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The impact of spiders on aphid populations in a strip‐managed apple orchard
Author(s) -
Wyss E.,
Niggli U.,
Nentwig W.
Publication year - 1995
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1111/j.1439-0418.1995.tb01320.x
Subject(s) - biology , orchard , aphid , predation , spider , agronomy , weed , ecology , horticulture
Aphids and their predators were studied in an apple orchard near Berne, Switzerland. To augment the density of the predators of aphids weed strips were sown in tramlines and along the border parallel to the first and the last row of trees in one half of the orchard (the other half served as control) in April 1992. Weekly visual observations, monthly beating‐tray samples, branch samples in winter, and assessment of the density of spider webs and their trapping efficiency on randomly chosen trees were carried out in 1993. During 1993, significant differences in the number of aphids, aphidophagous insects, and spiders were observed on the apple trees within both the strip‐managed area and the control area. The impact on aphids by the aphidophagous insects was important during the flowering time of weeds in spring and summer. In autumn, however, spiders (i.e. Araniella spp.) were the dominant predators of aphids on the trees; during this time of the year they were more abundant within the strip‐managed area of the orchard. With a higher density of webs, spiders significantly reduced the number of aphids able to return from their summer host plants. Consequently, less hatching aphids were found on branch samples of the strip‐managed area compared to the control area. The effects of the weed strips on spiders and aphidophagous insects, and the resulting impact of predation on the aphids are discussed.