Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Widespread, human-induced ecosystem degradation and the associated biodiversity loss pose a direct threat to human wellbeing. While there is no substitute for healthy, self-sustaining ecosystems, ecological restoration offers an attractive, and indeed inevitable, supplement where conservation alone is not sufficient to support ecosystem integrity. Restoration is undergoing a revolution, where evidence-based (EB) practice is emerging as a new approach to increase the chances of successfully achieving restoration goals. EB practice is based on the notion that implementation decisions need to be based on the appraisal and use of evidence of effectiveness of alternative options. The point of departure of this thesis is the contention that EB practice need not be dependent only on research evidence. The work presented herein thus addresses the production and use of evidence of effectiveness in restoration practice. Using ten restoration programs in South Africa, the quality of evidence produced in practice was assessed. Three components of evidence production that were evaluated were (i) baseline condition measurement; (ii) goal setting and (iii) monitoring. Results showed poor definition of goals; a bias towards the use of socio-economic goals and indicators; more monitoring of inputs than impact; and inconsistent and short-term monitoring of biophysical indicators. Practitioners regarded the evidence base as adequate, but cited a few challenges associated with planning and resource availability as attributing factors to the gaps observed. I propose that practitioners’ perception of the current evidence base poses an additional threat to the generation of a strong evidence base. In addition to the production of evidence, access to said evidence is a vital component of EB practice. In an exploration of how evidence is made available by practitioners, it became evident in that a considerable amount of the information that was not easily accessible in documented form was known by the practitioners. This highlights the need for a shift in practice culture towards the valuing and rewarding of the dissemination of information. An assessment of EB restoration would have been incomplete without a deliberate consideration of social factors. I thus conducted a case study of an invasive alien plant clearing program, to determine what drives the use of scientific evidence in decision making. I observed that organizational structure, policies, priorities and capacity influence, and even limit, the use of scientific evidence to inform decisions. The challenges to making restoration evidence-based are diverse in nature, ranging from poor planning of restoration work, which points to limited appreciation of the need to produce a strong evidence base, to a lack of instruments and incentives to drive the generation, dissemination and use of evidence that spans both the biophysical and social aspects of restoration. These challenges are largely rooted in the conventional way of approaching restoration from individual disciplinary perspectives, thus artificially simplifying and compartmentalizing a naturally complex problem like degradation. I end by proposing transdisciplinarity, which focuses on a holistic world view and the production of knowledge that embraces complexity, as a possible vehicle to help move the practice of restoration towards being evidence-based. / AFRIKAANSE OPSOMMING: Wydverspreide, mens-veroorsaakte agteruitgang van ekostelsels en die gepaardgaande verlies aan biodiversiteit hou 'n direkte bedreiging vir menslike welsyn in. Alhoewel daar geen plaasvervanger is vir 'n gesonde, selfonderhoudende ekostelsel is nie, bied ekologiese restourasie 'n aantreklike en inderdaad onvermydelik, vul waar bewaring alleen nie voldoende ekosisteem integriteit kan ondersteun nie. Restourasie ondergaan tans ‘n revolusie, waar bewys gebaseerde (BG) praktyk 'n opkomende nuwe benadering om die kanse van die suksesvolle bereiking van herstel doelwitte te verhoog. BG praktyk is gebaseer op die idee dat die uitvoering van besluite gebaseer moet word op die evaluering en die gebruik van bewyse van die effektiwiteit van alternatiewe opsies. Die punt van vertrek van hierdie proefskrif is die bewering dat BG praktyk nie noodwendig afhanklik van navorsings bewys hoef te wees nie. Die werk wat hier aangebied word spreek tot die produksie en gebruik van bewyse van effektiwiteit in die restourasie praktyk. Deur die gebruik van tien restourasie programme in Suid-Afrika is die kwaliteit van die bewyse in die praktyk geassesseer. Die drie komponente van bewyse produksie wat geëvalueer is sluit in (i) basislyn toestand meting, (ii) doelwitstelling en (iii) monitering. Resultate toon 'n swak definisie van doelwitte; 'n vooroordeel ten gunste van die gebruik van sosio-ekonomiese doelwitte en aanwysers; meer monitering van insette as die impak; en teenstrydige en kort-termyn monitering van biofisiese aanwysers. Beofenaars het die gebruik van bewys gebaseerde inligting as voldoende beskou, maar 'n paar uitdagings wat verband hou met die beplanning en die beskikbaarheid van bronne is aangehaal as kenmerkende faktore in die gapings wat tans waargeneem word. Ek stel voor dat beoefenaars se persepsie van die huidige bewysbasis praktyk 'n bykomende bedreiging vir die generasie van 'n sterk bewybasis praktyk inhou. Benewens die produksie van bewyse, is die toegang tot bewyse 'n belangrike komponent van die BG praktyk. In die verkenning van hoe bewyse beskikbaar gestel word deur beoefenaars, is dit duidelik dat 'n aansienlike aantal inligting wel bekend is aan beofenaars maar nie maklik toeganklik in gedokumenteerde vorm is nie. Dit beklemtoon die behoefte vir 'n verskuiwing in die praktyk kultuur tot die waardering en beloning van die verspreiding van inligting. 'n Beoordeling van die BG herstel sou onvolledig wees sonder 'n doelbewuste oorweging van sosiale faktore. Ek het dus 'n gevallestudie van 'n indringerplant verwyderings program uitgevoer om vas te stel wat die gebruik van wetenskaplike bewyse in besluitneming aandryf. Ek het opgemerk dat die organisatoriese struktuur, beleid, prioriteite en kapasiteit die gebruik van wetenskaplike bewyse kan beinvloed, en selfs beperk. Die uitdagings om herstelwerk bewys-gebaseerd te maak is uiteenlopend van aard, dit wissel van swak beplanning van herstel werk, wat dui op beperkte waardering van die behoefte om 'n sterk bewyse basis te produseer, 'n gebrek aan instrumente en aansporings vir die generasie van besyse, verspreiding en gebruik van bewyse wat strek oor beide die biofisiese en maatskaplike aspekte van die restaurasie. Hierdie uitdagings is grootliks gegrond op die konvensionele manier van restaurasie wat gebaseer is op individuele dissiplinêre perspektiewe,wat lei tot die kunsmatige simplifiseering van ‘n uiteraand komplekse problem soos agteruitgang. Ek eindig af deur die gebruik van transdissiplinariteit, wat fokus op 'n holistiese wêreldbeskouing en die produksie en kennis van kompleksiteit insluit voor te stel, as 'n moontlike voertuig om die skuif in praktyk van restourasie na n bewys-basis te vergemaklik.

Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2006. / Using the World Conservation Union’s (formerly the International Union for the Conservation of Nature) IUCN 2001 categories and criteria, the conservation status of the South African butterfly fauna has been reassessed. This study includes an assessment of the 62 globally threatened South African taxa and 1 that has a marginal distribution in this region.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The agricultural industry in South Africa is dominated by the use of insecticides. Producers rely heavily on chemicals that cause increased risk to health, the environment and ecology, rapid resistance development in key insect pests and pesticide residues on crops. The increased concern regarding the impact of these pest management practices on the environment and alternative pest management strategies are being investigated. Entomopathogenic nematodes (EPNs) have been identified as being promising biological control agents of key insect pests. The two EPN genera that have shown promise for use as biological control agents within an integrated pest management programme areSteinernema and Heterorhabditis. Commercialisation and the successful use of EPNs to control pests in North America, Australia, Europe and Asia have confirmed the effectiveness of these organisms as biological control agents. Unfortunately, EPNs in large enough numbers for commercial field applications are not yet available on the South African market. Large numbers of EPNs can be produced through either in vivo or in vitro culturing practices. The objective of this study was to streamline the in vivo production process by using two endemic EPN species, Heterorhabditis zealandica (SF41) and H. bacteriophora (SF351). These EPN isolates have been shown to be effective control agents of codling moth Cydia pomonella, false codling moth Thaumatotibia leucotreta, obscure mealybug Pseudococcus viburni, and the banded fruit weevil Phlyctinus callosus. A comparative study was conducted to identify suitable host insects for EPN production of local H. zealandica (SF41) and H. bacteriophora (SF351) strains. Hosts were selected according to their susceptibility to the two EPN species used, their general availability and the ease and cost of rearing. Wax moth larvae Galleria mellonella (WML) and mealworms Tenebrio molitor (MW) were selected as hosts. In order to produce nematodes of consistent quality, a continuous source of host insects reared on a standardised diet was required. WML and MW were each reared on five different diets in the dark at ±26°C. A superior diet for each host was selected according to the diet that produced, on average, the larvae with the highest body mass within a specific timeframe. The heaviest WML, at an average weight of 0.19 g per larva, were produced on a diet consisting of 118 g wheat flour, 206 g wheat bran, 118 g milk powder, 88 g brewer‟s yeast, 24 g wax powder, 175 ml honey and 175 ml glycerol. The heaviest MW larvae weighed, on average, 0.0154 g per larva, and were produced on a diet consisting of 100% wheat bran. To confirm the hypothesis that a linear relationship exists between the weight of a host and the number of nematodes produced from that host, a study was conducted to determine the number of H. zealandica and H. bacteriophora produced per g of host. WML, MW, codling moth larvae and false codling moth larvae were weighed individually and inoculated with the two nematode species respectively. In addition, nematode production in frozen MW and WML was tested. The number of nematodes harvested from each host was counted, and the average number of nematode progeny produced in each host was calculated. A significant linear correlation between the weight of WML and MW and the number of H. zealandica and H. bacteriophora respectively produced confirmed the hypothesis that nematode production within the specified host increases with an increase in host weight. WML produced the highest number of H. zealandica and H. bacteriophora per g of host (1 459 205 ± 113 670 and 1 898 512 ± 94 355), followed by MW larvae (836 690 ± 121 252 and 414 566 ± 67 017). Lower numbers of H. zealandica and H. bacteriophora per g codling moth (57 582 ± 10 026 and 39 653 ± 8 276) and per g false codling moth (192 867 ± 13 488 and 97 652 ± 23 404) were produced. Successful infection of a suitable insect host is one of the key factors in an efficient in vivo nematode production process. Three inoculation techniques were compared using H. zealandica and H. bacteriophora: inoculation with a pipette; shaking of hosts in the nematode inoculum; and immersion of hosts in the nematode suspension. With each inoculation technique, WML and MW were used as host larvae and were inoculated with nematodes at a concentration of 200 infective juveniles (IJs) / larva. The percentage mortality of insect hosts was determined after two days, and EPN infectivity, confirmed by colour change and dissection, after seven days. The highest percentage EPN infection was obtained using pipetting for both nematode isolates and hosts. Nematode infection rates for all nematode-host combinations obtained with pipetting were above 90%, with the exception of MW inoculation with H. bacteriophora, where the percentage of infection obtained was 76%. The current study conclusively demonstrated that variations in infection levels occur, depending on the inoculation technique used. In an additional effort to enhance infectivity during inoculation, H. zealandica, H. bacteriophora and MW were subjected to host-stressor regimes and to nematode- infectivity-enhancing additives. Three treatments, plus a control treatment, were compared. Exposing MW to 70°C tap water prior to inoculation did not increase infection levels. On the contrary, reduced infection levels were observed with host immersion in 70°C tap water followed by inoculation with H. bacteriophora, compared to the control. Only 12% infection was obtained compared to the 48% infection achieved in the control. Infection obtained using H. zealandica was 21%. Treating H. zealandica and H. bacteriophora IJs withMn2+SO4.H20 in a suspension, prior to inoculating MW, did not significantly enhance nematode virulence. Inoculation of MW with treated H. zealandica IJs led to an infection rate of 81%, compared to the control, with which 80% infection rate was