Bush coconut

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.

Australian entomologist Claude Fuller briefly described another species of insect inducing the bush coconut, Cystococcus echiniformis, in 1897.

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.

It is a combination of plant and animal: an adult female scale insect lives in a gall induced on a Corymbia, the bloodwood eucalypt.

[7] Females are generally soft-bodied although sclerotisation produces a hard dorsal 'button' and ventral pore plates.

[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.

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.

[2] The bush coconut gall is an abnormal growth of plant tissue that occurs on the leaves, twigs or branches of the host tree.

[2] Bush coconut galls have an uneven surface and variable shape but they are generally spherical and have the appearance of a small fruit.

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.

[7] The most common host plant is the desert bloodwood, Co. terminalis, giving the bush coconut the alternative name of 'bloodwood apple'.

[13] 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.

[2] The formation of the bush coconut gall is the result of a symbiotic relationship between the host and the female scale insect.

[7] The inside flesh of the bush coconut provides protection for the female scale insect, as well as nourishment for her and her offspring.

[7] Reproduction occurs when a male coccid inserts its abdomen through a small hole in the gall to mate with the female.

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.

[2] Bush coconuts are also found in the popular tourist destination, Alice Springs Desert Park in the Northern Territory.

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.

Cross-sectional diagram of a bush coconut
Sclerotised dorsal button of Cystococcus species C. pomiformis, C. echiniformis and C. campanidorsalis
Adult male C. campanidorsalis
A bush coconut gall on Corymbia opaca containing living scale insects of genus Cystococcus
Adult male C. pomiformis with female nymph shown to scale
Cluster of bush coconuts (genus Cystococcus ) on a bloodwood eucalypt tree ( Corymbia )