Aphids (also known as greenfly and blackfly) are unwelcome visitors that suck sap from plants. They cause significant damage to agriculture and reduce farmers' yields by damaging crops and spreading plant diseases.

Wheat is the most important UK crop with an annual value of about £1.2 billion. Currently a large proportion of UK wheat is treated with broad spectrum chemical insecticides to control cereal aphids that reduce yields by sucking sap from plants and by transmitting barley yellow dwarf virus. Unfortunately, repeated use of insecticides often leads to resistant aphids and kills other non-target insect species including the natural enemies of aphids, which could have a further impact on biodiversity.

Scientists at Rothamsted, funded by the UK Government through the Biotechnology and Biological Sciences Research (BBSRC) have been seeking novel ecological solutions to overcome this problem in wheat. One approach has been to use an odour, or alarm pheromone, which aphids produce to alert one another to danger. This odour, (E)-β-farnesene, is also produced by some plants as a natural defence mechanism and not only repels aphids but also attracts the natural enemies of aphids, e.g. ladybirds. Our scientists are using biotechnological tools to genetically engineer a wheat plant which produces high levels of this aphid repelling odour, which could help promote sustainable and environmentally friendly agriculture.