Zoology and Entomology
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Item Open Access Isolering en karakterisering van 'n aminopeptidase van die termiet, Trinervitermes trinervoides (Sjöstedt)(University of the Free State, 1979-11) Van der Westhuizen, Michiel Christiaan; Hewitt, P. H.; Du Toit, P. J.Abstract not availableItem Open Access Die mikroanatomie en histochemie van die ganglion nodosum en vagussenuwee by Gallus domesticus(University of the Free State, 1980-12) Van der Linde, Gideon Petrus; Dreyer, Maria V.Afrikaans: Die mikroanatomie, topografie, normale ligmikroskopie, histochemie (insluitende fluoressensie) asook ultrastruktuur van die voël (Gallus domesticus) ganglion nodosum is ondersoek in 13 klinies gesonde wit Leghorn hane. Na aanleiding van resultate is tot die gevolgtrekking gekom dat 3 tipes neurone voorkom, hoofsaaklik gebaseer op die Nissl-patroon varierend van vorm en verspreiding in die ganglion. Neurone word omring deur kerne van skedeselle met 'n GLER buisstelsel. Histochemiese data toon 'n positiewe RNA Nissl-liggaam reaksie asook noradrenalien op Nissl - liggame. Moontlike katesjolamines, serotonien en proterenhormoonkomplekse kom voor in senuvesels en neurone. Meer breë as smal gemiëlineerde senuvesels omring deur Schwannselle is teenwoordig.Item Open Access 'n Ondersoek na die rol van soöplankton in Roodeplaatdam(University of the Free State, 1983-10) Stofberg, Catharina Elizabeth; Seaman, M. T.English: Roodeplaat Dam is a warm monomictic and eutrophic waterbody, which is situated in a summer rainfall area. A definite thermocline and hypolimnion are found in summer, together with a high primary production, which gives rise to a large anaerobic hypolimnion during summer. The Pienaars River/Hartbees Spruit arm of the dam was much more turbid than the Edendale Spruit arm and the main basin of the dam. Large water inflows during summer had a dilutionary effect on the electrical conductivity, nitrate, nitrite, and phosphate concentrations. High chlorophill values and dominance for extended periods by the blue-green algae, Microcystis and Anabaena, were indications of the degree of eutrophication in the dam. Five fish species were found in Roodeplaat Dam, of which Oreochromis mossambicus and Chetia flaviventris were dominant. The fry of these species are known to be predators of zooplankton. Low total zooplankton biomass was found in summer because of decreased living space, due to a large anaerobic hypolimnion. The high zooplankton numbers during summer, in spite of low total biomass, resulted from a change of dominance from the large Daphnia spp. to the smaller Thermocyclops and Ceriodaphnia spp. There were marked increases in zooplankton numbers with the change of· phytoplankton dominance from blue-green algae to green algae and cryptomonads. Twenty two zooplankton species in numbers warranting examination were found in Roodeplaat Dam. By the use of correlation coefficients, Cluster Analysis and correlation with environmental conditions, the zooplankton were separated into eight groups. The most influential conditions governing the density of zooplankton taxa in Roodeplaat Dam were those relating to food type and temperature, and to a lesser extent pH and electrical conductivity. Thermocyclops oblongatus was present throughout the study period and dominated the zooplankton community. Extremely high annual p/B ratios of 82,63 and 88 were found by two production-determination methods. Correspondingly an annual production of 589,24 kgC.annum-1 was derived for the total zooplarikton population. In comparison with the zooplankton communities of other South African systems, Roodeplaat Dam's zooplankton corresponded most closely with that of Hartbeespoort Dam, which is also a warm monomictic and eutrophic system.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 'n Vergelykende studie van die groeivermoëns van vier tilapia spesies in natuurlike en intensiewe produksie-eenhede(University of the Free State, 1988-11) Van Zyl, Barend Johannes; Gaigher, I. G.; Seaman, M. T.English: The growth rates of four tilapia species were compared under natural and intensive conditions. This was done to find the fish species most suitable for fish farming purposes in South West Africa. All four species showed a high growth rate in their first year until they reached sexual maturity. Significant differences between the empirical lengths of certain age groups were found between O. mossambicus (Hardap dam), O. macrochir and T. r.rendalli from the Okavango and Cunene rivers. Significant differences between the empirical lengths of all the age groups were found between O. andersoniii from the Okavango river and O. macrochir from the Cunene river. Significant differences between empirical lengths of certain age groups were found in O. andersonii from the Okavango river, O. macrochir from the Okavango river and T. r.rendalli from the Okavango and Cunene rivers. O. macrochir and T. r.rendalli from the Okavangoriver showed the best length/mass ratio, followed by O. macrochir from the Cunene river and O. andersonii