SPIDER COMMUNITIES AFFECTED BY EXCLUSION NETS

Spiders are one of the most abundant natural enemies in apple orchards and have an important role in the biological control of harmful arthropods. Recently, coloured shade nets were introduced into management practices to improve the utilization of solar radiation by fruit trees and to exclude pest species. While the coloured netting in apple orchards had a positive effect on fruits, the secondary aim of our research was to analyse the influence the nets had on spider diversity and species composition. In this study we sampled the ground dwelling spider assemblage by pitfall trapping and identified spiders to species. Traps were placed under trees covered by four types of exclusion photo selective nets and uncovered (control) trees in an untreated experimental plot of an apple orchard. In total 456 individuals belonging to 13 families and 26 species of spiders were collected. Two wolf spider (Araneae, Lycosidae) species dominated the assemblages; Trochosa robusta (Simon, 1876) and Hogna radiata (Latreille, 1819) comprised 45% of the total adult catch. Spider abundance showed a declining trend over season in all treatments. Most importantly, there was no difference either between the abundance, species richness or the species composition of spiders in the treatments. The study strongly indicates that insect exclusion nets have no negative effect on ground dwelling spider assemblages.