netwal_meli/reproduction.htm]. 2013.</ref> Environmental factors, as well as accessibility of resources, affects the cyclic advancement of the colony. The cycle begins in February and ends around November or December.<ref name = "juan">{{cite journal |author=Juan Di Trani de la Hoz |title= Phenology of Bombus pennsylvanicus sonorus Say (Hymenoptera: Apidae) in Central Mexico |journal= Neotropical Entomology |volume=35 |issue=5 |pages= |year=2006 |pmc= |pmid= |doi= 10.1590 }}</ref> Female bees can yield eggs without the need for mating, a process known as [[haplodiploidy]]. Unfertilized eggs develop into males, whereas fertilized eggs develop into female workers or queen bees.<ref name= "bioweb"/> The reproductive cycle begins in July/August, when a male mates with a freshly hatched queen. The fertilized queen stays in hibernation until spring of the next year, waiting for the optimal conditions to search for a nest. In March, the queen bee gathers pollen and nectar, as a source of nutrition and to build a wax pot, and establishes her colony.<ref name= "bioweb"/> These colonies most likely arrange and initiate in February.<ref name="juan"/> Female workers develop through the pollen collected as it stimulates the ovaries to create eggs, which are fertilized from the males of year before. The queen continues to warm the eggs initially, then the eggs continue their life cycle of development: first larval stage, then pupae, and lastly adult female workers. The female workers care for the nest and eggs, whereas the queen lays eggs. This process of egg to adult bee takes about 4–5 weeks.<ref name= "bioweb"/> |
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Initial workers forage and increase the colony size by bringing resources for growth. Thus, workers that hatch later in the year, around midsummer, tend to be larger than initial worker bees.<ref name= "bioweb"/> The hives continue to grow,<ref name="juan"/> and in late summer there can be more than 200 worker bees. At the point when the size of the hive is sufficient, the queen stops production of a chemical that prevents ovarian production of certain females leading to specify the production of queen bee eggs and male eggs.<ref name= "bioweb"/> |
Initial workers forage and increase the colony size by bringing resources for growth. Thus, workers that hatch later in the year, around midsummer, tend to be larger than initial worker bees.<ref name= "bioweb"/> The hives continue to grow,<ref name="juan"/> and in late summer there can be more than 200 worker bees. At the point when the size of the hive is sufficient, the queen stops production of a chemical that prevents ovarian production of certain females leading to specify the production of queen bee eggs and male eggs.<ref name= "bioweb"/> |
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Certain female workers may produce their own eggs, but the queen will usually get rid of them. The constant battle between the queen and workers continue until late summer when the workers sting the queen to death. In the winter, the workers dies, but the queen bee eggs laid before hatch, and thus the cycle begins again.<ref name= "bioweb"/> |
Certain female workers may produce their own eggs, but the queen will usually get rid of them. The constant battle between the queen and workers continue until late summer when the workers sting the queen to death. In the winter, the workers dies, but the queen bee eggs laid before hatch, and thus the cycle begins again.<ref name= "bioweb"/> |
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==Gene flow and decline== |
==Gene flow and decline== |
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Bumblebee species have been found to deteriorate substantially in 1940-1960, and continue to decrease presently. Ranges of ''Bombus pensylvanicus'' have specifically decreased in Illinois, coinciding with agricultural investment within the state.<ref name = "Lozier">{{ |
Bumblebee species have been found to deteriorate substantially in 1940-1960, and continue to decrease presently. Ranges of ''Bombus pensylvanicus'' have specifically decreased in Illinois, coinciding with agricultural investment within the state.<ref name = "Lozier">{{cite journal |author= |title=ARTICLE TITLE |journal= Entomological Society of America |volume=29 |issue=11 |pages=8 |year=2006 |pmc= |pmid= |doi= 10.1111/j.1365-294X.2009.04160.x }}</ref> Lozier and Cameron performed microsatellite markers in Illinois to compare genetic variation of historical versus contemporary collections within ''Bombus pensylvanicus''. It was found that ''Bombus pensylvanicus'' had greater population structure, meaning that the population is less ideal in terms of the [[Hardy–Weinberg principle | Hardy-Weinberg equilibrium]]. It was found that genetic diversity has overall not been significantly altered over time, but there were some reductions in ''Bombus pensylvanicus''. Slight losses of genetic diversity in ''B. pensylvanicus'' may be an indication of the species’ decline. These results were expected because of the recent decrease in population, which would cause declines in genetic diversity for severe bottleneck situations. Thus, the alteration in gene flow may suggest potential future genetic differentiation of the ''B. pensylvanicus''. The decrease in ''B. pensylvanicus'' population has been found to contrast the increasing prevalence of [[Bombus impatiens]] in Illinois.<ref name = "esa">{{cite journal |author=Jeffrey D. Lozier| author=Syndney A. Cameron |title= Comparative genetic analyses of historical and contemporary collections highlight contrasting demographic histories for the bumble bees Bombus pensylvanicus and B. impatiens in Illinois |journal= Molecular Ecology |volume=18 |issue=9 |pages=1875-1886 |year=2009 |pmc= |pmid= |doi= }}</ref> |
