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Bush coconut

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Bush coconut
Cross-sectional diagram of a bush coconut
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Insecta
Order:
Hemiptera
Family:
Eriococcidae
Genus:
Cystococcus
Species:
C. pomiformis, C. echiniformis, C. campanidorsalis
Binomial name
Cystoccocus pomiformis, Cystoccocus echiniformis, Cystoccocus campanidorsalis
(Semple et al., 2015)

The bush coconut, or bloodwood apple, is an Australian bush tucker food. It is an insect gall with both plant and animal components: an adult female scale insect and her offspring (of genus Cystococcus) live in a gall induced on a bloodwood eucalypt tree (of genus Corymbia). Bush coconuts can vary from golf ball to tennis ball size. They have a hard and lumpy outer layer. The inner layer is a white flesh that contains the female insect and her offspring. There are three known species of Cystococcus responsible for forming the bush coconut: C. pomiformis, C. echiniformis and C. campanidorsalis. C. pomiformis is the most common species. The bush coconut is found in Western Australia, the Northern Territory, Queensland and New South Wales.

The bush coconut is picked from the host tree and cracked open to allow the flesh and scale insects to be eaten. Both have a high protein content and are used as a food source by humans and other animals. The name ‘bush coconut’ is derived from the white flesh of the inner layer, which is similar in appearance to that of a coconut, and the taste of the flesh has been said to have a coconut flavour. The bush coconut has been depicted in Indigenous Australian dreaming and used as inspiration in Indigenous Australian artwork.

Discovery

The bush coconut was not mentioned in early documents about Aboriginal insect foods and is considered one of the lessor known bush tucker foods utilised by Aborigines.[1] The bush coconut was first described by Walter Wilson Froggatt in 1893 as Brachyscelis pomiformis. Froggatt collected material from north-western Australia and listed two locations in his original description of the species: Torrens Creek, North Queensland and Barrier Ranges, North Western Australia. Froggatt noted Aborigines ate both the insect and soft flesh of the young gall.[2] The species identified by Froggatt has been revised several times from Brachyscelis pomiformis to Apiomorpha pomiformis, Ascelis pomiformis and finally to Cystococcus pomiformis. Claude Fuller briefly described another species of insect inducing the bush coconut, Cystococcus echiniformis, in 1897.[3] Fuller provided a more detailed description along with line drawings of the adult female and its gall in 1899.[4] Some scientists considered C. pomiformis and C. echiniformis to be of the genus Ascelis. This was, however, rejected in 1986 by P. J. Gullan and A. F. Cockburn who found that Ascelis and Cystococcus are closely-related but distinct genera.[5] P. Gullan and A. Cockburn identified what they suspected as a third species in a paper published in 1986.[5] This species was then named and formally described as C. campanidorsalis in 2015 by Semple et al.[6] Bush coconuts are found on many different species of bloodwood eucalypts (Corymbia genus) across Australia.[1]

Description

The bush coconut is an insect gall. It is a combination of plant and animal: an adult female scale insect lives in a gall induced on a bloodwood eucalypt.[6] It is composed of both the gall, the protective case of a female scale insect, as well as the insect itself.[6]

Scale insect

The insect inducing the formation of the bush coconut gall is taxonomically classified as a coccid in the genus Cystococcus. Three species have been identified: C. pomiformis and C. campanidorsalis and C. echiniformis. The most common species is C. pomiformis.[7] The live coccid is a yellow-green colour.[5]

Female

Sclerotised dorsal button of Cystococcus species C. pomiformis, C. echiniformis and C. campanidorsalis

The female Cystococcus has no legs, wings or antennae and has been described as ‘grub-like’. Females grow up to 4 cm long. The body is elliptical to sub-spherical in shape and yellow-green in colour.[6] The female scale insect lives within the fleshy interior of the gall.[7] The female’s anus is non-functional.[6] Females are generally soft-bodied although sclerotisation produces a hard dorsal 'button' and ventral pore plates. The button is used to plug the gall entrance and it is also the site where mating occurs.[8] The shape of the button distinguishes the species of Cystococcus. This allows the female to be identified without opening the gall. C. pomiformis has a convex-shaped button that varies from broad and dome-shaped to pointy and conical, C. campanidorsalis has a bell-shaped button and C. echiniformis has a concave-shaped button.[7]

