An in depth review is given of Host Plant Resistance research on borers in general, and on B. fusca in particular. The general biology and economic importance of B. fusca are also discussed. Several aspects of the general methodology of breeding for resistance to B. fusca are discussed. These topics include collection of overwintering larvae, termination of diapause, field infestation methodology and damage assessment. Approximately 20 first instar larvae were applied to the plant whorl when plants were about 30 - 40 cm tall. The primary method of damage assessment was to evaluate leaf damage on a 1 to 5 scale. Further criteria for selection of resistant germplasm are assessment of stunting due to stem boring and yield at harvest. The effect of plant resistance on B. fusca was investigated. There were clearly defined differences in leaf damage evident between different maize genotypes. Heritability of this resistance was demonstrated, and presumed to be an additive mechanism that reduced insect feeding, indicating antibiosis. There were significant differences between the number of larvae recovered from whorl tissue of different cultivars. This was ascribed to two resistance mechanisms exerting their effects within the first few days' feeding by larvae. One mechanism was short lived, but effective, antibiosis resulting in larval death, while the other, also short lived, was repellence, resulting in larval migration. Both mechanisms resulted in fewer larva feeding in the plants. Another longer lasting resistant mechanism affected larval growth and mass gain, resulting in smaller larvae. These mechanisms were found to be heritable traits. Differences in levels of resistance affecting larval mass gain were also determined for various parts of the tassel. For all inbreds, the peduncles were more susceptible than the tassel Cultivars also differed in the levels of resistance in the stern tissue. Resistance in leaf tissue did not necessarily mean that resistance occurred in the stern of that genotype. Some cultivars had resistance mechanisms present in both leaves and sterns, some had only one resistance mechanism in either part, and some were totally susceptible. The effect of the borer on the plant was investigated. Leaf damage was found to not be of any consequence, but severe stern damage caused extensive yield losses. There was good correlation between leaf damage and stern damage. Yield loss was most pronounced in longer season hybrids than in quick maturing hybrids. Methodologies utilized in the development of inbreds, populations and hybrids are discussed. It was concluded that borer resistant hybrids do have a place in the commercial market. However their performance under conditions of low or no infestation must be similar to that of other susceptible hybrids because control measures for B. fusca are not excessively expensive. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1989.

The focus of this study is the effect of environmental conditions on the social relationships among females in a free-ranging troop of chacma baboons (Papio cynocephalus ursinus), in a southern woodland habitat. The female dominance hierarchy, rank related differential costs and benefits to individuals, and the nature of special relationships between females, were followed. The study was conducted for a total of 18 months during three years, at Mkuzi Game Reserve, Zululand, South-Africa. The study troop occupy a rich woodland habitat with abundant food resources. Visibility under these conditions is poor and the baboons are subjected to leopard predation. Intra-troop competition for food among female primates and its effect on lifetime reproductive success, has been widely stressed to be a major cost for low ranking females. No evidence of competition for food was found among females at Mkuzi. It is suggested that the main cause for mortality may be predation by leopards, and that females compete mainly over a safe spatial position. The following characteristics of female sociality at Mkuzi may support this suggestion: 1. While no indication of rank related feeding behaviour, reproductive success, or 'attractiveness' to others was found, the higher ranking females had more access to central, and thus better protected, spatial positions in the troop. 2. The importance of social associations among females at Mkuzi seems to lie in mutual grooming and protection from predation by the vicinity to each other, and not in coalitionary support. Female associates were thus not necessarily adjacent ranking and probably not kin. 3. Although female dominance hierarchy was usually stable, the lowest ranking adult female has promoted her rank independently, following the disappearance of her only female associate and during her pregnancy, when she was probably subjected to high risk of predation. 4. Following troop fission, most females chose to improve their own rank position by adopting the AYS strategy (Abandon Your immediate Superior in rank), rather than joining associates. It is suggested that the resident males were responsible for the initiation of troop fission, in order to decrease the high cost of sexual competition to them, by reducing the number of males in each daughter troop. High intensity of competition between males was the result of the high female reproductive success. Risk of predation, and therefore the cost to individual females, increased after fission. This study may present an additional accumulating behavioural evidence on adaptations environmental conditions. the of flexibility primates example to of social and to various environmental conditions. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1993.

