The giant Fijian long-horned beetle (''Xixuthrus '') is native to the island of

Viti Levu Viti Levu (pronounced ; ) is the largest island in Fiji. It is the site of the country's capital and largest city, Suva, and home to a large majority of Fiji's population. Geology Fiji lies in a plate tectonics, tectonically complex area betwe ...

Fiji Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about ...

, and is one of the largest living insect species, with specimens around 15 cm long, excluding

legs A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element cap ...

, antennae, or jaws. It is closely related to the Taveuni beetle, which is only marginally smaller. These beetles have powerful jaws, and should be handled with care when alive—when threatened, they produce a loud and fearsome hissing noise by squeezing air out from under their

elytra An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometime ...

. The

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

habitat on its home island has suffered severe fragmentation by deforestation and habitat degradation by invasive species such as the

small Indian mongoose The small Indian mongoose (''Urva auropunctata'') is a mongoose species native to Iraq and northern India; it has also been introduced to several Caribbean and Pacific islands. Taxonomy ''Mangusta auropunctata'' was the scientific name proposed ...

, with other threats being

cyclone In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an ant ...

s that could devastate its remaining habitat, light pollution and human consumption of its larvae. Consequently, the beetle is regarded as rare and

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

''Xixuthrus heros'' is distributed in the lowland rainforests of south-east Viti Levu, with

Colo-i-Suva Forest Reserve Colo-I-Suva Forest Park is a nature reserve near Suva, Fiji. It offers hiking trails, swimming, and birdwatching. The forest is part of the Queen's Commonwealth Canopy. History Established in 1872, Colo-i-Suva Forest National Park in Fiji is a ...

being the stronghold; natives in some nearby villages continue to consume the larvae when they split decaying wood, which is then burnt for fuel, placing additional pressures on the population. Adult beetles have been recorded in the past flying to lights in the nursing college near Suva. A scientific study in 2001/2002 determined that there are, in fact, two distinct species which had been identified as ', one of them true ', the other being '' X. ganglbaueri''.

Life cycle

The life cycle of ''X. heros'' is yet to be fully understood. Observations and historical collections suggest that these beetles are more prevalent during the months of May to September. Both male and female ''X. heros'' are primarily nocturnal and embark on long-distance flights in their quest for mates and suitable host trees. Additionally, there is evidence suggesting that certain cerambycid beetles, including ''X. heros'', employ sex pheromones as attractants.Lal, S., Tuvou, L., Prasad, S., Gravelle, G., Cagitoba, A., Farley, L. and Olson, D. 2005. Fiji’s ''Xixuthrus'' longhorn beetles: Vulnerable, not extinct. ''Oryx'' 39(4): 370-374.

Habitat and threats

The habitat of ''X. heros'' is the decaying wood of large trees, typically those with a minimum diameter of 80 cm. Such substantial trees are rare in the region, with estimates indicating their presence at less than four per square kilometer. This habitat is under threat from activities like logging, land clearance for agriculture, and vulnerability to cyclone damage. Notably, ''Xixuthrus'' larvae have been associated with the creation of intriguing galleries within the buabua tree (''

Fagraea gracilipes ''Fagraea gracilipes'' is a species of flowering plant in the family Gentianaceae. It is endemic to Fiji, where it is known from only four of the islands. It is harvested for its valuable wood. In Fiji, it is threatened by overexploitation Over ...

'', Loganiaceae).

Logging

''Xixuthrus heros'' faces imminent threats primarily linked to logging activities. Large trees, vital for the species' survival, are at risk due to extensive logging and the conversion of native forests into agricultural lands. Lowland forest habitats are swiftly vanishing, and these sizeable trees, essential for larval development, are incredibly scarce in Fijian forests.

Agricultural encroachment and cyclones

The relentless clearance of lowland forests for agriculture further intensifies the species' vulnerability. This agricultural expansion hastens the disappearance of suitable habitats. Furthermore, the growing frequency and strength of cyclones present a significant threat to the entire range of ''X. heros''. These cyclones can cause extensive damage to the remaining habitat, potentially jeopardizing the survival of the species.

Human interactions and international trade

Fijians sometimes kill adult beetles due to their imposing size and loud hissing, particularly when attracted to electric lights. Additionally, the species has been collected for international trade, a practice that further exacerbates their scarcity. Any loss of larval or adult individuals before reproduction poses a substantial risk to the already vulnerable population.

References

External links

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''Xixuthrus heros'' pictures
In Russian but excellent images of several members of this genus including ''X. heros''. Locality information in English. {{Taxonbar, from=Q1526437 Prioninae Insects of Fiji Endemic fauna of Fiji Beetles described in 1868