from the Okavango river, O. mossambicus from Hardap dam and lastly T. r.rendalli from the Cuneneriver. O. macrochir from the Okavangoriver were found to be superior in length and mass to their counterparts in the Cuneneriver. After 84 days of hormone treatment, O. mossambicus and O. andersonii fingerlings showed the best growth rates with feed conversion rates of 2,6 and 2,2 respectively, followed by O. macrochir iwth a feed conversion rate of 2,7 and lastly T. r.rendalli with a feed conversion rate of 3,0. In the control group O. andersonii showed a better growth rate than O. mossambicus with feed conversion rates of 2,4 and 2,6 respectively. There were no significant differences in the growth rates of O. mossambicus and O. macrochir in the control group, with O. macrochir having a food conversion rate of 2,9. T. r.rendalli showed the poorest growth rate in the control group with a food conversion rate of 3,5. No correlation could be found between the mass of the female and the growth rate of her offspring. With the exception of O. andersonii, the hormone treatment O. mossambicus showed a better growth rate after day 84. O. macrochir after day 98 and T. r.rendalli from day 14, than the control group.Item Open Access Aspects of the behaviour and ecology of Gurney's Sugarbird Promerops Gurneyi verreaux, 1871, in Protea Woodland, South Africa(University of the Free State, 1998-11) De Swardt, Dawid Herklaas; Kok, O. B.English: Several aspects of the ecology of Gurney's Sugarbird were studied in the Lydenburg area (Mpumalanga) and at Sterkfontein Dam Nature Reserve and Qwaqwa National Park (Free State) during the period April1980 to June 1998. The distribution pattern of Gurney's Sugarbird is closely associated with that of Protea roupelliae along the Drakensberg escarpment in the Grassland Biome. Nectarivore densities at Protea clumps were affected by the size of clumps, flower availability and grasssland fires. Sugarbird densities were higher during winter, spring and early summer when sufficient flowers were available. Male sugarbirds were significantly larger than females in all body measurements, except tarsus length. Significant correlations were recorded between culmen/total head length and wing/tail length of the two sexes, and between maximum width of the bulged P6/wing length in males. Monthly variations in body mass were recorded in both sexes, and birds were heaviest during the November-March breeding season. Adults with long, fully-grown tail ornaments usually had longer wings, while males had wider bulged P6. Primary moult occurred between November to March, coinciding with the breeding season. Tail moult also occurred during this period and were replaced as soon as their condition worsened. The sugarbirds have a September-March breeding season, with a peak from November to December in the Lydenburg area. P. roupe/liae were usually selected for nesting sites, while P. caffra was also occasionally used. Nests were completed within five days by the female; mean nest height was 1,85 m. Nests were lined with the brown, fluffy seeds of P. roupelliae. Incubation period was 16-17 days, nestling period 21-23 days, and post-nestling period 20-30 days. Breeding success was 41,4%, higher than that of the Cape Sugarbird. Sugarbirds foraged mostly on the nectar of P. roupelliae, but during winter they fed on A/oe arborescens in nearby suburban areas and on mountain cliffs. Insect orders which predominated in the diet of Gurney's Sugarbird were Coleoptera and Hymenoptera. These insects also comprised the main arthropod fauna in P. roupelliae flowers. Bees and ants were recorded in both stomachs of sugarbirds and Protea flowers. Sugarbirds foraged on P. roupe/liae flowers by probing several times into a flower whilst moving clockwise on it. Beetles were taken from flowers and small flying insects hawked from the air. Movement and survival data for 93 individuals were obtained from 553 captured sugarbirds in the Lydenburg area. Recaptures showed fidelity to mountain sites, local movements between mountain sites, seasonal movements and individuals recaptured at the same suburban localities during winter. Peak in occurrence in suburban areas was from late May until early July, coinciding with the flowering season of Aloe arborescens. Sugarbird movements were after the peak flowering periods of P. roupelliae, birds leaving burnt Protea veld after fires and after seasons characterised by low annual rainfall. Annual survival in the Lydenburg area was estimated at 80,7%. Life expectancy was 4,6 years. Two individuals were recaptured after periods of 88 months and one after 74 months. Recapture data suggests a longevity of beyond seven years for this species. This longevity data represents the first of its kind for the species. The conservation of Gurney's Sugarbird and the' management of its Protea roupelliae habitat is a priority. Uncontrolled fires in grassland with P. roupe/liae trees, and logging of wood for fuel, have negative influences on bird and protea populations. The recommended fire regime for P. roupelliae