Bombylius major

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Bombylius major
Grosser Wollschweber Bombylius major.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Bombyliidae
Genus: Bombylius
Species:
B. major
Binomial name
Bombylius major
Synonyms

Large bee-fly or dark-edged bee-fly

Bombylius major (commonly named the large bee-fly, the dark-edged bee-fly or the greater bee fly) is a parasitic bee mimic fly. B. major is the most common type of fly within the Bombylius genus. The fly derives its name from its close resemblance to bumblebees and are often mistaken for them.

Contents

Bombylius major exhibits a unique flight behavior known as "yawing" [1] and plays a role in general pollination, without preference of flower types. [2] The fly does not bite, sting, or spread disease. [3] However, the fly uses this mimicry of bumblebees to its own advantage, allowing close access to host solitary bee and wasp nests in order to deposit its eggs. After hatching, the larvae find their way into the nests to parasitically feed on the grubs. [4]

Description

Bombylius major is part of the family Bombyliidae, with a reported 6000 species worldwide. [2] The subfamily Bombyliinae contains approximately 1100 identified species. [5] The genus Bombylius currently comprises around 450 described species. [2]

Bombylius major can be found from April to June throughout temperate Europe, North America and some parts of Asia, concentrated in the northern hemisphere. [2] The species occurs across a variety of environments, from arid to moist. [2]

Morphology

Large bee fly in early springtime (video, 2m 10s)

The adult body size varies from 6.3 to 12 mm in length and is considered a relatively medium-sized fly. The body color is dark, but is densely covered by a thick coat of lighter color hairs. [2] [6] The head is typically brown and black hairs, but the lower portion of the head is mostly white hairs. It has dark patches on the anterior half of the wings and long hairy legs that dangle while in flight. [7] The dark wing span can range from 8.4 to 14 mm and has a dark brown edge. [6] Their boldly patterned wings have a distinct dividing border through the horizontal middle between the dark and clear portions. Their antennae are typically very short and pointed. [7] Additionally, the species has long legs and a long rigid proboscis found in the front of the head, which is used to feed on the nectar of flowers. [6] The proboscis ranges from 5.5 to 7.5 mm in length. [2] While its wings continue to beat, its front legs grip the flower and its long rigid beak is inserted to collect the nectar. [8] Despite its fearsome appearance, the beak is quite harmless. [8] Males are typically smaller than females. [2] Movement is categorized by both hovering and darting between locations. [9] The flies also emit a high-pitched buzz. [7]

Mimicry

The species gets its common name from its similarity in appearance to bees. This mimicry likely confers some defense against predation. However, there are several distinguishing features: B. major has only one pair of wings (bees have two), extremely thin legs, and the head is very small, with a long rigid proboscis. [9]

Life cycle

Flicking an egg Bombylius egg ejection 290310 1504.gif
Flicking an egg
Bombylius major egg Bombylius major o1.JPG
Bombylius major egg

Bombylius major is mostly seen in the spring, beginning to appear at the end of March and large numbers seen until the end of May, with the species being sighted into June. [2] The fly is holometabolous. [2]

Bombylius major mating in Suzuka Mountains, Inabe, Mie prefecture, Japan. Bombylius major (mating).jpg
Bombylius major mating in Suzuka Mountains, Inabe, Mie prefecture, Japan.

Bombylius major has several host species, including the brood of solitary wasps and bees, particularly digging bees such as Andrena . Egg deposition takes place by the female hovering above the entrance of a host insect nest, usually a solitary bee, and throwing down her eggs using a flicking movement. [10] The larvae are hypermetamorphic parasitoids which then feed on the food stored, as well as the young solitary bees or wasps. If the female is unable to flick her eggs near the nest, she plants them on flowers visited by the host insects. The developing larvae then make their way to the host nest or attach themselves to the bees or wasps to then be carried to the nest. [10]

Egg

The parasitic eggs of B. major are produced in large numbers, however few will make it to the host insect burrow entrance. [9] The female fly will dip down and coat her rear abdomen with dust that covers the eggs as they leave the female.