Forest assemblage composition is determined by local ecological (e.g. patch area, species interactions), landscape (e.g. patch connectivity) and regional (e.g. historical change in forest distribution) processes. I investigated the relative effect of these processes on bird and frog assemblage composition in two isolated archipelagos of Afrotemperate forest in the Limpopo Province. The linear relationship between local and regional species diversity suggests that forest bird assemblages in the Limpopo Province are unsaturated. In addition, 66% of bird species and 42% of frog species in southern African forests are generalist species (i.e., forest associated as opposed to forest dependent), suggesting that matrix species have invaded forest assemblages. I thus argue that forest bird and frog assemblage composition is primarily determined by regional (historical) processes and that local ecological processes play a relatively minor role. Forests in the Limpopo Province were eliminated by major climatic changes during the Quaternary with major forest expansion only in the last 6000 years. Limpopo Province forest assemblages have thus established fairly recently. No forest dependent frogs and one forest dependent bird have established in the Limpopo Province forests from the relatively proximate forests in eastern Zimbabwe. This suggests that the Limpopo River catchment has acted as a significant barrier to the dispersal of forest vertebrate faunas. Cluster analyses showed that the forest bird and frog assemblages are essentially Afrotemperate and South African in origin with all forest dependent frogs and 97% of forest dependent birds occurring in the KwaZulu-Natal scarp forests. In addition the most important environmental gradient of change in the southern African forest bird faunas was the geographical distance from northern KwaZulu-Natal. This gradient is congruent with a major northward radiation of faunas from the KwaZulu-Natal scarp into the Limpopo Province. As a result the Limpopo Province forests have low biodiversity values compared to the KwaZulu-Natal scarp because forest frog and bird faunas are largely derived from the latter region. However, the importance of the Limpopo Province forests lies in their protection of threatened vertebrates as well as in providing landscape heterogeneity and ecological services to the surrounding matrix. Soutpansberg forest bird assemblages appear to be more robust and resilient and comprise a significantly greater proportion of forest associated species than those of the Limpopo Province Drakensberg. This is likely to be a consequence of more severe climatic extinction filtering of these faunas caused primarily by the proximity of the Soutpansberg forests to the arid Limpopo valley during the development of these forests. Consequently, regional and historical processes have played a relatively greater role in determining forest bird assemblages in the Soutpansberg than in the Limpopo Province Drakensberg and species richness in the former region was not significantly affected by local ecological processes (including forest area, isolation and habitat heterogeneity). Forest area and habitat heterogeneity did, however, affect forest bird species richness and abundance in the Limpopo Province Drakensberg where the relatively lower importance of regional processes (compared to the Soutpansberg) has combined with anthropogenic disturbance of smaller forests to increase the influence of local ecological processes. However, the role of local processes in determining local species richness is likely to increase in both archipelagos if the current rates of anthropogenic change and disturbance to forests are sustained. Forests greater than 138 ha (minimum critical patch size) are needed to avoid an island effect on bird species richness in the Limpopo Province Drakensberg. However, the long-term conservation of vertebrate assemblages in Limpopo province forests depends upon the successful conservation of evolutionary and landscape processes. This can best be achieved by maximising forest connectivity and landscape heterogeneity through the protection of both riparian corridors and forests of all sizes. The maintenance of historical dispersal routes, in particular connectivity along the escarpment with the scarp forests of KwaZulu-Natal, is important. This would require the protection of forests on the KwaZulu-Natal scarp and along the entire northern Drakensberg escarpment. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