obtained. Heterorhabditis bacteriophora caused 47% MW infection, compared to the control, which was subject to 48% infection. A combination of the two above-mentioned treatments did not enhance the infection levels either. Immersing MW into 70°C tap water prior to inoculation with nematodes treated with Mn2+SO4.H20 led to infection levels of 13% and 9% respectively when H. bacteriophora and H. zealandica were used. Future research is required to optimise the protocol used in this study of subjecting MW and local nematode isolates to stressor regimes. The ability of two formulations to maintain biological activity and virulence of H. zealandica was investigated. A quality standard control measure was used to measure the percentage survival and virulence of formulated H. zealandica over a period of 21 days. IJs were formulated into Pesta granules and coconut fibres, while nematodes stored in tap water served as the control. The numbers of live H. zealandica in Pesta granules and coconut fibres decreased drastically after seven days of storage. The survival of nematodes in Pesta granules dropped to 9.79% after 21 days compared to the control, where the survival rate was 79.79%. Nematode survival in coconut fibres was even lower, at 25.84% after seven days and 2.25% after 21 days. After 21 days in storage, 100%+of nematodes survived in the control for coconut fibres. The application of the standard quality control measure, which was used to determine the virulence of formulated H. zealandica, proved to be ineffective. Higher MW mortality rates were obtained in the control where no nematodes were added to larvae, compared to where nematodes were added in varying dosages. However, adjusting certain aspects in the protocol of this quality control measure specifically to accommodate local conditions could possibly make it a more effective tool for measuring endemic nematode virulence. / AFRIKAANSE OPSOMMING: Die landboubedryf in Suid-Afrika word oorheers deur die gebruik van insekdoders. Vervaardigers steun swaar op chemikalieë wat toenemend gesondheids-, omgewings- en ekologiese risiko's, asook die snelle ontwikkeling van weerstand in sleutelinsekteplae veroorsaak, en wat reste van plaagdoders op gewasse laat. Na aanleiding van toenemende besorgdheid oor die impak van hierdie plaagbestuurspraktyke op die omgewing, word alternatiewe plaagbestuurstrategieë ondersoek. Entomopatogeniese nematodes (EPNs) is geïdentifiseer as belowende biologiese beheeragente van sleutelinsekteplae. Die twee EPN genera wat belofte inhou vir gebruik as biologiese beheeragente binne 'n geïntegreerde plaagbestuursprogram is Steinernema en Heterorhabditis. Kommersialisering en die geslaagde gebruik van EPNs om insekplae te beheer in Noord-Amerika, Australië, Europa en Asië, het die doeltreffendheid van hierdie organismes as biologiese beheeragente bevestig. Ongelukkig is EPNs in groot genoeg getalle vir kommersiële aanwending in die veld nog nie op die Suid-Afrikaanse mark beskikbaar nie. Groot getalle EPNs kan deur in vivo en in vitro teling verkry word. Die doelwit van hierdie studie was om die in vivo produksieproses te stroomlyn deur die gebruik van twee endemiese EPN spesies, Heterorhabditis zealandica (SF41) en H. bacteriophora (SF351). Hierdie EPN isolate is deur navorsing bewys om doeltreffende beheeragente van kodlingmot Cydia pomonella, vals kodlingmot Thaumatotibia leucotreta, ligrooswitluis Pseudococcus viburni, en gebande vrugtekalanders Phlyctinus callosus te wees. 'n Vergelykende studie is gedoen om geskikte gasheerinsekte vir EPN produksie van plaaslike H. zealandica (SF41) en H. bacteriophora (SF351) isolate te vind. Gashere is geselekteer op grond van vatbaarheid vir die EPN spesie wat gebruik word, en algemene beskikbaarheid en gemak en koste van teling. Wasmotlarwes Galleria mellonella (WML) en meelwurms Tenebrio molitor (MW) is as gashere gekies. Ten einde nematodes van konsekwente kwaliteit te teel, word 'n deurlopende bron van gasheerinsekte benodig wat op 'n gestandaardiseerde dieet voed. WML en MW is onderskeidelik op vyf verskillende diëte geteel by ±26°C in die donker. Die beste dieet vir elke gasheer is gekies op grond van die dieet wat, gemiddeld, die swaarste larwes binne 'n spesifieke tydsraamwerk opgelewer het. Die swaarste WML, teen 'n gemiddelde massa van 0.19 g per larwe, is geteel op 'n dieet wat bestaan het uit 118 g koringmeel, 206 g semels, 118 g melkpoeier, 88 g brouersgis, 24 g verpoeierde was, 175 ml heuning en 175 ml gliserol. Die swaarste MW larwes het gemiddeld 0.0154 g per larwe geweeg en is geteel op 'n dieet van 100% semels. Ten einde die hipotese te bevestig dat 'n lineêre verwantskap bestaan tussen die massa van 'n insekgasheer en die aantal nematodes wat deur daardie gasheer geproduseer word, is 'n studie gedoen om die aantal H. zealandica en H. bacteriophora per gasheergram te bepaal. WML, MW, kodlingmotlarwes en vals kodlingmotlarwes is individueel geweeg en met infektiewe larwes van die twee onderskeidelike EPN spesies geïnokuleer. Daarbenewens is die vermeerdering van nematodes in bevrore MW en WML ook getoets. Die aantal nematodes wat in elke gasheer geoes is, is getel, en die gemiddelde nematode-afstammelinge in elke gasheer bereken. 'n Beduidende lineêre korrelasie tussen die massa van WML en MW en die aantal H. zealandica en H. bacteriophora wat onderskeidelik geproduseer is, het die hipotese bevestig dat nematode-vermeerdering binne hierdie gashere toeneem namate die gasheermassa toeneem. WML het die meeste H. zealandica en H. bacteriophera per gasheergram opgelewer (1 459 205± 113 670 en 1 898 512± 94 355 onderskeidelik), gevolg deur MW larwes (836 690± 121 252 en 414 566± 67 017 onderskeidelik). Laer getalle H. zealandica and H. bacteriophora per gram kodlingmot (57 582 ± 10 026 en 39 653 ± 8 276) en per gram vals kodlingmot (192 867 ± 13 488 en 97 652 ± 23 404) is egter geproduseer. Een van die sleutelfaktore vir die doeltreffendheid van die in vivo vermeerdering van nematodes is geslaagde gasheerinfeksie. Drie inokulasietegnieke is dus geëvalueer en vergelyk deur H. zealandica en H. bacteriophora te gebruik: inokulasie met 'n pipet, skud van gashere in 'n nematode-inokulum, en gasheerindompeling in 'n nematode-suspensie. WML en MW is as gashere gebruik vir elke inokulasietegniek, en is geïnokuleer met nematodes wat uit 'n konsentrasie van 200 infektiewe larwes (ILs) / insek larwe bestaan het. Die persentasie dooie insekgashere is na twee dae bepaal, en infeksie soos bevestig deur kleurverandering en disseksie, na sewe dae. Die hoogste persentasie infeksie deur sowel nematode-isolate as gashere te gebruik, was met die pipet-tegniek. Die infeksiekoerse vir alle nematode-gasheerkombinasies met die pipet-tegniek was hoër as 90%, met die uitsondering van MW-inokulasie met H. bacteriophora, waar die infeksie 76% was. Hierdie studie toon dat afwykings voorkom in die mate van gasheerinfeksie, na gelang van die inokulasietegniek wat gebruik is. In 'n bykomende poging om infeksie na inokulasie te verhoog, is H. zealandica, H. bacteriophora en MW onderwerp aan stressors en bymiddels om nematode-infeksie te bevorder. Drie behandelings, asook 'n kontrole-behandeling, is vergelyk. Infeksievlakke het nie verhoog deur MW voor inokulasie aan kraanwater van 70°C bloot te stel nie. Inteendeel, laer infeksievlakke is opgemerk waar gashere in kraanwater van 70°C gedompel is en daarna met H. bacteriophora geïnokuleer is, vergelyke met die kontrole. Gasheerinfeksie van slegs 12% is verkry, vergelyke met 48% in die kontrole. Infeksie van 21% is met H. zealandica verkry. Die virulensie van nematodes het nie beduidend toegeneem deur H. zealandica en H. bacteriophora IL in 'n suspensie met Mn2+SO4H20 te behandel voor MW geïnokuleer is nie. Inokulasie van MW met behandelde H. zealandica IL het tot 'n infeksie van 81% gelei, vergelyke met die kontrole waar 'n infeksie van 80% behaal is. H. bacteriophora het 'n MW-infeksie van 47% veroorsaak, vergelyke met die kontrole se infeksiekoers van 48%. 'n Kombinasie van die twee bogenoemde behandelings het eweneens nie gasheerinfeksievlakke verhoog nie. Die indompeling van meelwurms in kraanwater van 70°C voor inokulasie met nematodes wat met Mn2+SO4H20 behandel is, het tot gasheerinfeksie van 13% en 9% onderskeidelik gelei wanneer H. bacteriophora en H. zealandica gebruik is. Toekomstige navorsing is nodig om die protokol te verbeter wat in hierdie studie gebruik is om MW en plaaslike nematode-isolate aan stressors te onderwerp. 'n Ondersoek is gedoen na die vermoë van twee formulasies om biologiese aktiwiteit en virulensie van H. zealandica te onderhou. 'n Kwaliteitsstandaardtegniekis gebruik om weekliks die persentasie oorlewing en virulensie van geformuleerde H. zealandica oor 'n tydperk van 21 dae te meet. IL is in Pesta korrels en klappervesel geformuleer, terwyl nematodes in kraanwater gedien het as kontrole. Die aantal lewende H. zealandica in Pesta korrels en klappervesel het drasties verminder na sewe dae in die formulasie. Oorlewing van nematodes in Pesta korrels het gedaal tot 9.79% na 21 dae vergyleke met die kontrole, waar 79.79% oorleef het. Nog minder nematodes - 25.84% - het na sewe dae in die klappervesel oorleef, en slegs 2.25% na 21 dae. Na 21 dae van berging het 100%+ van nematodes oorleef in die kontrole vir klappervesel. Die toepassing van die kwaliteitsstandaardtegniek om die virulensie van geformuleerde H. zealandica te bepaal, het ondoeltreffend geblyk. Verhoogde MW sterftesyfers is verkry in die kontrole waar geen nematodes by die inseklarwes gevoeg is nie, vergelyke met die byvoeging van hoër dosisse nematodes. Nietemin, die aanpassing van sekere aspekte in die protokol van hierdie kwaliteitsbeheermeting om spesifiek plaaslike toestande in ag te neem, sou dit moontlik 'n meer doeltreffende middel kon maak om die virulensie van endemiese nematodes te bepaal.

Thesis (MSc (Conservation Ecology and Entomology))--Stellenbosch University, 2009. / ENGLISH ABSTRACT: An understanding of the interactions of herbivores, plant nutrients and soil properties is crucial for grazing management. Of particular interest are plant palatability and herbivore grazing preferences. These aspects, the focus of this thesis, were studied in a Swartland Shale Renosterveld and Swartland Alluvium Fynbos mosaic in the Western Cape of South Africa. This vegetation is classified as critically endangered due to the transformation of its landscape in favour of agricultural production and urban settlement. Pre-colonial herbivore vertebrates were hunted out by 1700, leading to a sparse knowledge of the early dynamics of the vegetation. However, currently game farmers and landowners are re-introducing selected species into the area. Thus, managers require knowledge on how to implement practical guidelines for best-practice grazing management. This study investigates, firstly, the relationship between plants and animals. This included seasonal assessment of seed germination from dung of bontebok and eland; the effect of stocking rates on plant palatability (crude protein, crude fibre, crude fat, moisture, tannin and mineral) of herbage was studied with the aim to understand how palatability influences herbivore forage decisions. Secondly, this study looked at how stocking rates influence soil nutrients (nitrogen, phosphorus), and others soil properties such as pH and soil moisture. The distribution of alien grasses was facilitated by grazers. About 58 % of grasses germinated from the dung of eland and Bontebok were alien species. Additionally, there was significant variation in palatability related to grazing pressure and plant maturity between sites and over seasons. Grasses on the high grazing site had higher carbohydrate (3%-5% higher) and protein content (1%-5% higher) than at the least grazed site. Mature grasses contained less water (10%-20%), but no obvious variation in tannin concentration than immature grasses. However, species such as Ficinia sp. showed variations with grazing pressure and maturity. Ficinia sp. on the high grazing site had higher tannin concentration (5mg/ml-22mg/ml) and crude protein (4%-9%) than at the least grazed site. When the plant ages, tannin concentration increase (ranging from 15% to19% higher). Two types of plant were recoreded according to their chemical response following grazing pressure. These types are 1) plants that are grazing tolerant and which produce more carbohydrate when grazed and 2) plants that are grazing intolerant under high grazing pressure and which produce chemical defence compounds such as tannin to deter herbivores attacks. The results indicate that in fynbos and renosterveld, the relationship between preference and plant chemical compounds is not consistent since no IV patterns emerged to explain