Venray: biological control of oak processionary caterpillars

In the Municipality of Venray a third of the tree stock in the area, some 11,000 trees, is oak. ‘We’ve been using Koppert’s nematode product Entonem as a curative measure against the oak processionary caterpillar for several years,’ explains Joep van Bergeijk, coordinator of oak processionary caterpillar management for the Municipality of Venray. ‘We use nematodes at locations in outlying areas where there might be protected species of butterfly and moth. The major benefit of Entonem is that nematodes kill fewer other caterpillars, which means they are less harmful to biodiversity. This is something that is high up on the political agenda, as well as being an important social issue.’

Entonem makes a big difference

According to Bergeijk, the results have been generally positive. ‘The trees that we have treated have been 90% cleared. What is interesting is that avenues running east to west are typically free of oak processionary caterpillar, while those running north to south still have some nests. It is possible that there has been more drift during spraying in those places, which means that the nematodes are more easily blown away. In some cases, we have to take curative action and extract the nests. But, on balance, Entonem makes a big difference to us in the fight against the oak processionary caterpillar.’