The Plants that Cry Wolf

Wednesday 25th June 2014

Buglife are deeply concerned by news that UK researchers are trialling a GM wheat that ‘cries wolf’, sending out a constant chemical help signal to ladybirds and other predators, a signal that is normally only produced when a plant is under attack from aphids or other herbivores.  Buglife is worried that this will create chemical smog over the landscape confusing herbivores and their enemies and damaging the natural ecosystems.

In this case the wheat produces (E)-β-farnesene, an aphid alarm pheromone that they produce to alert one another to danger. An odour also produced by some plants as a natural defence mechanism.  Not only does this chemical repel aphids, it also attracts their natural predators.

 Matt Shardlow, CEO of Buglife commented, “it would seem logical that the effects of introducing a field of crops that repels herbivores and attracts predators would be to increase yield in that field, but to reduce yield in the surrounding fields – which would have more herbivores and fewer predators.  Imagine being the farmer with the one unprotected field in the area, surrounded by fields repelling herbivores and attracting predators, a likely rapid uptake of the new crop seems likely.” 

Once the use of the crop is universal it is questionable whether the same benefit will be experienced as could be observed in a single field.  However repelled they are, the herbivores would need to lay their eggs somewhere and the predators in a smog of attracting pheromones would be less able to locate them.  This could reduce the overall abundance of predators more effectively than it would reduce the overall abundance of herbivores. 

Shardlow concluded, “One also has to question why plants do not naturally produce ‘cry wolf’ chemicals continuously, it would surely be to an individual plant’s benefit.  The answer must be that creating the pheromones has a cost in terms of energy and materials, a cost the plant avoids by only crying wolf when it is attacked.”

Buglife corresponded with the lead researcher at Rothamsted – Prof. John Pickett and Dr Louise Ball, ACRE secretary at Defra, they acknowledged Buglife’s concerns.

For more information on this  /blog/matt-shardlow-ceo/plants-cry-wolf or contact Paul Hetherington 07732 158128 or paul.hetherington@buglife.org.uk