Non-toxic pest control for wheat? Mathematician develops a chemical-free parasite deterrent

06 May 2019 --- Dr. Konstantin Blyuss, a University of Sussex mathematician, has developed a variety of wheat that precisely targets specific microscopic worms, called nematodes, without harming any other insects, birds or mammals. The procedure is a chemical-free process of bioengineering that involves exposing the wheat plant to natural biostimulants in order to stimulate the desired characteristic. The emergent practice is proving to be a desirable alternative to genetically modified crops, where it is easier to implement and more cost-effective, benefitting large-scale agricultural productivity.

Working together with biologists at the National Academy of Sciences of Ukraine, Dr. Blyuss and his team found that in soaking the wheat plant in a solution of biostimulants – metabolites of bacteria occurring naturally in the soil – the plant becomes a “Trojan horse” and begins producing special compounds, which are consumed by the nematodes, effectively killing them. Findings from the study are published in the journal Frontiers in Plant Science. 

As the non-toxic procedure targets the specific genes of the nematode, the researchers note there is no risk of harming other insects or animals. Moreover, the biostimulants “switch off” the plant’s own genes that are affected by the nematodes, making it more difficult for the parasite to harm the crop.

“Our natural biostimulants provide a good alternative [to GM crops] in that they do not require the genetic modification of crop plants, but rather stimulate the plant itself to synthesise necessary RNAi [RNA interference] compounds,” Dr. Blyuss tells FoodIngredientsFirst.

The researchers highlight the varying degrees of success in GMO applicability, as well as the stigma surrounding its practice, as challenges in effectively implementing RNAi. “An alternative is to deliver RNAi topically [through spraying], but this approach has had its own problems, such as the spray being washed away with rain, thus researchers have recently tried to improve this by planting dsRNA [a signal for gene-specific silencing of expression] on nanoparticles before spraying on crop fields,” says Dr. Blyuss.

The naturally occuring biostimulants are preferred over chemicals and GM crops as they are more affordable and can be used in the large scale cultivation of organic crops, the researchers say. The biostimulants can be applied either by soaking the seeds or roots in a solution containing the biostimulants or by adding the solution to the soil in which the plants are growing. 

“With a rising global population needing to be fed and an urgent need to switch from fossil fuels to biofuels, our research is an important step forward in the search for environmentally safe crop protection which doesn’t harm bees or other insects,” Dr. Blyuss concludes. 

Non-toxic pest control developed with mathematical modelling
Dr. Blyuss’ mathematical modelling explains how RNA interference works in plants and shows the most effective way to apply the biostimulants to keep the crop safe from the harmful nematodes.

The experiments revealed that soaking the seeds of the plants in the biostimulant solution increases the chances of the plants surviving by between 57-92 percent. The technique also reduces the level of nematode infestation by 73-83 percent, compared to plants grown without biostimulants.

“By using mathematical models, we learned how biostimulants are absorbed by wheat plants, so we now know the best way to deliver them. We’ve also looked at how the RNAi develops inside the plants and nematodes, how the plant is able to switch off specific genes involved in the process of nematode parasitism, thus stopping infestation and how parts of RNAi from plants, when ingested by nematodes, cause their death by silencing some of their essential genes,” says Dr. Blyuss.

“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. Moreover, the biostimulants themselves are truly natural, as they are nothing else but products of bacteria already living in the soil,” says Dr. Blyuss.

The next steps are to develop more advanced mathematical models of how biostimulants with multiple components can be taken up from the soil by both seeds and roots and to identify which of the most recently identified genetic targets in the nematode are most effective.

With newly emerging research demonstrating the degenerative effects of pesticides on honey bees and a push by the EU towards tighter control of these chemicals, a need for natural alternatives is underscored. “There is growing awareness that the heavy use of conventional pesticides in farming is causing great harm to biodiversity, resulting in pollution of soils and waterways with harmful toxins. We urgently need to find alternative, sustainable means to control crop pests,” says Professor Dave Goulson from the University of Sussex's School of Life Sciences, and a global expert on declining bee populations.

“While this work focused on a particular wheat nematode, we have already looked into using similar biostimulants for targeting parasitic nematodes of other crops, such as rapeseed, sugar beet and tomato and in each case biostimulants proved to be very effective,” Dr. Blyuss tells FoodIngredientsFirst.

By Benjamin Ferrer