Arachnocampa: Wikis

  
  

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Arachnocampa
Arachnocampa luminosa larvae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Subclass: Pterygota
Infraclass: Neoptera
Superorder: Endopterygota
Order: Diptera
Suborder: Nematocera
Infraorder: Bibionomorpha
Superfamily: Sciaroidea
Family: Keroplatidae
Genus: Arachnocampa
Species
Various - see text

Arachnocampa is a genus of four fungus gnat species which are, in their larval stage, glowworms. They are found mostly in New Zealand and Australia in caves and grottos, or sheltered places in forests.

The genus was called Bolitiphila, meaning mushroom lover, in the past. The name was changed in 1924 to Arachnocampa, meaning spider-grub, for the way the larvae hang silk threads to trap prey. The genus Arachnocampa belongs in the family Keroplatidae.

Contents

Common features

Arachnocampa species go through a life cycle of eggs hatching to larvae then pupating to an adult fly. They spend most of their life as larvae.

The larval stage lasts about 6 to 12 months, depending on food. The larva emerges from the egg only about 3 to 5 millimetres long, and through its life grows to about 3 centimeters.

The larva spins a nest out of silk on the ceiling of the cave and then hangs down as many as 70 threads of silk (called snares) from around the nest, each up to 30 or 40 cm long and holding droplets of mucus. The larvae can only live in a place out of the wind, to stop their lines being tangled, hence caves, overhangs or deep rainforest. In some species, the droplets of mucus on the silk threads are poisonous enhancing the trap's ability to subdue prey quickly.[1]

The larva glows to attract prey into its threads, perhaps luring them into believing they are outdoors, for the roof of a cave covered with larva can look remarkably like a starry sky at night. A hungry larva glows brighter than one which has just eaten.[2] Prey include midges, mayflies, caddis flies, mosquitos, moths, or even small snails or millipedes. When prey is caught by a line the larva pulls it up (at up to about 2 millimetres a second) and feeds. If prey is scarce the larvae will turn to cannibalism, eating other larvae, pupae or adult flies.

The glow is the result of a chemical reaction that involves luciferin, a waste product; luciferase, the enzyme that acts upon luciferin; adenosine triphosphate, the energy molecule; and oxygen. It occurs in modified excretory organs known as Malpighian tubules in the abdomen.[3]

The body of the larva is soft while the head capsule is hard. When it outgrows the head capsule it moults, shedding its skin. This happens four times through its life.

At the end of the larva stage it becomes a pupa, hanging down from the roof of the cave. The pupa stage lasts about 1 or 2 weeks and it glows intermittently. The male stops glowing a few days before emerging, the female's glow increases. The glow from the female is believed to be to attract a mate, and males may be waiting there when she emerges.

The adults (of both sexes) cannot feed and live only a short time. They glow, but only intermittently. Their sole purpose is to mate, and for the female to lay eggs. Adult insects are poor fliers and so will often remain in the same area, building a colony of glowworms. The female lays a total of about 130 eggs, in clumps of 40 or 50, and dies soon after laying. The eggs hatch after about 20 days and the cycle repeats.

The larvae are sensitive to light and disturbance and will retreat into their nests and stop glowing if they or their snares are touched. Generally they have few predators. Their greatest danger is from human interference.

Species

  • Arachnocampa luminosa is found in New Zealand, on both the North and South islands. Its Māori name is titiwai, meaning "projected over water". The Waitomo Caves on the North Island near Pirongia is one well-known habitat, the caves having become a popular tourist attraction. It was first known to science in 1871 when collected from a gold mine in the Thames region. At first it was thought to be related to the European glowworm beetle, but in 1886 a Christchurch teacher showed it was a larva of a gnat, not a beetle. The species was called Bolitiphila luminosa in 1891, before being renamed Arachnocampa in 1924. The harvestman spider preys on the luminosa eggs, larvae and pupae, and even the adult flies. Small orange harvestman spiders live in the same caves as the luminosa; larger spiders will come into the caves for food and shelter. A fungus also affects the luminosa; it gradually kills the larva. Fungus spores are spread by air movement, but since the larvae live out of the wind the spread of spores is limited. Arachnocampa luminosa is found only in New Zealand.
  • Arachnocampa Sp.Mt Buffalo. A colony of Arachnocampa has been found in an alpine cave on Mt Buffalo in Victoria. Early research suggests it is a new species, but related to the tasmaniensis and the New Zealand luminosa. Its presence suggests rainforest may have extended up the mountain in the past.[4] The Victorian Government presently has it listed (called the Mt Buffalo Glow-Worm) as a threatened species.[5]

Orfelia fultoni, a distantly related mycetophilid fly that also has luminescent larvae, can be found in the Appalachia area of the United States. Dismals Canyon, a National Natural Landmark in northwest Alabama, is one place these larvae may be viewed. These larvae don't make the hanging silk lines of Arachnocampa and produce light from a different part of their bodies.