One of the major costs of group living is increased competition due to social information. Social information allows foragers to gain information about the location and the quality of food patches from observing other group members. Ultimately, this allows social foragers to use resources more efficiently. However, the distribution and quality of food varies both spatially and temporally and social information may result in aggregations of foragers around favourable food patches when they are available. This results in individuals of various dominance ranks aggregating around food resources and competing for food. In order to understand how dominance and patch quality interact to determine foraging behaviour, various foraging models have been created. In particular, producer-scrounger social foraging models are used to understand foraging behaviour and patch choice under competitive conditions. In producer scrounger games, individuals can either find their own food patches (produce) or join other individuals at food patches (scrounge). This study focused on how the combination of patch holder dominance status and patch quality interacts to influence patch joining decisions by scroungers. According to producer-scrounger models scroungers only join patches held by subordinate individuals. However, I found that a scrounger will join any patch as long as the patch holder is not within the top five most ranked individuals in the herd. However, as patch quality increased, fewer of the top ranked patch holders were avoided at each patch quality. This suggests that foraging is a trade-off between the costs of an aggressive interaction and the benefits gained from each patch. Behavioural titrations found that the initial density of food at a patch needs to be 2.3 times greater for a scrounger to feed from the next dominant patch holder. At high patch qualities there was a threshold point where patch quality became the driving force behind patch joining decisions and no patch holders were avoided, no matter their dominance status. Scroungers that fed from the top ranked patch holders had the same intake rate when compared with feeding with subordinate patch holders. This could be due to an increased level of vigilance by the scrounger in order to avoid an aggressive interaction with the dominant patch holder. However, scrounger’s intake rate increased when they fed from dominant patch holders that were not the top ranked herd members. This suggests that only the top ranked herd members are aggressive enough to prevent scrounging attempts. A novel discovery of this study was that although the goats formed a linear dominance hierarchy, they did not forage in accordance with it, with lower ranking individuals avoiding dominant patch holders. This suggest that in social herbivores dominance hierarchies are not maintained to determine who has priority access to food. This study shows that even large differences in dominance are not sufficient enough to prevent scrounging decisions and only the top ranked patch holders have the ability to prevent joining attempts. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Cousine Island, Seychelles, is of major conservation significance as it is relatively pristine, and apparently the only tropical island over 20 ha with no alien invasive mammals. Such mammals, especially rodents, can impact substantially on arthropod faunas. This study focuses on the arthropods of the island that live in fallen logs and litter. The dominant log species are Pisonia grandis (Summerhayes, 1932), Ficus spp. and Cocos nucifera (Linnaeus, 1952). Stage of decomposition and forest type in which the logs occurred significantly influenced the composition and structure of the assemblages. Young logs were significantly richer in species than older logs, possibly due to the greater resources and more varied microhabitats in the younger logs. Log type was also important for arthropod species richness and abundance. Although P. grandis and Ficus spp. logs did not differ significantly, these two log types did differ greatly from C. nucifera which had a higher arthropod species richness, composition and abundance. However, these differences were only significant for recently fallen logs. As the logs decayed, their arthropod assemblages converged. Nevertheless, each log type had some arthropod species not present in another log type. This is important in terms of conservation, especially in the case of C. nucifera, which, according to one school of thought, should be removed from some Seychelles islands as it is considered an alien invasive. Arthropod assemblages in woody litter differed in composition depending on forest type in which they occurred. These woody litter assemblages were generally dissimilar to those in logs in the same forest type. Leaf litter was extremely poor in arthropod species. Species richness, both in logs and litter, was comparable to figures from temperate lands, possibly because the rich, topical fauna was ameliorated by small island size. As the logs are home to several Seychelles endemic species, their conservation is essential. Furthermore, as they are also the food base of certain threatened Seychelles vertebrates, their conservation is about conservation of a food chain on this unique tropical island. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

