“Shut mopane worm harvest for two years”, scientist recommends. 26 March 2018

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Leonie Joubert


A two or three year ban on harvesting mopane ‘worms’ in the central district of Botswana may be a way of arresting the dramatic decline in this important source of protein over the past decade, as drought, heat waves, and over-harvesting of the resource has caused a collapse in this insect population here.

According to Ephias Mugari, an ecologist and doctoral researcher at the University of Botswana, mopane caterpillar numbers in Bobirwa district in Botswana have dwindled in the past decade.

Mugari has been visiting the district since February 2016 to gauge the extent to which people here are depend on various ecosystems for wild sources of food and medicine, or fodder for their animals. His research is linking how rising global temperatures and shifting climate will impact on the availability of these natural resources.

Botswana is one of the sub-Saharan countries that’s most vulnerable to climate change, with people in this area reliant on ecosystem services. Those services that are linked with the healthy state of natural vegetation are likely to respond if the climate changes, Mugari explains.

‘Mopane caterpillars, what we call ‘phane’ in Botswana, are a key part of these ecosystem services. They’re an important source of protein and income, and the health of the mopane caterpillar population depends on the condition of the mopane woodlands, which are affected by rainfall.’

As a semi-desert country, Botswana is already vulnerable to climate change, with higher temperatures and longer, more severe drought becoming the ‘new normal’, according to Tiro Nkemelang, a climate scientist at the Botswana Institute of Technology Research and Innovation (BITRI).

‘Global temperature warming is already set to exceed 1.5°C above pre-industrial levels, but Botswana will cross that threshold much earlier because of its semi-arid climate,’ he says.

According to a recent climate modelling study done by the African Climate and Development Initiative (ACDI), based at the University of Cape Town in South Africa, researchers found that this 1.5°C average increase could occur as early as 2024.

This will result in greater temperature-related extremes: more heat waves, more warmer days, and fewer cooler days.

Periods of drought are expected to last longer, with fewer rainfall events breaking them, according to Nkemelang’s modelling, but when the rain events do come, they are likely to be more intense, resulting in flooding. The overall climate trend will be one that is hotter and drier.

Because people in semi-desert countries like Botswana are dependent on rain-fed agriculture, longer and more severe droughts with shortened and less predictable rain seasons will have significant impact on crop yields and food availability. When agriculture fails, communities are likely to lean more heavily on the natural environment for food for themselves, fodder for livestock, fuel and building materials, water, and so forth.

Mugari recommends that the state consider banning mopane caterpillar harvesting for two or three seasons, in order to allow the population of this natural resource to recover.



This editorial is the first segment of a 6-part journalistic series running on a weekly basis. This article was funded by ASSAR (Adaptation at Scale in Semi-Arid Regions), a research consortium looking at climate change in semi-arid parts of Africa and India.