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October 2003

Feature

 


Eat Your Bugs!


Rob Toms and Mashudu Thagwana

The edible stink-bugInsects are important as a source of protein as well as being traditional cultural delicacies in southern African countries such as Botswana, Mozambique, Zimbabwe, Zambia and South Africa. Mopane worms (caterpillars), locusts and termites are well known as food insects, but many others are also on the menu, including the edible stink-bug.

Stink-bugs are used in some cultures to add flavour to stews. In Venda they are eaten for their own sake.The edible stink-bug Encosternum delegorguei (Heteroptera, Tessaratomidae) known in Venda as 'thongolifha', is a useful winter harvest. Unlike the mopane worm, or Mashonzha, which overwinters underground in the subterranean pupa stage before turning into the mopane emperor moth, thongolifha overwinter in the adult stage and never go underground. This means that the fully grown thongolifha can be harvested in winter when there is little other food available.

Harvesters selling the prepared stinkbugsIn a group of 8 women collectors studied, it was found that the edible stink-bugs are collected at dawn while it is cold and they are less mobile. As the day warms up the bugs become extremely vigilant and fly away when disturbed. In South Africa's northern province of Limpopo and in its eastern province of Mpumalanga, the stinkbugs are harvested with naked hands and the defensive secretions of the bugs causes a characteristic orange stain. In some other regions the hands may be protected with a plastic bag. The harvested bugs are collected in large woven plastic bags, such as those used for maize meal.

Preparing the meal

Edible stink-bugs left to sundry.Edible stinkbugs after harvesting.The first step in the preparation is to separate all dead bugs, leaves and debris from the live bugs. The live bugs are placed in a bucket and a small amount of warm water is added before the bugs are stirred with a wooden spoon. This causes the bugs to release their alarm or defensive pheromones. The overpowering cloud of defensive secretions is so strong that it hurts the eyes and the harvesters turn their heads away and close their eyes to protect them. After a while, warm water is added and the insects are rinsed.

This process is repeated three times before the insects are boiled in water and killed. If any dead bugs are accidentally left with the live bugs, it is not possible for the dead bugs to release their defence secretions. These bugs can be identified during subsequent quality control because their ventral surface is blackened by the stink glands and they are rejected for human consumption. The cooked bugs are then sun dried on an empty maize bag.

The preparation procedure above can only be used for live bugs, so an alternative preparation is used for dead bugs. The heads of the dead bugs are removed and the thorax and abdomen are squeezed between the thumb and index finger. This causes a translucent pale green gland to be exuded through the neck of the dead insect, and this is wiped off on a rock. The bugs are then boiled and sun-dried as in the previous procedure. The dried
bugs may be eaten as snacks or sold at the markets. They can also be fried with salt and a little water, until the water evaporates and then served with pap (mealie meal).

Knowledge for sustainable harvesting

As is the case with the mopane worm,  knowledge of the biology of the insect is essential for sustainable harvesting. The preferred habitat, food plants and life cycle are all essential elements that need to be understood for successful sustainable harvesting. The information on these aspects are limited and further research is needed but our preliminary findings can possibly act as a pointer for further studies.

The most favoured harvesting area in South Africa is in the northeast, at a mountain outside Modjadji village near Duiwelskloof. This is interesting because the collectors travel approximately 200 kilometres to do the harvest. When Rob Toms and team first began to investigate the origin of this behaviour it was found that harvesting at Modjadji is a new development and that they used to harvest further west, in the area where the Sapekoe tea estates are situated, at Magoebaskloof. This suggests that they are travelling to Modjadji because environmental degradation caused by agriculture made their former harvesting area unsuitable for the bugs. However, Magoebaskloof is also far from Thohoyandou, so the original question is not answered. More research is needed to find out why the harvesters travel about 200 Km to collect bugs but we suspect that harvesting used to occur closer to the nearest big town, Thohoyandou, home to the University of Venda, and that unsustainable harvesting together with environmental degradation such as the development of tea estates, which wipe out indigenous plants, are probably the main causes of these changes.

Food plant for the bugs.At Modjadji the favourite food plant for the edible stinkbug in June is the evergreen shrub Dodonaea viscosa Jacq. var. angustifolia Benth. During our investigations we found that Dodonaea was regarded by the nature conservation staff in a nearby cycad reserve as an invasive plant, even though it is indigenous. The fact that Thongolifha appear to be feeding extensively on Dodonaea suggests that this edible insect could be seen as a natural way of keeping Dodonaea under control. In contrast, artificial control of Dodonaea will almost certainly damage the thongolifha harvest. Further research on the population dynamics of the insect and the host plant/s would be desirable.

Harvest after mating

As mentioned earlier, thongolifha have an incomplete metamorphosis. Unlike the mopane worm, which over-winters in the chrysalis or pupa stage, Thongolifha overwinters in the adult stage. The eggs are laid at the beginning of spring and the development of the nymphs occurs in summer. We have found that adult stink-bugs of both sexes are harvested in June, before the eggs have developed. All adults collected at this time are removed from the gene pool and excessive harvesting would not be sustainable. In theory it would be possible to harvest the entire population without affecting the population by harvesting the males after they have mated and the females after they have laid their eggs. In practice this would require more information about the biology including exactly when mating and egg laying takes place. However, this may lead to a drastic reduction in harvesting time and it may not be possible to harvest sufficiently to satisfy the harvesters.

Need for education

According to Toms, "During our research we have found that there is a great need for better education. Last year we found that there was a need for a poster on the life cycle of the mopane worm to bring indigenous knowledge into the classroom and a poster has been produced. We have now identified a need for a poster on sustainable harvesting of Thongolifha and are busy developing one. Sponsors are needed to bring both these posters into the classrooms of the Limpopo Provence where they have direct relevance. We also plan to get these posters into classrooms in other provinces where they can serve as examples of indigenous solutions to indigenous problems."

In the study of the harvesters, it was found that 7 out of 8 are pensioners aged from 60 to 70. The youngest member of the group was an unemployed woman aged 50. As part of a project on cultural and medicinal uses of insects, this work has been funded by the National Research Foundation (NRF) since 2001.


More information:

Please contact: Dr Rob Toms at the Transvaal Museum, South Africa - toms@nfi.co.za

Related Links:

- Mopane worms 

 

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