Parasitisation of Yponomeuta malinellus feeding on Crataegus monogyna in the allotment gardens in the city of Poznań, Poland

The apple ermine moth (Yponomeuta malinellus Zeller) is an economically important pest of apple trees and apple orchards. It is also a pest of ornamental trees and shrubs in urban habitats. The aim of our study was to determine the degree of parasitisation of the apple ermine moth pupae collected from the common hawthorn (Crataegus monogyna Jacquin) in the allotment gardens in Poznań, Poland, by parasitoids from the Ichneumonidae family, to determine parasitoid species and the dates when they start flying. Judged from the parasitisation of pupae, the parasitoids reduced the apple ermine moth population by 9.1% over the period 2014-2016. The apple ermine moth pupae were parasitised by the following six parasitoid species: Gelis areator (Panzer), Herpestomus brunnicornis (Gravenhorst), Itoplectis alternans (Gravenhorst), I. maculator (Fabricius), I. tunetana (Schmiedeknecht), and Pimpla turionushtana (Linnaeus). The most effective entomophages H. brunnicornis and I. tunetana reduced the apple ermine moth population by 3.2% and 2.7%, respectively. Our results suggest that the apple ermine population in urban allotment gardens exposed to heavy anthropogenic pressure can be reduced by parasitoids of the Ichneumonidae family. The degree of parasitisation of the moth in this particular urban habitat may be comparable to the degree of its parasitisation in orchards.