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Acanthoxyla prasina, the prickly stick insect, is a stick insect in the order Phasmatodea and the family Phasmatidae. It is native throughout New Zealand, although it is less frequently reported than "common" stick insect species. It has been introduced to Britain, predominantly Cornwall and Devon, and to the south-west region of the Republic of Ireland. It has a thorny skin, which is used as camouflage.

Identification
Acanthoxyla prasina is a large insect; their body length ranges from 7.5 to 11cm long when fully grown as adults. Their bodies tend to be wider than other stick insect species. They come in two different colour forms: green and brown in various shades. There are eight subspecies, some of which have prominent dark spines on the top of the thorax and abdomen. Acanthoxyla prasina have various number and size of their spines (prickles) including one characteristic spine on the underside of their abdomen, at the base of their subgenital plate. Acanthoxyla prasina has black spines across the top of individuals of A. prasina heads, mesothorax, metathorax, abdomen and femora. Their antennae are on average just slightly longer than the fore femora. The tail on the end of their abdomen is shorter and more circular than that of other subspecies.

Life cycle/Phenology
Acanthoxyla prasina has no male individuals; A. prasina are exclusively females. They reproduce through asexual reproduction called parthenogenesis. Parthenogenesis occurs when a gamete grows and develops into an embryo, without the need for fertilization. Prickly stick insects lay eggs 4.2mm long and 1.8mm high. Their eggs are brown/grey, oval shaped and are covered in small spines. Female stick insects lay their eggs on the ground, and they begin to hatch in spring when the weather warms. Lee found that each individual will lay hundreds of eggs in its lifetime. All the eggs that are laid have a 99% mortality rate. Despite the high mortality rate, their population still increases.

Hatchlings emerge as nymphs. At one day old they are approximately 2 cm long. Ananthoxyla prasina will moult approximately 5–6 times in roughly 6 months before reaching adult size. They usually moult at night. Once emerged, they will likely eat their old skin. Chudleigh found that most Acanthoxyla species’ life span is approximately 12–24 months.

Native range
Acanthoxyla prasina can be found throughout New Zealand, where it was originally endemic.

Introduced range
There are a few New Zealand stick insect species that have made it over or have been introduced to the United Kingdom. Salmon states that Ananthoxyla prasina was accidentally introduced to Paignton, UK in 1910. Other articles suggest Acanthoxyla prasina had also been and still is in the UK, although their sources discuss Acanthoxyla subspecies, not Acanthoxyla prasina. The species that are discussed are two subspecies of Ananthoxyla prasina; Acanthoxyla prasina inermis and Acanthoxyla prasina geisovii and a smooth stick insect Clitarchus hookeri. . All three of these species have been in the UK before 1940’s.

No male had ever been seen within the species or genus Acanthoxyla until 2016 when one was discovered within the introduced population from Cornwall. This single male individual was the result of a rare mutation. It is unknown if the male was capable of producing sperm or inseminating females as the specimen was killed, dried and added to part of the collection at the Natural History Museum in London.

Diet
Acanthoxyla prasina are forage feeders. A very noticeable characteristic is their shape and colour as they blend in with their food. These stick insects feed on a variety of native plants, as well as some introduced species such as coniferous trees; radiata pine, macrocarpa, cypress and common garden plants. Acanthoxyla prasina are nocturnal; they usually feed at night.

Predators
Birds are the most common predator of A. prasina. Many native and introduced species have been caught and suspected of feeding on them. Chudleigh noted that photographs hd been taken of several species of birds including sparrows, black birds and silver eyes feeding on A. prasina. Chaffinches and yellowhammers have also been photographed feeding these stick insects to their chicks. Camouflage, body structures and behaviors help A. prasina avoid and hide from their predators.

Māori Significance
Much of the knowledge and wisdom from tangata whenua of New Zealand stick insects has been scattered or lost. Stick insects were considered to be relatives of mantids and were called rō, whe and wairaka. Different tribes had their own stories and beliefs involving insects. If a stick insects or mantis crawl onto a woman it indicated she was pregnant and they type of insect being the indicator of the sex. When a mantis or stick insect falls onto a human in a forest, the area becomes considered a sacred site. The Māori also believed the presence of a stick insect would indicate that the land would not make a good garden. There is also the Māori legend of Tāne who was the creator of trees, birds and insects of the forest. Tāne pushed apart his parents Papatuanuku and Ranginui, so that there could be light for the forests. Allowing the trees, birds and insects to inhabit the forest and live. Being the god of forests, Tāne is considered the creator and insects his children, therefore they deserve respect.

Hybridization
The entire Acanthoxyla genus likely evolved by hybridization. This hybrid origin theory is highly likely as the genus contains diploid and triploid lineages. Morgan-Richards & Trewick suggests they believe their third hypothesis to be the most accurate: the genus Acanthoxyla may have risen from Clitarchus hookeri as the parent species by two or more hybridizations. The maternal species could be Pseudoclitarchus sentus or an extinct sexual Acanthoxyla. It has been observed that Acanthoxyla genus has low genetic diversity, suggesting poor differentiation.