woodland is during dry winter periods (June/July), rotated biennially, or as late winter-spring fires (August/September). The application of regular block burns or firebreaks in montane grassland will ensure less damage to tree canopies during accidental fires.Item Open Access Studies on stalk borers of maize and sorghum in Lesotho(University of the Free State, 1998-11) Ebenebe, Adama Audu; Van den Berg, Johnnie; Van der Linde, T. C de K.English: Investigations on various aspects of stalk borers of maize and sorghum were conducted in Lesotho during the 1995/96, 1996/97 and 1997/98 growing seasons. Aspects investigated were their distribution and relative abundance on these two crops; seasonal moth flight pattern of Busseola fusca; impact of natural stalk borer populations on maize and sorghum; response of some maize and sorghum varieties/hybrids to artificial infestations with B.fusca and Chilo partellus respectively; farmers' perceptions and farm management practices with regard to the management of stalk borers; relative efficacy of insecticides used for C. partellus control in Lesotho; effect of planting date of maize on B.fusca infestations; effect of intereropping with beans on B. fusca infestations in maize, and relative abundance of natural enemies of B. fusca and C. partellus. These investigations provided the following results: B. fusca was distributed throughout Lesotho and was important on both maize and sorghum. C. partellus occurred only in the central lowlands where it attacked only sorghum. Seasonal B. fusca moth flight activity was characterised by distinct periods of high and low activity, with three and two to three generations of moths per season in the lowlands and mountains respectively. Infestations of B. fusca in Lesotho caused substantial yield losses in susceptible maize varieties and hybrids. Lesotho's maize varieties and hybrids were observed to be susceptible, with yield losses of up to 39.4% observed under field conditions. Their susceptibility was further demonstrated through artificial infestations in glasshouse and field studies. The glasshouse study showed that the levels of antibiosis and antixenosis resistance to B. fusca in these varieties and hybrids were low, while the field studies showed only moderate resistance to foliar damage. Lesotho's sorghum varieties exhibited susceptibility to stalk borer damage, both under field conditions and artificial infestations with C. partellus. A glasshouse study also found antibiosis to be the main resistance mechanism against C. partellus larvae in whorls of resistant sorghum genotypes. The variety Tenant White, exhibited tolerance to damage, both under natural and artificial infestations.Lesotho's farmers regarded stalk borers as important pests. The commonly employed control measure was insecticide application. Although the use of routine farm management practices has potential for suppressing borer populations, they were not utilised in this regard. Comparison of the efficacy of six insecticides used for stalk borer control in Lesotho indicated granular formulations beta-cyfluthrin 0.05 % and carbaryl 2.5 % to be more effective against C. partellus larvae in sorghum whorls than spray formulations. Early planting of maize (in November) substantially reduced damage and yield loss caused by B.fusca. Intereropping maize with beans reduced damage and yield loss caused by B. fusca in maize. Furthermore, alternating rows of maize with rows of beans was more effective than alternating maize with beans within a row. The braconids Bracon sesamiae, Cotesia sesamiae, Euvipio sp. and Habrobracon brevicornis parasitized B. fusca larvae. Only B. sesamiae and C. sesamiae were recorded on C. partellus larvae. An unidentified ichneumonid was reared from C. partellus pupae, while a red ant species Dory/us sp. (Formicidae) was recorded as a predator of both B. fusca and C. partellus larvae. However, the activity of these natural enemies was generally low, increasing only towards the end of the growing season. These investigations have shown that stalk borer infestations are economically important in Lesotho. However, adopting such cultural practices as planting date adjustment, intereropping and destruction of crop residues can limit infestations. These practices, together with limited insecticide use, should form components of an integrated stalk borer management system. Future research efforts in Lesotho need to include the identification and development of maize and sorghum varieties and hybrids with high yields even under stalk borer infestations. Where such varieties are open-pollinated, they will be of particular benefit to the resource-poor farmers, who may not be able to afford hybrid seeds.