Oak processionary caterpillars, time for Entonem!

Oak processionary caterpillars are back and will be emerging from their eggs from April on. The hairy caterpillars live in communal webs and can affect the health of trees, animals and humans once they are mobile. The smaller the caterpillar, the more effective the biocontrol of this pest can be.

Koppert has been rearing the natural enemy of the processionary caterpillars for many years. The product is marketed under the name Entonem. Entonem contains entomopathogenic nematodes, which have proved to be an effective means of combatting the caterpillars in a natural way, ensuring that the oak processionary caterpillars are tackled while the bycatch of other caterpillars is presumed to be low as it is applied very early in the season.

The oak processionary caterpillar has long posed a challenge to local authorities and managers of green spaces. In Europe, the processionary caterpillars are found mainly in the Mediterranean Basin, the Atlantic seaboard, but have made alarming advances across most of Western Europe in recent years. In most of these regions, insecticide treatments cannot be used due to their effect on public health and the environment. Entonem therefore provides effective biological control of this pest that presents a health hazard in both rural and urban green areas. It is entirely safe for animals and humans.

The product is based on the entomopathogenic nematode Steinernema feltiae, which parasitize the processionary caterpillars. When the nematodes come into contact with the caterpillars, they penetrate them through their natural body openings. The nematodes then excrete bacteria from their digestive tract which convert the caterpillars’ tissue into a food source on which they feed and develop. This causes the caterpillars to die within a few days.

The nematodes must be ideally applied during the first to third stage of the caterpillars’ development. First and foremost because the smaller the caterpillars, the more effective the application of Entonem. This early application also prevents larvae from reaching later stages of development which can cause major health issues when caterpillars release their poisonous hairs.

Acting fast is crucial. When the trees have not yet developed their leaf mass, it significantly increases the chance of the nematodes coming into contact with the caterpillars. An accurate application of Entonem is important and should be carried out by specialist contractors. They will know where the caterpillars are and where to spray, precisely where the leaf buds will emerge. With Entonem the caterpillars have no chance.

‘Our nematode Steinernema feltiae has a curative effect on the oak processionary caterpillar,’ explains Koppert’s account manager, Arno van der Zwan. ‘Our own research confirms it, and now contractors confirm the effects too. Our nematodes can be sprayed onto the caterpillars in their first three stages. The smaller the caterpillar, the more effective the application.’