Doctoral Degrees (Zoology and Entomology)
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Item Open Access Activity patterns of birds in the central Free State, South Africa(University of the Free State, 2009-11) Van Niekerk, Daniël Johan; Kok, O. B.Activity patterns of bird species were studied at Glen Agricultural College within the grassland area of the central Free State, South Africa, during a period of 11 years (July 1997 - July 2008). The study focused on a specific grassland locality where 5-minute checklists were compiled continuously from dawn to dusk at least once a week for a total of 656 days. Data were also collected each minute for selected species. Additional observations in an adjacent tree and shrub dominated drainage line included I-minute checklists compiled during transects over a two-year period (late autumn 2000/1 to mid-autumn 2002/3) as well as surveys from a fixed position from dawn to approximately 70 minutes after sunrise during 2007/8. The central aim of the study was to quantify and explain annual, seasonal and daily activity patterns of all bird species recorded in the study area. This data is summarised in separate species accounts where aspects of the annual cycle, particularly breeding and moulting, were also considered. In addition, the potential influence of rainfall was investigated. The study reveals, for the first time, how the activity patterns of a southern African bird community change through time, and how the amount and timing of rainfall can influence these patterns. In spite of similarities amongst species when daily, seasonal and annual patterns are considered separately, the study also shows that each species is unique when all its data is considered simultaneously. Because activity patterns can have a substantial influence on the detectability of a species, the accuracy and usefulness of surveys aimed at estimating bird numbers is consequently questioned. The study at Glen also shows how activity patterns can be used to help unravel the annual cycle of species in a time and cost effective way.Item Open Access Advances in the systematics and ecology of African Corinnidae spiders (Arachnida: Araneae), with emphasis on the Castianeirinae(University of the Free State, 2012-01) Haddad, Charles Richard; vdM Louw, Schalk; Dippenaar-Schoeman, AnsieEnglish: The Corinnidae is one of 76 families of spiders (Arachnida: Araneae) presently recognised in the Afrotropical Region. By the end of the last century their taxonomy and systematics had been very poorly studied and no modern revisions existed on the group. At that time, 110 species in 22 genera were known from the region, making it a family with moderate species richness. The description of the new genus Hortipes Bosselaers & Ledoux, 1998 in the family Liocranidae signalled the start of modern systematics studies in that family, and following the transfer of Hortipes to the Corinnidae, of that family by default too. Since that time, 20 taxonomic papers have been published on the Afrotropical Corinnidae and 10 new genera (all endemic to the region) and 164 new species have been described, of which three species form part of the current study (Chapters 7 and 9). Several genera have also been transferred to or from the Corinnidae in those papers. Presently there are 35 genera and more than 270 species known from the region, with the Corinnidae now ranking eighth in species richness in the region. Most of the revisionary work so far has focused on the subfamilies Trachelinae and Phrurolithinae, while the Corinninae sensu lato and Castianeirinae have largely remained neglected. The broad aim of the current study was to focus on the systematics of the latter group, treat the taxonomy of each of the currently known genera, at least in part, and provide a basis for future work on the subfamily. As such, many of the smaller genera in the subfamily were revised in the Afrotropical Region and two new genera were described. The genus Apochinomma Pavesi, 1881, the only described genus of accurate antmimicking castianeirines from the region, is revised and separated into two species groups based on genitalic and abdominal morphology. The type species, A. formicaeforme Pavesi, 1881, is redescribed and three new species are described in the A. formicaeforme species group: A. malkini sp. nov., A. parva sp. nov. and A. tuberculata sp. nov.. Two new species, A. decepta sp. nov. and A. elongata sp. nov., are described in the A. decepta species group, although an additional species only known from juveniles can also be placed in the latter group. Members of the A. formicaeforme species mimic Polyrhachis ants and are mainly arboreal, while members of A. decepta species group are ground- or grass-dwelling and probably mimic ponerine ants. The genus Cambalida Simon, 1909 is revised and three species are transferred from Castianeira Keyserling, 1879 to Cambalida: C. deminuta (Simon, 1909) comb. nov., C. fulvipes (Simon, 1896) comb. nov. and C. loricifera (Simon, 1885) comb. nov.. An additional species is transferred from Brachyphaea Simon, 1895 to Cambalida: C. fagei (Caporiacco, 1939) comb. nov.. All of these species are redescribed, as is Cambalida coriacea Simon, 1909. Two species, Castianeira depygata Strand, 1916 syn. nov. and C. mestrali Lessert, 1921 syn. nov., are considered junior synonyms of C. fulvipes. The type material of the type species of the genus, C. insulana Simon, 1909 from Annobon Island, is lost, and only immature specimens have been subsequently collected from a nearby island. The species is regarded as a nomen dubium until fresh adult material can be collected. A replacement name, Cambalida simoni nom. nov., is proposed for Cambalida fulvipes Simon, 1909, the latter being a secondary junior homonym of Cambalida fulvipes (Simon, 1896) comb. nov.. The type material of C. simoni is also lost and it too is considered a nomen dubium. Five new species are described: C. compressa sp. nov., C. dippenaarae sp. nov., C. griswoldi sp. nov., C. lineata sp. nov. and C. unica sp. nov.. Castianeira Keyserling, 1879 is the largest genus in the Corinnidae with 131 described species, of which 22 are presently known from the Afrotropical Region. There is a very rich undescribed fauna known from the region, and the variable morphology of its component species would suggest it is polyphyletic and should be divided into several genera. For example, six species are misplaced and have been transferred to or synonymised with species in Cambalida or the new genus Copuetta gen. nov.. In the present study, five species are redescribed and illustrated for the first time based on the type material: C. delicatula Simon, 1909, C. formosula Simon, 1909, C. majungae Simon, 1896, C. phaeochroa Simon, 1909 and C. thomensis Simon, 1909. The female holotype of C. bicolor (Simon, 1890) lacks an abdomen and the species is considered a nomen dubium. The types of several Afrotropical species could not be traced as yet and the species should be redescribed, if possible, based on recently collected material from near their type localities. The ground-dwelling genus Copa Simon, 1885 is one of four genera in the Afrotropical Region that have cryptic colouration that bears a resemblance to that of wolf spiders (Lycosidae), hereafter referred to as cryptic lycosiform colouration. The type species of the genus, C. flavoplumosa Simon, 1885, is redescribed and proposed as a senior synonym of C. benina Strand, 1916 syn. nov. and C. benina nigra Lessert, 1933 syn. nov.. This is possibly the most widespread corinnid in the Afrotropical Region albeit that is has not yet been recorded from any of the islands. A new species, C. kei sp. nov., is described from South Africa. Copa agelenina Simon, 1910, originally described from a subadult female from southern Botswana, is considered a nomen dubium. Although the Madagascan fauna was not included in this revision, nearly 30 new species have been distinguished from museum collections, and once that fauna is revised it will provide an exceptional example of island radiation. In a revision of the Afrotropical species of the ant-mimicking genus Corinnomma Karsch, 1880, Apochinomma semiglabrum Simon, 1896 is redescribed from both sexes, and based on these descriptions it is transferred to Corinnomma as C. semiglabrum (Simon, 1896) comb. nov.. A new species, C. lawrencei sp. nov., is described from Mozambique, Tanzania and South Africa. The taxonomic status of C. olivaceum Simon, 1896 is discussed and the first illustrations of the female genitalic structures are presented. Since no fresh material of this species is available and the female holotype is badly faded, it is not thoroughly redescribed. An English translation of Simon’s (1896) Latin description of C. olivaceum is provided with the intention of more accurately describing the colouration of this species. The arboreal cryptic lycosiform castianeirine genus Echinax Deeleman-Reinhold, 2001, previously known only from South-East Asia, is recorded from the Afrotropical Region for the first time. Copa longespina Simon, 1909 is redescribed and the species is transferred to Echinax as E. longespina (Simon, 1909) comb. nov.. Six new species are described from both sexes: E. clara sp. nov., E. hesperis sp. nov., E. natalensis sp. nov., E. scharffi sp. nov., E. similis sp. nov. and E. spatulata sp. nov.. The genus Graptartia Simon, 1896, presently known only from Africa, is revised. The type species, G. granulosa Simon, 1896, is redescribed and the first genitalic sketches of the species are provided. Two new species, G. mutillica sp. nov. and G. tropicalis sp. nov., are described. Unique amongst African castianeirines, all species of Graptartia are mimics of wingless female velvet ants (Mutillidae). Although the genus Merenius Simon, 1909 is not revised, a single common species, Merenius alberti Lessert, 1923, is redescribed. The species was previously known only from South Africa, and is recorded for the first time from Mozambique, Swaziland and Zimbabwe. While most populations of M. alberti comprise the typical black morph of the species, a red morph is described for the first time here. As part of a field study to identify the potential models of the two colour morphs of M. alberti, spiders were collected by hand and ants by pitfall trapping in the Ndumo Game Reserve in northern KwaZulu-Natal, South Africa. The ants assemblages sampled at 20 sites in the reserve seem to indicate that the black morph is a generalised mimic of black ground-dwelling ants, most likely Camponotus cinctellus (Gerstäcker, 1859), Streblognathus peetersi Robertson, 2002 and Polyrhachis gagates F. Smith, 1858, while the red morph is a mimic of Anoplolepis custodiens (F. Smith, 1858) ants. Lastly, the genus Messapus Simon, 1898, presently placed in the Castianeirinae, is reviewed. The type species, M. martini Simon, 1898, clearly represents two different species, one a corinnine (female lectotype) and the other a castianeirine (male paralectotype). The female is redescribed and the true male described for the first time. Based on the redescription, Messapus is transferred to the Corinninae. Corinna natalis Pocock, 1898 is misplaced and is transferred to Messapus as M. natalis (Pocock, 1898) comb. nov., while Messapus secundus Strand, 1907 is misplaced