This study investigates the effects of forest fragmentation and matrix type on the diversity and distribution of epigaeic invertebrates in selected Afromontane forests of the KwaZulu-Natal midlands. The consequences of area reduction and matrix transformation, due to commercial forestry, for epigaeic invertebrate diversity, and the role of small forest fragments in their conservation, are particularly examined. Data are used to provide guidelines for the management and conservation of Afromontane forest and adjacent land use. Epigaeic invertebrates were sampled using pitfall-trapping quadrats set along gradsect lines in eleven Afromontane mistbelt mixed Podocarpus forests, five of which were surrounded by commercial pine, and five surrounded by the natural grassland matrix. The two sets of five forests were approximately matched in pairs by area (0.5ha to 215ha) and compared for differences in the epigaeic invertebrate communities to determine potential effects of fragmentation and landscape transformation on these communities. A large tract of forest (Leopards Bush Private Nature Reserve, 705ha, hereafter Leopards Bush) situated within the continuous Karkloof forest, served as the control. Trapping intensity increased with forest area. Invertebrates were identified to morphospecies, and where possible, further identification was carried out by specialists. A total of 61 282 epigaeic invertebrates, representing 168 morphospecies, were collected. There was a significant positive species-area effect evident in the Balgowan complex (grassland matrix), but not in the Gilboa complex (pine matrix). There was thus a confounding influence of the pine matrix in the Gilboa, since the matrix represented the single most important difference between the two forest complexes. In afforested landscapes it is thus crucial to conserve the largest intact forest fragments to preserve overall epigaeic invertebrate species richness. Density compensation was evident in the Balgowan complex but not in the Gilboa complex. Recolonisation dynamics may play a small role in the regional persistence of a species within forest in a pine matrix, and persistence would be ensured by the preservation of a small number of large forest fragments containing large, extinction-resistant populations. The establishment of ecologically functional grassland corridors (i.e. wide enough to maintain "natural" ecological processes) between mistbelt mixed Podocarpus forest fragments would facilitate dispersal of epigaeic invertebrates between forest fragments. The results of this study indicated that edge effects were experienced deeper in the forests than the expected 32m suggested by Kotze and Samways (1999) and thus any changes to the epigaeic invertebrate communities induced by edge effects had already taken place inthese forests. Cluster analyses revealed that twenty-two percent (n = 37) of invertebrate species recorded were common to all forests and these shared species were generalist feeders. The effect of matrix type on diversity of epigaeic invertebrate communities was most notable for large forests (i.e. over 30 ha). Large fragments with core areas unaffected by edge-induced disturbance would support more forest dependent species than small fragments due to a lower susceptibility to invasions. Although not significantly nested, epigaeic invertebrate communities in both forest complexes tended toward nestedness. Isolation of forest fragments appeared to play a lesser role than patch area in determining the invertebrate community composition. Assuming that communities are extinction-dominated, community convergence in small fragments has probably already occurred, with invasions from the matrix confounding patterns of deterministic extinction of forest-dependent epigaeic invertebrate species. A habitat disturbance gradient was evident from the relatively undisturbed control (Karkloof quadrats) to the more disturbed pine dominated Gilboa quadrats, with intermediate disturbance values for the Balgowan (natural grassland matrix) fragments. The undisturbed Karkloof forest was characterised by a deep, abundant leaf litter layer, dense sub-canopy, and an abundance of seedlings indicating high rates of natural regeneration. Leaf litter depth was the most important variable in explaining the variation of epigaeic invertebrate species. A "shopping basket" of eight selected ecological indicators are mostly unrelated species. In general, this study supports the wealth of evidence advocating the use of epigaeic invertebrates, especially Carabid and Staphylinid beetles, as ecological indicators. In this study, eight species were identified by canonical correspondence analysis as ecological indicators that were sensitive to forest disturbance. This suite of species in the mistbelt mixed Podocarpus forests of the KwaZulu-Natal midlands will provide an accurate indication of forest condition in summer when abundance data is used. