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June 2003

Feature

 


The Mopane Worm - 
Indigenous Knowledge in the Classroom


R.B. Toms, M.P. Thagwana and K.D. Lithole

If you enjoy game viewing, you will know about the "Big Five", but many will not know the "Big Twelve". Meet the mopane worm - one of the "Big Twelve African insects."

Mature caterpillar feeding on a mopane leaf. This is the stage that is harvested. Copyright R. Toms, Transvaal Museum.The "mopane worm" Imbrassia belina is probably the most important insect in southern Africa from a cultural point of view. Here it is well known as either Mashonzha, Masonja or Amasonja. It forms the basis of a multi-million rand trade in edible insects, providing a livelihood for many harvesters, traders and their families. However, the industry is not without problems. Droughts devastate the harvest on a regular basis and there are areas where overexploitation has led to local extinctions.

Dr Rob Toms and team at the Transvaal museum in South Africa set out to find just how much local communities and harvesters actually know about these edible delicacies and whether it is enough to save this 'golden' worm from extinction in certain areas. They stumbled across some myths, some truths and devised an ingenious plan of using this worm as a valuable teaching tool.

Meet the meat

1. Mopane worm eggs on a mopane leaf. Copyright R. Toms, Transvaal Museum.The mopane worm has a complex life cycle in which there is complete metamorphosis, or what is known as "holometabolous". The eggs are laid by a large and attractive moth, with a name to fit, the mopane emperor moth. Small worms hatch from the eggs and moult a few times before they reach maturity, the stage most sought after for harvesting. The worms that are not harvested leave the trees and pupate underground. The life cycle is completed when the adult moths emerge from the pupae, mate and lay eggs. If the Mopane worm at pupation. This process usually occurs underground. Copyright R. Toms, Transvaal Museum.cycle is broken at any point by excessive harvesting, for example, it will not be possible to maintain a sustainable harvest.

Mopane worm in schools

In research conducted in the Limpopo Province, Toms, Thagwana and Lithole soon established that there were many people, including school science and biology teachers, who simply did not know the life cycle of the mopane worm. They found this alarming because harvesting Mashonzha without knowledge of the life cycle is a bit like trying to farm maize without knowing that it is necessary to plant seeds.

4. An adult female mopane emperor moth. Copyright R. Toms, Transvaal MuseumThey discovered that the concept of sustainable harvesting is not practised according to basic scientific principles and that traditional myths still play a strong role in determining harvesting strategies for Mashonzha. Moreover, the mopane worm played no role in school education, an opportunity lost.

Myths - scattering the ashes

There is a myth that if young Mashonzha are harvested the older individuals will leave the area. According to another myth, when larvae leave the trees and burrow into the ground they are going to die.

In fact, the purpose of digging into the ground is to pupate, and this is essential to complete the life cycle. If the larval stage is thought to end in death, and is not seen as part of a life cycle, there is no reason to conserve the worm at this stage.

While most people surveyed had no suggestions of how the mopane worms could be reintroduced into areas where they had been over-harvested, the rest suggested scattering ashes. There is a myth that the ashes from the fires used to prepare worms for the market could be scattered in areas where the worms are extinct in an appropriate ritual. According to this legend, this will bring the Mashonzha back.

Recolonising the mopane worm

Natural re-colonization in fact can only be a slow process, because the moths only live for two to three days and must complete their reproductive processes in this time, leaving little time for dispersal. The only other stage with any dispersal potential is the worm or caterpillar stage where dispersal can only occur slowly over limited distances.

For natural dispersal to be at all effective it would need the assistance of local communities who are aware of the process and can place an embargo on harvesting in sensitive areas. Managed re-introductions could also be possible in certain areas, however this would not work without the support and co-operation of local communities. Without this support relocated insects would soon be harvested, providing a very expensive meal for a few people.

According to Toms, to manage a reintroduction it is necessary to identify at least one stage in the life cycle that can be reintroduced.

The chrysalis or pupa stage is seldom seen and is least well understood. It lives underground and is very important as an over-wintering stage. Copyright R. Toms, Transvaal Museum. Harvesting and relocation of eggs could work, but the time frame for this is limited. Relocation of larvae may be the most practical and the Mopane woodland project is gaining valuable experience investigating the controlled rearing of larvae in captivity. The collection of pupae in the field would be difficult and expensive and collecting moths would not be recommended because they are fragile and only live for two to three days. Eggs and larvae are possibly the best stages to relocate, but further research is needed in this area.

Competing with browsers

Many farmers are cashing in on the mopane worms, charging large amounts of money to mopane worm harvesters to use their land. There are some farmers however who manage fenced in browsers who view the worms with concern as competitors for the mopane tree leaves. They can rest assured - the worms are highly seasonal, so even if defoliation does takes place, the worms will never be present for long and regrowth of leaves will take place once the worms are harvested or have pupated. This process can result in the regrowth of fresh new leaves for the browsers. Farmers, it seems, could also do with a bit of education. Good management based on knowledge from research and indigenous knowledge and a sound relationship with the local harvesters, which allows for the planned removal of a controlled number of worms at an appropriate time, not only solves the problem of over utilisation of the trees by the worms, but also ensuring survival of the worms and a regular income from their harvest.

Domesticating the mopane worm - the way forward?

Mopane worms at the market in Thohoyandou. Copyright R. Toms, Transvaal Museum.Another way of developing the mopane worm resource is to investigate the possibility of a silk-worm like industry where domesticated Mashonzha are raised on leaves harvested from domesticated mopane trees. One of the advantages of moving in this direction is to make the industry less unpredictable, because it is strongly affected by environmental conditions such as droughts. A disadvantage of this approach is the cost of the research and the cost and difficulty in transferring the benefits of the research to the poorest of the poor. For a domesticated industry to succeed on a small scale and be accessible to the poorest of the poor, the cost of production will be have to be compared with the cost of wild worms or dried worms at the market. However, knowledge gained in experimental domestication trials are also potentially useful to efforts to optimise the wild crop. In areas where re-introductions are needed, knowledge of rearing and sustaining the larvae will be of great value in keeping them alive during the capture, transportation and subsequent release.

The mopane worm is one of our most spectacular well known insects and was chosen as one of the BIG 12 African Insects. Toms and his team at the Transvaal museum believe that this worm has great potential to be used as an icon in the teaching of indigenous knowledge, sustainable harvesting, conservation and food security.


More information:

The Transvaal Museum has produced a poster on the life cycle of the mopane worm and is making this available to schools. The poster emphasizes the importance of leaving some larvae to complete the life cycle is emphasized. It teaches learners that, it is more important to think about how many worms must be left behind than to think about how many can be harvested.

As a project on cultural and medicinal uses of insects, this work has been funded by the National Research Foundation (NRF) since 2001. 

For more information please contact: Dr Rob Toms at the Transvaal Museum, South Africa - toms@nfi.co.za




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