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

Abstract

As part of a broad agroecological project, spiders were collected in different blocks of a 6 ha experimental !PM apple orchard at Kecskemet-Szarkas, 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 "!PM" blocks were managed under an integrated pest management scheme. In the "IPM+flowers" blocks the same !PM 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 !PM 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.

Effect of pest management systems on foliage- and grass-dwelling spider communities in an apple orchard in Hungary

“…The major factors responsible for this are a direct effect of broad-spectrum insecticides and the lack of prey after the treatments. Other authors found that the abundance of spider communities did not differ significantly between IPM systems based on selective insecticides (diflubenzuron, fenoxycarb) and conventional management systems based on broad-spectrum insecticides (Olszak et al, 1992a;Samu et al, 1997). Olszak et al (1992a) considered that their results could be strongly influenced by prey density.…”

“…In the strips, where the herbaceous layer was manipulated, higher spider communities developed in the canopy, which was probably caused by the availability of suitable overwintering places for spiders and the higher prey density composed of indifferent insects coming from the herbaceous layer. Samu et al (1997) stated, however, that the relationship between canopy and herbaceous layer is limited because they have different spider family compositions and there is little evidence that adding herbs to the herbaceous layer would increase the abundance of spiders in the canopy.…”

“…However, in several studies, there was no increase in spider densities with use of the moderately toxic pesticides widely employed in IPM (e.g. diflubenzuron, fenoxycarb) compared with usage of broadspectrum insecticides (organophosphates, pyrethroids) (Olszak et al, 1992a;Samu et al, 1997). According to laboratory investigations, organophosphates, pyrethroids and diflubenzuron are generally toxic to spiders (Mansour, cited in Hassan et al, 1994).…”

Effects of agricultural diversification on the abundance, distribution, and pest control potential of spiders: a review

“…Some spiders will move vertically and search the crop plant. Even in apple orchards, some species found on the ground cover vegetation, below and between trees, were also found on the trees themselves (Samu et al, 1997;Yu-hua et al, 1997). Altieri & Schmidt (1986b), however, reported that high numbers of predators on cover crops did not always translate into higher numbers on the apple trees, and they advocated investigating whether mowing the cover crop would stimulate predators to ascend into the tree foliage.…”

Composição e diversidade da fauna de aranhas (Arachnida, Araneae) da Fazenda Nazareth, Município de José de Freitas, Piauí, Brasil

“…Esta subamostragem também é um reflexo da grande porcentagem de indivíduos imaturos (não passíveis de identificação específica) coletados através do GCE e das AQ, correspondendo a mais de 80% do total de indivíduos examinados, como também encontrado por Brierton et al (2003) e Samu et al (1997). Este fato é amenizado em famílias como Araneidae e Thomisidae, em que alguns táxons possuem características morfológicas distintivas permitindo seu reconhecimento em nível específico (Jiménez-Valverde & Lobo 2006).…”