They had to download parasites to save an endangered species

Wilkins’s Buntings are an endemic bird species living on the remote Nightingale Island, part of the Tristan da Cunha Archipelago in the South Atlantic. This species is closely related to the island’s only native tree, Phylica arborea, whose fruits form the basis of its diet. In 2011, an invasive insect, the brown moth (Coccus hesperidum), appeared on the island, which, by secreting honeydew, favors the development of pond mold.

This fungus covered the trees, disturbing the photosynthesis process, which led to their death and thus endangered the birds that depended on them.

Research from 2017 indicated that the bunting population was only 120 breeding pairs, which put this species on the verge of extinction. In 2019, the island was further hit by powerful storms that destroyed approximately 80% of its forests, deepening the crisis.

A tiny wasp saved Wilkins’s bunting

In the face of this disaster, the government of Tristan da Cunha, together with a team of naturalists and scientists, developed an extraordinary rescue plan. It was decided to bring the parasitic wasp Microterys nietneri to the island to help fight the invasive insect. At the same time, tree nurseries were established to rebuild the damaged ecosystem and strengthen the biological security of the island.

The project turned out to be difficult to implement. Due to the COVID-19 pandemic, the wasps had to make a long journey from London to Cape Town, where they were quarantined, and then reached the island by sea. The journey took almost a month. On site, it turned out that less than 10% of the insects survived difficult transport conditions.

Despite this, the first wasp release in April 2021 was a success. Subsequent releases in the following years helped stabilize the wasp population, which resulted in a reduction in the number of parasites attacking trees, thus contributing to the recovery of the Phylica forest.

The success of British scientists and ecologists

Research from February 2024 showed that the bunting population currently ranges from 60 to 90 pairs. Although this number is lower than in 2017, the revival of the forest and effective insect control give hope for the stabilization and further recovery of the bird population.

David Kinchin-Smith from the Royal Society for the Protection of Birds emphasizes that this project is an example of how determination, ecological knowledge and appropriate planning can reverse the fate of an endangered species.

Parasitic wasps have proven to be a key element in saving this unique ecosystem. Thanks to the support of UK government funds and the John Ellerman Foundation, it was possible not only to save Wilkins’s Bunting, but also to protect the island against future invasive threats.