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 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 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 Aspects of the morphology and life history of Oculotrema hippopotami (Polystomatidae: Monogenea)(University of the Free State, 1999-01) Moeng, Itumeleng Amos; Du Preez, L. H.; Kok, D. J.Being the only monogenean known from a warm-blooded animal and from a mammal Oculotrema hippopotami Stunkard (1924) took a major leap in monogenean evolution. After its description in 1924 various researchers rejected the claim that it came from the hippopotamus and made it out as a mislabeled specimen. It was only 40 years later that this parasite received full recognition. In spite of the fact that it was described more than seven decades ago, only a few papers on this parasite have seen the light. During 1996 this parasite was rediscovered in South Africa. A hippopotamus culling program in Kwazulu-Natal gave an opportunity to study this parasite. The present study is the first detailed attempt to study the morphology and life history of Oculotrema hippopotami. The approach in this study was as follows: 1. Background on the host's morphology, behaviour and phylogeny is given. The hippopotamus' eye is situated deep in the orbit with the result that a deep crevice is present all around the eye, which serves as habitat for the parasites. 2. The external morphology of the egg, oncomiracidium and adult parasite was studied USIng scannmg electron rrucroscopy. This is the first ever scanrung electron microscopical study of 0. hippopotami and this study revealed many new information. 3. The internal morphology of the adult parasite was studied histologically using wax sections. This revealed unique musculature in the mid piece that has never before been reported for any polystomatid parasite. 4. Sperm morphology and the ultrastructure of the musculature in the mid piece was studied at transmission electron mieroeope level. Indications are that the sperm morphology is very similar to that reported for other polystomatids. 5. Infection levels for different seasons were compared. In contrast with most other polystomatids that reproduce during the warmer summer months, 0. hippopotami lays eggs during the cooler winter months. 6. The parental care and behaviour of a pair of hippopotami with a newborn calf were studied. A very close bond with long periods of physical contact was observed. This could give an ideal opportunity for parasite transmission from mother to calf.Item Open Access Sessiline ciliophorans associated with Haliotis species (Mollusca: Archaeogastropoda) from the South Coast of South Afica(University of the Free State, 1999-06) Botes, Heléne; Basson, Linda; Van As, Liesl L.English: Abalone, locally known as perlemoen, are herbivorous marine gastropods with all species in one genus, Haliotis Linneaus, 1758. Abalone have been commercially exploited since ancient times. Along the southern African coast, the genus Haliotis comprises six endemic species. Surveys carried out from 1995 to 1999 at the De Hoop Nature Reserve along the south coast of South Africa, revealed the presence of scyphidiid peritrichs, of the genus Mantoscyphidia Jankowski, 1980, occurring in abundance on the gills of Haliotis spadicea Donovan, 1808 and H. midae Linnaeus, 1758. These were described as two new species, i.e. M spadiceae sp. nov. and M midae sp. nov. The mantoscyphidians in turn hosted ellobiophryids of the genus Caliperia Laird, 1953, which was also described as a new species, Caliperia perlemoenae sp. nov., occurring on both mantoscyphidian species. During the study a perlemoen aquaculture facility, Danger Point Abalone Farm, was also visited, specimens of H. midae were examined and found to harbour the same species of scyphidiid peritrich and caliperid than H. midae collected from the De Hoop Nature Reserve. In the present study, severe infections of redial, cercarial and metacercarial stages and a few adult specimens of a digenean trematode were also found in the digestive gland of Haliotis spadicea as well as on the gill filaments. In order to elucidate the symbiont/host associations field experiments and histopathological examinations were carried out. These led to the conclusions that the host/scyphidiid peritrich associations are most likely not parasitic. In the case of the mantoscyphidianlcaliperid association, no clear evidence was found that the caliperids are pathogenic to their mantoscyphidian hosts. On the other hand, the trematodes could be potential pathogens since they can cause tissue destruction and affect the reproductive organs in the host.Item Open Access The bio-ecology of the sheep scab mite Psoroptes ovis (Acari: Psoroptidae) Hering (1835)(University of the Free State, 1999-09) Meintjes, Theresa; Fourie, L. J.; Kok, D. J.English: Sheep scab, which is caused by the mite Psoroptes ovis, has been and is still today an impediment to sheep husbandry in many countries throughout the world. Despite the economic impact, sheep scab remains a serious veterinary problem in South Africa. The broad objectives of this study were to determine the adverse effects of P. ovis on the host, with special reference to Merino and Dorper sheep, and to examine various possible foci of infestation and host specificity. Furthermore, the effects of abiotic factors (relative humidity and temperature) on the off-host survival of P. ovis were determined. The