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Forest fragmentation is caused by the clearing of patches of indigenous vegetation for agriculture, urban development, and other human land uses. Such action results in patches of remnant natural vegetation being surrounded by altered vegetation. I investigate the effects of forest fragmentation and matrix type on avian diversity and assemblage structure in forest patches of the historically fragmented Karkloof / Balgowan forest range, KwaZulu-Natal, South Africa. This study compares the bird assemblage diversity and composition of indigenous forest patches surrounded by commercial forestry (Gilboa complex) with that surrounded by natural grassland matrix (Balgowan complex). Insularisation of Afromontane Mistbelt forest in KwaZulu-Natal has led to loss of species where forest fragments support fewer bird species than comparably sized patches of mainland forest. Small fragments within natural grassland have fewer bird species per unit area than larger fragments. Forest patch area-dependent density compensation is evident and bird assemblages appear saturated. Bird assemblages are characterised by a non-random species distribution pattern where area-dependent processes are dominant, and the loss of species from fragments follows a deterministic sequence. In forests in the plantation-dominated matrix no island-effect is detectable and it appears that forest patches are converging on the same bird species richness, regardless of forest size. No density compensation is evident and bird assemblages are not saturated. The sequence of species loss from forest patches is not as predictable, where a random yet prominent colonisation process exists. As commercial plantations provide suitable habitat cover for movement of forest birds, colonisation of both distant and small indigenous forest patches has been possible, reducing the effects of area-dependent extinction in the forest patches but also resulting in lower species richness in larger patches. Bird species of the Karkloof / Balgowan forest range appear to be fragmentation adapted, and most species are resilient to further landscape change. Certain species are however more prone to local extinction than others. The major predictors of extinction risk are body size, abundance status, and feeding guild. Patch area is the dominant force governing traits in the natural Balgowan complex where larger species with low natural abundance and an insectivorous diet are most prone to local extinction. In the Gilboa complex the nature of the plantation matrix appears to be masking the species natural responses to fragmentation making it difficult to predict which species are most at risk. In order to preserve maximum bird diversity, including high-risk species, the largest intact forest units (≥302ha) must be conserved. Evidently, the nature of the matrix affects avifaunal diversity and distribution in forest patches, and plantations have the capacity to significantly alter bird assemblage structure and composition in indigenous forest patches. Forest fragments must be considered as integrated parts of a complex landscape mosaic, and this study emphasises the importance of understanding landscape-scale processes. Knowledge of ecological and life history traits proves valuable for predicting community level response to landscape change. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

While many studies have been done on Lions, relatively little work has been conducted on how they interact with local habitats and the factors of importance in determining home ranges and territories. The interactions between predators and patchily distributed resources and the basic tenets of Ideal Free Distribution theory have been used in this study as the basis in explaining how lions distribute themselves in space and why they choose particular areas above others in regards territory location. The study was conducted in the Hluhluwe-Umfolozi Park, South Africa and involved the use of historical lion sightings data recorded between the years 1973 and 1999 inclusive. A variety of potential explanatory variables including vegetation, topography, rainfall, main river distribution, roads, hyaena den locations and prey were used in developing logistic models which were then used to predict areas most likely to be colonised by lion. Model predictions were tested against independently collected validation data from an introduced pride . Modelling was conducted at a 1km² grid cell size. In total, seventeen models were formulated for four lion variables, namely cubs, adult females in groups of two or more, adult males seen with adult females and adult males only. All models accounted for a significant amount of deviance (p<0.001) except for one cub model (p=0.003). Models which performed best in correlations with validation data were those formulated for adult females in groups of two or more and cubs (p<0.05). Variables of importance in these models included distance from main rivers and presence/absence of public roads. Preferences for travelling on roads were influenced by vegetation type, with thicket promoting travel on roads and the opposite being true of open woodland, however this was only true for females in groups of two or more. Main rivers represent high quality resource areas for lions in the reserve since they provide water, shelter, cover (hence ease of prey capture) and travel lines. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

