Spiders of the Foliage and Herbaceous Layer of an IPM Apple Orchard in Kecskemét-Szarkás, Hungary

Abstract

ABSTRACT As part of a broad agroecological project, spiders were collected in different blocks of a 6 ha experimental IPM apple orchard at Kecskemét-Szarkás, Hungary, in 1994. The orchard was divided into six blocks receiving different treatments: the two “traditional” blocks were treated with conventional intensive spraying; the two “IPM” blocks were managed under an integrated pest management scheme. In the “IPM+flowers” blocks the same IPM scheme was applied and, additionally, flowering herbs were sown between tree rows. Spiders were collected by branch beating from the foliage of apple trees in all blocks, and in the IPM+flowers blocks separately from herbaceous plants by shaking. The total catch of spiders represented at least 28 species (88% of all spiders were immature). The total number of spiders caught was not significantly different between treatment blocks. Cluster analysis revealed that spider family composition was the most similar between the canopies of the various IPM blocks, the canopy fauna of the traditional blocks was somewhat different from these, while family composition of the herbaceous layer was markedly different from that of the canopy stratum in any of the blocks. Within the IPM+flowers block, species similarity was moderate between the canopy and the herbs; Oxyopidae represented a common element in both strata. The present study indicated that the applied pest management schemes did not result in any significant difference in the spider assemblage of the treatment blocks. Spiders of the herbaceous layer were of different composition, and there is little evidence that adding vegetation to the herb layer would increase spider abundance on the trees. Causative factors of this phenomenon, however, should be examined in more detail with special reference to the availability of alternative prey and dispersal from neighbouring habitats.