Larvae

B. major adult Bombylius major - Burgenland.jpg
B. major adult

Larvae live parasitically in the nests of various solitary bees and wasps. [2] When the fly larva locates a host larva, it will consume it slowly, greatly increasing in size as it tightly holds onto the host, eventually becoming a pupa and overwintering. [9]

Pupae

White larvae gradually turn into a yellowish brown pupa, with distinct mouthparts, wings, antennae, and legs. [9]

Diet

Bombylius major feeding on nectar Bombylius major gathering nectar.jpg
Bombylius major feeding on nectar

The species sometimes acts as a nectar robber, sometimes as a pollinator; [11] this foraging behavior allows the species to feed on floral nectar and is an essential part of adult fly diets. This is facilitated by the characterizable long proboscis of the fly, which is horizontally inserted into the flower. [2] This occurs as the fly continues to buzz in the air, sometimes without touching either the anthers or stigma of the flower. [2] However, in some species such as Claytonia virginica, bee flies can be effective pollinators. [11] [12] The fly also consumes pollen as part of its diet, with considerable differences between the sexes. Males and females visit the same range of flowers as a food source. [13]

Along with one other species, Bombylius pygmaeus , B. major was observed to selectively (and almost exclusively) visit bluets at several North American sites despite the abundant presence of many other flowers. [14] Of the other pollinators present, these flies were also the most frequent visitors to the flowers. [14]

Female

In Russia, female B. major act in a narrow oligophagous manner, favoring a limited number of food sources, including pollen grains of Siberian squill ( Scilla siberica ), lesser celandine ( Ficaria verna ), and willow ( Salix caprea ) over dandelion ( Taraxacum officinale ), coltsfoot ( Tussilago farfara ), and primrose ( Primula vulgaris ). [13]

Male

In the same study, male B. major preferred plants similar to females, with the exception of dandelion. However, an examination of the gut showed a regularly lower amount of pollen than in females. Males consistently consume less quantities of pollen than females. Ingestion of pollen differs throughout a male life cycle, with more pollen being consumed in towards earlier stages. Overall, males had a preference for nectar and fed on significantly greater portions of nectar over pollen. [13]

Behavior

There is continued research on the behavior of B. major in respect to environmental factors, mating, and human interaction.

In flight 2014.03.29.-12-Mannheim Neckarau Waldpark-Grosser Wollschweber.jpeg
In flight

Flight

It has been discovered that the fly is capable of a unique type of flight behavior, which was discovered with the use of a high speed camera. In this behavior, the flies are seen to rotate around a vertical axis as they fly (this action is known as “yawing”). However, it is still unknown what can cause this behavior to be triggered and what purpose it serves, but a proposed explanation includes mating habits. [1]

Pollinator role

The B. major bee-fly is a common, generalist floral pollinator, meaning that it does not give preference to one flower over another, instead pollinating a wide variety of plant families and species. [2] [15] The fly uses its proboscis to carry and transfer the pollen. The species is a dominant pollinator within its community, sometimes even pollinating up to two thirds of the local flowers. In addition, B. major will visit and pollinate plants that attract few other species. Some types of flowers, for example Pulmonaria officinalis, will be almost exclusively pollinated by B. major, with other species contributing a negligible amount to that plants pollination. Some flower species, such as Delphinium tricorne , are even specifically adapted to the fly in terms of color, shape, and form. If given the choice, B. major will have a consistency in plant choice. [15]

Flower attraction

Long distance floral attraction is governed by optical sense, with color being the most important factor. The flies are typically more attracted to blue and violet colors, and occasionally yellow, over orange and pink. However, short distance floral attraction is based on the fly's olfactory sense. [2]

Sunbathing Bombylius major - Leithagebirge.jpg
Sunbathing

Activity

The fly is mostly active during day hours when the weather conditions are warm and sunny. B. major is attracted to sunnier places and is more likely to pollinate these areas, with a larger average of flower visits in areas of higher amounts of sunshine. The fly will hide in the trees during the night [2] and usually dart away from a cast shadow and occasionally hide in clean washing brought in fresh from the washing line and fly out causing unsettled behaviour in the discoverer. [9]

Related Research Articles

<span class="mw-page-title-main">Bee</span> Clade of insects

Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamily Apoidea. They are currently considered a clade, called Anthophila. There are over 20,000 known species of bees in seven recognized biological families. Some species – including honey bees, bumblebees, and stingless bees – live socially in colonies while most species (>90%) – including mason bees, carpenter bees, leafcutter bees, and sweat bees – are solitary.

<span class="mw-page-title-main">Hoverfly</span> Family of insects

Hoverflies, also called flower flies or syrphids, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprotrophs, eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores, preying on aphids, thrips, and other plant-sucking insects.

<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.

<span class="mw-page-title-main">Bombyliidae</span> Family of flies

The Bombyliidae are a family of flies, commonly known as bee flies. Adults generally feed on nectar and pollen, some being important pollinators. Larvae are mostly parasitoids of other insects.