and transferred to Merenius as M. secundus (Strand, 1907) comb. nov.. A new cryptic lycosiform genus, Copuetta gen. nov., with the type species C. maputa sp. nov., is established to accommodate the castianeirine male paralectotype of M. martini, and its matching female is described for the first time. Castianeira kibonotensis Lessert, 1921 syn. nov. is considered a junior synonym of Copa lacustris Strand, 1916 and the species is redescribed and transferred to Copuetta gen. nov. as C. lacustris (Strand, 1916) comb. nov.. An additional eleven new species of Copuetta gen. nov. are described: C. comorica sp. nov., C. erecta sp. nov., C. kakamega sp. nov., C. kwamgumi sp. nov., C. lesnei sp. nov., C. litipo sp. nov., C. lotzi sp. nov., C. magna sp. nov., C. naja sp. nov., C. uzungwa sp. nov. and C. wagneri sp. nov.. A second new cryptic lycosiform genus, Wasaka gen. nov., is described for four new species from tropical Africa: W. imitatrix sp. nov., W. montana sp. nov., W. occulta sp. nov. (type species) and W. ventralis sp. nov.. A phylogenetic analysis of the subfamily Castianeirinae from the Afrotropical Region was carried out. Forty-one ingroup taxa (Castianeirinae) were included, of which 39 were Afrotropical, one Australasian and one Brazilian. Outgroup taxa included three species of Trachelinae, one Phrurolithinae, two Corinninae and two Corinnidae incertae sedis, with Drassodes sesquidentatus Purcell, 1908 used to root the trees. Only species of Castianeirinae treated in this thesis and known from both sexes were included in the analysis. Analyses performed in Winclada, TNT and PAST all produced similar but very unsatisfactory results, with the outgroups grouping together with part of the Castianeirinae. Consequently, a second analysis was conducted with the exclusion of most of the outgroup taxa (except D. sesquidentatus and Corinninae). These results improved the resolution of the results considerably. but still did not resolve the placement of the Medmassa–Messapus clade within Castianeirinae; these genera can be considered to belong to Corinninae and should hypothetically have been placed outside the Castianeirinae clade. A single analysis produced in PAST produced the most parsimonious tree, with Medmassa–Messapus placed outside the Castianeirinae and each of the Afrotropical castianeirine genera as monophyletic. The results are inadequate to support any systematic changes in the Corinnidae, but future analyses need to include a more diverse range of castianeirine genera from outside the Afrotropical Region to better understand the relationships of the Afrotropical fauna. In the final chapter, the role of Castianeirinae as components of arthropod mimicry complexes is described for three species of ants, Anoplolepis custodiens (F. Smith, 1858), Polyrhachis gagates F. Smith, 1858 and Camponotus fulvopilosus (De Geer, 1778). There are respectively two out of 10, four out of six, and zero out of five species of Castianeirinae forming part of the arthropod complexes associated with these ants. All of these castianeirines are inaccurate (weak/ generalised) mimics of their models except for Apochinomma formicaeforme, which is an accurate (good/specialised) mimic of P. gagates. Colour polymorphism is also described for the first time in four species of Afrotropical Castianeirinae, i.e. Corinnomma semiglabrum, Merenius alberti, Castianeira cf. venustula (Pavesi, 1895) and Copa flavoplumosa. Three of these species are inaccurate mimics of ants, while C. flavoplumosa is a species with a widespread variant with cryptic lycosiform colouration and a nigrito form restricted mainly to tropical forests. High Castianeirinae biodiversity and endemism corresponds to most of the main Biodiversity Hotspots and Centres of Endemism (CE) in the Afrotropical Region: Maputaland-Pondoland-Albany CE (five endemics), Madagascar and Indian Ocean Islands CE (>30 endemics), East African Afromontane Forests CE (four endemics), East African Coastal Forests CE (five endemics), Guinean Forests of West Africa CE (seven endemics) and the Horn of Africa CE (one endemic). No endemic castianeirines have been recorded in the Succulent Karoo and Cape Floristic Region CE’s in southern Africa, although this corinnid fauna of these two CE’s is largely dominated by Trachelinae, most of which are endemics.Item Open Access Alternative methods of controlling the brown locust, Locustana pardalina (Walker)(University of the Free State, 2003-07) Price, Roger Edward; Van der Westhuizen, M. C.Outbreaks of the brown locust, Locustana pardalina (Walker), occur almost annually in the semi-arid Karoo region of South Africa and southern Namibia. Current suppressive control strategy relies on the application of fast-acting, synthetic pyrethroid insecticides, applied as ultra low volume drift sprays, to control gregarious brown locust targets at source within the Karoo outbreak region. However, the negative impact that the repeated application of insecticides may have on the rich diversity of endemic invertebrates and reptiles found in the Nama-Karoo biome is of great concern to landholders and conservationists. How to reduce the insecticide load and minimise the environmental impact in the Karoo and yet at the same time control this serious agricultural pest has become a controversial issue. There is thus an urgent need for more environmentally benign methods of locust control, as an alternative to the current spraying of insecticide. As part of a locust research project initiated by the Plant Protection Research Institute, Pretoria, the potential of various alternative methods of controlling the brown locust were evaluated against gregarious hopper populations in the laboratory and in the field. It was first important to update the available information on the background level of control provided by natural enemies and diseases of the brown locust. Although a range of natural enemies were found to prey upon the various life stages, their impact on brown locust populations in the present study was negligible. Of particular interest was a study of the impact of the sarcophagid fly, Wohlfarhtia pachytyli, which is a well-known facultative parasite of late instar brown locust hoppers and fledglings. However, field data suggested that the potential of the fly as a biological control agent may have been over estimated in the past, as the fly failed to cause more than 6% mortality of fledgling swarms in the present study. Before the first insecticides became available at the turn of the zo" century, farmers had to resort to mechanical methods to protect their crops and pastures from the ravages of locusts. Turning back the clock, the destruction of locust egg beds and the harvesting of locusts were re-examined as control methods. Excavation of locust eggs gave effective control, but the disturbance of the friable soils in the Karoo would damage the vegetation cover and cause severe erosion problems and is therefore not advocated. Harvesting of live locusts using nets or vacuum machines was not practical due to the avoidance behaviour of locusts. However, the harvesting of locust cadavers lying on the soil surface following insecticide spraying, once they had dried out and insecticide residues had broken down, was possible. With their high protein and fat content, the processing of locust cadavers into animal feed may become economically viable in future. Before organo-chlorine insecticides became available in the 1940s, bran bait containing sodium arsenite was extensively used for brown locust control. The baiting technique was re-evaluated in the present study using minute dose rates of the phenyl-pyrazol insecticide, fipronil, dissolved in water and mixed into wheat bran as the edible carrier. Bran bait containing 0.02% fipronil 200Se (Regent®) was prepared on site and was broadcast by hand onto the soil surface around bushes occupied by hopper bands as overnight roosting sites. Excellent control (>95%) of small and medium sized hopper bands was achieved, as long as baiting was undertaken shortly after sunrise, before hoppers scattered from the baited area. Baiting large band targets, or baiting later in the day once hoppers became active, was not effective. Baiting with 0.02% Regent® proved very effective if applied to compact, roosting hopper bands. It was also inexpensive and was easy to prepare and apply, requiring basic equipment and limited training. However, the logistics of the bulk transport, preparation and application of locust baits under operational conditions appear daunting. Insecticide barrier treatments using fipronil (Adonis® 5UL), applied to 21m-wide strips of Karoo vegetation at a dose rate of 12.5g a.i./ha, were used to intercept gregarious brown locust hopper bands marching through the veld. Barriers of Adonis® proved very effective against mobile L2-L3 bands and against small L4-L5 bands, giving >90% control within 48 hours. However, barriers sometimes failed to adequately control large and mobile L5 bands that had sufficient momentum to march through barriers before the majority of hoppers acquired a lethal dose of Adonis®. Barriers also proved less effective where the vegetation density was sparse or where the vegetation was unacceptable to locusts. The size and density of the hopper bands and the time of day when bands made contact with the barriers also appeared to influence efficacy. Despite these factors, Adonis® barriers were still considered to have potential for the control of brown locust hopper bands in the more remote areas of the Karoo, especially during the early stages of an outbreak when hopper bands are still young. However, barriers would have to be judiciously applied to restrict the environmental impact of Adonis® against non-target organisms. Large-scale operational trials are recommended. Insect Growth Regulators (IGRs) have shown promise when applied as barrier treatments against various locust and grasshopper species. However, laboratory experiments with the IGRs, flufenoxuron and teflubenzuron, applied to leaf discs and fed to L5 brown locust hoppers at dose rates of 3-l5Ilglg, gave variable mortality of 30-70%, with most mortality occurring as the hoppers attempted to moult. In another experiment, diflubenzuron (Dimilin OF6®), was sprayed onto maize plants at volume rates of l-3.f;ha and subsequently fed to L2 brown locust hoppers in the laboratory. Dimilin OF6® produced 100% mortality of L2 hoppers within Il days at all application rates, as long as hoppers were continuously exposed to treated vegetation. However, irregular exposure to Dimilin® during the inter-moult period produced unsatisfactory mortality, as the product is evidently non-accumulative and is readily excreted. The fact that brown locust hoppers have to be regularly exposed to IGR-treated vegetation, combined with the sporadic feeding behaviour and high mobility of brown locust hopper bands in the Karoo, would probably make IGR barriers unsuitable for brown locust control operations. In collaboration with nBC and the LUBILOSA programme (CABI Bioscience, Ascot, UK), the locust-killing fungus, Metarhizium anisopliae var. acridum, was imported and evaluated by PPRI locust researchers as a myco-insecticide agent in laboratory and field trials against the brown locust. Under suitable application