Spider ecology in pistachio orchards in South Africa
Loading...
Date
2003-05
Authors
Haddad, Charles Richard
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
English: As part of a larger biomonitoring project on pistachio nuts, Pistaciae vera
L. (Anacardiaceae), a new crop in South Africa, spiders (Arachnida: Araneae)
were surveyed over a 2-year period (January 2001 to December 2002) at
orchards on the farms Green Valley Nuts (GVN) and Remhoogte (REM) in the
Prieska district, Northern Cape Province, South Africa. This study aimed to
determine the diversity of spiders in the tree canopies, ground covers, and soil
surface, and aspects of the biology and pest control potential of common species
present. The various studies were conducted in the orchards GVN 1 (8 yrs old,
16 ha), GVN 19 (5 yrs old, 16 ha), and REM(9 yrs old, 1.5 ha).
A review was conducted to assess the effects of pesticide management on
the spider fauna of orchards. It was found IPM, organic and unsprayed orchards
supported a much greater diversity and abundance of spiders than
conventionally managed orchards. The effects of particular pesticides on spiders
were also assessed. Since the present study was conducted in IPM orchards one
could expect spiders to play an important role as predators of arthropod pests.
During the 2-year survey of arboreal spiders, 200 trees were sampled per
orchard primarily using insecticide fogging with dichlorvos as a knockdown
agent. A total of 18 families and 87 species were collected. Numbers and
diversity were highest in REM (n=2202, 70 spp.), followed by GVN 1 (n=2051,
64 spp.) and GVN 19 (n=1550, 47 spp.). Orchard age has a significant effect on
spider abundance and diversity. The jumping spider, Heliophanus pistaciae
Wesolowska (Salticidae), was strongly dominant, comprising an average of
53.8% of the fauna. Field observations on three common spiders, H. pistaciae,
Cheiracanthium furculatum Karsch (Miturgidae) and Neoscona subfusca (c. L.
Koch) (Araneidae), found them to prey on minor pest aphids (Aphididae), false
chinch bugs (Lygaeidae), leafhoppers (CicadeIIidae), thrips (Phlaeothripidae) and
leaf beetles (Chrysomelidae), indicating that they have potential as biological
control agents. Endosulphan and parathion applications apparently had a minimal
impact on the arboreal spiders, but further research is necessary to clarify this.
In the ground covers, 55 species in 14 families were collected between
July 2001 and July 2002 (10 samples, 2000 sweeps/orchard). Numbers and
diversity were highest in GVN 1 (n=631, 40 spp.), then REM (n=580, 35 spp.)
and GVN 19 (n=549, 36 spp.). Ground cover composition significantly affect
spider abundance, but not diversity. The lynx spider, Peucetia viridis (Blackwall)
(Oxyopidae), dominated the fauna (29.3%), and H. pistaciae was also common
(23.4%). Common spiders also preyed on the same pest organisms listed above
in the ground covers, indicating that predation in this stratum may limit pest
populations before they can reach damaging levels on the main crop.
In a comparison of the epigeic fauna of the three orchards and
undisturbed grassland ("veld"), pitfall traps (all sites) and active searching
(orchards only) were used to determine the diversity and abundance of spiders
from August 2001 to July 2002. Pitfall catches were highest and most diverse in
the veld (n=1112, 56 spp.), followed by REM(n=704, 35 spp.), GVN 1 (n=560,
26 spp.) and GVN 19 (n=428, 25 spp.). The dominant species in the orchards
was the sheet-weaver, Ostearius me/anopygius (0. P.-Cambridge) (Linyphiidae,
30% in the orchards), and the ground spider, Asemesthes /ineatus Purcell
(Gnaphosidae) in the veld (29.1%). Orchard disturbances had a significant
negative effect on the abundance and diversity of epigeic spiders. Families
dominating the pitfall trapping (Linyphiidae, Gnaphosidae, Lycosidae and
Salticidae) also dominated active searching, but their relative abundance varied
between methods.
In regard to its high abundance in pistachio orchards, the biology of H.
pistaciae was studied to create a better understanding of its role in pest control.
