SPIDERS OF THE FOLIAGE AND HERBACEOUS LAYER OF AN IPM APPLE ORCHARD IN KECSKEMET-SZARKAS, HUNGARY

As part of a broad agroecological project, spiders were collected in d ifferent blocks of a 6 ha experimental IPM apple orchard at Kecskemet- Szarkas, Hungary, in 1994. The orchard was divided into six blocks rec eiving different treatments: the two ''traditional'' blocks were treat ed with conventional intensive spraying; the two ''IPM'' blocks were m anaged under an integrated pest management scheme. In the ''IPM+flower s'' blocks the same IPM scheme was applied and, additionally, flowerin g herbs were sown between tree rows. Spiders were collected by branch beating from the foliage of apple trees in all blocks, and in the IPMflowers 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 significant ly 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 wa s somewhat different from these, while family composition of the herba ceous layer was markedly different from that of the canopy stratum in any of the blocks. Within the IPM+flowers block, species similarity wa s moderate between the canopy and the herbs; Oxyopidae represented a c ommon element in both strata. The present study indicated that the app lied pest management schemes did not result in any significant differe nce in the spider assemblage of the treatment blocks. Spiders of the h erbaceous layer were of different composition, and there is little evi dence that adding vegetation to the herb layer would increase spider a bundance on the trees. Causative factors of this phenomenon, however, should be examined in more derail with special reference to the availa bility of alternative prey and dispersal from neighbouring habitats.