The larvae of Keroplatidae also evidence blue luminescence and are found in almost all European countries, from Portugal in the southwest to Scandinavia in the northeast.

References

  1. ^ Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
  2. ^ Springbrook Glow Worms Research Centre
  3. ^ Green, L.B.S. (1979) The fine structure of the light organ of the New Zealand glow-worm Arachnocampa luminosa (Diptera: Mycetophilidae). Tissue and Cell 11: 457-465.
  4. ^ The Lure of Glow Worms, science feature at the Australian Broadcasting Commission
  5. ^ Threatened List April 2006, at the Victorian Department of Sustainability and Environment
  • The New Zealand Glowworm by V.B. Meyer-Rochow, 1990, Published by Waitomo Caves Museum Society. 60 pages (ISBN 0-908683-09) [The book can be obtained from: Waitomo Caves Museum, P.O.Box 12, WAITOMO CAVES, NEW ZEALAND]
  • The Glow-Worm, Ormiston Walker and Judy Kerdel, MacMillan New Zealand, 1990, ISBN 0-7329-0121-9. (A children's book.)
  • Glowworm article, Encyclopædia Britannica, 15th edition

Broadley, R.A. and Stringer, I.A.N. (2009) Larval behaviour of the New Zealand glowworm, Arachnocampa luminosa (Diptera: Keroplatidae), in bush and caves. In: V.B. Meyer-Rochow (Ed.), Bioluminescence in Focus - A Collection of Illuminating Essays (pp. 325-355). Research Signpost. Kerala.

Baker, C. H., (2008) Distribution and phylogenetic relationships of Australian glow-worms Arachnocampa (Diptera, Keroplatidae) Molecular Phylogenetics and Evolution 48: 506-514

Baker, C.H. and Merritt, D.J. (2003) Life cycle of an Australian glow-worm Arachnocampa flava Harrison (Diptera: Keroplatidae: Arachnocampa). Australian Entomologist 30(2): 45-55

Baker, C.H., (2003) Australian glow-worms: Managing an important biological resource. Australasian Cave and Karst Management Association Inc. 53: 13 – 16

Baker, C.H. (2002) Dipteran glow-worms: Marvellous maggots weave magic for tourists. (ed Skevington J.H. and Dang, P.T. Exploring the diversity of flies (Diptera). Biodiversity 3(4): 3-28

Baker, C.H., (2002) A biological basis for management of glow-worm populations of ecotourism significance. Wildlife Tourism Research report series: No 21, CRC for Sustainable Tourism, Gold Coast, QLD. 76 pp.

Broadley, R.A. and Stringer, I.A.N. (2001) Prey attraction by larvae of the New Zealand glowworm, Arachnocampa luminosa (Diptera: Mycetophilidae). Invertebrate Biology 120 (2): 170-177.

External links


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Phylum: Arthropoda
Subphylum: Hexapoda
Classis: Insecta
Cladus: Dicondylia
Cladus: Pterygota
Cladus: Metapterygota
Cladus: Neoptera
Cladus: Eumetabola
Cladus: Endopterygota
Superordo: Panorpida
Cladus: Antliophora
Ordo: Diptera
Subordo: Nematocera
Infraordo: Bibionomorpha
Superfamilia: Sciaroidea
Familia: Keroplatidae
Subfamilia: Arachnocampinae
Genus: Arachnocampa
Subgenera: A. (Arachnocampa) - A. (Campara) - A. (Lucifera)

References

  • Baker, C.H.; Graham, G.C.; Scott, K.D.; Cameron, S.L.; Yeates, D.K.; Merritt, D.J. 2008: Distribution and phylogenetic relationships of Australian glow-worms Arachnocampa (Diptera, Keroplatidae). Molecular phylogenetics and evolution, 48: 506-514.

Vernacular names

日本語: ヒカリキノコバエ属

Simple English

Arachnocampa is a family of flies. They are also called Fungus gnats. They occur in Australia and New Zealand. Their larvae are glowworms.

They were called Bolitphila (mushroom-lovers) until 1924. Then people found out that their larvae use silk threads to catch prey. Their current name means spider-grub.








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