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==Behavior== |
==Behavior== |
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===Resource partitioning=== |
===Resource partitioning=== |
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Johnson tested for intraspecific size differences as well as differences in resource utilization in ''Bombus pensylvanicus''. In Minnesota, flowers with short corollas and long corollas existed in single and mixed species stands. Foragers with short corollas and shorter proboscides were discovered in mixed species stands in contrast to foragers on species having lengthier corollas. Foragers’ proboscis lengths of species with long corollas paralleled that of short corollas in single species stands. Johnson concluded that ''Bombus pensylvanicus'' foragers would preference the corolla length that corresponds with their proboscis length. Further comparison of conspecific foragers of mixed versus single species stands revealed a shorter proboscis length for mixed species in comparison to single species stand for the short corolla. Johnson postulated that a diversity of flowering species may influence the specific bee that pollinates the species for single species stand.<ref name = "johnson">{{ |
Johnson tested for intraspecific size differences as well as differences in resource utilization in ''Bombus pensylvanicus''. In Minnesota, flowers with short corollas and long corollas existed in single and mixed species stands. Foragers with short corollas and shorter proboscides were discovered in mixed species stands in contrast to foragers on species having lengthier corollas. Foragers’ proboscis lengths of species with long corollas paralleled that of short corollas in single species stands. Johnson concluded that ''Bombus pensylvanicus'' foragers would preference the corolla length that corresponds with their proboscis length. Further comparison of conspecific foragers of mixed versus single species stands revealed a shorter proboscis length for mixed species in comparison to single species stand for the short corolla. Johnson postulated that a diversity of flowering species may influence the specific bee that pollinates the species for single species stand.<ref name = "johnson">{{cite journal |author=Johnson |title=Intraspecific Resource Partitioning in the Bumble Bees Bombus Ternarius and B. Pennsylvanicus |journal= Entomological Society of America |volume=67 |issue=111 |pages=138-138 |year=1986 |pmc= |pmid= |doi= }}</ref> |
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==Status== |
==Status== |
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Revision as of 16:39, 3 October 2015
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| Species: | B. pensylvanicus
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| The range of Bombus pensylvanicus. (Dashed line indicates former range.) | |
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Bombus pennsylvanicus [2] | |
Bombus pensylvanicus, also known as the American bumble bee,[3] is a species of bumblebee found in Eastern North America.[4] Its name is derived from the former Latin name B. americanorum.[5] Specifically, Bombus pensylvanicus ranges from the Eastern Great Plains to eastern and central US, southern Canada, Desert West, California, Oregon, and Mexico, but is not found in the Mountain West. Bombus pensylvanicus tends to live and nest in open farmland and fields. It feeds on food plants, favoring sunflowers, clovers, and other types of flowers. Bombus pensylvanicus was once the most prevalent species throughout the southern United States, but has recently decreased in number significantly.[4] Although its name suggests that the species is widespread, it is rarely seen in the northern portion of the noted range.[6]
Taxonomy and phylogenetics
Bombus pensylvanicus is part of the order Hymenoptera (consisting of ants, wasps, bees, and sawflies), the family Apidae (consisting of Cuckoo, Digger, Carpenter, Bumble, and Honeybees), the Subfamily Apinae (consisting of Honey, Orchid, Bumble, Long-horned, and Digger Bees), the genus Bombus (consisting of Bumble Bees), and the species pensylvanicus.[6] Bombus pensylvanicus is sometimes mistaken for B. terricola and B. auricomus,[7] but its closest relative is Bombus sonorus, found in Mexico and Arizona.[8] Although the species maintain differences in male genitalia, scientists sometimes treat Bombus sonorus as a subspecies of Bombus pensylvanicus.[9] Intermediate individuals have been found in Mexico, making it important to find further evidence to determine whether or not B. sonorus is a subspecies of B. pensylvanicus.[4]