nature and extent of sheep scab in small scale, predominantly black farming communities, were assessed and compared to commercial predominantly white farming communities. The results revealed the following: With the exception of neutrophils, haematological values remained within the normal range for infested Merino and Dorper sheep, during a 14 week assessment period. For both sheep breeds the albumin and globulin values were higher than the normal range during the entire 14 week observation period. Both sheep breeds displayed a slight decrease in albumin values and a slight increase in globulin values. At the termination of a 16 week assessment period, uninfested control Merino sheep gained a mean ·body mass of 3.44 kg which represented a Il. 60% increase in body mass, compared to the mean body mass decrease (6.4 kg) of infested Merino sheep. This represented a 23.43% decrease in body mass. The mean body mass of the infested Dorper sheep increased over the 16 week period by 4.56 kg (15.11%) compared to the 5.88 kg (18.28%) of the uninfested control Dorper sheep. Comparative studies on the rate of sheep scab lesion development indicated that there were profound differences between sheep breed and season. During the summer assessment of 1997 the mean lesion size on the Merino sheep expanded from 1.0 cm2 at two weeks post infestation to 342.2 cm2 at eight weeks post infestation, compared to the mean lesion size of 0.406 cm2 and 59.0 cm2, respectively, recorded at two and eight weeks post infestation on the Dorper sheep. Lesion growth for both sheep breeds were greater during the winter. Attempts to artificially infest Boer and Angora goats failed. No clinical signs of sheep scab developed on the goats during a nine week observation period. When a single artificially infested Merino and Dorper sheep were introduced during winter into a flock of nine uninfested sheep for each breed, it took 14 and 8 weeks, respectively, before all the sheep in the flocks displayed clinical signs of sheep scab. During summer it took 10 and 12 weeks, respectively, before all sheep in the two flocks displayed clinical signs of sheep scab. All developmental stages of the mites were found in proximal and distal parts of wool / hair tufts clipped from Merino and Dorper sheep. Immature and mature mites were readily transferred to wool/hair tufts placed onto, and later removed from infested sheep, confirming that direct contact between hosts is most probably the main means of transfer. A maximum mean off-host survival time of 15 days (T = 10°C and RH = 33% and 75%), 10.5 days (T = 10°C and RH = 75% and 90%) and 11.25 days (T = 10°C and RH = 90%) were recorded for nymphs, males and ovigerous females, respectively. The mean egg incubation time varied from 5.9 (±2.58) to 22.14 (±6.53) days. The longest time eggs took to hatch was 31 days (T = 10°C and RH = 75%). The longest mean larval longevity was 9.25 days (T = 10°C and RH = 90%). Under natural fluctuating conditions ovigerous females in glass vials containing Merino wool survived 20 days, compared to a maximum of 17 days of females in glass vials without Merino wool. A survey indicated that 36.36% of the sheep flocks in Botshabelo and 38.46% in Thaba Nchu, respectively, were infested with sheep scab. This high incidence was believed to be due to factors such as communal grazing systems, ignorance on the part of the farmers and the lack of financial means to purchase effective remedies to treat their sheep flocks.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 Open Access Caligid fish parasites from the South and East coast of South Africa(University of the Free State, 2000-03) Grobler, Nicolaas Johannes; Van As, J. G.; Olivier, P. A. S.English: Caligus Muller, 1785 are caligid copepods found almost exclusively on marine fish hosts. This genus is represented by more than 200 species in the oceans of the world and is the largest genus of parasitic copepods. A total of 39 species of Caligus parasites have been recorded off the coast of Africa, and 26 species are found along the South African coastline. Surveys carried out from 1992 to 1998 in Lake St Lucia and from 1997 to 1999 at De Hoop Nature Reserve and Jeffreys Bay along the coast of South Africa, revealed the presence of caligid copepods, of the genus Caligus MilIler, 1785, occurring on the body surfaces and gills of many estuarine and intertidal fish species. Four different species were collected from marine hosts namely, Caligus acanthopagri Lin, Ho & Chen, 1994, Caligus confusus Pillai, 1961, Caligus engraulidis Barnard, 1948, and Caligus mortis Kensley, 1970. The first three species mentioned were collected in Lake St Lucia, KwaZulu-Natal, on the east coast of South Africa, and C. mortis were collected at De Hoop Nature Reserve and Jeffreys Bay on the south coast of South Africa. In the present study, males of C. engraulidis and C. mortis are described for the first time and is new to science. Further studies revealed that interesting hypersymbionts were found attached to the caligids. Sessiline ciliophorans were found on