Susceptibility of apple varieties to infestation by aphids (Hemiptera: Aphididae) in Southern Bulgaria

Aphids regularly infest apple orchards and are considered as one of the most damaging species, especially in humid conditions. In 2021-2023, the collection of different species and the rate of infestation by aphids on different apple varieties were studied in the region of Plovdiv, Bulgaria. Among the four aphid species identified in the apple orchard, Aphis spiraecola and Dysaphis plantaginea were predominant, followed by Aphis pomi and Dysaphis devecta. The rate of infestation varied significantly among the apple varieties. The Gala Resistant was the most infested by the aphids with a population coefficient (K) 302.5, followed by the Crimson Crisp – 124, the Pinova – 91, and the Red del Mestar – 52.5. The least infested variety was the Super Chief – 0.9, followed by the Modi – 2.2, the Fujion – 2.8, the Enterprise – 7.2 and the Rosella – 19. Keywords: apples, varietal susceptibility, aphids