Researchers from Wageningen University & Research (WUR) and Leiden University have engineered a biological barrier that protects plants from diseases and pests. It concerns a sticky substance that is sprayed on leaves, to which pests stick. The researchers hope that this insect glue will help to reduce the use of toxic chemical pesticides. They published their findings in the scientific journal PNAS.
In February, the European Commission withdrew its proposal to halve the use of chemical pesticides. However, the goal of reducing their use remains due to the harmful effects of these pesticides on human, animal and environmental health. In the search for alternatives, scientists from WUR and Leiden University turned to nature for inspiration. "The carnivorous sundew plant has so-called glandular hairs that secrete a sticky substance to catch insects," says Thomas Kodger, Associate Professor of Physical Chemistry and Soft Matter. "We wanted to mimic this to protect our plants and crops in a natural way."
Targeted trap
The researchers succeeded in their endeavour. They transformed vegetable rice oil into a yellow, sticky substance by blowing air over it and grinding it into small particles using a laboratory blender. This results in beads of about one millimetre in diameter that are as sticky as duct tape. The size matches one of the common pest insect: thrips. By catching these insects, plants stay healthier and are less likely to become infected with fungi that the thrips carry with them. So far, the researchers mainly focused on this type of pest, but the insect glue may also work against other pests, such as the Suzuki fruit fly that currently threatens cherry cultivation. At the same time, the drops are small enough that beneficial insects, such as pollinators, do not get stuck.
Unlike chemical pesticides, insects are unlikely to develop resistance against this adhesive, Kodger thinks. "Insects have already evolved so that they avoid adhesion, for example through hairs on their body and a bumpy surface," he explains. "Increasing their body size remains one of the few escape methods from this sticky trap." That is not nearly as easy as developing tolerance to a chemical substance. If it happens at all, it takes many generations and only happens if the insect glue is used on a large scale.