both C. acanthopagri and C. engraulidis and represents a first record for South Africa. Udonella caligorum Johnston, 1835 were found on the caligid host C. engraulidis. This monogenean worm have a complicated history, for it was placed in different taxa and families since it was first described in 1835. Phylogenetic analysis as well as morphological analysis places this worm firmly as a polyonchoinean monogenean alongside the Gyrodactylidae. These hypersymbionts do not feed on the copepods and have no detrimental effects on their hosts.Item Open Access Environmental, manpower and financial analysis of locust control in South Africa(University of the Free State, 2000-03) Peters, Susanna Magdelena; Van der Westhuizen, M. C.English: The brown locust, Locustana pardalina (Walker), has regularly recurring outbreaks in the region Karoo region of South Africa. The endemic region comprises an area of approximately 40 million hectares. The locusts in the gregaria phase cause considerable damage to natural pastures and is in direct competition with stock farming. The National Department of Agriculture administers locust control campaigns. Trained volunteers (supervisors and assistants) in the locust districts conduct locust control campaigns and are remunerate for their efforts. Any sustainable agricultural setup and pest control should adhere to the following three criteria: environment, manpower and financial resources. This study was aimed at analyzing the 1996/97 locust control campaign, with the emphasis on the De Aar, Hanover, Hay and Postmasburg locust districts, based on these three criteria. The project was divided into two main parts: a component analysis for managerial purposes and a spatial analysis (in ArcView-GIS) for operational purposes. The component analysis was done on supervisor level within the districts and the spatial analysis was done on both farm and district levels. Great variation existed between the supervisors and districts analysed in all three criteria. The highest number of bands and swarms was controlled in the Hanover district (5392), followed by Hay (1 961) De Aar (1 519) and Postmasburg (859). The supervisors in the De Aar district controlled a higher percentage of hopper versus adult locusts (87 vs. 13 %). The opposite was encountered in Hanover (28 vs. 72 %), Hay (32 vs. 68 %) and Postmasburg (45 vs. 55 %). The highest total area (Ha) bands and swarms was sprayed in the De Aar district (Il 410), followed by Hanover (9 493), Hay (5 054) and Postmasburg (2 816). Locusts had the highest impact on grazing in the Hanover district. Effective control operations resulted in small areas of each district being sprayed: De Aar (2,13 %), Hanover (2,63 %), Hay (0,40 %) and Postmasburg (0,16 %). An early warning system to facilitate locust control is possible with the incorporation of reliable biotic and abiotic data. Dissimilarities in manpower utilisation were evident through the area (Ha) and amount of pesticide sprayed per assistant per day in the various districts. The highest numbers of supervisor (800) and assistant (2 039) days were recorded in the Hanover district and the lowest numbers (172 vs. 129) were recorded in the Postmasburg district. A geographic information system enables visual monitoring of job creation and socio-economic implications of locust control. The pesticide and travelling expenditure accounted for most of the expenses. The expenses per hectare (RlHa) were the highest in the Hay district (70,07) and the lowest in Postmasburg (23,17). The actual financial damage caused by the locusts was much lower than the potential financial loss. Investment return factors (IRF's) of more than one hundred were achieved in all the districts. The integrated operational and management information system enables visual access to extensive locust control data. This information system eases management by facilitating proper planning within and among campaigns.Item Open Access Aspects of the bio-ecology of the biting louse, Damalinia Limbata(University of the Free State, 2000-05) Brown, Leslie; Van der Linde, T. C. de K.; Fourie, L. J.English: Biting lice are well known ecto-parasites of vertebrates. Most wild and domesticated animals have one or more louse species, living on them. Although lice are a source of irritation to the host, they are not generally considered as economically important because they do not cause much physical damage. The sheep biting louse (Damalinia avis) has, however, been shown to cause losses in wool production and quality. Damalinia limbata are ecto-parasites on Angora goats and can cause the same type of losses to the farmer as the sheep biting louse. Very little research has been done on these lice and their impact on mohair production can therefore not be objectively assessed. The objectives of the current study were to investigate aspects of the biology and distribution of D. limbata and to promote more effective and economical management of these lice on commercial farms. The following were investigated: (1) Aspects of the morphology of D. limbata and