Damage caused by singing cicadas (Hemiptera: Cicadidae) in the field protective forest belts in South Dobrudzha, Bulgaria

Abstract

During the period 2020-2023, strong damage caused by singing cicadas (Hemiptera: Cicadidae) were registered on ash trees (Fraxinus spp.) in the field protective forest belts (FPFBs) in South Dobrudzha, northeastern Bulgaria. Bioacoustic studies have shown that the sounds are of Cicada orni. Many exuvia of the species were also found on the trunks and branches of ash trees. On the upper shoots and petioles, numerous oviposition holes were observed, which lead to leaf fall and drying of branch tips. In different FPFBs, tree crown damage ranges from a moderate (25-60% defoliation) to a severe (over 60% defoliation) degree. The attacks were stronger on Fraxinus excelsior and F. americana compared to F. angustifolia. The cicadas affect both old trees and young ash saplings. In young plantations, other tree species (Sophora japonica, Gleditsia triacanthos) were also affected. Imaginal activity of Cicada orni was recorded in July and August, and the peak of egg hatching occurred from early August to mid-September. The high number of Cicada orni necessitates the development of measures to control the pest in the FPFBs.