Weevil research to establish natural pest control method

Researchers at Harper Adams University are using tracking devices to monitor the movements of a common soft fruit pest in order to help growers to protect their crops.

The vine weevil (Otiorhynchus sulcatus) feeds on the roots and leaves of soft fruit and potted ornamental plants, causing damage and yield loss.

Work is now taking place through Defra funding to establish a non-chemical method to control adult vine weevils, by encouraging them to seek shelter in refuges filled with a naturally-occurring pathogen.

Harper Adams is contributing to the project by monitoring how far each weevil moves around the crop, to investigate their potential for spreading the spores of the pathogen to other vine weevils. As the weevils spread the pathogen through the crop they may create an epidemic within the pest population.

40 weevils have recently been released onto a crop of strawberry plants at the Crop and Environment Research Centre (CERC) on campus, ready to be tracked.

Dr Tom Pope, Research Entomologist, is leading the work at the Shropshire university, working alongside a postgraduate entomology student. He said: “To monitor the weevils’ movements, we have attached small radio tags to them, each with a unique ID number.

“Adult vine weevils are nocturnal and hide during the day, making them very hard to find again after releasing them into the crop. Using this electronic equipment we can scan the plants to find the weevils much more quickly and by checking the plants regularly, record the distance moved by each weevil.

“We spent some time testing the techniques to ensure that weevil-friendly adhesive is used and that the tags do not restrict the weevils’ movement.”

So far, the work has shown that the majority of the weevils have remained within the strawberry patch, but moved widely within it.

Although weevil larvae can be controlled by non-chemical methods, growers currently rely on insecticides to control the adults. It is hoped that the use of pathogen-filled refuges will give growers a viable alternative to the use of these chemicals.

Dr Pope added: “We are delighted that our work to understand how weevils move within a crop is assisting in the development of a non-chemical control method for this pest.”

The project, which is due for completion in 2015, is led by ADAS with contributions from Harper Adams University and the University of Warwick.

For more details visit the Harper Adams University website: www.harper-adams.ac.uk