In Uganda’s Kibale National Park, scientists have spent years doing the slow, unglamorous work of catching tiny wasps. The payoff is big: a clearer map of “dark biodiversity” – the vast share of species that are poorly known or not yet described – and practical clues for how to protect it before it disappears.

Most of Earth’s species have never been formally documented, making them easy to overlook in conservation plans. Biologists call these overlooked lineages “dark taxa.” They are especially abundant in tropical forests, where species, habitats, and ecological roles remain thinly studied.

The Biodiversity Unit at the University of Turku has made a specialty of unveiling this hidden diversity, describing new species each year, and building tools to slow global biodiversity loss.

A living lab for biodiversity

Kibale National Park offers a mosaic of habitats. These include tracts of largely undisturbed forest, areas recovering from past logging, and nearby farmland. That patchwork allowed researchers to ask a simple but powerful question: where, exactly, is the unknown diversity concentrated?

The team focused on ichneumonid wasps – one of the most diverse animal groups on the planet – and, within it, the subfamily Pimplinae.

These wasps don’t just buzz around flowers. They regulate other species by parasitizing the immature stages of insects and spiders, linking them tightly to the health of entire food webs.

“Ichneumonids are a very poorly known taxon in Africa – we estimate that over half of the species we found are new to science,” said doctoral researcher Emil Österman.

With so little baseline knowledge for tropical ichneumonids, the team used long-term, standardized sampling to see how Pimplinae diversity is distributed across Kibale’s different habitats.

Wasps link species and ecosystems

Because parasitoid wasps sit high in food webs, they are sensitive to disruptions below them. If the insects and spiders they rely on decline, parasitoids tend to follow.

That sensitivity makes Pimplinae useful indicators: shifts in their richness and abundance often mirror broader changes in biodiversity. The new work confirms what many ecologists have suspected but struggled to quantify in tropical Africa.

“Many of our finds weren’t unexpected, but we didn’t have data based on long-term collecting in the field,” said Tapani Hopkins, a researcher with the Biodiversity Unit.

“Now we can tell in greater detail how many more species there are in natural forest, and to what extent disturbed or logged tropical forest can harbor species.”

Farmland cannot match forest life

The headline result is encouraging for conservation: intact forest in Kibale harbors especially rich Pimplinae communities. Secondary forest that is regrowing after logging also supports far more species than adjacent farmland.

In other words, protecting remaining forest is essential, and letting disturbed forest recover pays real biodiversity dividends.

“Our results clearly show that African forest, including forest that is recovering from logging, maintains a species-rich Pimplinae fauna compared to, say, nearby farmland,” Österman said. “Species-rich habitats can be considered especially valuable in conserving unknown dark biodiversity.”

That matters for policy and on-the-ground management. If you want to safeguard the most unknown species, prioritize forests – and don’t write off recovering stands. They’re already doing important work.

Global forests store hidden diversity

The team also asked a bigger biogeographic question: how does African tropical diversity stack up against the New World?

Drawing on their parallel long-term collections in western Amazonia and Brazil’s coastal forests, the researchers found hints that South American rainforests may host even higher Pimplinae richness than Africa. However, African forests still harbor a rich fauna.

“Conserving dark taxa effectively requires a detailed knowledge of how biodiversity is distributed, both locally and at a global scale,” said Professor Ilari E. Sääksjärvi, who leads the Biodiversity Unit.

The comparison underscores a simple lesson: tropical forests on multiple continents are irreplaceable reservoirs of poorly known life.

Forest biodiversity loss accelerates

Parasitoid wasps are only one window into dark biodiversity. But they tell a familiar story: clearing or simplifying forests causes losses to ripple upward. Protecting or allowing forests to recover lets complex communities rebound – including species we haven’t named yet.

The Kibale study shows conservation can succeed despite limited taxonomy: protect habitats that concentrate hidden diversity. It also highlights the value of patient, long-term fieldwork in places where biodiversity is vanishing fastest.

“We will continue our field studies at different tropical forest sites, because that is where biodiversity is disappearing especially quickly. It is a fight against time. When a rainforest is destroyed, we lose countless species which we know nothing about,” Sääksjärvi concluded.

The study is published in the journal Insect Conservation and Diversity.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–