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.
[ 2004PistachioGroundCovers.pdf] 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.
[2005PistachioArborealSpiders.pdf] | 
Pistachio
fruit
Collecting
arachnids after fogging
|