what compounds drive preference. A combination of chemical compounds may be the reason for the selection by the grazers; alternatively, other compounds not included in the study may influence the forage selection by an herbivore. The second part of the study showed that stocking rates appeared to have a significant effect on soil properties investigated. Soil moisture was significantly affected by the stocking rate in autumn. The high grazing intensity site had the lowest soil moisture especially in autumn (10% lower than the control site), likely due to heavy trampling and soil compaction. pH was the lowest at the high grazing intensity site in all seasons compared to the control site. Likely reasons were the high deposition of nitrogen through dung and urine deposition, high removal of basic cations and animal exportation through hunting activities. Lastly, grazing maintains inorganic nitrogen at stable levels regardless of seasonal changes and increases the concentration of phosphorus especially under high grazing pressure compare to less grazed sites. The grazing dynamics of Swartland Shale Renosterveld - Swartland Alluvium Fynbos mosaic system are complex and multifaceted. Farmers need to pay attention to the nutritional status of plant species grazed to know whether they meet the nutritional requirements of the game in the area. Overstocking should be avoided in this system as it triggers the production of tanniferous compounds that could decrease the survivorship of herbivores. Moderate grazing 0.09 LAU/ha pressure provides the best stocking rates for effective grazing management. / AFRIKAANSE OPSOMMING: Vir suksesvolle weidingsbestuur is dit noodsaaklik om die interaksie tussen herbivore, plantvoedingstowwe en grondeienskappe te verstaan. Van besondere belang is plantsmaaklikheid en herbivore se weidingsvoorkeure. Hierdie aspekte, wat die fokus van hierdie tesis is, is bestudeer in ‘n Swartland Shale Renosterveld en Swartland Alluvium Fynbos-mosaïek in die Wes-Kaap Provinsie van Suid-Afrika. Hierdie plantegroei word as kritiek bedreigd geklassifiseer weens die transformering van sy landskap ten gunste van landbou-aktiwiteite en stedelike vestiging. Pre-koloniale herbivoor vertebrata is teen 1700 deur jagters uitgeroei, wat gelei het tot min kennis oor die vroeë dinamiek van die plantegroei. Wildsboere en grondeienaars is egter besig om geselekteerde spesies in die area te hervestig. Bestuurders moet dus weet hoe om praktiese riglyne vir beste-praktyk weidingsbestuur te implementeer. Hierdie studie ondersoek eerstens die verhouding tussen plante en diere. Dit sluit seisoenale evaluering van saadontkieming uit die mis van bontebokke en elande in; die effek van veegetalle op plantsmaaklikheid (ruproteïen, ruvesel, ru-vet, vogpeil, tannien en minerale) van die weiveld is bestudeer om vas te stel hoe plantsmaaklikheid herbivore se weidingsbesluite beïnvloed. Tweedens het die studie die invloed van veegetalle op grondvoedingstowwe (stikstof, fosfor) ondersoek, asook ander grondeienskappe soos pH en grondvogpeile. Die verspreiding van uitheemse grasse is deur weidende diere gefassiliteer. Ongeveer 58% van alle grasse wat uit die mis van elande en bontebokke ontkiem het, was uitheemse spesies. Verder was daar beduidende variasie in plantsmaaklikheid verwant aan beweidingsdruk en plantvolwassenheid tussen verskillende persele en oor seisoene. Grasse op die hoogs beweide persele het 3%-5% hoër koolhidraatinhoude en 1%-5% hoër proteïeninhoude gehad as die minder beweide persele. Volwasse grasse het 10%-20% minder water bevat as onvolwasse grasse, maar het nie in terme van tannienkonsentrasie van die onvolwasse grasse verskil nie. Spesies soos Ficinia sp. het variasies getoon met beweidingsdruk en volwassenheid. Ficinia sp. het op die hoog-beweide perseel ‘n hoër tannienkonsentrasie (5mg/ml-22mg/ml) en meer ruproteïen (4%-9%) gehad as op die minste beweide perseel. Wanneer die plant verouder, verhoog die toename in tannienkonsentrasie (met tussen 15% en 19%). Twee tipes plante is aangeteken volgens hul chemiese response ná beweidingsdruk. Hierdie tipes is 1) plante wat beweidingstolerant is en wat meer koolhidrate produseer wanneer hulle as weiding dien en 2) plante wat onder hoë beweidingsdruk beweidingsintolerant is en wat chemiese verbindings VI soos tannien produseer om herbivooraanvalle af te weer. Die resultate dui aan dat die verhouding tussen voorkeur en plante se chemiese verbindings nie konstant bly in fynbos en renosterveld nie, aangesien geen patrone na vore getree het wat kon verklaar watter verbindings bepalend is vir voorkeur nie. ‘n Kombinasie van chemiese verbindings mag die rede wees waarom die herbivore sekere plante verkies; alternatiewelik mag ‘n herbivoor se plantseleksie beïnvloed word deur chemiese verbindings anders as dié wat in hierdie studie ondersoek is. Die tweede deel van die studie het aangetoon dat veegetalle blyk ‘n beduidende invloed te hê op die grondeienskappe wat ondersoek is. Grondvogpeile is in die herfs beduidend beïnvloed deur die veegetalle. Die perseel met die hoë beweidingsintensiteit het die laagste grondvogpeil gehad, veral in die winter (10% laer as dié van die kontrole-perseel), waarskynlik weens erge getrappel en grondkompaktering. Vergeleke met die kontrole-perseel was pH die laagste op die perseel met die hoë beweidingsintensiteit, in alle seisoene. Waarskynlike redes hiervoor is die hoë neeerslag van stikstof deur mis- en uriene-neerslae, hoë verwydering van basiese katione en dierevervoer wat deur jagaktiwiteite teweeg gebring word. Laatstens behou weiding anorganiese stikstof teen stabiele vlakke ongeag van seisoenale veranderinge en toenames in die konsentrasie van fosfor, veral onder hoë beweidingsdruk vergeleke met minder beweide persele. Die weidingsdinamiek van die Swartland Shale Renosterveld - Swartland Alluvium Fynbosmosaïeksisteem is kompleks en veelvlakkig. Boere behoort aandag te skenk aan die voedingstofstatus van die plantspesies wat as weiding dien, sodat hulle kan weet of die voedingsbehoeftes van die wild in die omgewing bevredig word. Die aanhou van te veel vee in hierdie sisteem behoort vermy te word aangesien dit as sneller dien vir die produksie van tannienbevattende verbindings wat die oorlewingsvermoë van herbivore kan verlaag. Matige beweidingsdruk (0.09 LAU/ha) bied vir effektiewe weidingsbestuur die beste veegetalle.

