Alien Invasions: Invasive invertebrates


In the final post of the series we share the story of a new project based in St Helena led by the St Helena National Trust which aims to protect some of the endemic species found on the island from the growing threat of invasive invertebrates such as the common wasp and springbok mantis.

We hope that you have enjoyed this series so far, if you would like to read the entire series please follow these links for the first and second blog posts.

Conserving St Helena’s endemic invertebrates through invasive invertebrate control

St Helena is a small (47 square miles) UK Overseas Territory in the South Atlantic Ocean, with a population of around 4,500 people. In addition to its human population, the island is home to over 420 endemic terrestrial invertebrate species, making it a location of immense global importance. Unfortunately, many of these endemic species are under threat from invasive alien invertebrate species. An innovative new project led by the St Helena National Trust will facilitate endemic invertebrate recovery and re-establish their associated ecosystem functions by testing and establishing invasive invertebrate control methods. The focus will be on three of St Helena’s most invasive species, the common wasp (Vespula vulgaris), big-headed ant (Pheidole megacephala) and the springbok mantis (Miomantis caffra).

St Helena team member deploying wasp beer traps and surveying ants, Credit – Liza Fowler

Ants are a particular problem species for the island because they feed on endemic invertebrates and can damage native habitats. Ants rear other pest species such as aphids which threaten native plants and reduce abundance of beneficial invertebrates such as ladybirds. The big-headed ant also poses a threat to vertebrates and has been known to attack globally threatened St Helena plover chicks in their nests (known locally as the wirebird). We aim to begin trialling the control methods for the common wasp and big-headed ant in 2021. Insecticides will be used to target these species as they have shown positive success in other islands; the results will be carefully monitored to ensure that there are no unwanted impacts to local biodiversity. Control methods for the springbok mantis are currently under development and with the current lack of available resources the project will be one of the first to create and test methods specifically designed for the mantis.

To date, public engagement activities have included information stalls, workshops and citizen science programmes. The local team of four, with support from international experts in the UK, New Zealand and South Africa, hope to increase local capacity and knowledge in the battle against these invasive invertebrate species.

For more information on project DPLUS104 led by St Helena National Trust working in St Helena please click here. To read the full article from this project and others that were featured in the March 2021 edition of the newsletter, please click here.

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