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But the shea tree population has dramatically plummeted in recent year, it says.

It has traditionally been women who have gathered the nuts of the shea tree to produce Nilotica shea butter, prized globally for its cosmetic and culinary uses.

"The productivity has gone down. The trees are not flowering and fruiting the way they used to. Rain fluctuation has disrupted the shea tree's natural cycles," he said.

Chained by her ankle to a shea tree, her mother hovering nearby, she has two hollows in the earth which serve as her toilet and to hold drinking water.

In her lab in England, Darja will be analysing shea tree leaves to uncover why the caterpillars like them so much.