GM wheat no more
pest-resistant than ordinary crops, trial shows
GM wheat designed to repel aphids is no more effective at repelling the bugs than standard varieties a major field trial has revealed
June 25, 2015
A major field trial of GM wheat that is designed to repel aphids (small insects) has found the crop is no better protected against the pests than conventional wheat. The results come from two years of trials that compared aphid attacks on standard wheat plants with those suffered by a GM version modified to release a natural aphid repellent.
Scientists created the GM wheat strain in the hope that it would deter aphids, which devour the crops and can leave them with infections. They modified the wheat to produce a natural pheromone which aphids release when under attack from predators. The “aphid alarm” makes the bugs flee to safety. Aphids are not the only organisms that release the odour though. More than 400 plants have evolved to secrete the same substance, called E-betafarnesene, or EBF, including peppermint. The chemical doubles up as an attractant for some insects that kill aphids, such as parasitic wasps.
Prior to the field trial, lab tests at Rothamsted found that the pheromone worked as a highly-effective aphid repellent. The work bolstered researchers’ hopes that the trial would demonstrate the crop’s resilience against aphids in the wild. An aphid-resistant wheat crop could have huge benefits for farmers and the environment because the plants would no longer need to be sprayed with insecticides.
“The disappointing thing is that when we tested it in the field, we didn’t find any significant reduction in aphid settlement in the test plots,” said Toby Bruce, who worked on the trial. Details of the trial are published in the journal Scientific Reports.