''Deinacrida heteracantha'', also known as the ''Little Barrier giant wētā'' or ''wētāpunga'' (Maori: ''wētāpunga''), is a

wētā Wētā (also spelt weta) is the common name for a group of about 100 insect species in the families Anostostomatidae and Rhaphidophoridae endemic to New Zealand. They are giant flightless crickets, and some are among the heaviest insects in th ...

in the order

Orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grassho ...

and family

Anostostomatidae Anostostomatidae is a family of insects in the order Orthoptera, widely distributed in the southern hemisphere. It is named Mimnermidae or Henicidae in some taxonomies, and common names include ''king crickets'' in South Africa and ''wētā'' i ...

. It is 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 ...

, where it survived only on

Little Barrier Island Little Barrier Island, or Hauturu in Māori language (the official Māori title is ''Te Hauturu-o-Toi''), lies off the northeastern coast of New Zealand's North Island. Located to the north of Auckland, the island is separated from the mainla ...

, although it has been translocated to some other predator-free island conservation areas. This very large flightless wētā mainly feeds at night, but is also active during the day, when it can be found above ground in vegetation. It has been classified as vulnerable by the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

due to ongoing population declines and restricted distribution.

Description

''D. heteracantha'' can weigh up to 70 g, but on average weighs between 9–35 g. Average body length is around 75 mm (3 inches).Nasrecki, P. 2013. Grasshoppers and their relatives. Elsevier Inc. 3: 247-264.Field, L.H. 2001. The Biology of Wetas, King Crickets and their Allies. New York: CABI Publishing. It is a sexually dimorphic species, with the females being much larger than the males. These large wētā have a broad body and a round head, along with short mandibles. Compared to other cricket species wētā have relatively short antennae, but can deliver a strong kick with their hind legs. They are generally wingless. The species is mainly herbivorous and feeds on forest foliage.

Habitat

''D. heteracantha'' are arboreal forest insect dwellers found on Little Barrier Island which lies off the coast of New Zealand. This island is only in size. They once occupied forests in northern New Zealand including Northland and

Auckland Auckland (pronounced ) ( mi, Tāmaki Makaurau) is a large metropolitan city in the North Island of New Zealand. The List of New Zealand urban areas by population, most populous urban area in the country and the List of cities in Oceania by po ...

. Their habitat range on Little Barrier Island is from second-growth forests located on the lower slopes of the island to the mid-level tall kauri forest. The second-growth forest is dominated by silverfern,

nikau ''Rhopalostylis sapida'', commonly known as nīkau ( mi, nīkau), is a palm tree endemic to New Zealand, and the only palm native to mainland New Zealand. Etymology is a Māori word; in the closely related Eastern Polynesian languages of the ...

palm, mahoe, and

kohekohe Kohekohe (''Dysoxylum spectabile'') is a medium-sized tree in the Meliaceae family, native to New Zealand. It is found in lowland and coastal forests throughout most of the North Island and also occurs in the Marlborough Sounds in the north ...

Behaviour

As adults these giant wētā live a nomadic lifestyle. This type of lifestyle means that these wētā do not live in the same place, but move to a new location periodically.Encyclopædia Britannica. 2015. Nomadism. Accessed November 20, 2015 fro
Link text
/ref> They live a solitary lifestyle and most of their activity is done at night (i.e. feeding and moving). They can be found above ground level under loose bark or in the cavities of mahoe and

pohutukawa ''Metrosideros excelsa'', commonly known as pōhutukawa ( mi, pōhutukawa), New Zealand Christmas tree, New Zealand Christmas bush, and iron tree, is a coastal evergreen tree in the myrtle family, Myrtaceae, that produces a brilliant display o ...

trees. During the day and night males tend to move farther than the females. The male would follow the female by staying back about 25 cm from her; this is observed during the night time.

