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Ondokuz Mayıs University (OMU) and the Samsun Forestry Directorate have initiated a joint biological control operation by releasing Torymus sinensis, a natural enemy of the invasive chestnut gall wasp (Dryocosmus kuriphilus), into the environment to protect chestnut trees.

As part of this collaborative effort, 1,500 beneficial Torymus sinensis insects were released into a chestnut orchard located at the Ali Nihat Gökyiğit Chestnut Research Station, which operates under OMU’s Faculty of Agriculture. The initiative was carried out in cooperation with the Samsun Forestry Directorate as part of the biological control strategy against the chestnut gall wasp.

“The gall wasp can reduce chestnut yields by 50 to 70 percent”

Speaking to the press, Prof. Dr. Ümit Serdar from OMU’s Department of Horticulture explained that the gall wasp deforms chestnut buds, leading to a severe drop in yield.

“The gall wasp also prevents the trees from leafing properly. It can reduce chestnut production by 50 to 70 percent. So, it’s a highly destructive pest. It first entered Türkiye in 2013, initially detected in the province of Yalova. Eventually, it spread to the Black Sea region. Although we’ve identified resistant varieties here, most of our trees are still vulnerable. Therefore, biological control is crucial in the fight against this pest,” he said.

Prof. Dr. Serdar emphasized that Türkiye is a genetic center for chestnuts and continued:

“Türkiye produces about 70,000 to 75,000 tons of chestnuts annually, but the gall wasp now threatens our groves. The General Directorate of Forestry has produced Torymus sinensis in its laboratories as a countermeasure. The Samsun Forestry Directorate, operating under the Amasya Regional Directorate of Forestry, established its own laboratory in recent years and has significantly increased insect production. Today, we’re releasing some of these insects here at our research station, and others will be released in chestnut forests in the Salıpazarı district.”

“Impact on the gall wasp will be observed in 5 to 7 years”

Prof. Dr. Serdar noted that the beneficial Torymus sinensis species is expected to eliminate the gall wasp within five to seven years:

“We won’t see immediate results this year. After the release, the insects will lay eggs, and our teams will collect them at the end of the season. From these, we’ll raise new generations of Torymus sinensis. We will try to gather the galls formed by year’s end. In this way, our biological control efforts will continue.”