''Bombus ignitus'' is a species of
bumblebee
A bumblebee (or bumble bee, bumble-bee, or humble-bee) 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 gener ...
in the family
Apidae
Apidae is the largest family within the superfamily Apoidea, containing at least 5700 species of bees. The family includes some of the most commonly seen bees, including bumblebees and honey bees, but also includes stingless bees (also used for ...
. It is mainly distributed in Eastern Asia, commonly found in
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
,
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
and
Korea
Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
. It is used in China and Japan commercially as a pollinator.
''B. ignitus'' is a
eusocial
Eusociality (from Greek εὖ ''eu'' "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generat ...
insect with a queen that is
monandrous
In botanical terms, monandrous simply means to have a single stamen.
In orchids
A distinction between monandrous and other flowers is particularly relevant in the classification of orchids. The monandrous orchids form a clade consisting of the s ...
: 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.
Taxonomy
![Bombus ignitus 2](https://upload.wikimedia.org/wikipedia/commons/0/05/Bombus_ignitus_2.jpg)
''Bombus ignitus'' is part of the order
Hymenoptera
Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...
, which is the third largest order of insects. It is a member of the family
Apidae
Apidae is the largest family within the superfamily Apoidea, containing at least 5700 species of bees. The family includes some of the most commonly seen bees, including bumblebees and honey bees, but also includes stingless bees (also used for ...
, consisting of bees, and the subfamily
Apinae
The Apinae are the subfamily that includes the majority of bees in the family Apidae. It includes the familiar " corbiculate" (pollen basket) bees—bumblebees, honey bees, orchid bees, stingless bees, Africanized bees, and the extinct genus '' ...
, which contains the majority of species within
Apidae
Apidae is the largest family within the superfamily Apoidea, containing at least 5700 species of bees. The family includes some of the most commonly seen bees, including bumblebees and honey bees, but also includes stingless bees (also used for ...
. The subfamily
Apinae
The Apinae are the subfamily that includes the majority of bees in the family Apidae. It includes the familiar " corbiculate" (pollen basket) bees—bumblebees, honey bees, orchid bees, stingless bees, Africanized bees, and the extinct genus '' ...
consists of 14 tribes, including the tribe ''
Bombini
The Bombini are a tribe of large bristly apid bees which feed on pollen or nectar. Many species are social, forming nests of up to a few hundred individuals; other species, formerly classified as ''Psithyrus'' cuckoo bees, are brood parasites ...
'', which ''B. ignitus'' is a part of. ''Bombini'' contains a single living genus
''Bombus''. ''B. ignitus'' can be further classified into the subgenus ''Bombus sensu stricto,'' or ''Bombus'' in the sense of the original author.
The species name ''ignitus'' is a Latin adjective, meaning "containing fire."
Description
![Bumblebee staying on rose of Sharon (14474882447)](https://upload.wikimedia.org/wikipedia/commons/b/bf/Bumblebee_staying_on_rose_of_Sharon_%2814474882447%29.jpg)
''Bombus ignitus'' is a large bee characterized by a medium length tongue. Females have black bristles that cover the back of the
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
and the mid-legs. The abdomen is separated into five
tergum
A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the Anatomical terms of location#Dorsal and ventral, dorsal ('upper') portion of an arthropod segment other than the head. The Anatomical terms of location#Ante ...
. Starting from the thorax, the first three
terga
A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'ma ...
are black in color, whereas the fourth and fifth terga are orange-red in color. Males are characterized by golden yellow bristles that form two bands on the anterior and posterior thorax. Like the female, the male has an abdomen separated into five tergum. Starting from the thorax, the first two terga are golden yellow in color, differentiating males from females. The third tergum is black in color. The fourth and fifth terga, like the female, is orange-red in color. Compared to the female, the male compound eye is small. The antenna of males are shorter than the antenna of females, reaching only to the base of the wings. Compared to the males of other bumblebee species, the males of ''B. ignitus'' have greatly broadened penis valves that flare outwards to form a funnel shape. The queen has a body length of 19 mm. Workers have a body length of 15–17 mm. Males have a body length of 17 mm.
Distribution and habitat
''Bombus ignitus'' is found in the
Palearctic realm
The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa.
The realm consists of several bioregions: the Euro-Sibe ...
, primarily in East Asia.
This includes the more humid and temperate areas
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
,
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
, and
Korea
Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
.
Populations of ''B. ignitus'' can be found at a mean altitude of 1425 m at the western, southern, and eastern foothills of the
Sichuan Basin
The Sichuan Basin (), formerly transliterated as the Szechwan Basin, sometimes called the Red Basin, is a lowland region in southwestern China. It is surrounded by mountains on all sides and is drained by the upper Yangtze River and its tributa ...
. Though uncommon, populations have been found at lower altitudes.
Colony cycle
Colonies of ''B. ignitus'' are short-lived, with new colonies founded each year. Young queens mate with drones in the later summer, then hibernate and emerge in the following spring. Upon emerging from hibernation, these queens search for a suitable nesting site to start a colony. After a suitable site is found, these queen begin to gather pollen. A queen builds a mass of pollen at the nesting site, then lays her first batch of
diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
eggs. Workers emerge from this first batch of eggs. These workers start to forage two to three days after emerging. With the emergence of workers, the queen is able to spend more time on
oviposition
The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...
