Field margin vegetation as a bridge for predatory mites (Phytoseiidae) migration into raspberry plantations

Abstract: In the 2008 and 2009 growing seasons in middle-eastern Poland seven plantations and their margins were selected for detailed studies on the plant species role as the resource plants for predatory mites, the natural enemies of spider mites. Occurrence of the predatory mites (Phytoseiidae family) was regularly monitored during the growing season on plants growing in the close vicinity (a field verge) of a plantation and on its boundary. Two season observation confirmed that the effective reservoir for predatory mites were rather herbaceous plants than the trees and shrubs growing on the plantation edge. Numerous plant species surrounding raspberry plantations in Poland harbor predatory mites of the Phytoseiidae family. Plant species as: Corylus avellana, Geum urbanum and Urtica dioica were identified as a good reservoir of predatory mites. Their presence in the vicinity of plantations can potentially increase abundance of the Phytoseiidae mites on raspberry plantations. The highest population of the predatory mites was recorded on Rubus idaeus but not all recorded Phytoseiidae species are equally effective as natural enemies of spider mites. The herbaceous plants probably serve as “a bridge” between the permanent vegetation growing on the field margin and the raspberry plants.