conditions the myco-insecticide, applied at a standard dose rate of lOOgconidia/ha, regularly produced >90% mortality of hoppers maintained in cages, although speed of kill was slow, with median lethal times of 10.3 and 13.4 days for the ground and aerial application trials respectively. In most cases, acceptable >90% mortality was not achieved for at least three weeks after application. Despite the slow speed of kill, the myco-insecticide agent was considered a significant advance in locust control and the product was subsequently registered as Green Muscle® in South Africa in 1998. However, the lack of a knock-down action and the slow kill currently makes Green Muscle® unsuitable for operational use in the Karoo. The thousands of individual hopper bands treated during control campaigns, and the high mobility of bands, would make the recognition of treated and untreated targets by locust officers impossible. The hot and dry Karoo climate is also usually detrimental for the survival and transmission of fungal conidia, while the thermoregulation behaviour of brown locust hoppers enables them to effectively delay the onset of Metarhizium mycosis. An alternative application strategy needs to be developed and tested before Green Muscle® can be recommended for brown locust control. Other pathogenic micro-organisms evaluated in the laboratory for brown locust control were certain acid-tolerant strains of Bacillus thuringiensis and an entomopoxvirus isolated from a West African grasshopper, Odaleus senegalensis (De Geer). Unfortunately, none of these microorganisms proved virulent to the brown locust. The alternative locust control methods evaluated against the brown locust were all ranked according to various performance criteria and compared with the conventional spraying of ULV insecticides. Of the alternative control methods, only Adonis® barrier treatments and Regent® bait showed sufficient promise for brown locust control. However, none of the alternatives were considered suitable under all locust control situations to entirely replace the spot spraying of conventional ULV insecticides, which will thus remain the backbone of brown locust control strategy. Recommendations on the development of an lPM strategy for brown locust control, to incorporate barrier treatments and baiting in certain areas of the Karoo in order to complement conventional insecticide spraying, are given.Item Open Access Aspekte van die algemene biologie van Culex (culex) theileri Theobald (Diptera: Culicidae)(University of the Free State, 1984-01) Van der Linde, Theunis Christiaan De Klerk; Van Pletzen, R.; Hewitt, P. H.English: Since little is known of the occurence, distribution and possible vector roles of mosquitoes in the western Orange Free State, a trapping survey was undertaken to determine the species richness, relative abundance and seasonal fluctuations of mosquitoes in this region. Trapping of mosquitoes was done at weekly intervals from 1976 to 1978 on the farm Daniëlskuil, 30 km west of Bloemfontein. Twentyfive species were found to be present, of which eight had not previously been recorded from the Orange Free State. Culex (Culex) theileri Theobald was the most abundant species, accounting for 55,44% of the total catch. The temporal distribution and abundance of the seven dominant species viz. Aedes caballus, Ae. juppi, Ae. lineatopennis, Ae. durbanensis-group, Anopheles squamosus, Cx. theileri and Cx. univittatus were analyzed in terms of meteorological parameters such as air temperature, water temperature, relative pumidity and rainfall, all of which were recorded continuously. From these it was concluded that temperature and saturation deficit proved to be the most important variables. A Cx. theileri colony was established in the laboratory. Field observations and laboratory experiments led to the following rearing procedure and environmental conditions: Adults were held at 27°C and 65% RH with a day-night cycle of 12 hours each, which included a dawn and a dusk of one hour each respectively. Adults were fed on 7,5% sugar water and pigeons were used for bloodmeals. Optimum oviposition occured when individual gravid females were placed in pill vials containing 10 ml of water in which larvae had developed. Larvae were held in 0,02 M NaCI in shallow pans at 27°C. They were fed a mixture of brewer's yeast and an infant cereal. An electronmicroscopic study of the surface structure of the eggs revealed that the exochorion of the egg can be divided into four main regions viz. an anterior pole, a transitional region, an attachment region and a posterior pole. A cup-shaped corolla filled with gelatine-like material is present on the anterior pole and a prominent oil droplet on the posterior pole. In the attachment area the exochorion bears knobs with gaps between them. The knobs of adjacent eggs are arranged in such a way that adjacent eggs are joined to one another in a similar way as a press-stud operates. The eggs are thus held together to form a raft. Mating before or after a bloodmeal had no significant effect on the number of eggs produced. Intake of sugar after a bloodmeal had a detrimental effect on the number of egg-rafts produced, but not on the number of eggs per raft. Females which fed on white rats produced significantly more eggs than those which had fed on pigeons. The females, however, which fed on male rats produced large numbers of nonviable eggs. Aging prior to a bloodmeal resulted in decreased egg production. Repeated bloodmeals and oviposition by young females did not cause a decline in egg production or viability. Females oviposited during late dusk. They preferred 0,01 - 0,08 M NaCl solutions with a dark background. Furthermore, solutions in which larvae or pupae were reared, or which contained bacteria, were even more attractive. If offered no choice females oviposted on the available aqueous solution. Although temperatures below 15°C and above 33°C had a detrimental effect on oögenesis, no effect on selection of a suitable oviposition site could be established. The eggs are not particularly temperature sensitive during embryogenesis, but hatching does not occur below 12°C or above 36°C. The optimum developmental temperature was 27°C. NaCI concentrations above 0,08 M led to a decrease in the hatching percentage, while above 0,16 M no hatching took place. The temperature extremes of 12°C and 36°C were lethal to the larvae. The optimum temperature was 27°C. Increases in NaCI concentration up to 0,06 M had only a slight effect of larval developmental time. Thereafter a rapid increase in mortality occured. A direct correlation between survival of adults, temperature and saturation deficit was established. Sugar and bloodfed females survived longer at temperatures 6°C - 24°C and saturation deficits of 0,4 and 0,8 kPa. The results obtained form both field and laboratory studies were used in an attempt to explain the occurrence, temporal distribution and abundance of Cx. theileri.Item Open Access Aspekte van die ekologie van avifauna op 'n binnelandse lughawe(University of the Free State, 1999-11) Kok, Alettta Catharina; Kok, O. B.; Van der Linde, T. C. de K.English: Owing to the world-wide increase in air traffic the number and intensity of collisions between birds and aircraft have increased accordingly. Bird strikes are not only responsible for considerable physical damage and fmancial losses, but also endanger human lives unnecessarily. Aspects of the ecology of avifauna at the Bloemfontein airport were, therefore, investigated in order to reduce hazards posed by birds at inland airports. Plant surveys conducted during 1994 and 1995 confirm the classification of the study area as a chy Cymbopogon-Themeda veld type. Based on botanical composition and basal cover the veld is in a relatively good condition. Regularly mowed experimental plots were characterised by a greater variety of plant species consisting of a lower percentage of climax grasses and a larger component of pioneer grasses, forbs and dwarf shrubs compared to undisturbed tall grass areas. A total of 270 pitfall traps were used over a continuous period of 15 months to determine the diversity, relative abundance and seasonal variation of terrestrial invertebrates in the study area. Members of seven classes, 23 orders and 57 families were identified of which insects comprised the most important component by far. As .opposed to this, flying and plantliving invertebrates which were monitored on a monthly basis by means of sweep-nets were represented by only two classes, comprising 13 orders and 70 families. Mouse trapping and incidental catches of smaller vertebrates in pitfall traps suggest a limited presence of amphibia, reptiles and small mammals. Broadly speaking significantly more invertebrates were collected during the wet than during the dry season. Evidently, the opposite trend applies with regard to the sampling of reptiles and small mammals. Although no direct relationship between catches and rainfall as environmental factor could be demonstrated, a significant correlation with temperature was indicated. Over a period of eleven years approximately 5 000 individuals representing 51 bird species which, potentially, posed a threat to aviation were collected at the Bloemfontein airport. More than half of the species concerned can be considered as I medium-sized terrestrial birds of which the crowned plover (Vane/Ius coronatus) is by far the most important. A similar species composition occurred at the Kimberley airport, in contrast to the greater percentage of water associated birds at the Johannesburg airport. Indirectly, food availability appears to be one of the main environmental factors involved in the presence of, amongst others, the five dominant bird species at the Bloemfontein airport. Analyses of the stomach contents of 3 544 bird carcasses from the Bloemfontein airport, supplemented by 906 stomach contents from the Johannesburg and Kimberley airports, indicate that insects can generally be considered the main food source of the birds concerned. Based on dry mass composition the Isoptera, followed by the Coleoptera and Orthoptera, constitute the most important component in the diet. The Isoptera, more specifically the harvester telmite (Hodotermes mossambicusi), is, moreover, the only important prey taxon showing a conspicuous utilisation peak during the relative food shortage of the dry season. Evidently, temporary superabundant food sources which periodically come about in grassland habitats are opportunistically utilised by the birds. Indications are that habitat manipulation at airports can serve as an effective long-term bird control strategy. Based on the superabundant availability of invertebrate prey species in short grass areas compared to that in tall grass, a socalled tall grass policy would not only lead to the reduction of available food sources, but would also hamper the prey searching abilities of the largely insectivorous avifauna. According to results obtained, chemical manipulation can also be successfully employed to limit the presence of harvester termites, the staple food of the majority of terrestrial bird species in grassland habitat, thereby bringing about a reduction in bird numbers. At the same time, a five layered model is discussed setting out the responsibilities