D. avis. (2) Environmental temperatures prevalent on the body of Angora goats. (3) The number of nymphal instars of D. limbata. (4) Seasonal changes in the populations of D. limbata. (5) The influence of D. limbata on the body mass of Angora goats and the production and quality of mohair, as well as the efficacy of different control methods. Field experiments were conducted on the farm Preezfontein (29°50'S, 25° 19'E), situated 10 km from the town Fauresmith, about 130 km southwest of Bloemfontein in the south-western Free State. The veld type of this area is defined as 'False Upper Karoo' and falls in the Karoo biorne. The Free State is a summer rainfall region with an average precipitation of 450-500 mm per annum, with hot summers and cold winters and droughts occurring regularly. D. limbata and D. avis were compared using general morphological characters, morphometric measurements of various body regions and placement of dorsal and ventral abdominal sclerites. D. limbata has a more robust appearance than D. avis. Females of both D. limbata and D. avis were on average 1.611 mm long and the males had average lengths of 1.378 mm and 1.255 mm, respectively. Male D. ovis had solid dorsal plates where as D. limbata males had dorsal plates, which were transversally split, on segments IV and V. Temperature studies, on the micro-habitat of D. limbata, showed that the temperature against the skin of an Angora goat is relatively constant at approximately 35°C. All attempts to establish a laboratory colony of D. limbata were unsuccessful. D. limbata was found to have three nymphal instars before reaching adulthood. Instar 1 had average head-capsule widths and lengths of 0.252 mm and 0.202 mm, respectively. The second and third instars had head-capsule widths of 0.364 mm and 0.467 mm and lengths of 0.305 mm and 0.425 mm respectively. The louse populations increased during spring and early summer, peaking in mid summer. Mid winter shearing seemed to have a greater impact on the louse populations than mid summer shearing. D. limbata moves around the body of Angora goats, being more abundant on the ventral areas of the body during summer and more evenly dispersed over the body during winter. It was found that D. limbata does not have an adverse influence on the body mass of Angora goats, but does adversely affect mohair production and quality. The average loss in mohair production was 12 % and individual losses of as much as 25 % were recorded, representing substantial financial losses to the farmer. D. limbata was effectively controlled by Deltamethrin when applied as either a backline treatment or as a lateral application with a Tikspray applicator.Item Open Access Myxosporean parasites (Myxozoa: Myxosporea) infecting fishes in the Okavango River system, Botswana(University of the Free State, 2000-06) Reed, Cecile Catharine; Basson, Linda; Van As, Liesl L.English: The Class Myxosporea Butschli, 1882 comprises an enormous group of spore forming obligatory parasites that are able to infect any organ of the hosts in which they are found. Myxosporeans mostly parasitise fish and to date there are more than 1300 species known from fishes throughout the world. In Africa, approximately 84 species have been described from primarily freshwater fish. Research on myxosporeans in southern Africa is very limited, with only a few publications appearing from the coast of South Africa during the early 20th century. In Botswana no research has ever been conducted on myxosporean parasites infecting fishes. Botswana contains one of the worlds largest inland delta systems formed by the Okavango River, which flows in a southeasterly direction from Angola. Knowledge on the fishes as well as their parasites is essential for the well being of a unique body of water such as this. Since myxosporean parasites of fish hold the potential to be pathogenic to their hosts and have been known to cause serious economical losses in aquaculture industries throughout the world, it is thus essential to determine the distribution and biodiversity of these parasites in the Okavango River and Delta in Botswana. The main aims of this project were to investigate the available literature regarding African myxosporeans, compile a database of species infecting freshwater fishes in Africa and to investigate the taxonomic status, species biodiversity and prevalence of myxosporeans infecting fishes in the Okavango River and Delta in Botswana. Fieldwork for this project was conducted in June and July 1998 and 1999 in the Okavango and a total of 275 fishes belonging to 31 species from nine different families were examined for the presence of myxosporean parasites. Five myxosporeans from the genus Henneguya Thélohan, 1892 were collected from four different fish hosts. Only one of these was identified as a known species and was described in this dissertation. A comprehensive morphological description of the four unknown species was also provided. Eight myxosporeans from the genus Myxobolus Butschli, 1882 were also found infecting nine different fish hosts, of which four were identified