Giant jewel beetle
giant jewel beetle (English); lebitsi or lebitsi-kgoma (Sepedi); polilo khooana (Sesotho); shitambela (Xitsonga); reuse juweelkewer (Afrikaans).
The giant jewel beetle is a favourite protein-rich insect delicacy in many rural communities of Limpopo Province. Their lazy nature makes them an easy catch, as they spend most of their time clinging to thorny bush trees. Although not as colourful as most Buprestidae beetles, their body length and size make them one of the biggest beetles within the family and genus Sternocera.
How to recognise a giant jewel beetle
Sternocera orissa is the largest beetle within the Buprestidae family with a body length of up to 37 mm. It is easily recognisable by its black-coloured body and a yellowish to white colour on the head, just above the compound eyes. Their pronotum (plate-like structure that covers the thorax) is white or yellowish with grooves and a patch on each side. The rows of grooves and white or yellowish patches are also present at the base and along the side of each of the two wing cases of the beetle – the elytra. In most literature, the colour of the elytra is also described as being green-black or blue-black, with white to yellow eyespots and markings. The metathoracic wings with distal cell are complete and elongated. The hair on body is either short, in sharply defined zones, or absent.
Adult Sternocera orissa can fly during the day or at night. However, they are generally clumsy and reluctant fliers. They spend most of their time on tree branches and flowers. It is not known whether this behaviour is related to their body size.
Sternocera orissa is adapted to moist to dry, and often very hot savanna, bushveld and sand forest habitats. Notable countries in which the species can be found include Botswana, Mozambique, Namibia, southern Malawi, South Africa, Tanzania and Zambia. South African populations are widely recorded in the east, south and western parts of the Limpopo Province.
In savanna habitats, Sternocera orissa mainly occurs on flowering thorn trees. They are easily noticeable as they cling to branches of mostly Vachellia and/or Senegalia trees (formerly Acacia), Dichrostachys cinerea (sickle-bush) and Gymnosporia senegalensis (confetti spike-thorn).
Adults feed on foliage (especially of Vachellia, Senegalia trees and Dichrostachys species) as well as nectar. Larvae are free-living root-feeders.
SEX and LIFE CYCLES
Sex: Sternocera orissa displays sexual reproduction. Adult females are generally bigger than their male counterparts. Females lay eggs (during mid-December to late January) in bark crevices, and larvae tunnel into wood and plant stems. At times, eggs are laid into the soils or dropped onto the ground. Females have a single reproductive cycle annually. Adults are relatively short-lived, whereas the immature stages can take as long as 35 years to complete their development.
Family life: Giant jewel beetles tend to be social and often semi-gregarious, occurring in small communities.
THE BIG PICTURE
Friends and Foes
No direct predators are known for Sternocera orissa. However, resource competition (i.e. for nectar and pollen) is common; since Vachellia and/or Senegalia are good pollen species for other insects (i.e. honey bees). Humans are likely the most important enemy due to extensive harvesting for consumption. Also, the collection of Vachellia and/or Senegalia and Dichrostachys trees for fuelwood and pole fencing reduces habitats and nesting areas for Sternocera orissa.
Sternocera orissa’s heat-loving nature and their ability to tolerate very high temperatures allow them to thrive in conditions where other beetles may struggle. This heat tolerance seems to be a common trait among beetles in the Buprestidae family.
Poorer world without me
Sternocera orissa is one of the most consumed insects in South Africa, amongst the likes of grasshoppers, termites, mopani worms and stinkbugs. It provides a good source of protein and costs less (compared to animal protein), making it ideal for collection and consumption for poorer rural communities in addressing food shortages and malnutrition. The knowledge of harvesting, preparations and storage has filtered through generations of various communities where Sternocera orissa is a reliable food source.
People & I
The collection and eating of insects is a common practice for most marginalised rural areas in Africa. In South Africa, Sternocera orissa is widely consumed in the Blouberg area (Senwabarwana – formerly Bochum), Mokopane (Waterberg District), Giyani (Mopani District), Khureng (Ga-Mphahlele), Magatle (Zebediela) and Ga-Masemola (Jane Furse area). Methods of harvesting and preparing vary among communities – so is the perception of taste and nutritional value. Of particular interest is the observation by the San of the central Kalahari and Botswana, who indicate that the taste of Sternocera orissa is similar to that of eland meat (Taurotragus oryx). Also, the protein content of Stermocera orissa has been demonstrated to be higher than the protein content of most conventional food (i.e. fish, pork and chicken). Generally, communities roast or fry and eat the entire beetle after removing the wings and legs.
Conservation status and what the future holds
The conservation status of Sternocera orissa has never been evaluated. Therefore, the species is not under any formal protection or conservation measures. Overharvesting and loss of habitat are the two main activities likely to threaten the population in the near future.
Stermocera orissa is one of the 26 species within the Sternocera genus. They belong to the family Buprestidae, a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colours. Within the family Buprestidae, the genera Sternocera and Aata share more resemblance to each other than to other members of the family. In particular, the general body shape, size and ovipositor (egg laying organ in insects) are assumed to be similar. Thus Sternocera is derived from an ancestor close to Aata. There is only one known species in the Aata genus, Aata finchi (Waterhouse, 1884). However, two known subspecies of Sternocera orissa (Sternocera orissa variabilis Kerremans, 1886 and Sternocera orissa luctifera Klug, 1855) have been described and these occur widely across the African continent.
References and further reading
- African Sternocera, S. orissa group: http://utenti.romascuola.net/bups/sterafr2.htm (Accessed on 03 March 2016).
- Egan, B.A. 2013. Culturally and economically significant edible insects in the Blouberg region, Limpopo Province, South Africa. PhD thesis, University of Limpopo, Sovenga, South Africa.
- Holm, E. 1979. Revision of the genera of the tribe Julodini (Coleoptera: Buprestidae). Journal of the Entomological Society of South Africa 42(1): 89–114.
- Holm, E. & Gussmann, S. 1992. Revision of the genus Sternocera Eschscholtz of Africa (Coleoptera: Burprestidae). Entomology Memoir No. 85, Agricultural Research Council. Pp 1–86.
- Picker, M., Griffiths, C.L. & Weaving, A. 2004. Field guide to insects of South Africa. Struik Nature, Cape Town.
- Shadung, K.G. 2012. Influence of drying method and location on proximate chemical composition of African metallic wood boring beetle, Sternocera orissa (Coleoptera: Buprestidae) in Republic of South Africa. African Journal of Food Science 6(6): 155–158.
- Shadung, K.G. 2012. Improving attractiveness of an insect pest through value-addition: a possible insect management strategy. MSc Dissertation, University of Limpopo, Sovenga, South Africa.
- Global Biodiversity Information Facility: http://www.gbif.org/species/6003649 (Accessed on 30 March 2016)
SANBI (GMO Programme)
S. orissa Buquet, 1837