pesticide
Sticky pesticide to protect crops from
insects
Thijs Bierman.
Dutch scientists have engineered a sticky substance that protects plants from diseases and pests by trapping them when they land on plant leaves, incapacitating them. The researchers hope that this ‘insect glue’, which they described in the journal PNAS, will help to reduce the use of toxic chemical pesticides.
I
Thrips caught in sticky droplets on a chrysanthemum leaf.
“The large drops are clearly more successful,”
n the search for alternatives to potentially
harmful chemical pesticides, scientists from
— although contact with food cannot be ruled out.
said Thijs Bierman, a PhD candidate at the Institute
“The advantage of our pesticide over chemical
of Biology Leiden. “Presumably, the thrips need to
pesticides is that you can see the small, yellow drops;
get stuck with a minimum body surface area. This
you can wash it off with water and dish soap,” Kodger
is also observed in carnivorous plants.”
said. If the substance is ingested, Kodger expects it
Wageningen University & Research (WUR) and
So far the scientists have mainly focused
to be no more harmful than frying fat, given that it
Leiden University turned to nature for inspiration.
on thrips, but the insect glue may also work
is derived from vegetable oil, but scientists still need
As explained by Thomas Kodger, an associate
against other pests, such as the Suzuki fruit fly
to investigate how (un)healthy it is exactly.
professor at WUR, “The carnivorous sundew plant
that currently threatens cherry cultivation. At
In the future, farmers may be able to spray
has so-called glandular hairs that secrete a sticky
the same time, the drops are small enough that
the sticky pesticide on their fields using existing
substance to catch insects. We wanted to mimic this
beneficial insects, such as pollinators, do not get
chemical sprayers, as a special additive in the
to protect our plants and crops in a natural way.”
stuck. Furthermore, pest insects are unlikely to
mixture ensures that the beads do not stick to
develop resistance against this adhesive.
each other or the machine. The researchers must,
The researchers transformed vegetable oil into a yellow, sticky substance by blowing air
“Insects have already evolved so that they
however, assess the environmental impact of this,
over it and grinding it into small particles using
avoid adhesion, for example through hairs on
as they would rather not dump large amounts of
a laboratory blender. This resulted in beads of
their body and a bumpy surface, [so] increasing
cooking oil onto the fields. They are also looking
about 1 mm in diameter that are as sticky as duct
their body size remains one of the few escape
to understand how the substance will affect the
tape, and similar in size to Californian thrips
methods from this sticky trap,” Kodger explained.
natural enemies of thrips, which are often used
(Frankliniella occidentalis) — common pest
This evolution is not nearly as easy as developing
by farmers for biological control.
insects that cause major problems worldwide in
tolerance to a chemical substance; it would take
In addition, the scientists are exploring
greenhouse horticulture.
many generations, if it happens at all, and would
possibilities to incorporate repellent or attractive
only occur if the insect glue is used on a large scale.
scents into the pesticide to make it even more
drops on plant leaves, with these drops catching
After application, the sticky substance remains
effective, and to utilise various waste oils based
the thrips inside them. By catching these insects,
on the leaves for three months, which is long
on availability, adapting their process accordingly.
plants stay healthier and are less likely to become
enough to control pests until harvest. By spraying
They aim to launch a spin-off company to further
infected with fungi that the thrips carry with them.
crops before the fruits develop, farmers minimise
develop and market their innovation, with plans
And the larger the drops, the greater the catch.
the chance of the pesticide getting onto the food
to start up by the end of the year.
The pesticide was sprayed as thick, sticky
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