The names of the three species of scale insect inducing bush coconuts reflect observable features. The name campanidorsalis comes from the bell-shaped button, with campana meaning bell in Latin, and that it is located dorsal rather than caudal.[6] Pomiformis means ‘apple-like’ in Latin and refers to the shape and size of the gall C. pomiformjs induces.[9] Echiniformis is a Latin word meaning shaped like a hedgehog and may refer to the knobbled shape and uneven texture of the gall induced by C. echiniformis.[6]

Another distinguishing feature of the female scale insects is the pattern of their ventral pore-plates.[6] Pore plates are an olfactory (smell) sense organ found in insects.[10] In Cystoccocus, each pore plate of the adult female is composed of pores that are clustered together and surrounded by a sclerotised cuticle to form the plate. The pore plates function to produce a white, powdery wax when the insect is living. The function of this wax is unknown.[6] C. echiniformis has unpatterned clustering of pore plates. The pore plates on C. campanidorsalis are clearly separated by transverse bands.[6] C. pomiformis have pore plates that cluster around the vulva and are not clearly separated into transverse bands of sclerotisation.[6]

Adult male C. campanidorsalis

Male

It is difficult to distinguish different species of adult males within the genus Cystococcus. Adult male bodies are up to 9.5 mm long and they have an elongated abdomen which is likely an adaptation to enable mating through the gall entrance.[6] Males have purple wings that allow the transport of the immature female offspring out of the gall.[7] Each gall holds between 1700 to 4600 males.[1]

Bush coconut gall

A bush coconut gall on Corymbia opaca containing living scale insects of genus Cystococcus
Dark-coloured old bush coconut gall on Corymbia opaca

The bush coconut gall is an abnormal growth of plant tissue that occurs on the leaves, twigs or branches of the host tree, a bloodwood eucalypt (Corymbia species).[1] Bush coconut galls have an uneven surface and variable shape but they are generally spherical and have the appearance of a small fruit. The size of the galls varies within and between species. Size generally ranges from that of a golf ball to a tennis ball.[6] The gall produced by C. pomiformis has the largest average size.[6] The bush coconut gall has a hard outer layer and a soft, fleshy inside layer that lines the cavity housing the adult female scale insect.[5] The outer layer has surface texture ranging from smooth to lumpy and knobbled.[7] The inner layer is a milky white flesh up to 1 cm in depth.[1] The white flesh and cross-sectional appearance contribute to the name 'bush coconut' because they are similar in appearance to a coconut.[1] The white flesh is also said to have a coconut-like taste.[11] In mature galls, the female insect is attached to the inner wall at a thin attachment point with a small hole to the exterior. The female insect and her offspring feed off the fleshy layer.[6]

The appearance of the galls differs slightly between the species of Cystococcus. C. campanidorsalis induce galls of diameter 18-28 mm and the gall surface usually has a loose, flaky outer layer that has colour ranging from light to dark brown. C. echiniformis induces galls with diameter of 16-49 mm. The surface texture varies from smooth to rough and the colour is generally cream-brown but changes to grey or black as the female insect ages and dies. C. pomiformis usually induce galls that have a uneven and lumpy surface with diameter 13-90 mm. The gall surface is usually pale and creamy-brown in colour when the insect is alive, but darkens and the surface becomes knobbled when the insect dies.[6]

The bush coconut forms on the branches and stems of trees of the Corymbia genus. The most common host plant is the desert bloodwood, Co. terminalis, giving the bush coconut the alternative name of ‘bloodwood apple’.[12] The bush coconut gall has two leaf-life projections which may function to camouflage it from animals, including cockatoos and parrots, who may feed on the scale insect.[12] Bush coconuts are usually found in clusters on small, young branches of the host tree.[12] The lifespan of the bush coconut is eighteen to twenty-six weeks.[1]

Ecology

The formation of the bush coconut gall is the result of a symbiotic relationship between the host tree and the female scale insect.[6] The immature female, known as a nymph, settles on a small branch of a tree of the Corymbia genus. Over several weeks, the female embeds herself in the plant tissue and then injects a chemical into the host tree. The plant activates a defence mechanism in response and this induces formation of a knobbly growth of plant tissue, known as a gall. The female insect lives and breeds within the gall for the remainder of her life.[8] The piercing of the plant tissue by the female scale insect allows it to feed on the tree sap and grow.[11]

Adult male C. pomiformis with female nymph shown to scale.

