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Closing in on suzukii

Fruits grown in open fields and tunnels are facing more and more damage from Drosophila suzukii, an invasive pest that is increasingly affecting the European and American fruit growers. Biobest was the first biocontrol company to develop and market a trapping system for this pest, which in many independent studies has been shown to be the most effective monitoring tool. In the meantime Biobest has also been hard at work to pioneer an efficient biocontrol solution. Based on years of screening native natural enemies, the parasitic wasp Trichopria drosophilae has been identified as an excellent candidate.

Since a couple of years soft fruit growers and winemakers in entire Europe are facing a new threat: the vinegar fly Drosophila suzukii. This Asian pest insect is a cousin of our European vinegar- or banana flies, but is much more damaging. Initially it invaded South Europe, but has soon spread across the entire continent. Annual yield losses run into millions.

One of the particular problems with suzukii is that the female flies lay their eggs inside the ripening fruit. This means that crop damage can be extremely severe and it also makes larvae hard to control with pesticides or with natural predators. Currently, there are various systems on the market for monitoring and trapping the adults. Earlier this year at the Phytoma conference in Valencia, a group of independent experts presented Biobest’s Droso Trap™ as the best option for trapping suzukii.

In the meantime, Biobest’s R&D department  has been doing extensive research in order to identify a biological control strategy for Drosophila suzukii. Native parasitic wasps have been the focus of this search for over two years. Six different wasps have been collected by Biobest in an intensive screening. “The problem with many native parasitic wasps is that suzukii is able to encapsulate the wasps’ eggs or larvae, so that they can’t hatch,” says Felix Wäckers, R&D director at Biobest. “But our researcher dedicated to this project found one species that’s immune for this encapsulation and is just as successful in developing on this invasive pest as it is on the native vinegar flies.”

“We tested several strains of Trichopria,” says Wäckers. On the basis of extensive laboratory trials, we selected the strain which showed the highest level of parasitism. “In addition we developed a unique method for efficient mass production of the beneficial insect.”

Currently we are running large-scale field trials in Belgium, France and Italy and results are expected by the end of this year. Wäckers: “On the basis of these results we will be able to determine the potential of Trichopria under commercial conditions. “We realize that fruit growers and winemakers are eagerly waiting for a biological solution of this problem. We work hard to pioneer these solutions,” says Wäckers.

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