<span class="mw-page-title-main">Entomophily</span> Form of pollination by insects

Entomophily or insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Flowers pollinated by insects typically advertise themselves with bright colours, sometimes with conspicuous patterns leading to rewards of pollen and nectar; they may also have an attractive scent which in some cases mimics insect pheromones. Insect pollinators such as bees have adaptations for their role, such as lapping or sucking mouthparts to take in nectar, and in some species also pollen baskets on their hind legs. This required the coevolution of insects and flowering plants in the development of pollination behaviour by the insects and pollination mechanisms by the flowers, benefiting both groups. Both the size and the density of a population are known to affect pollination and subsequent reproductive performance.

<span class="mw-page-title-main">Acroceridae</span> Family of flies

The Acroceridae are a small family of odd-looking flies. They have a hump-backed appearance with a strikingly small head, generally with a long proboscis for accessing nectar. They are rare and not widely known. The most frequently applied common names are small-headed flies or hunch-back flies. Many are bee or wasp mimics. Because they are parasitoids of spiders, they also are sometimes known as spider flies.

<i>Bombylius</i> Genus of flies

Bombylius is a large genus of flies belonging to the family Bombyliidae. They are known as the bee-flies, due to their striking resemblance to bees and bumblebees, and are distributed worldwide. One species of the genus, Bombylius major, is widely distributed throughout the northern hemisphere and is very well known.

<i>Eristalis tenax</i> Species of fly

Eristalis tenax, the common drone fly, is a common, migratory, cosmopolitan species of hover fly. It is the most widely distributed syrphid species in the world, and is known from all regions except the Antarctic. It has been introduced into North America and is widely established. It can be found in gardens and fields in Europe and Australia. It has also been found in the Himalayas.

<span class="mw-page-title-main">Eastern carpenter bee</span> Species of insect

Xylocopa virginica, sometimes referred to as the eastern carpenter bee, extends through the eastern United States and into Canada. They are sympatric with Xylocopa micans in much of southeastern United States. They nest in various types of wood and eat pollen and nectar. In X. virginica, dominant females do not focus solely on egg-laying, as in other bee species considered to have "queens". Instead, dominant X. virginica females are responsible for a full gamut of activities including reproduction, foraging, and nest construction, whereas subordinate bees may engage in little activity outside of guarding the nest.

<i>Philanthus gibbosus</i> Species of wasp

Philanthus gibbosus, the hump-backed beewolf, is a species of bee-hunting wasp and is the most common and widespread member of the genus in North America. P. gibbosus is of the order Hymenoptera and the genus Philanthus. It is native to the Midwestern United States and the western Appalachians. P. gibbosus are often observed to visit flowers and other plants in search of insect prey to feed their young. The prey that P. gibbosus catches is then coated in a layer of pollen and fed to the young wasps.

<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.

<span class="mw-page-title-main">Alkali bee</span> Species of insect

The alkali bee, Nomia melanderi, is a ground-nesting bee native to deserts and semi-arid desert basins of the western United States. It was described by Theodore Dru Alison Cockerell in 1906. While solitary, these bees nest near each other and can form extremely dense aggregations in areas with favorable conditions.

Diptera is an order of winged insects commonly known as flies. Diptera, which are one of the most successful groups of organisms on Earth, are very diverse biologically. None are truly marine but they occupy virtually every terrestrial niche. Many have co-evolved in association with plants and animals. The Diptera are a very significant group in the decomposition and degeneration of plant and animal matter, are instrumental in the breakdown and release of nutrients back into the soil, and whose larvae supplement the diet of higher agrarian organisms. They are also an important component in food chains.

<i>Xylocopa nasalis</i> Species of bee

The Oriental carpenter bee, Xylocopa nasalis, or Xylocopa (Biluna) nasalis, is a species of carpenter bee. It is widely distributed in Southeast Asian countries. It is a major pollinator within its ecosystem, and is often mistaken for a bumblebee. The species leads a solitary lifestyle with a highly female-biased colony in the nest.

<i>Euglossa cordata</i> Species of bee

Euglossa cordata is a primitively eusocial orchid bee of the American tropics. The species is known for its green body color and ability to fly distances of over 50 km. Males mostly disperse and leave their home nests, while females have been observed to possess philopatric behavior. Because of this, sightings are rare and little is known about the species. However, it has been observed that adults who pollinate certain species of orchids will become intoxicated during the pollination.

<i>Hyperalonia morio</i> Species of fly

Hyperalonia morio is a species of bee flies in the family Bombyliidae.

<i>Bombylius canescens</i> Species of fly

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<i>Xenox tigrinus</i> Species of fly

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<span class="mw-page-title-main">Hover (behaviour)</span> Ability of some flying animals and insects

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References

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