Citizen science campaign launched to help UK respond to threat of bacterium which can kill popular garden plants

Neophilaenus likely lineatus - Photo by Claire Harkin

Photo by Claire Harkin

Cercopis vulnerata - Photo by Claire Harkin

A lecturer from the University of Sussex has joined forces with the Royal Horticultural Society (RHS) and Forest Research to launch a public campaign to help the UK respond to the threat of Xylella fastidiosa, a bacterium that results in the disease and death of many popular garden plants.

Gardeners, nature lovers and citizen scientists across the UK are being asked to help map the distribution of spittlebugs, one of the chief carriers of Xylella, that can be found in gardens, meadows, grasslands and woodlands from April to late June.

Spittlebugs, also called froghoppers, are small, sap-sucking insects that can transmit Xylella as they move between and feed on plants.

Dr Alan Stewart, Reader in Ecology at the University of Sussex, says: “Records of spittle submitted by the public will help us to build up a picture of where spittlebugs are found, what plants they feed on and how much they move around. This information will be essential for deciding how best to respond should Xylella arrive in the UK.”

The most common species in the UK is the meadow spittlebug (Philaenus spumarius). Adults measure 1/2 cm long, vary in pattern and colour from pale brown to black and can jump up to 70 cm. There are ten species of spittlebug in the UK and the young – called nymphs - all produce whitish, frothy blobs of spittle on leaves and branches.

Dr Claire Harkin, Postdoctoral Research Fellow at the University of Sussex, says: “Adult froghoppers, which will be around later in the year, are a bit more elusive, but the spittle is really easy to spot, so it’s a great way for people to start contributing important citizen science data. Any records submitted by the public will add vital pieces to the puzzle of how we can best protect our countryside should the Xylella bacteria arrive here”.

Each volunteer is being asked to report sightings of spittle online through iRecord (https://www.brc.ac.uk/irecord/xylem-feeding-insects). Volunteers will need to report their name, the location the spittle was seen and when, and most importantly the species of plant on which it was found. This information will help researchers understand how Xylella might enter and spread in the UK.

Gerard Clover, Head of Plant Heath at the RHS, says: “Xylella remains our number one concern but is not an issue bound by the garden fence. Understanding how and where the disease’s primary vectors move is fundamental to understanding how we can stop the devastation of our gardens and environment should it arrive.”

This citizen science study forms part of a broader research project called BRIGIT, being delivered by a consortium of eleven leading UK research organisations, all working to enhance UK surveillance and response to Xylella fastidiosa.

While Xylella is not yet present in the UK, it is already established in areas of Italy, France and Spain and has resulted in the death of millions of olive trees in southern Italy.

Unlike most pests and diseases which are host-specific, Xylella affects more than 500 different plant species with garden favourites such as lavender, oleander, rosemary and flowering cherry all at risk in the UK. The disease prevents water from being transported from the roots to leaves with plants often exhibiting symptoms that can be confused with other common problems such as drought or frost damage.

If found in the UK, all host plants within 100m would need to be destroyed and there would be immediate restrictions on movement of specified plants within a 5 km radius for up to five years - striking a death knell for surrounding nurseries and garden centres.

In light of the threat of Xylella, the RHS has revised its plant health policy and called on gardeners and the industry to future proof gardens by purchasing host plants that are UK-sourced or grown and maintaining varied plantings.

The launch of the spittlebug survey follows an updated assessment on the risks posed by Xylella fastidiosa to plants and crops in the European Union by the European Food Safety Authority earlier this week.

Click here for further information about the survey and froghoppers. Please note that spittlebugs are innocent carriers of Xylella in certain countries outside the UK. In this country, however, they are not pests, so there is no need to remove them. The survey is helping to gather data to inform a response should the disease ever reach the UK.