Approval Given for Species Release to Reduce the Spread of Oriental Chestnut Gall Wasp

The UK’s Chief Plant Health Officer has announced approval has been given for the release of a parasitoid wasp called Torymus sinensis to help reduce the spread of Oriental Chestnut Gall Wasp in England to protect the health of sweet chestnut trees.

Torymus sinensis is already present naturally in England but in very low numbers. The species has been released to build population numbers to act as a biological control agent against the Oriental Chestnut Gall Wasp.

Oriental Chestnut Gall Wasp was first found in England in 2015. The wasp causes galls on the buds and leaves of sweet chestnut which damage the tree. In high numbers, the gall wasp can weaken sweet chestnut trees and make them more vulnerable to other pests and diseases, including Sweet Chestnut Blight.

The release follows extensive research commissioned by the Department for the Environment Food and Rural Affairs in partnership with Fera Science Ltd, a risk assessment and testing to ensure the safe, controlled release of the parasitoid in the UK. Fera Science Ltd will control the release, with a programme of monitoring for the next 10 years.