of all the role players associated with the implementation of a successful bird control programme. Key words: Airport, avifauna, bird hazard, feeding ecology, harvester termites, pitfall trapping, grassland, habitat manipulation, management.Item Metadata only Assessing small-scale fisheries potential of Gariep Dam, South Africa's largest impoundment(University of the Free State, 2022-07) Swanepoel, Pieter Johannes; Van As, L. L.; Ellender, B. R.; Barkhuizen, L. M.South African inland fisheries are considered poorly developed and fish resources are mainly utilised by recreational and subsistence fishers. The South African government has identified inland fisheries as an opportunity to contribute to food security, job creation and economic development, and has established a mandate to develop this sector. The Gariep Dam is South Africa’s largest freshwater reservoir, and its fish resources can potentially be utilised by the small-scale fisheries sector. The objectives of this study were to assess the fisheries potential of Gariep Dam by determine the viability of small-scale fisheries development by establishing up-to-date utilisation rates, determining fish abundance and catch rates, and assessing the viability of various harvest strategies. To assess resource status, a fisheries-independent multi-method approach was applied using gillnets, fyke nets and longlines to determine relative abundance, population structure and harvest potential. Fisheries-dependent roving creel surveys and angler counts were conducted to assess the recent utilisation of fish resources. To complement previous biological assessments of other species, Clarias gariepinus was studied to understand the biology, ecology, and population dynamics of this species in Gariep Dam. To assess potential development, a fisheries management plan that determined harvest costs, fish prices and financial viability was included. Labeobarbus aeneus dominated gillnet catches, with an average catch per unit effort of 5.7 ± 4.1 kg.net-1.night-1, which comprised 63% of the species composition. The remainder of gillnet catches comprised C. gariepinus (16%), Labeo capensis (10%), Labeobarbus kimberleyensis (10%) and Labeo umbratus (1%). Longlines proved to be successful in harvesting C. gariepinus, with an average catch per unit effort of 35 ± 24 kg.20-hooks-1.night-1, with very low catch rates for fyke nets. The longline catches were dominated by C. gariepinus (99%) with low numbers of L. kimberleyensis (1%). Roving creel surveys revealed that the Covid-19 pandemic had a major effect on the current hook-and-line fishery that was dominated by subsistence anglers, while recreational fishing disappeared during this period. A large proportion of the subsistence fishing sector were found to be out of work with unemployment rates of 70.9% and 34.5% in the two angling areas. Angler catches were dominated by L. aeneus (37.3%), followed by Cyprinus carpio (32.7%), C. gariepinus (13.7%), L. capensis (14.1%) and L. kimberleyensis (1.4%). The angling effort was estimated at an average of 42 ± 1 anglers.day-1 for the Gariep Dam which harvested an estimated 27 tonnes.year-1 during the sampling period. Clarias gariepinus from the Gariep Dam represents a stable population that matures late (5.2 years for males and 3.3 years for females), is dominated by old fish (Amax = 32 years) and exhibits slow growth (Lt = 1 013.28 (1-e0.092(t+7.78)) and a low natural mortality rate (0.369 year-1). These characteristics point towards a species that is likely to be utilised by inland fishers; however, spawning stock should be protected through special refuge areas. e study has revealed that the existing hook-and-line fishery is very important to the local communities surrounding the Gariep Dam and should be recognised and protected from future inland fisheries development. Results of the study indicate that a sustainable small-scale fishery is possible in the form of a longline fishery harvesting 40 tonnes.year-1 of C. gariepinus and a gillnet fishery using a 100 mm mesh size to harvest L. aeneus if they are separated by area to protect the current fishery. The financial analysis, however, indicated that substantial fishing effort will be required to harvest the projected amount of fish. With the recent price of freshwater fish (ZAR 13.50–16.00), a longline fishery is likely to be feasible, but a gillnet fishery is unlikely to generate sufficient revenue based on catch rates for a small-scale sector. The results of this study have been used to inform specific recommendations to develop inland fisheries for Gariep Dam, which can be used by government for decision-making.Item Open Access An assessment of fish and fisheries in impoundments in the upper Orange-Senqu River Basin and Lower Vaal River Basin(University of the Free State, 2016) Barkhuizen, Leon Martin; Weyl, O. L. F.; Van As, J. G.South Africa is an arid country that, as a result of the need to store water for domestic, industrial and agricultural use, has invested heavily in the construction of impoundments which now cover a total of approximately 3 000 km2. Faced with high levels of poverty and unemployment, South Africa is increasingly considering developing fisheries in freshwater impoundments to provide economic opportunities and food security in rural areas. To be effective, such development needs to be guided by information on current utilisation, fish species composition and abundance, as well as the impact of potential harvest methods. Unfortunately, inland fisheries have received limited interest in a country with large marine fisheries and a history of failures in developing inland commercial fisheries. As a result, there is a general lack of even basic information on fish communities in impoundments and their utilisation. This thesis attempts to address this paucity of information in the Free State Province (FSP) by conducting a rapid appraisal of the fisheries potential of impoundments using empirical approaches; collating a 35 year time series of catch returns from recreational angling tournaments and commercial fisheries; conducting surveys to determine fish species composition in 21 impoundments and testing a new fishing gear. The FSP has the largest inland water surface area (145 677 ha) in South Africa and is situated centrally within the Orange-Senqu River Basin that is drained by the Orange-Senqu and Vaal River Systems. As a result of complete lack of data on inland fisheries in the FSP, a scoring system (based on empirical estimations of potential fish yield and water level fluctuations) was developed to provide information on the potential of impoundments for the development of commercial fisheries. Applying different models to Morphoedaphic index (MEI) data provided the first estimates of yields ranging from very conservative to highly opportunistic (e.g. for Gariep Dam from 5.0 to 58.5 kg ha-1 y-1). As predicted by most MEI-based models, impoundments situated at high altitudes with large average depth, with least fluctuation in water levels, had the least potential for the establishment of fisheries. Data on commercial fisheries were collated from various field stations and digitised. This provided the first complete database of commercial fisheries yields in South Africa. Between 1979 and 2014, a total of 9 036 tons of fish were harvested by commercial fishery enterprises operating sporadically at seven impoundments. Commercial fisheries yields were dominated by Bloemhof Dam (73%) and Kalkfontein Dam (23%) with sporadic attempts to develop commercial fisheries in the five other impoundments, contributing only 4% to the total yield over the 35 year period. The gear used to harvest fish determined which species were caught, with the indigenous cyprinids, namely Orange River mudfish Labeo capensis, moggel Labeo umbratus and smallmouth yellowfish Labeobarbus aeneus dominating catches when gill nets were used, while common carp Cyprinus carpio dominated when seine nets were used. Only two commercial ventures operated at one impoundment (Bloemhof Dam) on a continuous basis for more than 32 years. Prior knowledge, skills and experience and most importantly a pre-existing and self initiated market were identified as determinants of success. Data from license sales demonstrate that the recreational fishery sector in the FSP comprises 7 710 licensed recreational anglers. Of these, 748 are affiliated with 30 angling clubs. An analysis of historical data indicated that there has been a decrease of 76% in the number of recreational anglers since 1971 (based on license sales). Over the period 1974 to 2014 available data show that at least 4 817 angling tournaments were held at 17 impoundments. Historical analysis of participation indicates a decline in angling tournament participation. This was in support of the trends observed using license sales data. The total recorded catch for these tournaments was 414 tons. The recreational fishery was dominated by C. carpio that contributed 81% to the total weight and 77% of the total number of fish landed. Experimental fishing surveys conducted during this study, sampled 23 831 fish from the 21 impoundments surveyed. Sixteen species were sampled, with the bulk of the catches consisting of four large cyprinid species (L. capensis, L. umbratus, L. aeneus and C. carpio), and the sharptooth catfish Clarias gariepinus. On average, 7.6 ± 1.4 and 6.0 ± 1.1 species were sampled per impoundment in the Vaal River and Orange-Senqu River Systems respectively. Fish assemblages in different impoundments were similar (average Jaccard’s Index of Similarity of 64.2%). Examination of population structure (using length frequencies) indicated that most species sampled were established with evidence of several year classes of adults as well as young of year. An assessment of fyke nets as a potential harvesting gear demonstrated that this gear might be a suitable passive gear for small-scale fisheries. Eleven fish species were caught with fyke nets, with catches dominated by four large cyprinid species (L. capensis, L. umbratus, L. aeneus and C. carpio), and C. gariepinus of which most are important angling species, except L. umbratus. The preliminary assessment of the suitability of fyke nets as gear for smallscale fisheries has revealed a number of research questions and once these have been addressed, fyke nets might become the gear of choice in future inland fisheries development in central South Africa. With the new interest in the development and promotion of inland fisheries in South Africa to address government’s policy objectives of job creation and poverty alleviation, this thesis will contribute to the knowledge base, as for the first time in South Africa such a comprehensive study on an assessment of fish and fisheries within impoundments has been done. This thesis will provide baseline information which may support and inform the policy development process for inland fisheries in South Africa that was initiated during February 2015 by the National Department of Agriculture, Forestry and Fisheries.Item Open Access The bio-ecology and control of Coproica vagans and Coproica hirtula (diptera: Sphaeroceridae) in cattle feedlots(University of the Free State, 1998-12) Badenhorst, Daniel; Van der Linde, T. C. D. K.; Louw, S. V. D. M.English: Sphaeroceridae are generally known as "lesser dung flies". These are small to medium sized dark-brown to blackish flies ranging from about 0.5 mm to 6 mm in length. They are saprophagous and occur throughout the tropical and subtropical regions of the world. A unique scenario involving Sphaeroceridae flies that constitute a serious problem at South African feedlots is discussed. Two species, namely Coproica vagans (Haliday) and Coproica hirtula (Rondani) are both associated with cattle dung at feedlots, with the former species reflecting dominance. The flies cause a nuisance to the cattle by forming black clouds of swarming flies. It therefore became imperative to find a way to control these flies. The establishment of separate sphaerocerid laboratory colonies from which experimental studies could be conducted was successful and is described. The seasonal occurrence and relative abundance of the Diptera fauna occurring within undisturbed cattle droppings exposed to shaded and sunny locations in the central Free State was investigated. The Sphaeroceridae was of particular interest, but only five presumably new species were discovered among the 21 fly species reared from these droppings. No C. vagans or C. hirtula specimens were encountered. The influence of physical parameters such as temperature and moisture content of the dung on the development and survival of immature stages and adult flies is described. Temperature had a major effect on all stages of both species, and both too low and too high temperatures led to severe mortality. Optimum developmental temperatures were between 24°C and 30°C. The development time of all stages also increased with a decrease in temperature. Moisture content of the dung had the same influence on all stages of the Sphaeroceridae, and optimum moisture content levels were at approximately 90%. Development times also increased somewhat with a decrease in moisture content levels of the dung. Oviposition by adult females of both sphaerocerid species and the influence of temperature and photo periodicy was determined and is described. Oviposition continued for more than 60 days at colder temperatures, although the number of eggs produced was often very low. Higher temperatures on the other hand resulted in large numbers of eggs produced by sphaerocerid females (up to 607 eggs per female) at 24°C, but the duration of oviposition dropped. Different photoperiods had no severe effect on oviposition or egg production. Development and survival of immature stages and adult Sphaeroceridae were also influenced by the type of dung which they were offered and the effect of this phenomenon on the flies is also described. Some dung types, e.g. horse, buffalo and rhino dung, had a negative influence on larval and adult survival most probably as a result of the higher fiber contents of these dung types. The other dung types such as cattle, sheep and elephant dung, led to successful development and survival of all stages. Biological control was attempted with several Coleoptera (a staphylinid, Philonthus caffer (Boheman) and scarabaeids Aphodius pseudolividus Balthasar and Harmogaster strydomi Endrëdi), Diptera (Musea xanthomelas Wiedemann and Coboldia fuscipes (Meigen)) and mite species. These biological control agents all failed to control Sphaeroceridae numbers mainly because of their inability to survive in wet feedlot dung. Chemical control on the other hand produced positive results and seemed like the only option available. Several insecticides and chemicals were tested but only two, namely Neporex (cyromazine) and Scatterkill (piperonyl butoxide), showed irradication potential. A further advantage of Scatterkill is its long residual effect in feedlot dung.Item Open Access Biological control pre-release studies on the ecological impacts and biotic interactions of Robinia pseudoacacia L. (Black locust) with indegenous fauna and flora in South Africa(University of the Free State, 2021-05-28) Chikowore, Gerald; Chidawanyika, Frank; Martin, Grant D.The growing invasion of Afromontane grassland ecosystems of South Africa by Robinia pseudoacacia, a tree from North America is threatening this fragile and fast disappearing biome. Despite numerous studies on the species in the northern hemisphere, a serious lack of information in the southern hemisphere was noted. With the species targeted for biological control in South Africa, there is a need to understand its impacts in a local context and set baseline indicators for future evaluation of management interventions. Thus, multi-scaled studies to determine and quantify the impacts of this IAP were undertaken in the eastern Free State Province of South Africa. These included interactions between the invasive alien tree, biotic and abiotic components of the ecosystem, and implications of control on human wellbeing. Robinia pseudoacacia functional traits such as phenology, canopy cover, tree diameter and population demographics such as population density were measured including how these influence abiotic components of the ecosystem such as temperature and light availability (microclimatic conditions). Furthermore, the cascading effects of environmental modification on native vegetation and grassland arthropods as well as interruption of key ecosystem services such as rangeland condition and pollination in agro-ecological ecosystems were evaluated. Contributions of the invasive alien tree to livelihoods of invaded communities were also assessed inorder to avoid any conflict of interest that may arise from its management. Results showed that invasion by R. pseudoacacia significantly transforms understory microclimatic conditions. Temperatures were at least 2ºC lower under R. pseudoacacia stands as compared to uninvaded grassland while light availability differed by at least 1200 lumens-ft2. Grass communities subsequently differed by 96% between invaded plots and adjacent uninvaded grassland. Species richness was significantly lower in the understory where there was a dominance of exotic grasses . Furthermore, these habitat conditions differentially affect grassland arthropod assemblages, with grasshoppers in the family Acrididae, the most common grassland taxa to be excluded from invaded sites. Apart from the absence of thier main host plants, invasion mediated differences in microenvironments appeared to be the main driver of this shift in arthropod assemblages. This study also provided evidence that important ecosystem services such as grazing and pollination, are affected by R.pseudoacacia invasion. Apart from the reduction in available rangeland, changes in grass communities also significantly lowers the grazing capacity of rangelands. Differences in grass species composition between invaded and uninvaded rangeland resulted in a reduction in range condition especially under smaller and dense R. pseudoacacia stands. Furthermore, results from paired flower visitation rates in an agro-ecological system showed that R. pseudoacacia shares pollinators with apples. Since the two plants develop flowers during the same period, there is competition for key pollinators such as Apis mellifera. Hence, successful pillonation of apples is compromised with a potential reduction in fruit yield and quality. A survey conducted in this study showed that while the tree is currently being utilised by peri-urban dwellers, it is not the preferred species for several functions. Several respondents cited harvesting difficulties (due to thorns) and poor firewood qualities (production of bad smoke) as the major reasons for the underutilisation of R. pseudoacacia. Moreover, its contribution to household incomes is very insignificant while several negative impacts such as reduction in building space and uncontrollable spreading were noted. Information generated from this study shows that R. pseudoacacia is negatively affecting grassland ecosystems and subsequent ecosystem services. Therefore, there is a need to find a sustainable management solution for the species. Considering the limited success achieved by current management efforts, biological control is expected to be the major technique implemented for the species. Several impacts quantified in this study can be used to prioritise the species for management as well as a baseline for evaluation of future management interventions.Item Open Access The biology of gnathiid isopod parasites and their role as vectors of fish blood parasites in South Africa(University of the Free State, 2000-12) Smit, Nicholas Jacobus; Van As, J. G.; Basson, Linda; Russell, Angela DaviesEnglish: Research on marine fish parasites has been largely neglected in South Africa. This is especially true for the temporary fish parasites of the isopod family Gnathiidae and fish blood parasites of the family Haemogregarinidae. In this study, surveys were carried out to determine the presence of gnathiid isopods and fish haemogregarines associated with different intertidal and sub-tidal fish hosts over a period of four years, at two different localities on the South African south coast. The study also focussed on the relationship between gnathiids and haemogregarines, specifically the possibility that the gnathiid Gnathia africana Barnard, 1914 might be a vector of the fish blood parasite Haemogregarina bigemina Laveran and Mesnil, 1901. Laboratory work was conducted to elucidate the life cycle of G. cfricana. It was found that G. cfricana has three larval stages, consisting of three unfed (zuphea) and three fed (praniza) stages, with the final stage praniza larvae moulting into either male or female adults. Forty days after their last feed as praniza 3 larvae, mature females release stage 1 zuphea larvae. Detailed information was also supplied on the feeding and digestion length for each larval stage. The females of G. africana were re-described from the material collected. Furthermore, other gnathiid larvae, not resembling any of the known species from South Africa, were collected from three species of elasmobranchs as well as the evileye pufferfish. Both groups of larvae were kept in the laboratory, where they moulted into adult males that did not conform to the description of any other gnathiid species in South Africa, or worldwide. These specimens were described as new species (Gnathia pantherinum sp. n. and G. pipindae sp. n.), using light and scanning electron microscope observations. Extensive information was also provided on the final life cycle stages of G panthertnum sp. n. Special attention was given to finding distinguishing characteristics to identify females and larvae of various species in the absence of males. Comparing material in this study with information from the literature showed that the morphology of the pleotelson and cephalosome appendages of females and larvae could be successfully used as differentiating characteristics. The research conducted on fish haemogregarines led to new distribution and host records for two known species, and the description of two new, but un-named species. Development stages of H. bigemina were found in the gut of G. africana larvae that had fed on H. bigemina-infected host fish. The data obtained from these results was used to compile a complete life cycle for H. bigemina in both the fish and the arthropod host.Item Open Access Branchial