The core business of the Belgian company Viridaxis is the production of parasitic wasps that attack aphids in crops. ‘Up until today, our products can be used in various protected crops, such as soft fruits, vegetables and ornamental plants’, Nicolas Dassonville, product specialist at Viridaxis says. ‘This year we also did our first field trials in open cherry orchards. So the cooperation within the BIOCOMES-network has enabled us to step outside!’
Parasitic wasp on a cherry tree flower. Picture: Viridaxis.
Identifications of wasps
The new line of biological control in open crops, started with the identification of useful parasitic wasps, Dassonville explains. ‘This is where we got valuable assistance of the Serbian BIOCOMES-partners at the University of Belgrade. They sampled, identified and selected the wasp species that have the potential to attack the aphids that infest fruit tree crops.’
Rearing the new wasps
The next step was to rear these potentially interesting wasps, in the patented system of the company. Using an artificial diet, the mummies of the parasitic wasps are produced without the need of plants. Later, the mummies are placed in the crops that need protection from aphids.
This spring, the first field trials were performed in cooperation with another BIOCOMES-partner, the Belgian Research Station for Fruit, PCF. ‘They have a very good network of growers and have experience in Integrated Pest Management in fruit tree orchards’, Dassonville says. ‘One of the difficulties we encountered was the combination of our biological control with the necessary spraying against fruit flies. Luckily, the time window between blooming of the cherry trees and the spraying was long enough for us to test the new product and get valuable results.’
‘It goes without saying that biological control is the preferred method when it comes to sustainability. But there is not a reliable biological solution for every pest and disease. Therefore, in Integrated Pest Management we simply cannot do without chemical products yet’, Dassonville says. ‘So we must collaborate with the chemical companies to develop pest control strategies, integrating biological and chemical methods that are compatible with each other. In this respect, the presence of chemical companies in the BIOCOMES consortium is certainly an added value of this project.’
From cherry to peaches
The cherry is a relatively simple crop, with only one relevant aphid species. To Dassonville and his colleagues, it’s the step outside the protected environment that is the challenge. We are currently analyzing the results of the first season of field trials in orchards. When the control of aphids in cherry orchards through parasitic wasps proves to be successful, work on other crops like plums, peaches or apricots is waiting. The network of BIOCOMES-partners greatly facilitates this work.’
Aphids in fruit crops