as known species and described. Detailed descriptions of the four unknown species were provided. It was also found that some fish species showed very high gill infections of these parasites, which may cause some form of respiratory deficiency. This current investigation into myxosporean parasites infecting fishes in the Okavango River System in Botswana provided new insight into the distribution of myxosporeans in southern Africa and has also opened the door for future research in this unique group.Item Open Access Interactions between ticks and dogs in the greater Bloemfontein(University of the Free State, 2000-11) Jocobs, Phillip Andrew Herman; Fourie, L. J.; Kok, D. J.The present study was conducted in the greater Bloemfontein area and focussed on the interaction between ticks and dogs. The sampling localities included Bloemfontein, Botshabelo and Thaba Nchu, and various sub-divisions thereof Rhipicephalus sanguineus and Haemaphysalis leachi, being dog ticks and the expected dominant species, were subject to close scrutiny. The present study was a comparative one which consisted of both field and laboratory work and which was designed to address several objectives. The first objective was to study tick diversity, prevalence and relative density. The second objective was to study the effect of various abiotic factors (temperature, relative humidity and photoperiod) on the development rate and survival of eggs, larvae and nymphs of the two dominant species. The third objective was to examine the influence that social factors (e.g. attitudes of dog owners, socio-economic levels, education and awareness, development levels in terms of infrastructure) have on the relationship between ticks and dogs. The results of the present study indicated that the dogs in the greater Bloemfontien were parasitised by at least nine different species. The species with the highest prevalence (and relative density) were R. sanguineus (73.5% and 27.4) and H. leach; (22.4% and 5.8). Other species constituted less than 1.2% of the total sample and were regarded as being incidental. These species included Boophilus decoloratus, Hyalomma truncatum, Rhipicephalus evertsi evertsi, Ixodes rubicundus, Rhipicephalus sp., Rhipicephalus gertrudae and Rhipicephalus follis. There was a clear distinction between the different attachment sites of the two dominant species and both species displayed seasonal patterns. Greater numbers of the two dominant species were found during the warm summer months and very few during the cold winter months. Daily egg production of the two dominant species was similar to that of other ixodid ticks while the pre-oviposition and incubation periods decreased with an increase in temperature. Pre-oviposition periods for R. sanguineus ranged from 4.8 (25°C, 90%RH) to 21.0 (15°C, 40%RH) days and for H. leachi from 4.3 (30°C, 90%RH) to 12.1 (15°C, 40%RH) days. Incubation periods for R. sanguineus ranged from 19.0 (30°C, 90%RH) to 72.0 (15°C, 90%RH) days and for H. leachi, from 15.5 (30°C, 90%RH) to 66.7 (15°C, 40%RH) days. The fecundity ofR. sanguineus ranged from 10.3 (15°C, 40%RH) to 17.2 (25°C, 90%RH), while for H. leachi it ranged from 7.7 (15°C, 40%RH) to 16.3 (15°C, 90%RH) eggs per mg body mass. The fecundity for both species, at a specific temperature, increased with an increase in relative humidity. Generally, unfed larvae and nymphs of both species survived for longer periods at lower temperatures. The pre-moult period of larvae and nymphs of both species decreased with an increase in temperature. Both engorged larvae and nymphs of both species displayed a circadian drop-off rhythm. The general condition of the dogs in the affluent localities were better than those found in other localities. Dogs tested positive for Ehrlichia canis and Ehrlichia chaffeensis in all localities but was the highest in Thaba Nchu. The mean number of dogs in the different localities did not differ significantly. Generally speaking most respondents did indicate concern for their dogs and many saw ticks as being a problem. However, the level of education was a determining factor when it came to the understanding of the relevant diseases and the vectors thereof Ignorance and a lack of necessary resources were important factors contributing to poor animal health in the greater Bloemfontein. The attitudes displayed by dog owners also contributed towards the general condition of the dogs sampled. There is little information available on R. sanguineus and H. leachi generally and particularly in the greater Bloemfontein. The present study has provided some basic information regarding (i) the diversity, prevalence and relative density, (ii) the effects of abiotic factors on eggs, larvae and nymphs, and (iii) the influence that social factors (particularly the attitudes of dog owners) have on the relationship between these two dominant tick species and dogs This type of information can contribute substantially towards endeavours to effectively control the tick species that parasitise our dogs.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.