monogenean parasites (Monogenea: Dactylogyridae) of characin fishes from the Okavango river and Delta, Botswana(University of the Free State, 1998-12) Christison, Kevin William; Van As, J. G.; Basson, LindaEnglish: The fishes of the Okavango System, Botswana, are of considerable economical and ecological importance. Recently, scientists and local fishermen have reported a dramatic decline in the fish stocks of the Okavango River and Delta. There are many reasons for this decline to which fish parasites ~may at least be a contributing factor. In recent surveys to the Okavango, monogeneans have been found to be of the most prominent parasites infesting the Okavango fishes. The tigerfish, Hydrocynus vittatus Castelnau 1861, especially, show high infestations of the branchial monogeneans, Annulotrema pikei (Price, Peebles & Bamford 1969). The genera Annulotrema Paperna & Thurston 1969 and Characidotrema Paperna & Thurston 1968, are exclusively parasites of characiform fish in Africa. In the Okavango the characiforms are represented by five species, Brycinus lateralis ( Boulenger 1900), Hepsetus odoe (Bloch 1794), Hydrocynus vittatus, Mieralestes acutidens (Peters 1852) en Rhabdalestes maunensis (Fowler 1935), all of which, are infested by species of the genus Annulotrema and only one, Brycinus lateralis (Boulenger 1900), is infested by a species of the genus Charcidotrema. During two field trips to the Okavango System, five Annulotrema species were collected; three of which are known species and two new species. This is the first record of monogeneans from Botswana and represents the southern most distribution recorded of A. curvipenis Paperna 1969 & A. hepseti Paperna & Thurston 1969. Comparative descriptions of the three known species are given and the two new species are described as A. micralesti sp. n. and A. rhabdalesti sp. n. Mixed infestations of A. curvipenis and Characidotrema nursei Ergens 1973 were also recorded from the gills of Brycinus lateralis. This also represents the southernmost, recorded distribution of C. nursei. Investigation of histological sections revealed that although these monogeneans occurred in relatively high numbers on the gills of the fish, the pathology they caused was limited. Examination of the infestation statistics showed that these parasites exhibit site preferences to the gills on which they occurred. This preference is influenced by the number of monogeneans of the same or other species as well as the number of other parasites occurring on the gills of the fish hosts. When considering the results, these monogenean parasites do not seem to cause severe harm to the host fish. Any changes in the environment could alter the face of this parasite-host relationship dramatically and hence the potential pathogenicity of these parasites should, however, not be ignored.Item Open Access Branchial monogenean parasites (Monogenea: Dactylogyridae) of fishes from the Okavango River and Delta, Botswana(University of the Free State, 2002-06) Christison, Kevin William; Van As, J. G.; Basson, LindaEnglish: The Okavango Delta has received much popularity for the host of wildlife that it sustains. More recently it has gained increasing interest for the rich diversity of fish species that occur there. The fishes of the Okavango are also becoming increasingly important as a natural resource attracting revenue to Botswana in the forms of ecotourism and aquaculture and also as an important food source for the local community. The Okavango Delta is a flood driven system and much of the fish distribution throughout the Delta and the timing of certain behavioural activities are dependent on the timing and magnitude of the flood. For the purpose of determining the distribution of fish parasites throughout the system, the distribution of the fish hosts was determined and it was found that fish community structure could be used to distinguish different habitat types within the different ecological regions. Fifty-nine of the expected 68 fish species for the Delta have been collected. These species represent 12 families of which the families Cichlidae and the Cyprinidae are the most abundant, making up about 50 percent of the species collectively. Various parasites have been collected from these fishes of which the monogeneans seem to be the most prevalent and abundant and currently represent approximately 36% of the parasites collected. Most of the monogeneans recorded thus far were representatives of the subclass Polyonchoinea. Of these, all belonged to the families Dactylogyridae and Gyrodactylidae. Of the monogenean parasites infesting the Okavango fishes, the representatives of the family Dactylogyridae were the most diverse. Genera of African dactylogyrids are either endemic to Africa or belong to genera with wider geographical ranges. In general dactylogyrids are host specific and their zoo geographical affinities are therefore linked to the faunistic origin of their hosts. The distribution of dactylogyrid species within Africa is determined by the distribution pattern of their hosts. Twenty-two dactylogyrid species comprising seven genera were recorded, of these 10 species were previously undescribed. This study represents the first records of representatives of the class Monogenea from Botswana and hence the Okavango Delta.Item Open Access Characterisation of treated domestic wastewater and its potential use for small scale urban agriculture in Bulawayo: balancing health and environmental needs(University of the Free State, 2014-03) Makoni, Fungai Sexton Ndawana; Thekisoe, O. M. M.; Mbati, P. A.The use of urban wastewater for agriculture crop production is receiving renewed attention in most parts of the world due to the increasing scarcity of water. Water scarcity has placed pressure on the ability of households to meet their basic needs as the intermittent supply of water has created a demand for other sources of water, such as wastewater for irrigation, which can either be expensive or dangerous to public health. In this regard it might seem obvious to view wastewater as a major source of water for Bulawayo, Zimbabwe, particularly for irrigation. The general objective of the study was to characterise and determine treated domestic wastewater parameters that are of agricultural, public health and environmental importance for use in urban agriculture irrigation in Bulawayo. The study critically assessed the wastewater quality being used for urban agriculture in relation to its characteristics, the possible impacts on environment health and also quantifying the socio economic factors that can be derived from its use and, based on this assessment, to formulate a strategy for sustainable treated domestic wastewater use for irrigation. Data collection for this study was conducted in Bulawayo urban area and the gum plantation from 2005 - 2010. Extensive wastewater quality analysis was carried out and results of effluent analysis of key parameters, nitrogen and phosphorous were found to be 11.5 mg/l ± 4.4 and 13.5 mg/l ±14.9 respectively, which were within the World Health Organisation (WHO) (2006) acceptable range. These results aided to confirm that the treated domestic wastewater is of acceptable quality and hence has potential to be used for irrigating crops such as maize, beans and vegetables (chomolier) with minimal risk. Effluent heavy metals concentration in the form of Cadmium (Cd) and lead (Pb) measured values of 0.027 mg/l ± 0.01 and 0.45 mg/l respectively and were within the acceptable levels according to the WHO guidelines and Zimbabwe National Water Authority (ZINWA) standards. Heavy metal soil content was also observed to be within the acceptable limits with both Cd and Pb showing strong correlation with soil pH (r2= 1). Vegetable tissue analysis did not detect any significant levels of Cd and Pb in vegetable samples including Chomolier (not detected),maize (not detected), and beans (not detected), which then confirmed the conclusion that the treated domestic wastewater has potential for agricultural irrigation provided the quality of the effluent would not change drastically from the observed status which was measured over five years. With regard to social acceptance and economic benefits, the study revealed that acceptance for use of treated domestic wastewater and consumption of produce from its use was high amongst the farmers with 88.9% of respondents acknowledging no problem in using the treated domestic wastewater. Estimation of financial benefits were derived using the conventional market based approach which then revealed that an income of about US$1000 per plot/year is feasible if a proper management system is put in place. Findings of this study confirm that use of treated domestic wastewater for urban irrigation can improve livelihoods of the resource limited farmers despite the health challenges associated with its use. Majority of the famers reported that use of treated domestic wastewater for agriculture has contributed significantly to their socio- economic lifestyles by making extra income to cover school fees (44.6%), medication (9.85%) and food (99.1%). Apart from the financial benefits observed, calculations using the FAO formula for nutrient contribution, the study indicated that the treated domestic wastewater which was used contributed approximately 92 kg/ha/year, 108 kg/ha/year and 281.6 kg/ha/year of nitrogen, phosphorus and potassium respectively hence improving soil fertility of the sandy loam soils found at the farming area. Evaluation of the findings in relation to the recommended guidelines and standards of Food and Agricultural Organisation (FAO)/WHO and ZINWA suggests that the treated domestic wastewater used at the gum plantation is suitable for crop irrigation specifically for the following crops: chomolier, maize and beans that were investigated over time. In addition the benefits of using the treated domestic wastewater were noted to have the potential to enhance proper management of wastewater irrigation as proposed in the strategy as it proved to be a reliable water resource. Adherence to the strategy that is proposed in this thesis of involving stakeholders, addressing policy and legal issues, supporting research and outreach, marketing and periodic monitoring of effluent, soil and plant quality parameters will ensure successful, safe, long-term wastewater irrigation that will balance human and environmental needs.Item Open Access Ecological analysis of Afromontane grasslands in the Eastern Free State using the biotope quality index(University of the Free State, 2023) Modise, Serero Abiot; Bredenhand, Emile; Stander, Marga; Rakotoarivelo, AndrinajoroEnvironmental disturbance poses threats to conservation efforts in highland montane grassland in temperate regions prone to land transformation, overgrazing, habitat fragmentation, soil erosion, uncontrolled fires and plant invasion. In this study, the Biotope Quality Index (𝘉𝘘𝘐) was adopted and applied as a species surrogate to evaluate impact of disturbance on the Afromontane grassland vegetation types namely Sandy Eastern Free State, Basotho Montane Shrubland and North Drakensberg Highlands Drakensberg Grasslands in the Golden Gate Highlands National Park. In addition, the Biotope Conservation Status (𝘉𝘊𝘚) was developed as an additional to 𝘉𝘘𝘐 to