The inside flesh of the bush coconut provides protection for the female scale insect, as well as nourishment for her and her offspring.[6] Reproduction occurs when a male coccid inserts its abdomen through a small hole in the gall to mate with the female.[11] Reproduction involves a process known as sexual dichronism, in which the adult female controls the sex allocation of her offspring in order to produce males and females at different times. The adult female gives birth to the male offspring first. The males feed on the flesh of the bush coconut and develop into winged adults. Once the males have almost matured within the gall, female offspring are produced. When the mother dies, the immature wingless female offspring are transported out of the maternal gall on their male "brothers" elongated abdomens and deposited onto a host tree to start the cycle again.[13] The males then fly off to find mates. The behaviour of the males is called intersexual phoresy.[6]


Distribution and Habitat

Cluster of bush coconuts (genus Cystococcus) on a bloodwood eucalypt tree (Corymbia)

The bush coconut is commonly found in the savannah woodlands and dry sclerophyll forests of northern and central Australia, but populations have been found in Queensland, Western Australia and New South Wales.[1] Bush coconuts are also found in the popular tourist destination, Alice Springs Desert Park in the Northern Territory.[14]

C. pomiformis has been found in north Western Australia, the Northern Territory and Queensland. Host trees include Co. cliftoniana, Co. collina, Co. deserticola, Co. dichromophloia, Co. drysdalensis, Co. erythrophloia, Co. hamersleyana, Co. intermedia and Co. terminalis. C. echiniformis is found in north Western Australia, the Northern Territory, west Queensland and far-north-west New South Wales. Host trees include Co. chippendalei, Co. clarksoniana, Co. foelscheana, Co. greeniana, Co. lenziana, Co. polycarpa, Co. ptychocarpa and Co. terminalis. C. campanidorsalis was first found in central Brisbane in 2015. The only known host tree is Co. trachyphloia.[6]

Cultivation and Use

Bush coconuts are often collected during the cold season, usually in April or May, while they still contain the living insect.[1] They are picked from the host tree and then cracked open with a rock or other hard object. The gall may be softened by placing it on hot ashes. The flesh lining of the gall is scraped out and the insect and flesh are consumed.[15] The bush coconut is bush tucker and a food source for Indigenous Australians and also for birds and other insects.[6] The insect has a sweet, juicy taste and has high water content.[14] The water inside the insect is known as the bush coconut juice.[16] The galls also provide shelter for a number of other arthropods including tree crickets, ants and spiders.[6]

Nutrition

Bush coconuts provide a good source of protein to the diet. A research study of the nutrition of the bush coconut from Cystococcus pomiformis living in a gall on the Corymbia opaca found both male and female insects have high protein content and high gross energy.[1] The range of gross energy was 15.12 to 25.13 MJ/kg for females and 22.56 to 26.87 MJ/kg for males. The lining of the gall, in comparison, has much lower gross energy with.a range of 14.15 to 16.67 MJ/kg.[1]

Cultural Significance

The bush coconut is of cultural significance to Australian Indigenous peoples because of its use as a bush tucker food. It has been incorporated into Dreamtime and is the subject of many Indigenous paintings and sculptures.[17]

The bush coconut is called Merne arrkirlpangkwerle in the Arrernte language of Central Australia. The Arrernte call the scale insect angure. The bush coconut is known as the barlabil by the Gija people, Aboriginal Australians from the East Kimberley area of Western Australia.[18] Aboriginal Australians of the Warumungu group located in the Northern Territory call the bush coconut waljji kanttaji jangu.[19] The Warlpiri people of Lajamanu in the Northern Territory call the bush coconut kanta jukurrpa.[20]