Arboreal populations peaked between December and March, depending on the
year of sampling. Ground cover populations peak in early summer (December-
January), which suggests a vertical migration to the tree canopies early in
summer. Various aspects of the feeding and reproductive behaviour of this
species were observed in the laboratory, and described. Egg production in the
field was greatest in early summer, but declined in subsequent months. An
average of 12.6 eggs are produced per egg sac (n=88). An egg parasite,
Odontacolus sp. (Scelionidae), and an undetermined polysphictine ichneumonid
wasp, parasitic on adult females of H. pistaciae only, were associated with this
spider.
The predation potential of H. pistaciae on the minor pest Nysius natalensis
Evans (Lygaeidae) was assessed in laboratory and field tests. Predation rates
were compared with vinegar flies, Drosophila melanogaster Meigen
(Drosophilidae). Predation rates were significantly higher for both male and
female spiders on D. melanogaster than N. natalensis during both days of the
48-hour-long tests. Predation of N. natalensis increased significantly for both
sexes during the second day of the tests. Preference tests indicated a high
preference of D. melanogaster, with increasing capture of N. natalensis with
time. In the field, female H. pistaciae (n=8) preyed on a mean of 1.38 N.
natalensis in 24 hrs. Factors affecting prey capture rates may be prey size,
palatability and activity.
The present study showed spiders to be a diverse and abundant group of
generalist predators in pistachio orchards, with 143 species representing 31
families collected in the surveys of the three strata. They may play an important
role in the suppression of minor pests before they reach levels that may be
damaging to pistachio trees and nuts. Further research is needed to clarify their
predatory impact on pests, effects of pesticides, and the relative abundance and
diversity of spiders in other orchard crops in the Prieska district.
Afrikaans: As deel van 'n groter biomoniteering projeck op pistachio neute, Pistachio vera L. (Anacardiaceae), 'n nuwe gewas in Suid-Afrika, was spinnekoppe (Arachnida: Araneae) versameloor 'n 2-jaar periode (Januarie 2001 tot Desember 2002) in boorde op die plase Green Valley Nuts (GVN) en Remhoogte (REM) in die Prieska distrik, Noord-Kaap Provinsie, Suid-Afrika. Hierdie studie se hoofdoele was om die diversiteit van spinnekoppe in die bome, in grondbedekkings en op die grond te bepaal, en aspekte van die biologie en plaagbeheer potensiaal van algemene spesies wat voorkom. Die verskillende studies was in die boorde GVN 1 (8 jaar oud, 16 ha), GVN 19 (5 jaar oud, 16 ha) en REM(9 jaar oud, 16 ha) unitgevoer. 'n Literatuur studie was unitgevoer om die effekte van bestuurstrategië op spinnekoppe in boorde te bepaal. Daar is gevind dat spinnekop diversiteit en voorkoms baie hoer is in GPB, organise en onbesproeide boorde as in konvensioneel bestuurde boorde is. Die effekte van verskillende plaagdoders op spinnekoppe is ook ondersoek. Aangesien die huidige studie uitgevoer is in GPB pistachio boorde, kan daar verwag word dat spinnekoppe 'n belangrike rol as predatore sal speel. Gedurende die 2-jaar studie van boom spinnekoppe was daar op 200 bome per boord versamel, primer met bespuiting van dishlorvos as 'n afslaan agent. 'n Totaal van 28 families en 87 spesies is versamel. Aantalle en diversitiet van spinnekoppe was hoogste in REM (n=2202, 70 spp.), gevolg deur GVN 1 (n=2051, 64 spp.) en GVN 19 (n=1550, 47 spp.). Boord ouderdom het 'n merkwaardige effek gahad op die aantalle en diversitiet van spinnekoppe versamel. Die springspinnekop, Heliophanus pistaciae Wesolowska (Salticidae), was baie numeries dominant, en het 'n gemiddeld van 53.8% van die fauna bygdra. Veld obserwasies op drie algemene spesies, H. pistaciae, die langbeensakspinnekop, Cheiracanthium furculatum Karsch (Miturgidae), en die wawielwebspinnekop, Neoscona subfusca (c. L. Koch) (Araneidae), het gevind dat hulle op verskeie plae, insluitend plantluise (Aphididae), besies (Lygaeidae), bladspringers (CicadeIIidae), blaaspootjies (Phlaeothripidae) en blaar kewers (Chrysomelidae) voed, wat aandui dat spinnekoppe moontlik 'n rol speel as biologiese beheer agente. Toedienings van die plaagdoders endosulfaan en parathion het blykbaar 'n onmerkwaardige effek op die fauna gehad, maar verder navorsing is nodig om vas te stelof dit wel die geval is. In die grond bedekkings was 55 spesies in 14 families tussen Julie 2001 en Julie 2002 versamel (10 monsters, 2000 swaale/boord), Nommers en diversiteit was hoogste in GVN 1 (n=631, 40 spp.), gevolg deur REM(n=580, 35 spp.) en GVN 19 (n=549, 36 spp.). Die komposisie van die grondbedekking het 'n merkwaardige effek op aantalle spinnekoppe gehad, maar nie op diversiteit nie. Die groen tierspinnekop, Peucetia viridis (Blackwall) (Oxyopidae), was die vollopste spesie (29.3%), gevolg deur H. pistaciae (23.4%). Algemene spinnekoppe was gesien om op die bogenoemde plae in die grondbeddeking te proei, wat aandui dat predasie in hierdie stratum kan plaagaantalle beperk, en keer dat hulle skadelike vlakke op die pistachio bome bereik. In 'n vergelykende studie van die grondelewende fauna van die drie boorde en onversteurde veld, was putvalle (alle "sites'') en aktiewe soektogte (boorde alleen) gebruik om die diversiteit en vollopheid van spinnekoppe te bepaal. Die studie is uitgevoer tussen Augustus 2001 en Julie 2002. Aaantalle was hoogste in putvalle in die veld (n=1112, 56 spp.), gevolg deur REM(n=704, 35 spp.), GVN 1 (n=560, 26 spp.) en GVN 19 (n=428, 25 spp.). Die dominante spesie in die boorde was die rooistert hangmatwebspinnekop, Ostearius melanopygius (0. P.-Cambridge) (Linyphiidae, 30% in die boorde), en die muisspinnekop, Asemesthes lineatus PureelI (Gnaphosidae), in die veld (29.1%). Versteuringe in die boorde het 'n merkwaardige negatiewe effek op die vollopheid en diversiteit van grondlewende spinnekoppe. Families wat vollopste in die putvalle was (Linyphiidae, Gnaphosidae, Lycosidae en Salticidae) was ook dominant in die soektogte, maar hulle relatiewe vollopheid het verskil tussen metodes. Die biologie van H. pistaciae was bestuudeer in aanmerking van dié spesie se vollopheid in pistachio boorde. Dit was gemik om die rol van dié spesie in plaagbeheer beter te verstaan. Populasies in die bome het gepiek tussen Desember en Maart, aanhangende van die jaar. In die grondbedekkings het populasies in vroeg somer gepiek (Desember-Januarie), wat 'n vertikale trek die bome in aandui. In die laboratorium was verkeie aspekte van die reproduktieween voedingsgedrag bestudeer en beskryf. Eier produksie in die veld is hoogste in Januarie, en daal af in die maande wat volg. 'n Gemiddeld van 12.6 eiers is geproduseer per eier sak (n=88). 'n Eier parasite, Odontacolus sp. (Scelionidae), en 'n polysphictine ichneumonid wesp, wat net op wyfie spinnekoppe parasiteer, was geassosieër met dié spesie. Die predasie potensiaal van H. pistaciae on die plaag Nysius natalensis Evans (Lygaeidae) was in laboratorium en veldtoetse bepaal. Predasie tempos was vergelyk met asynvlieë, Drosophila melanogaster Meigen (Drosophilidae). Predasie tempos was merkwaardig hoër op D. melanogasterdeur altwee dae van die 48-uur studie. Predasie op N. natalensis het merkwaardig verhoog gedurende die tweede dag van die studies. Voorkeur toetse het 'n hoë voorkeur vir D. melanogaster bewys, maar die proporsie N. natalensis gevang het verhoog met tyd. In die pistachio bome het wyfie H. pistaciae (n=B) 'n gemiddeld van 1.38 N. natalensis in 24 ure gevang. Prooi grootte, smaaklikheid en ektiwiteit kan predasie rates beinvloed. Hierdie studie het gewys dat spinnekoppe is 'n diverse en algemene groep predatore in pistachio boorde, met 143 spesies van 31 families versamel in die drie strata. Hulle mag 'n belangrike rol speel om plae te beheer voordat hulle vlakke mag raak wat skade aan die bome en neute aanrig. Verdere navorsing is benodig om hulle predatoriese impak op plae te verstaan, effekte van plaagdoders op spinnekoppe, asook die relatiewe vollopheid van spinnekoppe op ander boord gewasse in die Prieska distrik.
