Sundew-inspired spray may turn crop plants into pest-catchers

Inspired by a carnivorous plant, scientists have created a sticky spray that could kill pest insects as effectively as traditional toxic pesticides. And what’s more, it’s derived from plain ol’ vegetable oil.

It’s no secret that most conventional pesticides are harmful to both people and the environment. They can also be quite expensive, so if farmers can avoid using them, so much the better.

Seeking a more eco-friendly alternative, researchers from the Netherlands’ Wageningen and Leiden universities recently looked to the carnivorous sundew plant.

Its leaves are covered in tiny “glandular hairs” (aka trichomes) which secrete a sticky substance. When insects land on the leaves, they get stuck in that substance and are subsequently digested by enzymes produced by the plant.

For their version of the sundew’s sticky stuff, the scientists started with a blend of vegetable-based triglyceride oils, which they dried and then milled into the form of 1-mm-wide beads. These beads are “as sticky as duct tape” thanks to nanoscale indentations on their surface.

A chrysanthemum plant, after being sprayed as part of the study
A chrysanthemum plant, after being sprayed as part of the study

Thomas Kodger, Wageningen University & Research

When a solution of the beads is sprayed onto the leaves of a plant, the tiny spheres remain adhered to the leaves for at least three months, even withstanding rain.

During that time, any small pest insects that land on the leaves will get stuck on the beads and immobilized, quickly leading to their death. Insects known as thrips are the main target of the technology, as they may infect plants with lethal viruses if not immobilized.

A tube-tailed thrips – and yes, that is the singular form of the word
A tube-tailed thrips – and yes, that is the singular form of the word

Alandmanson/C.C. 4.0

Importantly, however, beneficial insects such as bees and butterflies are large enough that the beads won’t stick to them. An additive in the spray should also keep it from clogging existing agricultural spraying systems. And as an added bonus, insects shouldn’t build up a resistance to the spray – such is not the case with traditional pesticides.

Ideally, the spray would be applied to crops before the plants fruit. That way, the fruits/grains themselves wouldn’t get sprayed. However, even if they did, the spray can reportedly be easily washed off using dish soap and water. The beads are clearly visible as yellow specs.

Additionally, even if ingested, the spray is likely no more harmful than unaltered vegetable oil … although more research does need to be conducted on its effect on the body. The scientists are also assessing how quickly the spray biodegrades in the soil.

A spinoff company is now being formed to commercialize the technology. The study is described in a paper that was recently published in the journal, PNAS.

“It is rewarding to witness our idea potentially changing the world within my lifetime,” says the lead scientist, Wageningen University’s Assoc. Prof. Thomas Kodger.

Source: Wageningen University & Research

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