Thesis (PhD (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / Dispersal plays an essential role in determining the distribution of populations of species, especially species expanding their ranges. Two disciplines are concerned with gaining understanding of spread of species, namely restoration ecology and invasion biology. Con- ceptual understanding of dispersal, its mechanisms and its management is essential to both disciplines. Nevertheless, the disciplines have quite opposite objectives: in restoration ecol- ogy, spread of indigenous species into transformed landscapes is promoted, while invasion biology aims to prevent the (further) spread of alien species into pristine or restored habi- tats. Despite these two opposite objectives of facilitating spread and preventing spread of their respective target species, these disciplines have essentially the same requirements in terms of information needed for restoration. In this thesis, I will present two modelling studies—one looking at the impact of two different seed-feeding alien control agents on the spread of Hakea sericea, the other investigating the recolonisation by Dicerothamnus rhinocerotis of an old field dominated by Cynodon dactylon. Based on these studies, I will draw conclusions for the management in each case. In a second step, I will compare these two seemingly-different studies and draw conclusions on how these two disciplines can learn from each other, and how conclusions drawn and management recommendations developed for the one discipline can be translated for the other. The invasion biology study concluded that seed-feeding biocontrol agents do have a considerable impact on the velocity of the spread of the target species. In addition, management recommendations included the possibility of substituting seed-feeding biocontrol agents with an increased fire frequency where the negative impact on natural vegetation, on the site invaded by the target species, is acceptable. The restoration study concluded that the main impact on the velocity of spread, and the speed of the return of the shrub species onto the old fields, is the availability of micro-sites. A sensitivity analysis showed the even a slight change from 1% to 2% increases the velocity and pattern of spread dramatically. The other parameters playing an important role are the mean rate of establishment and the time span between

Thesis (PhD (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / The Okavango Delta, Botswana, is a unique ecosystem and this is reflected in its extraordinary biodiversity. The Nile crocodile (Crocodylus niloticus Laurenti) is the apex predator, and performs a number of vital functions in this system, making it a keystone species. The panhandle crocodile population has declined significantly over the last 80 years and is now threatened as a result of past over-exploitation and present human disturbance. In order to effectively conserve this species and in turn the health of this important region it is imperative to gain an understanding of their ecology and population dynamics. The population status of the Nile crocodile in the panhandle region of the Okavango Delta, Botswana, was assessed using a combination of capture-mark-recapture surveys, spotlight surveys and aerial surveys. The capture-mark-recapture experiment was conducted continuously from 2002 - 2006. A total of 1717 individuals, ranging in size from 136 mm – 2780 mm SVL, were captured, of which 224 animals were recaptured. Using a Bayesian technique, the total annual population in the panhandle region of the Okavango Delta was estimated to be 2 570 ± 151.06 individuals, with an adult population of 649.2 individuals with the number of breeding females estimated to be 364 individuals. It was concluded that this population cannot sustain the further harvest of breeding animals prior to the increase and stabilization of the population. Spotlight counts revealed a decline in the encounter-rate of crocodiles on the Okavango River with time, although more long-term data needs to be collected to confirm this trend. During the low-water season (September - February), 22.34 % of all crocodiles were observed, while during the flood-season only 13.34 % were observed, yielding correction factors for spotlight surveys of 4.46 (low-water) and 7.49 (high-water) for all animals in the panhandle. Two aerial surveys, conducted at the low-water and high-water peaks yielded total estimates of 588 (77.7 % of adults) during the low-water period and 350 (56.7 % of adults) during the high-water period. Correction factors of 1.28 (low-water) and 1.77 (high-water) were calculated for aerial surveys. An annual average of 50 nests was located in the panhandle, representing a 50 - 60 % decrease over the last 20 years. In regions with high human disturbance, breeding females situated their nests in hidden locations, away from accessible channels. Hatchlings exhibited elongation of the jaw in order to capture smaller prey items and morphometric shifts in jaw shape coincided with a dietary change at 400 mm SVL. The jaw became broader and deeper as animals matured, presumably in preparation for larger mammalian prey. The average growth rate of recaptured yearlings was 0.198 ± 0.116 mm.d-1 SVL and was closely correlated to the amount of time an individual spent in above-average water temperatures. Body condition (RCF) was significantly and positively correlated with a rise in water-level and negatively correlated to time spent in above-average water and air temperatures. Average RCF values were intersected when animals had spent 50 % of their time in above-average temperatures and water level. Generally crocodiles in the panhandle showed no significant sex-related differences in their sizes or the distances they travelled. The majority of recaptures (62.5 %) moved less than 500 m from the initial capture site. Adults in the panhandle occupied definite ranges, within which were preferred core areas where the majority of their time was spent. The panhandle crocodile population has declined significantly over the last 80 years, and is now threatened as a result of past over-exploitation and present human disturbance. The management of this population, including both its conservation and sustainable commercial utilisation, requires an adaptive strategy based on accurate monitoring procedures.

Thesis (PhD (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / The Cape Peninsula is an area of outstanding biological importance, having 158 endemic angiosperm species in only 470 km2. The peninsula invertebrates are known to be highly endemic, yet very little else is known about them. This study has four components: (1) ascertaining whether the influence of environmental variables on epigaeic, foliage and aerial invertebrate assemblages of Table Mountain, (2) determinination of the influence of Table Mountain’s fires and land transformation, on the local invertebrate assemblage, (3), identification of areas of conservation priority and influential environmental variables across the entire Cape Peninsula, and (4) determinination whether invertebrate food availability is a restricting factor for the localised and threatened Knysna warbler (Bradypterus sylvaticus), which inhabits the forests on the east side of Table Mountain. Epigaeic, foliage and aerial invertebrates were intensively sampled using a suite of techniques. Sites were chosen to allow for comparisons between vegetation structure and type, elevation and aspect. Vegetation structure and elevation were the most important environmental variables in determining species composition. Fynbos had a higher beta diversity of epigaeic and aerial invertebrates than forests, so the conservation of as much fynbos as possible is needed. The forests had many unique and endemic species, highlighting their conservation importance. As elevation had a strong influence, yet only the higher elevations receive extensive conservation, it is critical to conserve as much of the disturbed and fragmented lower elevations as soon as possible. There was little correlation between the diversity of aerial and epigaeic‐foliage invertebrate assemblages. Thus, the aerial and epigaeic‐foliage invertebrate assemblages need to be assessed separately.

