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Villa alternata

By Jayna Sames

Geographic Range

Villa alternata is a bee fly species found on every continent except Antarctica. Bombyliidae are a relatively early diverging lineage within the large radiation of flies known as Brachycera (short-horned flies). This genus of bee flies evolved before the breakup of Pangea. (Greathead, 1981)

Habitat

Since Villa alternata is found on all continents except Antarctica, it is found in a large variety of habitats with varying rainfall, temperature and soil types. Its habitat must be rich in its' host species (noctuid moths and tenebrionid beetles). These bee flies are found in dunes, sandy scrub regions, forests, grasslands, taiga, marshes, and bogs. (Falck, 2009; Hull, 1973; Kits, et al., 2008; Yeates and Lambkin, 1994)

Physical Description

This Bombyliidae species has a short proboscis. These bee flies are covered in hairs and scales that vary from golden yellow to black and white, often with bands of bright scales on the abdominal tergites and with tufts of black and white or yellowish hairs at the end of the abdomen. The wings of Villa alternata are almost entirely clear with a slight brown hue at the wing base. One pale pile exists on each pleuron. On the sides of segment three of the abdomen is a black pile. Tarsal claws of forelegs are much smaller than those of other legs. The fore tibia have either prominent spines or the sides of abdomen are found to have long, flattened scales, but the fly never has both characters. Villa alternata typically has a rounded head. The males have a brilliant mat of silvery patagial scales. On the wing of genus Villa, the forking of the radial sector takes place at or near the r-m cross-vein, and never at a greater distance than the length of that vein. A sectoral cross-vein may be present, but is usually absent and contact of cells 1M-2 and u-1 are not longer than the base of Cu-1. The antennal style is minute or absent and there are no pulvilli in most of the species. The species of this genus are more or less densely clothed with pile and tomentum.

Since their habitat can vary so much, the appearance of Villa may not be strictly uniform. Populations found in areas of high temperature, low rainfall and sandy soil are predominantly lighter in color than those found in areas of lower temperature, higher rainfall and heavier soil. (Falck, 2009; Kits, et al., 2008)

  • Range length
    10 to 17 mm
    0.39 to 0.67 in

Development

Bee flies are holometabolous and develop through hypermetamorphosis in which the 1st instar larva is inquiline, living in a sand chamber and left to find a host by itself. The larvae commonly parasitizes the larvae of Noctuid moths (Noctuidae) or in some areas tenebrionid beetles (Tenebrionidae). Once the larva finds a host and penetrates the host's nests, where it turns into a sedentary parasitoid. The pupa is equipped with spines/spikes that enable it to break free from the host pupa. It drills out of the nest, where it emerges as a flying adult equipped with sex organs. (Falck, 2009; Yeates and Lambkin, 2013)

Reproduction

Female bee flies fly to elevated landmarks solely for the purpose of mating with males that have aggregated there. This phenomenon is known as "hilltopping." No interactive courtship behavior was detectable prior to midair coupling to engage in mating. Females are free to choose mates but males have been observed intercepting a female as she flies over him. It is not known whether females can prevent matings after being grabbed. Copulations last over 100 minutes on average.

Territorial fights between males before choosing a mate involve aerial collisions during which modified spines on the wing margins produce scars on the bodies of opponents. Territory owners and mating males are not different in size or age from the remainder of the male population. (Yeates and Dodson, 1990)

After mating, Villa alternata adult females find a crack or hole in the ground and position themselves to make a sand chamber. The females then fill this chamber with sand, dust, saw-dust, or other fine particles. This behavior is undertaken to prevent the eggs from sticking together, as they are flicked off the female and land one by one to the ground where host species are in high density. In oviposition, the female gives the abdomen a down-ward flick, touches hind tarsi to the ground, hovers again for a second or two, releases another egg. Hundreds of eggs are deposited in the sand chamber in a matter of hours. Villa appear commonly in the months of May to August in North American temperate climates, so reproduction likely takes place in the spring and summer. (Falck, 2009; Toft, 1983)

  • Breeding season
    Mating takes place in the spring and summer.

There seems to be no known parental investment by male bee flies, but there may be a possibility for the storage of nutrient rich ejaculate into the female during copulation. Copulation for Bombyliidae lasts 2 to 15 minutes, providing the potential for transfer of large quantities of sperm or other components into the female for use to develop and sustain offspring. Female investment lies in the energy and resources they invest towards the formation of the zygote and the collecting and gluing of small particles of substrate to eggs before flicking them off their bodies. (Yeates and Greathead, 1997)

  • Parental Investment
  • pre-hatching/birth
    • provisioning

Lifespan/Longevity

The lifespan of Villa alternata is not known, but in the American southwest, the majority of noted Villa alternata carry out their adult lives in August. It is likely that adults live for about a month. (Toft, 1983)

  • Average lifespan
    Status: wild
    1 months

Behavior

Bee flies are very mobile, hovering or skillfully flying in their adult life. Bee flies are solitary as adults except for the hours when they mate or when males partake in territorial fights. Territorial fights for mates between males involve aerial collisions, usually within range of the hilltopping area. Bee fly males have modified spines on the wing margins that can cut into the bodies of male opponents. Bombyliidae are diurnal and most active in the presence of sunlight. Larvae stay in groups in the host insect before emerging. (Kits, et al., 2008; Yeates and Dodson, 1990)

Communication and Perception

Most Dipteran parasitoids that rely on immatures for host contact produce actively searching larvae. Such planidiform larvae have evolved independently in families such as Bombyliidae which allows larvae to find hosts inaccessible to adult bee flies. Little is known about the type of perception used for larvae to do so. There is little known about social behaviors in Bombyliidae, but it is likely that vision and chemoreception are used. (Feener and Brown, 1997)

