Organisation - September 14, 2017

Catching weevils

Roelof Kleis

On the table in of one of the Nergena greenhouses stand long rows of potted astilbes. Healthy plants with plenty of leaves and a robust root ball. This is the nursery for entomologist Rob van Tol’s black vine weevils.

photo Margiet van Vianen

Van Tol, a researcher at Bio-interactions and Plant Health, Wageningen Research, carefully inserts between 10 and 30 miniscule orange eggs into each clump. ‘My material for next year.’ The adult beetles can then be called on to do their job. In this case: walking into a trap. In collaboration with businesses, Van Tol has developed a new insect trap. It couldn’t be photographed: trade secret. Biological pest control is Van Tol’s core business. Since 1991 he has been working on ways of conquering this weevil, so dreaded by horticulturalists. First using odours, and recently working mainly with traps. With the latest trap he thinks he stands a good chance of winning the battle against the black vine weevil. The design is the result of trial and error. At dawn after a night of feeding, the weevils go looking for a hiding place. The trap provides one, only it proves to allow only one-way traffic. How effective the trap will prove should become clear next year when Van Tol releases the weevils into cages containing a small rhododendron, to feed and… walk into the trap. ‘Exciting. The proof of principle after a year of testing and developing.’