Afrikaans: As deel van 'n groter biomoniteering projeck op pistachio neute, Pistachio vera L. (Anacardiaceae), 'n nuwe gewas in Suid-Afrika, was spinnekoppe (Arachnida: Araneae) versameloor 'n 2-jaar periode (Januarie 2001 tot Desember 2002) in boorde op die plase Green Valley Nuts (GVN) en Remhoogte (REM) in die Prieska distrik, Noord-Kaap Provinsie, Suid-Afrika. Hierdie studie se hoofdoele was om die diversiteit van spinnekoppe in die bome, in grondbedekkings en op die grond te bepaal, en aspekte van die biologie en plaagbeheer potensiaal van algemene spesies wat voorkom. Die verskillende studies was in die boorde GVN 1 (8 jaar oud, 16 ha), GVN 19 (5 jaar oud, 16 ha) en REM(9 jaar oud, 16 ha) unitgevoer. 'n Literatuur studie was unitgevoer om die effekte van bestuurstrategië op spinnekoppe in boorde te bepaal. Daar is gevind dat spinnekop diversiteit en voorkoms baie hoer is in GPB, organise en onbesproeide boorde as in konvensioneel bestuurde boorde is. Die effekte van verskillende plaagdoders op spinnekoppe is ook ondersoek. Aangesien die huidige studie uitgevoer is in GPB pistachio boorde, kan daar verwag word dat spinnekoppe 'n belangrike rol as predatore sal speel. Gedurende die 2-jaar studie van boom spinnekoppe was daar op 200 bome per boord versamel, primer met bespuiting van dishlorvos as 'n afslaan agent. 'n Totaal van 28 families en 87 spesies is versamel. Aantalle en diversitiet van spinnekoppe was hoogste in REM (n=2202, 70 spp.), gevolg deur GVN 1 (n=2051, 64 spp.) en GVN 19 (n=1550, 47 spp.). Boord ouderdom het 'n merkwaardige effek gahad op die aantalle en diversitiet van spinnekoppe versamel. Die springspinnekop, Heliophanus pistaciae Wesolowska (Salticidae), was baie numeries dominant, en het 'n gemiddeld van 53.8% van die fauna bygdra. Veld obserwasies op drie algemene spesies, H. pistaciae, die langbeensakspinnekop, Cheiracanthium furculatum Karsch (Miturgidae), en die wawielwebspinnekop, Neoscona subfusca (c. L. Koch) (Araneidae), het gevind dat hulle op verskeie plae, insluitend plantluise (Aphididae), besies (Lygaeidae), bladspringers (CicadeIIidae), blaaspootjies (Phlaeothripidae) en blaar kewers (Chrysomelidae) voed, wat aandui dat spinnekoppe moontlik 'n rol speel as biologiese beheer agente. Toedienings van die plaagdoders endosulfaan en parathion het blykbaar 'n onmerkwaardige effek op die fauna gehad, maar verder navorsing is nodig om vas te stelof dit wel die geval is. In die grond bedekkings was 55 spesies in 14 families tussen Julie 2001 en Julie 2002 versamel (10 monsters, 2000 swaale/boord), Nommers en diversiteit was hoogste in GVN 1 (n=631, 40 spp.), gevolg deur REM(n=580, 35 spp.) en GVN 19 (n=549, 36 spp.). Die komposisie van die grondbedekking het 'n merkwaardige effek op aantalle spinnekoppe gehad, maar nie op diversiteit nie. Die groen tierspinnekop, Peucetia viridis (Blackwall) (Oxyopidae), was die vollopste spesie (29.3%), gevolg deur H. pistaciae (23.4%). Algemene spinnekoppe was gesien om op die bogenoemde plae in die grondbeddeking te proei, wat aandui dat predasie in hierdie stratum kan plaagaantalle beperk, en keer dat hulle skadelike vlakke op die pistachio bome