See also

References

  1. ^ a b c d e f g h i j k Yen, A; Flavel, M; Bilney, C; Brown, L; Butler, S; Crossing, K; Jois, M; Napaltjarri, Y; Napaltjarri, Y; West, P; Wright, B (24 October 2016). "The bush coconut (scale insect gall) as food at Kiwirrkurra, Western Australia". Journal of Insects as Food and Feed. 2 (4): 293–299. doi:10.3920/jiff2016.0039. ISSN 2352-4588.
  2. ^ Froggatt, Walter W. (1893). "Notes on the family Brachyscelidae, with some account of their parasites, and descriptions of new species, Part I". Proceedings of the Linnean Society of New South Wales. 7: 353–372.
  3. ^ Fuller, Claude (1897). "Some Coccidae of Western Australia". Journal of the Western Australia Bureau of Agriculture. 4: 1344–1346.
  4. ^ Fuller, Claude (1899). "Notes and descriptions of some species of Western Australian Coccidae". The Transactions of the Entomological Society of London 1899. 14: 435–473.
  5. ^ a b c d Gullan, P. J.; Cockburn, A. F. (1986). "Sexual dichronism and intersexual phoresy in gall-forming coccoids". Oecologia. 68: 632–634. doi:10.1007/BF00378784.
  6. ^ a b c d e f g h i j k l m n o p q r s t u v Semple, Thomas L.; Gullan, Penny J.; Hodgson, Christopher J.; Hardy, Nate B.; Cook, Lyn G. (2015). "Systematic review of the Australian 'bush-coconut' genus Cystococcus (Hemiptera: Eriococcidae) uncovers a new species from Queensland". Invertebrate Systematics. 29 (3): 287. doi:10.1071/is14061. ISSN 1445-5226.
  7. ^ a b c d e University of Massachusetts Amherst and U.S. Department of Agriculture & Hardy Lab (2021). "Cystococcus pomiformis". ScaleNet. Retrieved 1 January 2022.{{cite web}}: CS1 maint: url-status (link)
  8. ^ a b Cook, L. (2016). "Sibling rivalry or chivalry: why do male bush coconuts carry their little sisters?". The Australia and Pacific Science Foundation. Retrieved 31 December 2021.{{cite web}}: CS1 maint: url-status (link)
  9. ^ "Bartramia pomiformis Tray -- Shade --Out of Stock". MountainMoss. Retrieved 31 December 2021.
  10. ^ "Definition of PORE-PLATE". www.merriam-webster.com. Retrieved 1 January 2022.
  11. ^ a b c "The Gall of Nature". Queensland Museum. 2015. Retrieved 1 January 2022.{{cite web}}: CS1 maint: url-status (link)
  12. ^ a b c Austin, Andrew D; Yeates, David K; Cassis, Gerasimos; Fletcher, Murray J; La Salle, John; Lawrence, John F; McQuillan, Peter B; Mound, Laurence A; J Bickel, Dan; Gullan, Penny J; Hales, Dinah F. (2004). "Insects 'Down Under'- Diversity, endemism and evolution of the Australian insect fauna: examples from select orders". Australian Journal of Entomology. 43 (3): 216–234. doi:10.1111/j.1326-6756.2004.00448.x. ISSN 1326-6756.
  13. ^ "Hiding in plain sight – a new species discovered in South East Queensland". University of Queensland Australia. 2015. Retrieved 31 December 2021.{{cite web}}: CS1 maint: url-status (link)
  14. ^ a b "Australia's Bush Coconuts Are Neither Coconuts nor Bushes". Atlas Obscura. Retrieved 31 December 2021.
  15. ^ "Bush Coconut - Arca del Gusto". Slow Food Foundation. Retrieved 31 December 2021.
  16. ^ "Tennant Creek – Sacred Dances". Australian Screen. Retrieved 31 December 2021.{{cite web}}: CS1 maint: url-status (link)
  17. ^ "Arrkarma (bloodwood apple) (from 'Bush tucker' series) 2009". Queensland Art Gallery & Gallery of Modern Art. Retrieved 31 December 2021.{{cite web}}: CS1 maint: url-status (link)
  18. ^ "Gija Bush Food and Medicine". Indigenous Community Television. Retrieved 1 January 2022.{{cite web}}: CS1 maint: url-status (link)
  19. ^ "Warumungu". Wurrppujinta Anyul Mappu. Retrieved 31 December 2021.{{cite web}}: CS1 maint: url-status (link)
  20. ^ Jones, Barbara (2011). A grammar of Wangkajunga: a language of the Great Sandy Desert of North Western Australia. Canberra: Pacific Linguistics. p. 299. ISBN 9780858836488.



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