indicate the impact of environmental disturbance on conservation efforts in protected areas. Chapter 1 begins with a brief history that highlights the importance of temperate grasslands and the role that protected areas play in the conservation of sensitive biomes. In Chapter 2, the most regularly used environmental quality indices, their application domain (air, water and terrestrial), arithmetic formulation, development and application process as well as suggestions into continuous usage and nomenclature of those environmental indices were reviewed. Chapter 3 indicates how the 𝘉𝘘𝘐 was adopted into the 𝘉𝘘𝘐veg for vegetation ecology analysis, using three common plant species abundance-cover scales (Domin, Braun-Blanquet and percentage density), and results suggested that, for 𝘉𝘘𝘐, species list must include most plants present in the vegetation type to allow variation within data points. Furthermore, 𝘉𝘘𝘐veg was able to indicate variation in sites which were affected by relatively high degree of soil erosion, plant invasion / encroachment and long-term effects of historical agricultural practices. Moreover, the application of the 𝘉𝘘𝘐 as a species surrogate was demonstrated, with inclusion of the 𝘉𝘊𝘚 add-on as well as a ArcGIS Feature Analysis parameter, to illustrate the conservation status of the Sandy Eastern Free State in Chapter 4 and the Basotho Montane Shrubland grassland vegetation type in Chapter 5 using arthropod assemblages to evaluate as a unit of measure. Furthermore, the inclusion of the 𝘉𝘘𝘐 as a species surrogate for rapid bioassessments and biomonitoring was supported using both plant communities and arthropod assemblages to highlight the impact of environmental disturbances in the Highlands Drakensberg Grassland vegetation unit in Chapter 6. In conclusion, 𝘉𝘘𝘐 indicated the ability to use plants as a unit of measure and its flexibility for common vegetation abundance-cover scales. Again, 𝘉𝘘𝘐 was able to highlight the impacts of environmental disturbances on plant communities and arthropod assemblages. Therefore, it is recommended that 𝘉𝘘𝘐 and 𝘉𝘊𝘚 be used as a surrogate for bioassessment and biomonitoring to assess impacts of disturbance toward and to indicate the conservation status of important ecosystems, bioregions, or biotopes.Item Open Access The ecology and ecophysiology of Marion Island house mice, Mus Musculus L.(University of the Free State, 1999) Avanant, Nico Loubser; Kok, O. B.; Smith, V. R.English: This thesis presents the results of a studv of the biotic and abiotic conditions experienced by house mice on Marion Island, their morphological and reproductional adaptations to island conditions, the seasonal changes in their diet. and of the densities and biomasses of their prey items. By establishing burrow systems and sheltered aboveground runways nuce experience a microelimate that is far less harsh than the macroelimatie regime. In terms of warmth, this extends the season of mouse activity significantly compared with what would be allowed by the macroclimate. House mice are opportunistic feeders and this plays a major role in their survival under the harsh conditions on Marion Island. The mice are primarily carnivores and impact severely on soil macroinvertebrate populations, annually removing up to several times the average instantaneous standing crop of some macroinvertebrate populations. Since macroinvertebrates are cardinal agents of ecosystem functioning by being the main mediators of nutrient cycling on the island, their predation by mice has severe ecological implications. Between 1979/80 and 1992/93 the densities and biomasses of the mouse's major invertebrate prey species have decreased. The percentage composition of the various prey types in the macroinvertebrate population has also changed. These changes have caused changes in the composition of the mouse's diet. Seasonal changes in reproductive status, sex ratio, age structure, body mass and length, kidney- and adrenal mass, and length and shape of intestines were determined, in order to provide information concerning the house mouse's response to fluctuating environmental parameters and to assess the levels of stress experienced by mice at different times of the year. Stress levels are influenced by population density, sex, reproductive status, temperature and availability of food. In 1992/93 mice had significantly larger body to tail length ratios than in 1979/80, despite the fact that the island warmed considerably in the interim. This warming has allowed a significantly longer breeding season, perhaps by as much as two months. It is suggested that this is the reason that end of season densities are now considerably higher than in 1979/80.Item Open Access Ecology, taxonomy and possible life cycles of blood protozoans infecting crag lizards (Pseudocordylus spp.) from the eastern Free State highlands(University of the Free State, 2012-01) Van As, Johann; Smit, Nico; Davies Russell, Angela; Heideman, NeilEnglish: The study of blood parasites of reptiles is a relatively new and unexplored field in South Africa. Therefore, the general aims of this research were to explore the haemoparasite fauna of cordylid lizards, Pseudocordylus melanotus, Pseudocordylus subviridis and Pseudocordylus langi, and especially to search for the definitive hosts and likely vectors of their haemogregarines. Surveys of lizard blood were conducted at various altitudinal gradients on the Sentinel Trail in the escarpment area of the Drakensberg, and at the top of Platberg, near Harrismith, both in the Free State. Five species of haemogregarines were identified, all suspected to belong to the genus Hepatozoon, and none was known from previously published records. These occurred in the blood of P. melanotus, P. langi and P. subviridis from the two disjunct study sites, and mostly were accompanied by other haemoparasites including a saurian malaria, so-called Sauroplasma, and filarial nematodes. Developmental stages of two of the Hepatozoon spp. were documented in the internal organs of P. melanotus and P. subviridis by means of light and confocal microscopy, histology, and transmission electron microscopy. Life stages were also observed in ectoparasitic lizard mites, by means of stained histological sections, and in stained squashes of mites and mosquitoes. Three species of experimentally reared mosquitoes were found to act as likely definitive hosts for Hepatozoon spp. of P. melanotus and P. subviridis, while wild caught Culex (Afroculex) lineata appeared to serve as a definitive host, and therefore possible vector for an Hepatozoon species of P. melanotus at the top of Platberg. A saurian malaria that appeared to have features of two previously described species was recorded in P. melanotus and P. subviridis. New locality records for so-called Sauroplasma and filarial nematodes were also documented for the three species of crag lizards. Some aspects of the fine structure of two haemogregarines, the Plasmodium sp. and so-called Sauroplasma infections were recorded for the first time in the erythrocytes of the Pseudocordylus spp. Differential leucocyte and thrombocyte counts were performed on the three crag lizard species and, with erythrocyte characteristics, compared with those of cordylid lizards in previous studies. Several types of leucocytes were characterized ultrastructurally, as well as by light microscopy, and attempts were made to correlate statistically leucocyte counts, and host and environmental data, with parasite loads. Finally, mites and mosquitoes associated with crag lizards were explored further as possible vectors of lizard haemoparasites, and studied using light and scanning electron microscopy.Item Open Access Evolutionary, physiological and phenological responses of Spodoptera frugiperda to climate change(University of the Free State, 2023) Mbande, Abongile; Chidawanyika, F.; Mutamiswa, R.The threat of biological invasions due to global climate change and anthropogenic activities is growing globally. Environmental changes, such as increasing mean temperatures due to global climate warming, may exacerbate the spread of invasive insect species by improving their voltinism, survival, reproductive success and geographic range expansion. The fall armyworm (FAW) Spodoptera frugiperda is one of the most economically important invasive insect pests attacking sub-Saharan Africa (SSA) staple crops, such as maize and sorghum. First reported in West Africa in 2016, FAW has spread to the rest of SSA. Key questions arising from this rapid geographic expansion is how climate and its physiological attributes aid its invasion potential. This is particularly important in this era of global climate change where phenological mismatches are known to also influence their host utilization and survival across different life-stages and physiological status such as mating or feeding. Evolutionary responses at individual and population also play a pivotal role in survival and population persistence across various temporal scales. This study explored the evolutionary, physiological and phenological responses of S. frugiperda to climate change. First, I measured the effects of short-term exposure to heat shock on physiological responses vis critical thermal limits (critical thermal minima [CTmin] and critical thermal maxima [CT max]), and ecological traits vis reproductive success (fecundity [number of eggs per female] and hatching success) and longevity using virgin adults following heat shock at 32, 35, and 38 °C for 2 hours. Second, I assessed the effects of repeatable exposure to cold (CTmin) and chill coma recovery time (CCRT) for 0; 24; 48 and 72 hours and the body lipid content (BLC) and body water content (BWC) on adult fall armyworm (24 h old). Last, I investigated the thermal tolerance of S. frugiperda at 3, 6 and 9 days old adults heat shocked at adult, pupal and larval stages, at 40℃ for 2 hours. Heat shock improved tolerance to heat (measured as CTmax) but negatively affected cold tolerance (measured as CTmin). Males were more vulnerable to heat stress than females. Interestingly, heat shock also reduced fecundity, hatching success and adult longevity. Cold tolerance measured as CTmin improved with repeated exposure in 5th instar larvae, virgin males, and females while CCRT improved in 4th, 5th and 6th instar larvae following repeated cold exposure. Heat tolerance in virgin females showed highest CTmax in 6 day olds while it fluctuated in males. Mated males had higher CTmax than mated females across all heat shocked developmental stages. This study shows that, under heat stress, reproductive fitness in FAW is largely compromised due to low fecundity and stress resistance that is dependent on mating status, age and life-stage. Taken together, the results show that thermal variation has fitness consequences for FAW at both individual and population level. These results provide valuable data that inform mechanistic models for the geographic distribution of FAW under variable climate scenarios. This will especially be critical in developing early warning systems and area-wide strategies for FAW control.Item Open Access Fish myxosporeans from the Okavango Delta, Botswana and the south coast of South Africa(University of the Free State, 2003-12) Reed, Cecile Catharine; Basson, Linda; Van As, Liesl