Food Habits

Villa alternata is a pollen eater and nectar feeder. It has a relatively short proboscis in relation to other Bombyliidae. This species is known to feed on small flowers such as Chrysothamnus viscidiflorus in the common Asteraceae family. Such feeding is noted in the American Southwest. Female bee flies spend large amounts of time feeding, up to 8 times that of males. Food obtained by adults has the potential to constitute a substantial part of the nutritional investment in reproduction. (Toft, 1983)

  • Animal Foods
  • insects
  • Plant Foods
  • nectar
  • pollen

Predation

Birds are predators of Villa alternata. Bee flies demonstrate Batesian mimicry of Hymenoptera. The bee flies share similar colors, patterns, and a similar stout and woolly body as many wasps and bees. Mimicking wasps and bees, which are known to sting predators, is beneficial to Villa alternata, since predators may assume it is a stinging hymenopteran and avoid trying to eat it. (Yeates and Lambkin, 1994; Yeates and Lambkin, 2013)

  • Anti-predator Adaptations
  • mimic
  • Known Predators

Ecosystem Roles

Villa alternata larvae parasitize Noctuid moths (Noctuidae), which feed on nectar rich flowers and woody plants. Noctuid moths in turn parasitize agricultural pests with its cutworm larvae. The bee fly larval parasitoids on Noctuid moths may impact moth populations in a habitat patch, indirectly effecting the growth or decline of nectar rich flowers and agricultural pests in the area.

This genus of bee fly also parasitizes tenebrionid beetles (Tenebrionidae), which feed on a variety grasses such as bluegrass and sagebrush. This also suggests that Villa alternata may have an indirect affect on the local success of such grasses if they are limited in abundance. The ecological impact of Villa may be broad in regards to the species affected due to the wide range of habitats and climate this genus can live. (Hull, 1973; Kits, et al., 2008; Sheldon and Beedlow, 1988; Yela and Herrera, 1993)

Species Used as Host

Economic Importance for Humans: Positive

Villa alternata is known to be a parasitoid of Noctuidae moths. Noctuid moth larvae are known to be pests of agricultural crops. Villa alternata likely can control these noctuid pest populations, decreasing the potential economic losses resulting from crop damage. Bombyliidae are also pollinators on many types of flowering plants, some of which may be beneficial to humans. (Wiegmann, 2011)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Villa alternata on humans.

Conservation Status

Villa alternata has no special conservation status. (McGinley, 1993)

Other Comments

There is little literature available on Villa alternata. More research needs to be done on predatory threats to the species, behavioral tendencies, longevity, and general characteristics that V. alternata has in specific habitats.

Contributors

Jayna Sames (author), University of Michigan Biological Station, Brian Scholtens (editor), University of Michigan Biological Station, Angela Miner (editor), Animal Diversity Web Staff.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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Neotropical

living in the southern part of the New World. In other words, Central and South America.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body

marsh

marshes are wetland areas often dominated by grasses and reeds.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

nectarivore

an animal that mainly eats nectar from flowers

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

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oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

Falck, M. 2009. The Norwegian species of Villa Lioy, 1864 (Diptera, Bombyliidae). Norwegian Journal of Entomology, 56: 120–130.

Feener, D., B. Brown. 1997. Diptera as Parasitoids. Annual Review of Entomology, 2: 73-97.

Greathead, D. 1981. The Villa group of genera in Africa and Eurasia with a review of the genera comprising Thyridanthrax sensu Bezzi 1924 (Diptera: Bombyliidae). Journal of Natural History, 15:2: 309-326.

Hull, F. 1973. Bee flies of the world: the genera of the family Bombyliidae (1973). Washington D.C.: Smithsonian Institution Press.

Kits, J., S. Marshall, N. Evenhuis. 2008. The bee flies (Diptera: Bombyliidae) of Ontario, with a key to the species of eastern Canada. Canadian Journal of Arthropod Identification, 6: 1-52.

McGinley, R. 1993. Where's the management in collection's management: planning for improved care, greater use, and growth of collections.. National Museum of Natural History, 1: 309-338.

Sheldon, J., P. Beedlow. 1988. Diets of Darkling Beetles (Coleoptera: Tenebrionidae) Within a Shrub-Steppe Ecosystem. Entomological Society of America, 81: 782-791.

Toft, K. 1983. Community patterns of neetivorous adult parasitoids (Diptera, Bombyliidae) on their resources. Oecologia, 57: 200-215.

Wiegmann, B. 2011. Overcoming the effects of rogue taxa: Evolutionary relationships of the bee flies. PloS Currents, 5: 1-13.

Yeates, D., D. Greathead. 1997. The evolutionary pattern of host use in the Bombyliidae (Diptera): a diverse family of parasitoid flies.. Biological Journal of the Linnean Society, 50: 149-185.

Yeates, D., G. Dodson. 1990. The Mating System of a Bee Fly (Diptera: Bombyliidae). I. Non-Resource-Based Hilltop Territoriality and a Resource-Based Alternative. Journal of Insect Behavior, 3: 1-15.

Yeates, D., C. Lambkin. 1994. "Bombyliidae" (On-line). Tree of Life Web Project. Accessed July 24, 2013 at http://tolweb.org/Bombyliidae.

Yeates, D., C. Lambkin. 2013. "Family Bombyliidae- Bee Flies" (On-line). Bug Guide. Accessed August 09, 2013 at http://bugguide.net/node/view/185.

Yela, J., C. Herrera. 1993. Seasonality and lifecycles of woody plant feeding noctuid moths (Lepidoptera, Noctuidae) in Mediterranian Habitats. Ecological Entomology, 18: 259-269.

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