Description and identification
Bombus pensylvanicus is characterized as a long-tongued, widespread species with a contrast of lighter color in the southwest, from sonorus, and darker color pattern in the east, from pensylvanicus.[4] Specific characteristics include: a yellow thoracic dorsum, a black posterior, 3 initial alternating black and white tergal segments, a long and lanky malar space,[6] and short hair,[4] because of which the species is often times confused with Bombus fervidus or Bombus auricomus.[6] It is similar in colour and range to the yellow bumblebee (Bombus fervidus).[10] In terms of characteristics within the hive, a larger queen measures 22–26 mm compared to worker at 13–19 mm. Additionally, males have an outward penis valve head with a broad banana shape.[4]
Morphology
Cameron observed that bees of the genus Bombus tend to have a comparable morphology throughout their range, thus signifying that behavioral adaptations may play a large part in colonizing different habitats. Mimetic evolution is postulated to account for both interspecific and intraspecific variation in colour pattern. Eastern North American B. pensylvanicus and western North American B. sonorus are taxa that maintain a similar morphology, but have distinct color patterns. This demonstrates introgression of B. sonorus from Mexico and Arizona from B. pensylvanicus of Missouri. Thus, allopatric species taxa that have differentiating color characteristics may be conspecific. Evidence of introgression postulates that B. sonorus are not derived from the same ancestral group relative to the Missouri pensylvanicus genetic sequences.[8]
Distribution and habitat
Bombus pensylvanicus ranges from the Eastern Great Plains to eastern and central US and southern Canada, Desert West, California, Oregon, and Mexico, but is not found in the Mountain West.[4] Its geographic division is centered in Middle and North America. It is further postulated that B. pensylvanicus originated from Canada, Continental US, or Mexico, all areas of which the species is native.[11] B. pensylvanicus generally nests in fields of long grass, but may sometimes nest underground. The species utilizes bundles of hay or long grass to create sheltered nests above ground. Some nest in established crevices and burrows, such as old bird nests, rodent burrows, or in cinder blocks.[6] The species has become rarer than previously, declining in mainly northern parts of its range.[6]
Colony cycle
Bombus pensylvanicus maintains a reproductive cycle that it similar to other species of bumblebee.[12] Environmental factors, as well as accessibility of resources, affects the cyclic advancement of the colony. The cycle begins in February and ends around November or December.[13] Female bees can yield eggs without the need for mating, a process known as haplodiploidy. Unfertilized eggs develop into males, whereas fertilized eggs develop into female workers or queen bees.[12] The reproductive cycle begins in July/August, when a male mates with a freshly hatched queen. The fertilized queen stays in hibernation until spring of the next year, waiting for the optimal conditions to search for a nest. In March, the queen bee gathers pollen and nectar, as a source of nutrition and to build a wax pot, and establishes her colony.[12] These colonies most likely arrange and initiate in February.[13] Female workers develop through the pollen collected as it stimulates the ovaries to create eggs, which are fertilized from the males of year before. The queen continues to warm the eggs initially, then the eggs continue their life cycle of development: first larval stage, then pupae, and lastly adult female workers. The female workers care for the nest and eggs, whereas the queen lays eggs. This process of egg to adult bee takes about 4–5 weeks.[12] Initial workers forage and increase the colony size by bringing resources for growth. Thus, workers that hatch later in the year, around midsummer, tend to be larger than initial worker bees.[12] The hives continue to grow,[13] and in late summer there can be more than 200 worker bees. At the point when the size of the hive is sufficient, the queen stops production of a chemical that prevents ovarian production of certain females leading to specify the production of queen bee eggs and male eggs.[12] Certain female workers may produce their own eggs, but the queen will usually get rid of them. The constant battle between the queen and workers continue until late summer when the workers sting the queen to death. In the winter, the workers dies, but the queen bee eggs laid before hatch, and thus the cycle begins again.[12]
Stability within the colony
