Species Composition of Spider (Araneae) Assemblages in Apple and Pear Orchards in the Carpathian Basin

Abstract

The species richness and composition of spider assemblages were investigated in the canopy, herbaceous-layer and at ground level when differently treated with pesticide and in abandoned apple and pear orchards in the Carpathian Basin. Furthermore attention was paid to the bark-inhabiting spider fauna. Altogether 20,283 individuals were collected belonging to 21 families; 165 spider species have been identified to species level and further nine spider taxa were determined up to generic level. More than 20% of the Hungarian spider fauna was represented in the orchards. In the canopies, 103 species were found in apple orchards and 70 species in pear orchards. The similarity (Jaccard index) between apple and pear in the canopy is 45%. The species richness in each orchard varied between 22 and 56 species. In the herbaceous layer, 66 species were found in apple orchards and 43 species in pear orchards. Most of the species belonged to the families Araneidae, Salticidae, Thomisidae, Theridiidae. Species of hunting spiders were represented by 55%, web-building spiders by 45% of the entire fauna. The canopy and the herbaceous layer inhabiting fauna overlapped. Out of the 76 herbaceouslayer inhabiting species, 59 occurred also in the canopy. The similarity (Jaccard index) in species composition between the canopy and the herbaceous-layer is 45%. The most widely occurring species in orchard canopies in decreasing order were: Philodromus cespitum, Theridion impressum, Theridion pinastri, Oxyopes heterophthalmus, Araniella opistographa; on the bark: Philodromus cespitum, Xysticus spp. (lanio, cristatus), Drassodes lapidosus, Theridion pinastri, Clubiona marmorata; in the herbaceous-layer: Xysticus spp. (cristatus, ulmi), Oxyopes heterophthalmus, Pisaura mirabilis, Mangora acalypha, Araneus diadematus; on the ground-level: Xysticus kochi, Titanoeca schineri, Pardosa agrestis, Alopecosa sulzeri, Harpactea rubicunda. This species could play a role in the natural control of orchard pests in IPM systems in the Carpathian Basin. Three species collected in the canopy of apple and pear orchards, Enoplognatha latimana, Philodromus longipalpis and Euophrys monticola were not recorded from Hungary until the present study.