| Prickly stick insect | |
|---|---|
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Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Phasmatodea |
| Family: | Phasmatidae |
| Genus: | Acanthoxyla |
| Species: | A. prasina
|
| Binomial name | |
| Acanthoxyla prasina (Westwood, 1859)
| |
| Synonyms | |
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Acanthoxyla prasina, the prickly stick insect, is a stick insect in the order Phasmatodea and the family Phasmatidae.[1] 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.[2][3] It has a thorny skin, which is used as camouflage.[4]
Identification
editAcanthoxyla prasina is a large insect; their body length ranges from 7.5 to 11cm long when fully grown as adults.[5] 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.[6] 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
editAcanthoxyla prasina has no male individuals; A. prasina are exclusively females. They reproduce through asexual reproduction called parthenogenesis.[7] 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. [5] 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.[8] Lee [3] 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.[5] Ananthoxyla prasina will moult approximately 5–6 times in roughly 6 months before reaching adult size.[9] They usually moult at night. Once emerged, they will likely eat their old skin. Chudleigh[8] found that most Acanthoxyla species’ life span is approximately 12–24 months.
Distribution and habitat
editNative range
editAcanthoxyla prasina can be found throughout New Zealand, where it was originally endemic.[10]
Introduced range
editThere are a few New Zealand stick insect species that have made it over or have been introduced to the United Kingdom. Salmon[11] 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 [3] and a smooth stick insect Clitarchus hookeri.[12]. 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.[12] 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.[13]
Diet
editAcanthoxyla prasina are forage feeders.[7] 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.[6] Acanthoxyla prasina are nocturnal; they usually feed at night.
Predators
editBirds are the most common predator of A. prasina. Many native and introduced species have been caught and suspected of feeding on them. Chudleigh[8] 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.[14]
Māori Significance
editMuch of the knowledge and wisdom from tangata whenua of New Zealand stick insects has been scattered or lost.[6][14] 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.[6] 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.[14]
Hybridization
editThe entire Acanthoxyla genus likely evolved by hybridization. This hybrid origin theory is highly likely as the genus contains diploid and triploid lineages. [6][15] Morgan-Richards & Trewick[16] 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.[16]
See also
editReferences
edit- ^ "Acanthoxyla prasina (Westwood, 1859)". phasmida.speciesfile.org. 2021. Archived from the original on 2016-03-29. Retrieved 2021-03-07.
- ^ "Acanthoxyla prasina (National Biodiversity Network Atlas)". nbnatlas.org. 2021. Retrieved 2021-07-17.
- ^ a b c Lee, Malcolm (1998). "An updated survey of the distribution of the stick insects of Britain" (PDF). Phasmid Studies. 7 (1): 18–25. Retrieved 2024-04-02.
- ^ "Insect poses prickly questions" on Otago Daily Times website, viewed 2013-10-16
- ^ a b c Salmon, John Tenison (1991). The Stick Insects of New Zealand. Reed. ISBN 0790002116.
{{cite book}}: CS1 maint: date and year (link) - ^ a b c d e Trewick, Steve (2005). Stick insects. Auckland N.Z: Reed. ISBN 186948570X.
{{cite book}}: CS1 maint: date and year (link) - ^ a b Buckley, Thomas (2024). "Stick insects (Phasmatodea)". Manaaki Whenua Landcare Research.
- ^ a b c Chudleigh, Brian (2007). "STICK INSECTS: The skinny world of stick insects". New Zealand Geographic. 083.
- ^ "Prickly Stick Insect Acanthoxyla prasina". Entomological Society of New Zealand. 2023-06-03. Retrieved 2023-06-03.
- ^ "Species Details". New Zealand Threat Classification System (NZTCS). 2023-06-03. Retrieved 2023-06-03.
- ^ Salmon, John (1955). "Stick Insects". Tuatara: Journal of Biological Society. 5 (3).
- ^ a b Brock, Paul D; Lee, Malcolm; Morgan-Richards, Mary; Trewick, Steven A (2017). "Missing stickman found: the first male of the parthenogenetic New Zealand phasmid genus Acanthoxyla uvarov, 1944, discovered in the united kingdom". Acropos (60): 16–23. ISSN 1478-8128. Retrieved 2021-07-17.
- ^ ainge Roy, Eleanor (2018-02-06). "New Zealand female-only stick insect produces 'rogue' male in UK". The Guardian. Retrieved 2021-07-17.
- ^ a b c Trewick, Steve (2007). "Stick insects". Te Ara.
- ^ Myers, S., Trewick, S., & Morgan‐Richards, M (2012). "Multiple lines of evidence suggest mosaic polyploidy in the hybrid parthenogenetic stick insect lineage Acanthoxyla". Insect Conservation and Diversity. 6 (4): 537–548. doi:10.1111/icad.12008.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b Morgan-Richards, M., & Trewick, S (2005). "Hybrid origin of a parthenogenetic genus?". Molecular Ecology. 14 (7): 2133–2142. doi:10.1111/j.1365-294X.2005.02575.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
External links
edit
- Acanthoxyla prasina discussed on RNZ Critter of the Week, 17 September 2021