Bombus pensylvanicus has a varying stability within its colony cycle. Queens are considered the dominant caste because they are usually the largest bees of the colony. As worker male bees grow larger in average wing length, they become the dominant caste as the number of queens decrease. Wing length of males vary depending upon the point of colony development. Initial males that found the colony tend to have a smaller wing length than the first or second generation of the colony. Food supply is scarce, at first, as the queen is the forager. Until July, the workers are the foraging caste and an enormous increase in body size is observed. The worker proportions decrease when reproductive males develop, representing a turning point in the colony, as male size increase until active bees develop to the size of a queen near November and December when the worker population dissipates. Queens maintain the least amount of standard deviation for average wing length and thus are the most stable caste in the colony. It is postulated that this is because queens are made in a short time span when colony resources have reached its threshold. The activity of B. pensylvanicus in a subtropical zone resemble that of species in temperate zones, maintaining periods where there are no active bees.[13]
Interaction with other species
Predators
Although Bombus pensylvanicus maintains a cautionary coloration and defensive stinger, it faces many predators. Predation is likely be caused by attack to gain the resources of the hive, which contains carbohydrate and protein abundant nectar, larvae, and pollen. Predators consist of mostly mammals such as skunks, bears, raccoons. Furthermore, bumble bees are predated by birds for food. Foragers are frequently predated by invertebrates. Crab spiders and cryptically colored ambush bugs ambush bees at flowers to catch them. Robber flies resemble bumble bees and clasp the bumble bees, insert them with enzymes, then eat their internal organs. Wasps, such as the Beewolf, arrest bees then paralyze them with venom, using them to nourish the wasp’s larvae. Assassin bugs and dragonflies are also common predators of the bee.[4]
Parasites
Bumble bees are generally host to a diversity of parasitoids in which the larvae grows inside the living host.[4] The majority of parasitoids for bumble bees are flies and about 30 percent or more bees within the area can be infected. The process of parasitism consists of the fly attaching to the bee in flight and inserting her oviposits between the terga of the bee. The larval fly hatches within the bee host and develops by feeding on the host’s tissues. The bee lives for about two weeks before dying. The fly then pupates and spends the winter inside the bee, fully developed, before it emerges the following year. North American Bumble Bees are also hosted by one parasitoid wasp, Braconidae: syntretus sp. and the moth, B. variabilis.[7] Hibernating Queen bumble bees are parasitized by a nematode worm, Sphaerularia bombi. This parasite does not reduce life span, but instead causes the sterilization of the queen. It has been observed that affected queens forage two to three weeks later than those that are unaffected.[4] Parasitic microorganisms also use bees as their host. Parasitic microorganisms’ effects may be lethal or sublethal. Pathogens may be transmitted within a colony or the bee may be infected at flowers. Trachael mites (Locustacarus buchneri) leads to reduced foraging efficiency by living in the bee’s alveoli. Certain protozoans and fungi consume the host tissue or gut substances of the bumble bee’s digestive tract, decreasing foraging efficiency, life span, and thus the colony fitness. Bees may contain symbiotic bacteria that offer some immunity to pathogens. Further exposure to habitat loss as well as pesticide exposure may lead to bee predisposition, thus promoting the species’ decay.[4]
Mimicry
Since bees are characterized by a distinct color pattern as well as a defensive sting, they have been subject to mimicry in order to gain its known protective mark. Bumble bees are resembled by sawflies, other bees, day-flying moths, beetles, and flies. Cimbicid sawflies resemble bees, but have swollen antenna tips as a distinguisher. Other bees, such as carpenter and digger bees, contain a striking resemblance to bumble bees, but males contain a yellow clypeus and females have hindlegs with brushes rather than a pollen basket, which is a characteristic of bumble bees. Clearwing hawk moths (Sphingidae such as Hemaris thetis) resemble bumble bees while foraging through flowers, but are distinct with skinny legs and spindle antennae. Bumble flower beetles (Scarabaeidae such as Euphoria inda) maintains a similar flight behavior to bumble bees like flying close to plants and buzzing loudly. The longhorned beetle also has a color scheme paralleling bumble bees. Flower flies are especially similar mimics of bumble bees, such as the robber fly, deer bot fly, and bee fly. Bumble bees have developed Mullerian mimicry as a reinforced defense against predators.[4]
Gene flow and decline
