Assessment of biological efficacy of plant protection products against the adults of flat-headed root borer Capnodis tenebrionis L. (Buprestidae) in stone fruit orchards in Bulgaria

The flat-headed root borer (Capnodis tenebrionis L.) is one of the most destructive pests affecting stone and pome fruit orchards in Bulgaria. In recent years, a significant increase in pest population density has been observed, which could be attributed to several factors: rising ambient temperatures, prolonged drought conditions, abandoned orchard lands, and the restriction of a large number of insecticides due to their high toxicity and detrimental effects on the environment and human health. The current research was conducted in 2025 in a plum orchard at the Fruit Growing Institute - Plovdiv, Bulgaria. The biological efficacy of six synthetical and two biological insecticides was evaluated against the adults of C. tenebrionis. Among the chemical products, the highest biological efficacy was observed for Chlorantraniliprole (Coragen) and Lambda-cyhalothrin (Karate Zeon) (30%), while the other active substances resulted in mortality rates below 20%. The only product that showed no toxicity was esfenvalerate (Sumi Alpha). The product, based on Beauveria bassiana caused 30% mortality of the adults on the ninth day after treatment. Keywords: flat-headed root borer , Capnodis tenebrionis , biological control, chemical control