L.; Dykova, IvaEnglish: Myxozoans form a diverse and economically important group of endoparasites that have been intriguing researchers ever since the early1800's. These parasites are notorious, having been associated with the devastating effects many species have shown in aquaculture and fisheries industries throughout the world. Research on both freshwater and marine myxosporeans in Africa is limited to a few countries and has, until recently, been largely neglected in southern Africa. In recognition of the need to investigate the presence of fi sh-infecting myxosporeans in both the freshwater and marine environments of southern Africa, a study was initiated in 1997 investigating the biodiversity of myxosporeans infecting fi shes in two very unique southern African localities. Firstly, the Okavango River and Delta in Botswana contains one of the worlds largest inland deltas composed of about 18 000 km2 waterways. Situated in the middle of the Kalahari Desert, this pristine wetland is the only one of its kind that forms an inland delta and one of the few river systems in the world that is visible from space. The research on myxosporeans infecting marine fi shes was conducted along the Cape south coast of South Africa, which has one of the most diverse marine fauna and flora compositions in the world of which 13 % is endemic. This study aimed to review all existing literature concerning freshwater and marine fish-infecting myxosporeans in Africa, report on the biodiversity and prevalence of fi sh-infecting myxosporeans in the Okavango River and Delta, Botswana, investigate the pathogenic potential of myxosporeans infecting the Okavango fi shes, determine the taxonomic status, species biodiversity and prevalence of myxosporeans infecting fi shes along the Cape south coast, South Africa and investigate the pathogenic potential of myxosporeans infecting intertidal and surf zone fi shes along the Cape south coast of South Afri ca. The examination of 285 8 fi shes representing 14 families and 65 species on several field trips to the Okavango Ri ver and Delta from 1997 to 2001 revealed the presence of 29 different fish infecting myxosporeans representing the genera Henneguya Thelohan, 1892 and Myxobolus Btitschli, 1882. Six of these species have been described as new in three articles prior to this study. Another two new species have been recorded in this thesis, together with the records of 14 miscellaneous species that have never been described before, but require more materi al for the completion of species descriptions. During the course of nine surveys conducted along the Cape south coast of South Africa since March 1998, a total of 410 fishes representing 33 species were examined for parasitic infections. Results from these surveys revealed the presence of 15 different myxosporean species. Three species from the genus Ceratomyxa Thelohan, 1892, one species from the genus Henneguya, two from the genus Myxidium Biltschli, 1882, one species from the genus Myxobolus and one species from the genus Sphaeromyxa Thelohan, 1892 are described in this thesis. Two keys for the identification of both the freshwater, as well as marine and estuarine fish-infecting myxosporeans in Africa are presented as a conclusion to this study. The results obtained from this study have laid the foundation for the continuation of research on these parasites in southern Africa and has provided an insight into the great diversity of myxosporeans infecting southern African fishes.Item Open Access Forensic entomology: the influence of the burning of a body on insect succession and calculation of the postmortem interval(University of the Free State, 2009) Kolver, Jacobus Hendrik; Van der Linde, Theunis C.Forensic entomology is the application of the study of insects and other arthropods which are associated with legal issues and certain suspected criminal events. Successional studies have been successfully applied in criminal cases to determine the postmortem interval (PMI). This research was done to establish the influence of burning on a body’s decomposition, insect succession and calculation of the PMI. Field trials were conducted during different seasons of successive years on the campus of the University of the Free State, Bloemfontein, South Africa. The experimental site where the field experiments were conducted, consists of 24 hectares of open grassveld with a few scattered trees. Four pig (Sus scrofa) carcasses were used during each trial, one carcass as control and three carcasses burnt with different volumes of LRP petrol to a CGS level 2 or 3 burn injury with varying degrees of charring. The carcasses were sampled daily for arthropod activity, carcass mass, decompositional stage and microclimate. The control and SB (slightly burnt) carcasses decomposed at a similar rate during the warmer seasons. During the colder seasons, the SB carcass decomposed faster than the control carcass. The slowest decomposition occurred at the MB (medium burnt) and HB (heavily burnt) carcasses. Burning had an effect on the colonisation of Chrysomya chloropyga, Chrysomya marginalis and Chrysomya albiceps. Oviposition occurred simultaneously at all carcasses (autumn, spring & during heavy rainfall in summer ), at the burnt carcasses one day prior to the control carcass (spring & summer) and at the burnt carcasses three to five days prior to the control carcass (autumn & winter). An exception occurred during a single trial when oviposition occurred at the burnt carcasses five days after oviposition at the control carcass (winter). During the warmer seasons oviposition time was shorter, resulting in maggots of similar age at all of the carcasses. During the colder seasons oviposition time was extended, resulting in maggots of different ages and instars on the same carcass and between carcasses. During all trials, except for the summer trail with heavy prolonged rainfall, only the control carcasses reached the Dry/Remains Stage. The burnt carcasses only reached the Advanced Decomposition Stage during the same timeframe. Calliphoridae were the dominant Diptera during all trials. Dominant Diptera species, in numerical order, were Chrysomya marginalis, Chrysomya albiceps and Chrysomya chloropyga. Muscidae adults were recorded during all trials, but no maggots were observed or collected. Coleoptera were dominated by Dermestes maculatus (adults and larvae) and Necrobia rufipes (adults). Coleoptera dominance increased with the level of burning. Differences in arthropod succession between the carcasses occurred due to the effect of burning on the time of oviposition. The PMI calculated for a burnt body would be one to five days shorter than the PMI for an unburnt body, depending on the extent of bloating of the burnt body, the season and ambient temperature. During warmer months the PMI of a burnt body and an unburnt body would essentially be the same due to simultaneous oviposition. Laboratory trials revealed that feeding on burnt media caused C. chloropyga maggots to reach pupation one day faster than the control. No significant difference was found between the treatments for the development time from pupation until adult eclosion. No significant difference was found between the treatments for the mean total development time for C. chloropyga. A 10.6% higher survival until adulthood was found on the burnt media than the control. Morphometrics revealed a higher pupal mass for the control than the burnt media. No signifant difference was found for the adult dry mass and wing length for the control and the burnt media.Item Open Access The influence of clothing, wrapping and physical trauma on carcass decomposition and arthropod succession in central South Africa(University of the Free State, 2006-06) Kelly, Janine Anne; Van der Linde, Theuns C.; Anderson, Gail S.English: Forensic entomology is the study of arthropods associated with bodies. Arthropod successional studies have been successfully used to estimate a postmortem interval. This research was to determine the influence of a) seasons, b) clothing, c) wrapping and d) knife wounds on carcass decomposition and arthropod succession. The experimental site consisted of a 26 hectares grass field interspersed with trees. For the wrapped trials, six pig (Sus scrofa) carcasses were divided into three sample groups, each with a clothed carcass and an unclothed carcass wrapped in sheeting. Arthropod sampling was done (i) daily, (ii) five day intervals and (iii) ten day intervals. Two additional unwrapped carcasses, one with clothes and one without, were sampled daily as controls. For the wounds trials six carcasses were divided into three groups. Each group consisted of a carcass with clothes and one without clothes. The wounds consisted of (i) a knife wound to the throat, (ii) three deep knife wounds, in the back, in the front thoracic and in the front abdominal region. The controls, were without any wounds. Oviposition occurred simultaneously and was not delayed or hastened by the presence of wrapping, clothing or wounds. However, during the winter wrapped trials there was a delay of four days. In winter, the carcasses remained acceptable to Diptera for oviposition over an extended period. Oviposition continued up to two months after placement, whilst in the warmer seasons oviposition occurred within the first few days. The Diptera did not select the wounds as oviposition sites. Calliphoridae and Sacrophagidae were the dominant Diptera recorded during all the trials. In the autumn and summer seasons Chrysomya marginalis and Chrysomya albiceps were the dominant species. In the spring seasons, the dominant species were Chrysomya chloropyga and C. albiceps. In the winter seasons, Sarcophaga cruentata , C. chloropyga, Calliphora vicina, and Lucilia spp. were the species breeding on the carcasses. Muscidae adults were present during all the seasons, but no maggots of this family were recorded. Due to the short oviposition time during warmer seasons, the maggots were of a similar age at any time. Due to the extended oviposition that occurred during winter, different instar groups, often the same species, were present at any time. In all seasons the Coleoptera community present on the carcasses were dominated by Dermestes maculatus (adults and larvae) and Necrobia rufipes. In the summer Thanatophilus micans (adults and larvae) and Histeridae spp. were also recorded on the carcasses. There was no overall difference in arthropod succession between any of the carcasses. During the autumn seasons, noticeable predation by C. albiceps maggots on C. marginalis maggots was observed. There was limited maggot predation during the spring trials and some predation observed during the summer trials. Presence of clothing, wrapping and wounds had no influence the Coleoptera community. In the winter seasons, D. maculatus larvae were found while the maggots were still present on the carcasses. In summer seasons, they were only present after maggot migration. Significant maggot mortality was associated with the wrapped carcasses during the warmer seasons. The presence of the sheets or clothing did allow the maggots to move more freely on the surface of the carcasses, especially in the summer. Less skin remained on the wrapped or clothed carcasses after the maggots migrated to pupate.