Новозеландский светлячок: Биология и особенности Arachnocampa luminosa

Species of fly

Arachnocampa luminosa (Skuse, 1891), commonly known as New Zealand glowworm or simply glowworm, is a species of fungus gnat endemic to New Zealand. The larval stage and the imago produce a blue green bioluminescence. Its Māori name is titiwai, meaning "projected over water". The first written record of the species dates from 1871 when it was collected from a gold mine in New Zealand's Thames region. At first it was thought to be related to the European glowworm beetle (Lampyris noctiluca) but, in 1886, a Christchurch teacher showed it was a larva of a gnat, not a beetle. The species was first formally described in 1891 with the species name Bolitiphila luminosa and was assigned to the family Mycetophilidae. In 1924, it was placed within a new genus of its own, Arachnocampa, because the wing venation of the adults and the behaviour of the larvae differed significantly from other Bolitophila fly species.

Arachnocampa luminosa is widespread in both the North and the South Island of New Zealand although populations generally occur in cave systems and in native bush where prey species are available and humidity is high. Some sites have become popular destinations for tourists wanting to see the glowworms. These include the caves in Waitomo, Waipu, Inglewood and Te Ana au, and also in areas of native vegetation such as the Wellington Botanical Gardens.

The spherical eggs (0.75mm in diameter) are usually deposited directly onto the cave wall. Upon hatching, the cylindrical larva immediately begins to glow. When they first emerge they are usually between 3 and 5 millimeters long, and will grow to between 30 and 40mm across several months. The larva may move around on the surface of the cave or bank before selecting a site to begin producing its silk nest. After five larval instars, the larva will suspend itself on a long thread and pupates over up to 24 hours. The pupal phase lasts about two weeks. During this time, the pupa continue to glow although males eventually lose their glow. The adults which eventually emerge are poor fliers.

This luminescent species resides in dark, cool and damp places such as caves and their diet is predatory, they use their bluish green glow to lure in their prey.

The larvae of this species glow to attract prey into their threads. and, like other species exhibiting bioluminescence, this glow is produced as a result a luciferase enzyme acting upon a small molecule of luciferin. It occurs in modified excretory organs known as Malpighian tubules in the abdomen. The luciferase enzyme in this species shares similarities with the protein that occurs in fireflies. However, the luciferin that the enzyme acts upon is entirely different to that of fireflies and, indeed, other currently known bioluminescent systems. However, there is little evidence to support this. It is possible that the bioluminescence in adults is simply a carry over from the larval form because the Malpighian tubules are unaffected during metamorphosis.