Thesis (PhD(Agric))--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The genus Helicotylenchus Steiner of the family Holplolaimidae is reviewed. The different morphometric and morphological characters used in species description are discussed. Thirty-five species occurring in South Africa, French Guiana and the French Caribbean Islands are redescribed, based on type and other material. A new species, viz. H. marethae n.sp. is described from South Africa. Apart from line drawings SEM micrographs are included for most species. / AFRIKAANSE OPSOMMING: In hierdie monograaf van die genus Helicotylenchus van die familie Hoplolaimidae, word die verskillende morfologiese en morfometriese eienskappe gebruik in spesie beskrywings, bespreek. Vyf-en-dertig van die spesies wat in Suid- Afrika, Frans Guiana en die Franse Karibiese Eilande voorkom word op grond van tipe of ander materiaal herbeskryf. 'n Nuwe spesie H. marethae afkomstig vanaf Suid- Afrika word beskryf. Behalwe vir lyntekeninge word SEM mikrograwe van meeste van die spesies ook gegee.

Thesis (PhD(Agric))--Stellenbosch University, 2012. / The sugarcane borer, Eldana saccharina Walker (Lepidoptera: Pyralidae) is the most limiting factor in the South African sugar industry with losses to this insect pest estimated to be at least ZAR60 million per annum. Because of its cryptic nature as well as the fact that E. saccharina is both indigenous to Africa and occurs on several host plants, attempts to control or eradicate it using several available methods have not been very successful. However, the sterile insect technique (SIT) is one of the newer control methods that can be incorporated into an area-wide integrated pest management (AW-IPM) programme to achieve better control or eradication. The implementation of the SIT program needs to go through a series of well-researched phases in order to be successful. In the first of this multi-phase project, it was determined that E. saccharina is susceptible to ionizing radiation, and is thus a suitable candidate for the SIT development against it and that a sub-sterilizing dose of 200 Gy is sufficient to induce F1(inherited) sterility in male and complete sterility in female moths respectively. The results presented here are discussed in the context of further development of the SIT as an addition to the arsenal of tactics in an AW-IPM programme against E. saccharina. Based on these initial findings, the study examined the lek and mating behavior of male moths subjected to three radiation doses (150, 200, 250 Gy) against normal non-irradiated/fertile moths. Both mass-rearing and irradiation of E. saccharina led to a quantitative departure of male mating behavior away from that exhibited by their wild counterparts. However, treated males are still able to form leks and mate with wild females. Male E. saccharina irradiated at all three doses tested were found to be as active and competitive as wild males, but in some of the traits measured, performance diminished significantly with an increase in the radiation dosage. In general, the performance of moths treated at 200 Gy did not differ significantly from that of moths treated at 150 Gy and therefore the former dose is ideal for SIT development since it results in a lower residual F1 fertility than the latter. The level of mating competitiveness and compatibility was assessed under both laboratory and semi-field conditions in pairwise comparisons consisting of laboratory reared vs. wild (L-W), 200 Gy irradiated vs. wild (S-W) and laboratory reared vs. irradiated moths (L-S). Based on the results from the more robust field cage assays, the mating indices generated indicated that the mass-reared E. saccharina strain produced in South Africa has not yet evolved sexual behaviours suggestive of incipient pre-mating isolation barriers with local wild strains. Wild moths did not discriminate against either the partially sterile or laboratory reared moths and most importantly, the irradiated males mated significantly more than their wild counterparts regardless of the type of female. The irradiated insects could therefore achieve the purpose for which they are intended upon release into the field. Third, the critical thermal limits (CTLs) to activity at high and low temperatures (i.e. critical thermal maxima “CTmax” and minima “CTmin”) of different E. saccharina strains/treatments were investigated under standard experimental conditions. The effect of laboratory rearing and increasing radiation dosage on thermal tolerance of the adult stage of E. saccharina was explored. There were highly significant differences between the laboratory-reared and wild strain and also between non-irradiated and irradiated strains in both CTmax and CTmin. Laboratory reared E. saccharina moths were more heat tolerant compared to wild moths for both genders while in the case of CTmin, the reverse was true. Irradiation had a negative effect on both CTmax and CTmin. Moths treated at the lowest radiation dose were more cold and heat tolerant than those treated at higher dosages thereby reinforcing the importance of lower dosages rather than those that induce full sterility against E. saccharina. In general, gender effects on the CTLs were non-significant. Pilot sterile male releases in shade house trials to measure the impact of sustained releases of partially sterile adult males at an over-flooding moth ratio of 10T: 1U (treated to untreated),were conducted to measure their efficacy to stop E. saccharina incursions and suppress populations prior to testing in pilot studies under true season-long and area wide conditions. Results from the current study demonstrated that releasing partially irradiated (200 Gy) adult male moths at the afore mentioned release rate significantly reduced sugarcane stalk damage as well as lowered the number of fertile progeny from F1to succeeding generations in a stable E. saccharina population initiated in a cage house. There were more damaged internodes per stalk in the control than in the sugarcane receiving regular releases of partially sterile male moths. Overall, there were significantly more undamaged stalks in the treated sugarcane than the untreated control. Furthermore, there were significantly more larvae per stalk retrieved from the control compared to the treated sugarcane suggesting that the sustained release of steriles was efficacious in reducing emergence of fertile larvae in the succeeding generations. The results of this study indicate that there is considerable scope for the SIT against E. saccharina.