Life cycle and reproduction

The life cycle of ''D. heteracantha'' is not tied to the seasons. They can live for up to two years. Eggs are laid in the summer months from October to December. The eggs will then hatch in March and April of the following year. ''D. heteracantha'' mate most months out of the year except for the winter months from June–August. Copulation will start in the morning and continue throughout the day. During copulation the

spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...

from the male is inserted into the female's subgenital plate. Females lay their eggs at night into moist soil. Each egg is laid singly or in groups of five in area that is about 15 cm² and about 2–3 cm deep. Females only produce an indefinite amount of eggs. Females lay eggs for the rest of their lives, but only a limited number of them are fertilised during each copulation. The eggs incubate on average for 125 days and only 36% of the eggs survive to hatch.Richards, A.O. 1973. A comparative study of the biology of the giant wetas Deinacrida heteracantha and D. fallai (Orthoptera: Henicidae) from New Zealand. Journal of Zoology 169: 195-236 After the eggs hatch there are ten

instars 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 ...

that they go through until death. In females the

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

becomes visible at the third instar. At the sixth instar the difference between male and female sexes becomes obvious. Each instar lasts on average between five and six weeks. ''D. heteracantha'' has an extra instar compared to other species in its genus, this extra instar is what makes the nymphal period longer and their overall body size larger. ''D. heteracantha'' show no courtship rituals. No stridulatory signals have been observed; sex recognition is done by contact only.

Sound generation

''D. heteracantha'' possesses a stridulatory apparatus. This apparatus is the sound producing organ based on the mechanism of rubbing one body part against another body part. There is a great variety in these structures seen in Orthoptera. Certain behaviours are associated with the sounds being produced by the Orthoptera.Field, L.H. 1993. Structure and evolution of stridulatory mechanisms in New Zealand Wetas (Orthoptera: Stenopelmatidae). International Journal of Insect Morphology and Embryology (22): 163-183. In the case of ''D. heteracantha'' there is a wide variation in the gross morphology of their stridulatory structures. Their stridulation plays a role in

interspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...

defense mechanisms. They use a femoro-abdominal mechanism to produce sound. This mechanism has two parts to it, a femoral peg and an abdominal ridge. The femoral pegs are an elongated and raised structure. There are two abdominal ridges present on ''D. heteracantha'', a major and minor ridge. The major ridge is longer and higher than the minor ridge. The minor ridge does not normally come in contact with the femoral pegs. ''D. heteracantha'' has a wide-band linear magnitude spectra (kHz) that they produce for defensive sounds. They have a major peak at 20 kHz and a minor peak around 40–50 kHz. The shape of their stridulatory mechanism is why they can produce these frequency ranges.Field, L.H. 1981. Stridulatory structures and acoustic spectra of seven species of New Zealand wetas (Orthoptera: Stenopelmatidae). International Journal of Insect Morphology and Embryology (11): 39-51.

Threats

While ''D. heteracantha'' were commonly seen on Little Barrier Island in the 1950s, numbers have declined strongly since then. Predation rather than habitat destruction is regarded as the main cause for this.Gibbs, G. and M., McIntyre. 1997. Abundance and future options for wetapunga on Little Barrier Island. Science for Conservation 48: 1-25. . Feral cats were present on the island until they were completely eradicated in the 1980s, and may have fed on vulnerable juvenile ''D. heteracantha''.

Polynesian rat The Polynesian rat, Pacific rat or little rat (''Rattus exulans''), known to the Māori as ''kiore'', is the third most widespread species of rat in the world behind the brown rat and black rat. The Polynesian rat originated in Southeast Asia, a ...

s (''Rattus exulans''), or "kiore" in the

Māori language Māori (), or ('the Māori language'), also known as ('the language'), is an Eastern Polynesian language spoken by the Māori people, the indigenous population of mainland New Zealand. Closely related to Cook Islands Māori, Tuamotuan, and ...

