Sticky insects: plants protected with biological glue
Drained leaves and plants stripped bare. Insects can completely destroy crops. Soon, these situations may be behind us, with the new pesticide developed by Leiden and Wageningen researchers. With their plant-based ‘insect glue’, insects are incapacitated.
‘Carnivorous plants, such as sundews, trap their prey with sticky hairs,’ says Thijs Bierman, a PhD candidate at the Institute of Biology Leiden. That inspired him and his colleagues to create a similar ‘insect glue’ made from plant oil. They spray it as thick, sticky drops on the leaves. In this way, they attempted to capture Californian thrips (Frankliniella occidentalis), a small insect that causes major problems worldwide in greenhouse horticulture.
Larger drops have a greater effect
The PhD candidate tested the effectiveness of sticky drops of various sizes and oils. ‘We managed to trap thrips in the drops! So, there's a good chance that our drops can protect plants against small insects.’ And the larger the drops, the greater the catch. ‘The large drops are clearly more successful. Presumably, the thrips need to get stuck with a minimum body surface area. This is also observed in carnivorous plants.’
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Thrips caught in sticky droplets on a chrysanthemum leaf. Credit: Thijs Bierman -
Californian thrips caught in the hairs of a sundew-plant. Credit: Thijs Bierman
Defense against biological control?
The research continues. Bierman: ‘We are now investigating whether this substance truly provides complete protection for the plant. Also, we’re exploring possibilities to incorporate repellent or attractive scents into our sticky drops to make them even more effective. And we want to understand what happens to the natural enemies of thrips. Farmers often use them for biological control, so we definitely don't want to trap them.’
Learn more about the production and safety of the sticky drops in WUR’s article on the PNAS-publication.
This research is a collaboration of Leiden University, Wageningen University & Research, Aeres University of Applied Sciences Almere and University of Groningen. It is funded by a NWA-ORC grant of professor emeritus Peter Klinkhamer.
Bierman previously published an article earlier this year in Journal of Pest Sciences. It is, he demonstrates the effects of the drops on leaf damage and thrips reproduction.