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As part of a biomonitoring programme on pistachio orchards in South Africa, spiders were collected from tree canopies in three orchards from January 2001 to December 2002, using an insecticide mistblower and dichlorvos as a knockdown agent. Sampling was conducted in two orchards (GVN 1 and GVN 19) on the Green Valley Nuts Estate, and one orchard (REM) on the farm Remhoogte. In total, 5843 spiders were collected, representing 18 families and 88 species.Numbers and diversitywere highest inREM(n = 2240, 69 species.), followed byGVN1 (n = 2055, 64 species) and GVN 19 (n = 1548, 47 species). Three species dominated the spider fauna: the jumping spider Heliophanus pistachioWesoowska (53.4%), the sac spider Cheiracanthium furculatum Karsch (12.7%) and the orb-web spider Neoscona subfusca (C L Koch) (6.4%). There were significantly more spiders during 2001 and 2002 in the older orchards, GVN 1 and REM, than in the younger orchard, GVN 19. Differences in abundance between orchards differed between months, with no consistent pattern. Sørensen’s quotient values indicated a greater similarity between the faunas of the two older orchards than between the older orchards and the young orchard, indicating that orchard age has an effect on diversity. Spiders are abundant generalist predators in pistachio orchards, and probably play an important role in pest control.
Citation
Haddad C. R., Dippenaar-Schoeman A. S. & Pekár S. (2005): Arboreal spiders (Arachnida: Araneae) in pistachio orchards in South Africa. African Plant Protection 11: 32–41.Gallery
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