''Arachnocampa luminosa'' (Skuse, 1891), commonly known as New Zealand glowworm or simply glowworm, is a species of
fungus gnat
Fungus gnats are small, dark, short-lived gnats, of the families Sciaridae, Diadocidiidae, Ditomyiidae, Keroplatidae, Bolitophilidae, and Mycetophilidae (order Diptera); they comprise six of the seven families placed in the superfamily Sciaroide ...
endemic to
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
. The
larval
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The l ...
stage and the
imago
In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...
produce a blue-green
bioluminescence
Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...
.
The species is known to dwell in caves and on sheltered banks in native bush where humidity is high. Its
Māori
Māori or Maori can refer to:
Relating to the Māori people
* Māori people of New Zealand, or members of that group
* Māori language, the language of the Māori people of New Zealand
* Māori culture
* Cook Islanders, the Māori people of the C ...
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 Gold Mine may refer to:
*Gold Mine (board game)
*Gold Mine (Long Beach), an arena
*"Gold Mine", a song by Joyner Lucas from the 2020 album '' ADHD''
See also
* ''Gold'' (1974 film), based on the novel ''Gold Mine'' by Wilbur Smith
*Gold mining
...
in New Zealand's
Thames
The River Thames ( ), known alternatively in parts as the River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the second-longest in the United Kingdom, after the R ...
region. At first it was thought to be related to the European glowworm beetle (''
Lampyris noctiluca
''Lampyris noctiluca'', the common glow-worm of Europe (see also "glowworm"), is the type species of beetle in the genus ''Lampyris'' and the family Lampyridae.
''Lampyris noctiluca'' presents a conspicuous sexual dimorphism. The males are winge ...
'') but, in 1886, a
Christchurch
Christchurch ( ; mi, Ōtautahi) is the largest city in the South Island of New Zealand and the seat of the Canterbury Region. Christchurch lies on the South Island's east coast, just north of Banks Peninsula on Pegasus Bay. The Avon River / ...
teacher showed it was a larva of a
gnat
A gnat () is any of many species of tiny flying insects in the dipterid suborder Nematocera, especially those in the families Mycetophilidae, Anisopodidae and Sciaridae. They can be both biting and non-biting. Most often they fly in large num ...
, not a beetle.
The species was first formally described in 1891 with the species name ''Bolitiphila luminosa'' and was assigned to the family
Mycetophilidae
The Mycetophilidae are a family of small flies, forming the bulk of those species known as fungus gnats. About 3000 described species are placed in 150 genera, but the true number of species is undoubtedly much higher. They are generally found ...
. 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. It was given the genus name (meaning "spider-worm") on the basis of its building a silk nest and using silk threads to capture prey.
Distribution
''Arachnocampa luminosa'' is widespread in both the
North
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography.
Etymology
T ...
and the
South Island
The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...
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
Waitomo is a rural community in the King Country region of New Zealand's North Island. There are several solutional cave systems in the area around the village, which are popular tourist attractions. Restaurants and accommodation are centred in ...
,
Waipu,
Inglewood and
Te Anau
Te Anau is a town in the Southland region of the South Island of New Zealand. In Maori, Te-Anau means the Place of the Swirling Waters. It is on the eastern shore of Lake Te Anau in Fiordland. Te Anau is 155 kilometres north of Invercargill an ...
,
and also in areas of native vegetation such as the
Wellington Botanical Gardens.
Life cycle
The spherical eggs (0.75mm in diameter) are usually deposited directly onto the cave wall. Upon hatching, the cylindrical
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
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.
Most larvae emerge during the spring.
The larva spins a nest out of silk on the ceiling of the cave and then hangs down up to 30 silk threads along which it regularly places small sticky droplets.
Their prey largely include other small
Diptera
Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
(especially
midges
A midge is any small fly, including species in several families of non-mosquito Nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some midg ...
)
although glowworm living on banks may also trap spiders and other non-flying invertebrates.
When prey is entangled in a snare, the larva pulls it up by ingesting the snare and starts feeding on the prey alive.
After five larval
instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...
s,
the larva will suspend itself on a long thread and
pupa
A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
tes over up to 24 hours. The pupal phase lasts about two weeks. During this time, the
pupa
A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
continue to glow although males eventually lose their glow. The adults which eventually emerge are poor fliers.
Adults usually emerge during the winter and tend to live for up to 76 hours in the case of females and up to 96 hours in the case of males.
Females usually lay over 100 eggs and eggs usually hatch after about 20 days.
Sources of mortality for glowworms include predation by cave
harvestmen
The Opiliones (formerly Phalangida) are an order of arachnids colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs. , over 6,650 species of harvestmen have been discovered worldwide, although the total number of ext ...
