Surrounding Semi-Natural Vegetation as a Source of Aphidophagous Syrphids (Diptera, Syrphidae) for Aphid Control in Apple Orchards

Abstract

The influence of different semi-natural surroundings adjacent to apple orchards on the occurrence of predatory syrphids and biological control of Aphis pomi Deg. and Dysaphis plantaginea Pass. was compared. Two methods of catching hoverflies were used: yellow traps to collect the adults and hand picking to get the larvae from aphid colonies. A total of 1029 Syrphidae (26 species belonging to 14 genera) of subfamily Syrphinae were collected in Moericke traps from apple orchards and their boundaries. At all sites, a much greater number of hoverflies was collected in the surroundings (638 specimens) than in the orchards (391 specimens). In apple orchards, 134 syrphids belonging to 10 species were reared from A. pomi and D. plantaginea colonies. In both cases, the dominants were Episyrphus balteatus (Deg.) Eupeodes corollae (Fabr.), Syrphus vitripennis Meig. and S. scripta (L.), suggesting that hoverflies are attracted by plants flowering in semi-natural habitats in the vicinity of the orchard, and they then migrate to the orchard and reduce the aphid colonies. The results confirmed the positive influence of natural surroundings on the conservation of aphid predators.