bereik. In 'n vergelykende studie van die grondelewende fauna van die drie boorde en onversteurde veld, was putvalle (alle "sites'') en aktiewe soektogte (boorde alleen) gebruik om die diversiteit en vollopheid van spinnekoppe te bepaal. Die studie is uitgevoer tussen Augustus 2001 en Julie 2002. Aaantalle was hoogste in putvalle in die veld (n=1112, 56 spp.), gevolg deur REM(n=704, 35 spp.), GVN 1 (n=560, 26 spp.) en GVN 19 (n=428, 25 spp.). Die dominante spesie in die boorde was die rooistert hangmatwebspinnekop, Ostearius melanopygius (0. P.-Cambridge) (Linyphiidae, 30% in die boorde), en die muisspinnekop, Asemesthes lineatus PureelI (Gnaphosidae), in die veld (29.1%). Versteuringe in die boorde het 'n merkwaardige negatiewe effek op die vollopheid en diversiteit van grondlewende spinnekoppe. Families wat vollopste in die putvalle was (Linyphiidae, Gnaphosidae, Lycosidae en Salticidae) was ook dominant in die soektogte, maar hulle relatiewe vollopheid het verskil tussen metodes. Die biologie van H. pistaciae was bestuudeer in aanmerking van dié spesie se vollopheid in pistachio boorde. Dit was gemik om die rol van dié spesie in plaagbeheer beter te verstaan. Populasies in die bome het gepiek tussen Desember en Maart, aanhangende van die jaar. In die grondbedekkings het populasies in vroeg somer gepiek (Desember-Januarie), wat 'n vertikale trek die bome in aandui. In die laboratorium was verkeie aspekte van die reproduktieween voedingsgedrag bestudeer en beskryf. Eier produksie in die veld is hoogste in Januarie, en daal af in die maande wat volg. 'n Gemiddeld van 12.6 eiers is geproduseer per eier sak (n=88). 'n Eier parasite, Odontacolus sp. (Scelionidae), en 'n polysphictine ichneumonid wesp, wat net op wyfie spinnekoppe parasiteer, was geassosieër met dié spesie. Die predasie potensiaal van H. pistaciae on die plaag Nysius natalensis Evans (Lygaeidae) was in laboratorium en veldtoetse bepaal. Predasie tempos was vergelyk met asynvlieë, Drosophila melanogaster Meigen (Drosophilidae). Predasie tempos was merkwaardig hoër op D. melanogasterdeur altwee dae van die 48-uur studie. Predasie op N. natalensis het merkwaardig verhoog gedurende die tweede dag van die studies. Voorkeur toetse het 'n hoë voorkeur vir D. melanogaster bewys, maar die proporsie N. natalensis gevang het verhoog met tyd. In die pistachio bome het wyfie H. pistaciae (n=B) 'n gemiddeld van 1.38 N. natalensis in 24 ure gevang. Prooi grootte, smaaklikheid en ektiwiteit kan predasie rates beinvloed. Hierdie studie het gewys dat spinnekoppe is 'n diverse en algemene groep predatore in pistachio boorde, met 143 spesies van 31 families versamel in die drie strata. Hulle mag 'n belangrike rol speel om plae te beheer voordat hulle vlakke mag raak wat skade aan die bome en neute aanrig. Verdere navorsing is benodig om hulle predatoriese impak op plae te verstaan, effekte van plaagdoders op spinnekoppe, asook die relatiewe vollopheid van spinnekoppe op ander boord gewasse in die Prieska distrik.
Description
Keywords
Spiders -- South Africa, Pistachio -- Diseases and pests -- Control, Dissertation (M.Sc. (Zoology and Etomology))--University of the Free State, 2003