(including the short-legged harvestmen, ''
Hendea myersi cavernicola {{Short description, none
This is a list of the described species of the harvestman family Triaenonychidae. The data is taken from Joel Hallan's Biology Catalog.
Triaenonychinae
Triaenonychinae Sørensen, in L. Koch 1886
* '' Acumontia'' Loman, ...
'', and the long-legged harvestmen, ''
Megalopsalis tumida)'', parasitic fungi (''
Tolypocladium
''Tolypocladium'' is a genus of fungi within the family Ophiocordycipitaceae. It includes species that are parasites of other fungi, insect pathogens, rotifer pathogens and soil inhabiting species with uncertain ecological roles. ''Tolypocladium' ...
'' sp.), and possibly cannibalism when adults become entangled in other larvae's silk threads although evidence is mixed.
Behavior And Ecology
This
luminescent
Luminescence is spontaneous emission of light by a substance not resulting from heat; or "cold light".
It is thus a form of cold-body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions or stress on a cryst ...
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. Compared to other caves the Temperature and Humidity inside the Glowworm Cave are atypical. When comparing climatic data from 1977–80 and 1955 it is shown that the cave was more stable in 1955 than it is now, this increase in climatic variability is thought to be due to the fact that in 1975 the entrance was unblocked forcing the cave to behave as a wind tunnel.
The behavior observed of both the pupae and adult New Zealand glowworm has shown that the longest stage that the Arachnocampa goes through is its larval stage which can last up to a year. Females of the A. Luminosa are the ones that are actually luminescent but it is still unknown whether or not the female's light is what attracts a male opposed to pheromones, especially when it could possibly be both. Their eyes are designed to function well with the spectral range that covers UV to green wavelengths, adult A. Luminosa are not very good fliers and they only live for a few days, on top of that they do not feed either.
Bioluminescence
The larvae of this species glow to attract prey into their threads.
The glow has a maximum wavelength of 487 nm and, like other species exhibiting bioluminescence, this glow is produced as a result a
luciferase
Luciferase is a generic term for the class of oxidative enzymes that produce bioluminescence, and is usually distinguished from a photoprotein. The name was first used by Raphaël Dubois who invented the words ''luciferin'' and ''luciferase'', ...
enzyme acting upon a small molecule of
luciferin
Luciferin (from the Latin ''lucifer'', "light-bearer") is a generic term for the light-emitting compound found in organisms that generate bioluminescence. Luciferins typically undergo an enzyme-catalyzed reaction with molecular oxygen. The result ...
.
It occurs in modified excretory organs known as
Malpighian tubules
The Malpighian tubule system is a type of excretory and osmoregulatory system found in some insects, myriapods, arachnids and tardigrades.
The system consists of branching tubules extending from the alimentary canal that absorbs solutes, water, ...
in the abdomen.
The luciferase enzyme in this species shares similarities with the protein that occurs in
fireflies
The Lampyridae are a family (biology), family of Elateroidea, elateroid beetles with more than 2,000 described species, many of which are bioluminescence, light-emitting. They are soft-bodied beetles commonly called fireflies, lightning bugs, ...
. However, the luciferin that the enzyme acts upon is entirely different to that of fireflies and, indeed, other currently known bioluminescent systems.
The pupae and adults of this species also produce light although the purpose is not clear. One suggestion has been that the light allows adult males to find potential mates. However, there is little evidence to support this. It is possible that the bio-luminescence in adults is simply a carry-over from the larval form because the
Malpighian tubules
The Malpighian tubule system is a type of excretory and osmoregulatory system found in some insects, myriapods, arachnids and tardigrades.
The system consists of branching tubules extending from the alimentary canal that absorbs solutes, water, ...
are unaffected during metamorphosis.
References
Further reading
* ''The Glow-Worm'', Ormiston Walker and Judy Kerdel, MacMillan New Zealand, 1990, . (A children's book.)
* ''Glowworm'' article,
Encyclopædia Britannica
The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various time ...
, 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.
External links
* ''Arachnocampa luminosa'' discussed on
RNZ
Radio New Zealand ( mi, Te Reo Irirangi o Aotearoa), commonly known as Radio NZ or simply RNZ, is a New Zealand public-service radio broadcaster and Crown entity that was established under the Radio New Zealand Act 1995. It operates news and cu ...
''Critter of the Week''
20 July 2018Soil Bugs - An illustrated guide to the New Zealand invertebratesGlowworm article in the ''Encyclopaedia of New Zealand 1966''2009-10-25)
{{Taxonbar, from=Q2859380
Keroplatidae
Diptera of New Zealand
Insects of Australia
Bioluminescent insects
Cave insects
Insects described in 1891