. During the late summer, many new queens and new drones are produced. Only mated queens will hibernate through the fall and winter, then emerge in the spring.
Behavior
Division of labor
''Bombus ignitus'' exhibits a size dependent division of labor. An aforaging gene, ''Bifor'', has been isolated in ''B. ignitus''. ''Bifor'' expression negatively correlated with size, with higher levels of expression found in the smaller nurses. Foragers are larger in size and have lower levels of ''Bifor'' expression.
Mating behavior
''Bombus ignitus'' is
monandrous
In botanical terms, monandrous simply means to have a single stamen.
In orchids
A distinction between monandrous and other flowers is particularly relevant in the classification of orchids. The monandrous orchids form a clade consisting of the s ...
; the
queen
Queen or QUEEN may refer to:
Monarchy
* Queen regnant, a female monarch of a Kingdom
** List of queens regnant
* Queen consort, the wife of a reigning king
* Queen dowager, the widow of a king
* Queen mother, a queen dowager who is the mother ...
mates with only a single drone to form a colony. All
workers
The workforce or labour force is a concept referring to the pool of human beings either in employment or in unemployment. It is generally used to describe those working for a single company or industry, but can also apply to a geographic regio ...
and new queens, as a result, are descendants of the queen and a single drone.
This monandrous behavior decreases the amount of genetic variation present in a single colony relative to that of a polygynous or polyandrous species.
Reproductive suppression
Both the queen and workers possess the ability to reproduce. The queen suppresses the reproductive actions of workers through increased aggressive action against reproductively active workers and destruction of eggs laid by workers. In colonies still dominated by the queen, the vast majority of drones are derived from the queen. In colonies where the queen has died, roughly half the drones are born from workers.
Kin selection
Haplodiploidy
''Bombus ignitus'', like many bees, exhibit
Haplodiploidy
Haplodiploidy is a sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid. Haplodiploidy is sometimes called arrhenotoky.
Haplodiploidy determines the sex ...
.
Diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
queens produce diploid workers and new queens from fertilized eggs.
Haploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
drones are produced from unfertilized eggs, laid by either the queen or workers.
All sperm produced by a drone is identical, containing its exact haploid DNA. Variation arises from females, who produce genetically variant eggs through
meiosis
Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately resu ...
. Sex is determined under a single-locus complementary sex determination (sl-CSD) system, where multiple alleles at a single locus determine the sex of an individual. Sex locus heterozygotes develop as females, while hemizygous and homozygous eggs develop as haploid and diploid males.
Genetic relatedness within colonies
As the queens of ''B. ignitus'' mate with only one male, the workers are more closely related to other workers (with whom they share an average of seventy five percent of their genes with) than to the queen (who they only share half their genes with). With respect to male offspring, workers are more closely related to the sons of other workers, sharing an average of 37.5 percent of their genes with them, than the sons of the queen, who they only share 25% of their genes with.
Worker queen conflict
Worker policing, manifested through aggressive actions against fertile workers and removal of the eggs of workers, has been observed in colonies of ''B. ignitus''. Similarly, reproductive workers have been observed taking aggressive behavior against founding queens. These include eating the eggs laid by the queen and laying eggs themselves, as well as attacking the queen herself. In an analysis of seven ''B. ignitus'' colonies, the survival rate of colony founding queens was 72%. These queens had damaged wings or bodies, which suggests numerous conflicts with workers.
Human importance
Agricultural
''Bombus ignitus'' is currently used for agricultural pollination in China and Japan.
The species has been chosen as a reliable species for commercial mass-production in Korea, though issues of
diapause
In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It ...
management must still be addressed. ''B. ignitus'' was chosen over the already established bumblebee, ''
Bombus terrestris
''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 wher ...
'', for fear of competition or genetic contamination by mating with native bumblebee species.
Medical
The protein BiVSPI, Found in the venom of ''B. ignitus,'' has been identified as a
serine protease inhibitor
Serpins are a superfamily of proteins with similar structures that were first identified for their protease inhibition activity and are found in all kingdoms of life. The acronym serpin was originally coined because the first serpins to be i ...
. BiVSPI exhibits antimicrobial functions, and has been found to inhibit the growth of
Gram-positive bacteria
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall.
Gram-positive bact ...
and fungi. The
cDNA
In genetics, complementary DNA (cDNA) is DNA synthesized from a single-stranded RNA (e.g., messenger RNA (mRNA) or microRNA (miRNA)) template in a reaction catalyzed by the enzyme reverse transcriptase. cDNA is often used to express a speci ...
of four antibacterial peptide genes - apidaecin, hymenoptaecin, abaecin, and
defensin
Defensins are small cysteine-rich cationic proteins across cellular life, including vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, ...
- were isolated and cloned from ''B. ignitus.'' Synthesized abaecin has been shown to inhibit the growth of Gram- negative bacteria, but had little inhibitory effect towards the growth of Gram-positive bacteria.
References
{{Taxonbar, from=Q870370
Bumblebees
Insects described in 1869