Scientists at Rothamsted Research have created new insect repellent odours that could help with crop protection pesticides.

Together with Cardiff University, the scientists have combined the techniques to imitate a naturally occurring smell, researchers say.

The non-naturally produced smell molecules look differently but work similarly to the original odour. At a time when insect pests are increasingly becoming resistant to conventional pesticide control, this research represents an important step forward in adding to the much needed alternative insect pest control toolbox, researchers say.

Through providing an enzyme which creates the smell, with a range of precursors called substrates the scientists were able to make the similar smelling odour molecules, they say.

The scientists then questioned the effectiveness of the resulting imitations to function as insect repellents, which involved behavioural experiments using aphids; one of the major pests of crops.

Researchers said that further studies attached electrodes to the antenna of live aphids and every time the aphids could detect an odour the electrodes took a recording of the response.

They found that several of the newly produced imitation odours were found to have the expected repellent activity against aphids.

In what the scientists say was an unexpected twist, one produced odour attracted aphids which they say may provide an opportunity to control aphid populations by luring the pest into a ‘trap-and-kill’ device.

Researchers say that the study highlights the potential to use this novel approach in the identification and production of a range of imitation insect repellent or attractant odours, not just for aphids.

Dr Sabrina Touchet, who carried out the experimental work for this research at Cardiff University, said this research is a start of a promising step forward in designing new semiochemicals.

“By modifying the substrate of the enzyme and the enzyme itself it is possible to readily enable the biosynthesis of a non-natural ligand (odour) that is still close to the natural one.

“These results provide good opportunities to improve natural compound properties to use them in the field to guide (repel or attract) insects,” she said.