Thesis (PhD) -- Stellenbosch University, 1989. / ENGLISH ABSTRACT: Arthropod communities of five proteaceous species viz. Protea repens. P. neriifolia. P.cynaroides,
Leucospermum cordifolium and Leucadendron /aureolum were studied. A faunal list of the insects was
compiled according to the feeding guilds of insects. Six phytophagous guilds were recognized: flower
visitors, thrips, endophages, ectophages, sap-suckers, and ants. The guild composition, species packing and
seasonal distribution for the free-IMng insects, spiders and other arthropods were investigated on the
different plant species. The ants, flower visitors and sap-sucking species found on the plant species, were
very similar, but the number of leaf chewing species common to all the plant species was low, suggesting
that some species were monophagous. Insect abundance increased during the wet winter months when the
plants were in flower. Of the total number of herbivores collected, flower visitors represented 69,5%, leaf
feeders 14,5% and sap-suckers 16,1 %. The chewers constituted 60,1% of the total herbivore. biomass. Leaf
damage increased with age ; young leaves were practically free of herbivore damage, while older leaves
were stm acceptable as food. The degree of insect damage differed amongst the plant species varying from
2% to 15%. The following leaf characteristics were investigated to determine the factors involved in defence
against insect herbivory : total phenolic content, protein precipitating ability, cyanogenesis, nitrogen content,
leaf toughness, woodiness and fibre content lt appears that the plant species use different mechanisms to
protect their leaves. The infructescences of Protea repens were exploited by the larvae of four Coleoptera
and four Lepidoptera species. The community structure of these phytophagous insects was determined
largely by negative interactions. Various strategies are followed (e.g. niche segregation in time and space)
to lessen interspecific competition. / AFRIKAANSE OPSOMMING: 'n Studie van die arthropoocl gemeenskap op vyf proteasoorte, naamlik Protea repens. P. neriffolia. P.
cynaroides. Leucospennum cordffolium en Leucadendron laureolum is gedoen. 'n Faunalys van insekte
volgens hul voedingsgDdes is saamgestel. Die insekte is in ses fitofage gDdes verdeel naamlik
blombesoekers, blaaspootjies, endovoeders, ektovoeders, sapsuiers en miere. Die samestelling van die
gDdes, spesie-rangskikking en seisoenale verspreiding is bepaal vir die vrylewende insekte, spinnekoppe en
ander arthropode. Die miere, blombesoekers en sapsuierspesies wat op die plantsoorte gevind is, is byna
dieselfde, maar verslalle in die blaarvoederspesies is gevind wat 'n aanduiding is dat sommige spesies
monofaag mag wees. Gedurende die nat wintermaande toon die insekgetalle 'n toename. Blombesoekers
verteenwoordig 69,5%, blaarvoeders 14,5% en sapsuiers 16,1% van die aantal insekherbivore wat versamel
is. Die kouers vorm 60,1% van die totale herbivoor biomassa Soos die blare verouder, neem die skade
op die blare toe; jong blare toon byna geen skade nie, terwyl ouer blare steeds geskik is vir insekvoedsel.
Die insekskade op die blare wissel by die verslallende plante tussen 2% en 15%. Om te bepaal watter
blaareienskappe moontlik 'n rol kan speel in blaarverdediging teen insekte is die volgende ondersoek: totale
fenoliese inhoud, die vermoe om proteiene te presipiteer, sianogenese. stikstofinhoud, blaartaaiheid,
houtagtigheid en veselinhoud. Dit wil voorkom asof die plante verskillende meganismes gebruik om die blare
te beskerm. Saadkoppe van Protea repens word deur vier Coleoptera en vier Lepidoptera spesies benut
Die gemeenskapstruktuur van die boarders word tot 'n groat mate bepaal deur negatiewe interaksies.
Verskeie strategiee word gevolg (bv. nissegregasie in ~ en ruimte) om kompetisie tussen spesies te
verminder.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/66615 |
| Date | January 1989 |
| Creators | Coetzee, J. H.(Jacobus Hendrik) |
| Contributors | Giliomee, J. H., Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology & Entomology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 124 p. : ill. |
| Rights | Stellenbosch University |
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