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The loss and degradation of habitat is recognised as the greatest threat to invertebrate biodiversity. Restoration practices have the potential to reduce these impacts. The Seychelles giant millipede (SGM), Sechelleptus seychellarum, is a threatened and functionally important macro-detritivore endemic to the Seychelles granitic islands. The broad objective of this dissertation was to investigate selected aspects of the restoration ecology of the SGM, with the intention of making practical restoration recommendations that can be used to assist in the conservation of this species. This study was carried out on Cousine Island, Seychelles between 1998 and 2009, in the context of the large-scale plant community restoration that has taken place on the island. Large fluctuations in millipede population densities were found between 1998 and 2009. In 2002, 2003, 2005 and 2007 millipede densities were low, while densities were high in 1998 and 2009. Although the SGM is active all year round, its surface activity was positively correlated with rainfall, with density high during the high rainfall period (i.e. October – April) and low during the low rainfall period (i.e. May – September). Female:male:juvenile ratios were ~ 3:1:1. The implications are that translocations should preferably be done in years of high millipede densities and during the wet season. Alien coconut trees did not affect SGM density, but negatively affected its foraging behaviour, whereas bamboo stands negatively affected both its density and foraging behaviour. The SGM showed feeding preferences for Pisonia grandis and Ficus sp. leaf litter types. Alien bamboo and coconut pose a varied threat to the SGM, and their removal and replacement by indigenous forest species (e.g. P. grandis and Ficus sp.) should form part of an island’s restoration programme. SGM density was an order of magnitude lower in the restored area compared to the natural forest. In contrast, SGM physical condition improved significantly in the restored area, as vegetation structure increased. Furthermore, SGM behaviour in the restored area switched from a predominantly walking to a predominantly feeding behaviour over the study period, resulting in the forest restoration programme on Cousine increasing the foraging area of the SGM by 43%. SGM spatial density did not significantly correlate with edaphic and litter properties, but did positively correlate with the toposcape (i.e. elevation and granitic rock cover). Granite rock crevices in forest covered areas were important diurnal refuges for the SGM, as microclimate conditions in non-forest covered rock refuges were unsuitable. SGM physical condition was significantly lower in non-shaded crevices compared to those shaded by forest. Low granite rock cover in the restored forest limited the SGM colonisation of this area in large numbers, despite canopy cover in the restored forest being comparable with that in the reference natural forest. As most restoration practices are primarily vegetation-based, this study demonstrates that such an approach can be inadequate for restoring habitat for target invertebrates, as many species’ habitat requirements extend beyond that of vegetation. For the SGM, selecting restoration sites that already have abundant rock cover would be the most practical way to increase SGM habitat through forest restoration practices. Taking into consideration the habitat requirements of target invertebrates can help in setting or redirecting restoration goals and thus enhance the conservation value of such practices. / AFRIKAANSE OPSOMMING: Die verlies en agteruitgang van habitat word alom beskou as die grootste bedreiging var die biodiversiteit van ongewerweldes. Herstellingspraktyke kan hierdie agteruitgang verminder of stop. Die Seychelle Reuse Duisendpoot (SGM), Sechelleptus seychellarum, is 'n bedreigde en funksioneel belangrike makro-detritusvoeder wat endemies is aan die Seychelle graniet-eilande. Die breë doelstelling van hierdie verhandeling is die doen van navorsing om praktiese aanbevelings te kan maak om die habitat van die SGM tot so ‘n mate te herstel dat die spesie kan bly voortbestaan. Hierdie studie is tussen 1998 en 2009 uitgevoer op Cousine Island, Seychelles, nadat ‘n grootskaalse herstellingsfase van die plantgemeenskap plaasgevind het. Groot skommelings in duisendpootgetalle is waargeneem tussen 1998 en 2009, viz. duisendpootgetalle was laag in 2002, 2003, 2005 en 2007, terwyl dit hoog was in 1998 en 2009. Alhoewel die SGM gedurende die hele jaar aktief is, is hulle tog in groter getalle aanwesig in die tydperke met hoë reënval (Oktober-April) en laag in die droë tydperk (Mei-September). Die verhouding van wyfies, mannetjies en onvolwassenes was deurgaans ~ 3:1:1. Dit bring mee dat hervestiging van SGM verkieslik gedoen moet word wanneer hul populasies hoog is en dan ook in die nat seisoen. Uitheemse klapperbome het geen invloed op SGM getalle gehad nie, alhoewel hul voedingsgedrag negatief beïnvloed is deur dié bome. Bamboesbosse darenteen, beïnvloed beide populasiedigtheid en voedingsgedrag van SGM negatief. Verder is daar gevind dat Pisonia grandis en Ficus sp. blaardetritus voorkeurvoedsel vir SGM is. Die verwydering van die uitheemse bamboes en klapperbome en vervanging daarvan met inheemse woudspesies (P. grandis en Ficus sp.) moet dus deel vorm van die eiland se herstelprogram om sodoende die SGM te bevoordeel. Die SGM-bevolkingsdigtheid was 'n grootte-orde laer in die herstelde gebied in vergelyking met die natuurlike bos, maar hul fisiese toestand het aansienlik verbeter in die herstelde gebied, waarskynlik omdat die plantegroei as geheel verbeter het. Verder het die SGM se gedrag gedurende die studietydperk in die herstelde area oorgegaan vanaf ‘n oorwegend loopgedrag om na kos te soek, na ‘n oorwegend voedende gedrag. Die vervanging van uitheemse- met inheemse boomspesies op Cousine Island het dus die voedingsarea van SGM met tot 43% verhoog. Die ruimtelike SGM populasiedigtheid is nie beduidend beïnvloed deur blaardetritus nie, maar is wel positief beïnvloed deur die topografie (hoogte en granietbedekking). Bebosde graniet rotsskeure bied belangrike toevlugsoorde vir SGM gedurende die dag, terwyl die mikroklimaat wat deur onbebosde rotsskeure veroorsaak word, totaal ongeskik is vir SGM. Die fisiese toestand van SGM was ook aansienlik swakker in die nie bebosde rotsskeure teenoor dié van die bebosde areas. In herstelde bos met min granietskuiling was die herkolonisering van SGM ook getalsgewys laer alhoewel die bosbedekking vergelykbaar was met dié van die inheemse bos. Dit bewys dus dat herstellingspraktyke wat hoofsaaklik plantegroei teiken, nie altyd die teikenspesie bevoordeel nie, maar dat ‘n meer holistiese benadering wat alle habitatvoorkeure in ag neem, toegepas moet word. Om SGM te bevoordeel moet herstel areas vir herbebossing dus gekies word waar daar reeds genoegsame granietskuiling is. Deur die habitatvereistes van ongewerwelde teikenspesies in ag te neem kan die herstellingspraktyke meer oordeelkundig ingestel word en sodoende kan die bewaringswaarde van sulke praktyke verbeter word.