, are one of the top predators of ''D. heteracantha'', preying mostly on juveniles wētās which they kill during the night. An increase of the Polynesian rat population occurred after feral cats were eradicated. As saddlebacks prey on the wētā during the day, ''D. heteracantha'' are thus under constant predation pressure. There is evidence suggesting that these rats have a negative impact on the population of these wētā, as is commonly the case with invasive rodents.St. Clair, J.J.H. 2011. The impacts of invasive rodents on island invertebrates. Biological Conservation (144): 68-81. The removal of the kiore in 2004 was a success. The population size grew back each year and a four-fold increase was reported six years after the removal.Green, C. J, G.W, Gibbs, and P.A, Barrett. (2011). Wetapunga (Deinacrida heteracantha) population changes following Pacific rat (Rattus exulans) eradication on Little barrier Island. IUCN, Gland, Switzerland: 305-308. Other predators include

tuatara Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...

(''Sphenodon punctatus''),

gecko Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates throughout the world. They range from . Geckos ar ...

s, the

North Island brown kiwi The North Island brown kiwi (''Apteryx mantelli''; ''Apteryx australis'' or ''Apteryx bulleri'' as before 2000, still used in some sources) is a species of kiwi that is widespread in the northern two-thirds of the North Island of New Zealand and ...

(''Apteryx mantelli'') during the night, and

kingfisher Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found in the tropical regions of Africa, Asia, and Oceania, ...

s and the

long-tailed cuckoo The Pacific long-tailed cuckoo (''Urodynamis taitensis''), also known as the long-tailed cuckoo, long-tailed koel, sparrow hawk, home owl, screecher, screamer or in Māori, is a species of the Cuculidae bird family (the cuckoos). It is a migrat ...

(''Urodynamis taitensis'') by day.

Captive breeding and release

''D. heteracantha'' is currently classified as vulnerable by the

. Since 2008 the Department of Conservation has been involved in a captive breeding and release programme to mitigate the risk of having the entire population resident on one island. Individuals captured on Hauturu/Little Barrier Island have been successfully bred in captivity at Butterfly Creek and Auckland Zoo. The descendants have been released onto

Motuora Motuora is an island nature reserve in the western Hauraki Gulf, on the north-eastern coast of New Zealand's North Island. It lies some south-west of Kawau Island, east of Mahurangi Heads and north of the city of Auckland. History Although ...

and

Tiritiri Matangi Island Tiritiri Matangi Island is located in the Hauraki Gulf of New Zealand, east of the Whangaparaoa Peninsula in the North Island and north east of Auckland. The island is an open nature reserve managed by the Supporters of Tiritiri Matangi Incorpo ...

s. Additionally adults from Hauturu/Little Barrier Island have been transferred directly to Motuora. It is hoped that the released ''D. heteracantha'' will eventually build up self-sustaining populations on these additional predator free islands. In 2016 adult female has been observed on Tiritiri Matangi Island in the area where the first population was released. She can only be a descendant of the initial translocated population of 25 individuals released in 2011. Individuals translocated onto Tiritiri Matangi island in 2014 have been observed mating. In 2018, 300 wētāpunga from Auckland Zoo were translocated to an island in the Noises; at that point 4300 captive-bred individuals had been released on islands in the Hauraki Gulf.

References

__External_links_

*_''Deinacrida_heteracantha''_discussed_in_Radio_New_Zealand.html" "title="ublication date: 1882?
BUGZ
* 1999
Four new species of giant weta, ''Deinacrida'' (Orthoptera: Anostostomatidae: Deinacridinae) from New Zealand.
''Journal of the Royal Society of New Zealand'', 29(4): 307–324. * ; 2004: Phylogenetics of New Zealand's tree, giant and tusked weta (Orthoptera: Anostostomatidae): evidence from mitochondrial DNA. ''Journal of Orthoptera research'', 13(2): 185–196.
JSTOR
* 1963
The rediscovery of a giant weta, ''Deinacrida heteracantha'', on the North Island mainland.
''New Zealand entomologist'', 3(2): 9–13.
BUGZ

External links

* ''Deinacrida heteracantha'' discussed in Radio New Zealand">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''
30 August 2022
{{Taxonbar, from=Q308158 Weta Anostostomatidae Insects described in 1842 Endemic fauna of New Zealand Taxonomy articles created by Polbot Endemic insects of New Zealand