Pistachio nuts, Pistacia vera, are under development as a new crop in South Africa. Ongoing biomonitoring into the insect and arachnid guild structures in the Pistachio orchards at Green Valley Nuts, near Prieska in the Northern Cape Province) forms part of a larger sustainable IPM program on nuts in South Africa.

Spiders were sampled in a survey at GVN and Remhoogte (a separate locality close to GVN) from January to March 2001. Orchard 1 (16 ha, 8 years old) and Orchard 19 (16 ha, 5 years old) at GVN, and a single orchard at Remhoogte (1.5 ha, 9 years old), were sampled. Ten trees per orchard were sampled per month using the fogging method and Dichlorvos (150ml/100l) as a knockdown agent. All loose bark and dry leaves were also removed and worked through and any arthropods present were sampled. All specimens were sampled by hand and preserved in 70% ethanol. Ground cover sampling using sweep nets was also done to determine species common to the trees and ground cover vegetation.

A total of 1215 spiders representing 14 families was collected during the three month survey. Immature spiders dominated in all three orchards during all three sampling periods. Population data (% of immatures, males, females, total numbers) for the three month period can be summarised as follows: numbers were highest at Orchard 1 (65.8%, 17.4%, 16.8%, n=602), followed by Remhoogte (73.9%, 13.1%, 13.0%, n=352) and Orchard 19 (47.3%, 22.7%, 30.1%, n=256).

The spider fauna shows a very skewed dominance with Salticidae the most abundant family in Orchard 1 (81.2%), Remhoogte (58.8%) and Orchard 19 (82.4%). It seems that factors such as tree canopy size, presence or absence of bark and dry leaves, climatic conditions, and orchard size may be the main influences on spider abundance. Preliminary data of spider prey items includes Thysanoptera (Phlaeothripidae), Coleoptera (Bruchidae, Coccinellidae, Chrysomelidae), Diptera (Tephritidae, Muscidae, Cecidomyidae), Acari (Tetranychidae), and various Lepidoptera larvae. The effect of chemical spraying on spider numbers and parasitism of spiders and their eggs is also being investigated.

This resulted in further surveys.

Main investigator: Charles Haddad (University of the Free State).

Further reading:

Haddad, C. R., Louw, S. VdM. & Dippenaar-Schoeman, A. S. 2004. An assessment of the biological control potential of Heliophanus pistaciae (Araneae: Salticidae) on Nysius natalensis (Hemiptera: Lygaeidae), a pest of pistachio nuts. Biological Control 31: 83-90.

Haddad, C. R.,Louw, S VdM & Dippenaar-Schoeman, A. S. 2004. Spiders (Araneae) in ground covers of pistachio orchards in South Africa. African Plant Protection 10: 97-107.

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.

Pistachio fruit
Pistachio fruit

Collecting arachnids after fogging
Collecting arachnids after fogging

Spiders in Agro-Ecosystems

Spiders in cotton orchards

Spiders in avocado orchards

Spiders in macadamia orchards

Spiders in citrus orchards

Spiders in strawberry fields

Spiders on grapes

Spiders as predators of termites

Spiders as predators of mites

Salticidae: Thyene sp.