A nontoxic form of pest control can protect wheat

Pest control needs to be a vital part of agricultural if we are to feed the billions of people on earth. Each year as much as $130 billion worth of crops are lost to diseases caused by microscopic worms known as nematodes alone. Yet the pesticides used widely to keep nematodes in check tend to be highly toxic. They can harm insects, including pollinators like honeybees.

The answer then lies in less invasive forms of pest control. A team of scientists, led by Dr. Konstantin Blyuss, a mathematician at the School of Mathematical and Physical Sciences at the University of Sussex, has come up with just such a solution: “RNA interference” aimed at targeting a species of nematode that damages wheat crops.

His team has devised a method to “silence”  harmful nematode genes by using biostimulants derived from bacteria that occur naturally in soil. These stimulants also “switch off” genes in wheat that are affected by the nematodes, which helps further protect plants from the parasite.

When biostimulants are applied to wheat, a gene silencing process is triggered. The biostimulants can be applied to plants either by soaking their seeds or roots in a special solution or by adding the solution to soil used for growing wheat. “By soaking the seeds of the plant in the solution of biostimulants, the plant becomes a ‘Trojan horse’ for delivering special compounds produced inside the plants to the nematodes, which then kills them,” Blyuss says. “We’ve targeted the specific genes of the nematode, so we know this won’t affect other creatures.”

The biostimulants take effect only on specific nematodes, as well as wheat genes, and they leave insects unaffected. Better yet: they are naturally occurring, which means they could freely be used in organic farming to protect crops from the parasite.

During trials members of the team, who have published their findings in the journal Frontiers in Plant Science, soaked the seeds of wheat plants in their biostimulant solution. They found that doing so increased plants’ chances of survival by between 57% and 92%. The process also reduced nematode infestation levels by between 73% and 83%, as compared to plants grown without the use of biostimulants.

The scientists are now working on developing new strains of soil bacteria and extracting their metabolites to develop new tools for controlling wheat nematodes in an environmentally friendly manner.

“Biostimulants effectively act as an ‘inoculation’ against nematode infestation. They achieve their effect by mobilising plants’ internal machinery to produce compounds that protect plants against nematodes, while simultaneously causing nematode death,” Blyuss says.

“The plants produced using biostimulants have much better crop yields and higher resistance to pests, but they are no different from other plants that have been artificially bred to have some useful characteristic,” he adds. “Moreover, the biostimulants themselves are truly natural, as they are nothing else but products of bacteria already living in the soil.”