This study was conducted to determine the effects of different levels of dietary tannin on the physiology of Boer goats. In particular, dietary intake, digestibility, gastrointestinal tract (GIT) histology and presence of bacteria along the GIT were measured. In addition the ability of goats to detoxify tannins by measuring liver and kidney mass; and urinary glucuronic acid concentration was investigated. Commercialized tannin was used because of wide variation of tannin levels, which can be affected by season, species, and part of the plant. Thirty adult, male goats were fed one of five diet treatments of different tannin levels (0%, 5%, 10%, 15% and 20%) for 6 weeks following which they were kept in metabolic crates for data collection for a further 10 days. Dietary intake of feed decreased significantly as tannin levels increased between the diets. Digestibility of dry matter (DM) tended to decrease with increasing tannin levels. However, digestibility of crude proteins (CP), organic matter, neutral detergent fibre and acid neutral detergent fibre decreased Significantly with increasing tannin levels. Faecal CP increased while urinary CP decreased with increasing tannin levels. There was no tannin present in the faeces. It appears that goats cope with low levels of tannin ingestion. There appears to be a threshold above which greater tannin ingestion has detrimental effects. The linear decreased dietary intake with increased tannin level may indicate that goats limit their intake of tannin below some threshold as a defence strategy. Differences in the histopathology of the oesophagus, reticulum, rumen, abomasum and duodenum were evaluated. Animals on the control diet had more protozoa present in the GIT than the other diets. Number and types of bacteria observed in the reticulum and rumen increased with tannin level in the diet. These may be responsible for tannin-protein complex degradation. Few bacteria were observed in the abomasum. There was a loss of epithelial cells and erosion of microvilli in duodenum with increased tannin levels, which would impair absorption of nutrients. The width of the keratinized GIT epithelial layer increased and villi height decreased as tannin levels increased which could further reduce nutrient absorption. Goats in the present study did not show detoxification abilities because the liver and kidney masses, and urinary glucuronic acid concentration did not increase with increased dietary tannin levels In summary, condensed tannins as large compounds appear to be metabolized and absorbed from the GIT. However, it is not clear if they are detoxified at the epithelial mucosa interface. The main detrimental effect of tannin on goats appears to be the reduction of feed intake and increased faecal CP. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Rainfall is the most important factor limiting primary production, and hence food availability, in ecosystems. This study tests the thesis that, under conditions where rainfall is unpredictable and food supply varies spatially and temporally from year-to-year, physiological energy-saving mechanisms should evolve in animals for which migration is not an option to avoid periods of low habitat productivity. Apart from the normally erratic rainfall patterns characteristic of arid regions, unpredictable seasonal rainfall may also occur in mesic zones as a consequence of climatic phenomena such as the El Niño Southern Oscillations (ENSO). Using two hypothetical models, this study attempts to determine whether the respective evolutionary history of both aridity and ENSO can be detected in the various phenotypic physiological traits of Rhabdomys pumilio from across southern Africa. Model 1 predicts that a gradient of conservatism of physiological traits related to metabolism, will be detectable along an aridity gradient. Model 2 predicts an increase in the conservatism of similar traits correlated with both the aridity gradient and the gradient of negative rainfall anomalies that are associated with the ENSO. Measurements of circadian rhythms of body temperature and oxygen consumption of individuals of R. pumilio collected from six sites across southern Africa showed that the geographic variation in the physiological traits and proximate responses of this species was explained better by Model 2 than by Model 1. Furthermore, for some traits and proximate responses of this species it was shown that, although the stresses associated with unpredictable rainfall occur less frequently in non-desert ENSO-zones, they are nevertheless sufficient to mimic the selection pressures of rainfall unpredictability in arid zones. This study also highlighted the low basal rates of metabolism and the other conservative physiological traits of this species as a whole. The basal metabolic rate of 0.819 mlO₂g/h and the minimum wet thermal conductance of 0.110 mlO₂/g/h/ºC are lower than that predicted by allometry. The circadian amplitude of body temperature of 2.52°C and the circadian amplitude of oxygen consumption of 1.39 mlO₂/g/h were higher than those predicted by allometric equations. These deviations from predicted values were attributed to the adaptedness of this species to the physiological energy stresses associated with unpredictable resource availability in southern Africa. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.