Aphids are serious pests of wheat and other arable crops cultivated in the UK, transmitting viruses and reducing yield. Farmers spray insecticides to control aphids when infestations become severe due to lack of an alternative approach. Scientists at Rothamsted Research conducted experiments to discover whether wheat could be genetically modified (GM) to produce an aphid alarm pheromone and whether it would repel aphids in the lab and field. This would allow farmers to reduce insecticide spraying, benefiting the environment and making farming more sustainable.
Although the GM wheat did not repel aphids in the field, the five-year project did score some notable successes. The use of genetic engineering to provide wheat able to produce the aphid alarm pheromone (E)-β-farnesene (Eβf) was successful and robust - this is a world first and an important proof of concept in plant science overall. GM wheat plants produced the pheromone in significant quantities without major unexpected changes seen in the appearance or performance of the new wheat plants, which looked and yielded as normal.
In addition, in laboratory experiments aphids were successfully repelled by the Eβf signal. Scientists went on to test the GM plants in open field conditions. However, in the field trials there was no statistically significant difference in aphid infestation between the GM wheat and the conventional wheat used as a control (both of the same variety, Cadenza).
Professor Huw Jones, senior molecular biologist at Rothamsted Research with oversight for the genetic changes in the plants said: "As scientists we are trained to treat our experimental data objectively and dispassionately but I was definitely disappointed. We had hoped that this technique would offer a way to reduce the use of insecticides in pest control in arable farming. As so often happens, this experiment shows that the real world environment is much more complicated than the laboratory."
Rothamsted scientists think that the aphids may simply have become habituated to the constant production of the alarm pheromone - this might be akin to people ignoring a car alarm that never stops ringing. This opens up the prospect for further scientific work at Rothamsted to try to better mimic the production of the pheromone in nature.
Helen Ferrier, NFU Chief Science Adviser said:
"Field trials are extremely important in developing new crops to help farmers tackle serious problems like aphids. It's important to test newly developed crops to see if what happens in the lab happens in the field, which is where crops will be grown commercially.
With ever fewer crop protection chemicals now available other ways to protect food production from pests are urgently needed- if chemistry is not available as a tool, we must turn to biology, through breeding, to help crops protect themselves. Biotechnology is an important and exciting tool to do this."
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