Bumblebee species have been found to deteriorate substantially in 1940-1960, and continue to decrease presently. Ranges of Bombus pensylvanicus have specifically decreased in Illinois, coinciding with agricultural investment within the state.[14] Lozier and Cameron performed microsatellite markers in Illinois to compare genetic variation of historical versus contemporary collections within Bombus pensylvanicus. It was found that Bombus pensylvanicus had greater population structure, meaning that the population is less ideal in terms of the Hardy-Weinberg equilibrium. It was found that genetic diversity has overall not been significantly altered over time, but there were some reductions in Bombus pensylvanicus. Slight losses of genetic diversity in B. pensylvanicus may be an indication of the species’ decline. These results were expected because of the recent decrease in population, which would cause declines in genetic diversity for severe bottleneck situations. Thus, the alteration in gene flow may suggest potential future genetic differentiation of the B. pensylvanicus. The decrease in B. pensylvanicus population has been found to contrast the increasing prevalence of Bombus impatiens in Illinois.[5]
Behavior
Pollinator behavior
Wesselingh and Arnold found Bombus pensylvanicus represents an abundance of visits to the ''Iris fulva'', red flowered, and ''Iris brevicaulis'', blue flowered. Bombus pensylvanicus preferenced purple flowered hybrids. The bees continued to visit the nearest flowers the majority of the time, thus demonstrating that movements were usually between a diversity of flower types rather than prioritizing only one type of flower. Thus, a lack of intermediate genotypes of iris hybrids is not due to pollinator preference by Bombus pensylvanicus, but rather, pollinating behavior is done through mixed mating of alternating flower types of different pollination syndromes.[15]
Resource partitioning
Johnson tested for intraspecific size differences as well as differences in resource utilization in Bombus pensylvanicus. In Minnesota, flowers with short corollas and long corollas existed in single and mixed species stands. Foragers with short corollas and shorter proboscides were discovered in mixed species stands in contrast to foragers on species having lengthier corollas. Foragers’ proboscis lengths of species with long corollas paralleled that of short corollas in single species stands. Johnson concluded that Bombus pensylvanicus foragers would preference the corolla length that corresponds with their proboscis length. Further comparison of conspecific foragers of mixed versus single species stands revealed a shorter proboscis length for mixed species in comparison to single species stand for the short corolla. Johnson postulated that a diversity of flowering species may influence the specific bee that pollinates the species for single species stand.[16]
Status
Current research states that Bombus pensylvanicus is uncommon and most likely declining. As stated in previous sections, the northern range of Bombus pensylvanicus has significantly decreased. Once the most abundant species throughout the southern United States, Bombus pensylvanicus has declined to become a rare species that has been extirpated in certain areas and suffered declines in others. Conservation efforts are encouraged in order to maintain the species including agriculture with wildlife-friendly techniques including hedgerows and pest management.[14]
References
- ^ "Bombus pennsylvanicus". Integrated Taxonomic Information System.
- ^ "Thoracobombus". Natural History Museum.
- ^ Eaton ER, Kaufman K. (2007) Kaufman Field Guide to Insects of North America. New York: Houghton Mifflin. p. 344.
- ^ a b c d e f g h i j k l Williams, Paul H. (2014). "Bumble Bees of North America : An Identification Guide": 208.
{{cite journal}}: Cite journal requires|journal=(help) - ^ a b "ARTICLE TITLE". Entomological Society of America. 29 (11): 8. 2006. Cite error: The named reference "esa" was defined multiple times with different content (see the help page).
- ^ a b c d e f Bug Guide. [1]. 21 July 2006.
- ^ a b Colla; Richardson; Williams (2011). "Bumble Bees of the Eastern United States": 104.
{{cite journal}}: Cite journal requires|journal=(help) - ^ a b S.A. Cameron; H. M. Hines; P. H. Williams (2007). "A Comprehensive Phylogeny of the Bumble Bee (Bombus)". Biological Journal of the Linnean Society. 91: 161–188.
- ^ NatureServe Explorer. [2].
- ^ Bombus fervidus, Discover Life
- ^ Itis Report. [3].
- ^ a b c d e f g Bombus pensylvanicus. [4]. 2013.
- ^ a b c d Juan Di Trani de la Hoz (2006). "Phenology of Bombus pennsylvanicus sonorus Say (Hymenoptera: Apidae) in Central Mexico". Neotropical Entomology. 35 (5). doi:10.1590.
{{cite journal}}: Check|doi=value (help) - ^ a b "ARTICLE TITLE". Entomological Society of America. 29 (11): 8. 2006. doi:10.1111/j.1365-294X.2009.04160.x.
- ^ Template:Wiley Online Library
- ^ Johnson (1986). "Intraspecific Resource Partitioning in the Bumble Bees Bombus Ternarius and B. Pennsylvanicus". Entomological Society of America. 67 (111): 138–138.