Kin-selection theory states that individuals can increase their total fitness both through direct reproduction and through reproduction of relatives. The recently developed social contract theory asserts that dominant females should yield some direct reproduction to the subordinates in order to keep them in the colony. The theory predicts that a dominant will cede more reproduction to an unrelated subordinate than to a related subordinate since it will take more to keep her. I found that the social wasp, Polistes dominulus, is unusual in that foundresses regularly nest with non-relatives, even when relatives are available on other nests. This offers the opportunity to test one of the basic predictions of social contract theory, that reproductive skew increases as relatedness among co-foundresses increases. Subordinates of the collected colonies did get a small fraction of direct reproduction, but there was no difference in skew among colonies with different co-foundress relatednesses, contrary to skew theory predictions. Subordinates's relatedness to the queen does not affect colony efficiency. This study found no sign of either higher cooperation in colonies with more related females or greater conflicts in colonies founded by unrelated females.

Genetic data was obtained from a colony of Parachartergus colobopterus using DNA microsatellites. A colony cycle referred to as cyclical oligogyny is believed to account for the high relatedness in this polygynous species. The genetic data was analyzed to support the presence of cyclical oligogyny and determine some of the specific mechanisms behind it. Specifically, queen reduction, increasing reproductive dominance, sexual specialization by queens, and maternity of males (worker vs. queen) were examined. There was evidence for queen reduction occurring in this colony. To the contrary, no support was found for either increasing reproductive dominance or sexual specialization among the queens. It appears that the queens produced all of the males in this colony. This concurs with a worker preference for queen laying of the males that was seen in relatedness estimates.

Several transitions to higher levels of biological organization have punctuated the history of life. These transitions occur when cooperative alliances lead to the integration of non-identical partners into more complex wholes. Yet there is inevitable conflict within these cooperative alliances. In the following chapters I investigate reproductive conflicts of interest between cooperators within insect societies and chimeric multicellular organisms. In the first chapter I show that in the tropical wasp, Parachartergus colobopterus, workers use aggression toward totipotent, emerging females to influence the reproductive future of the latter. By doing this workers resolve conflict over who reproduces in accord with their collective interests. In the second chapter I show that environmental heterogeneity can affect the outcome of conflict between co-aggregating clonal lineages of Dictyostelium discoideum. This helps account for the coexistence of cheaters and victims in natural populations of D. discoideum.

Invasive species, fire suppression and nutrient deposition, as distinct disturbance factors, have altered Texas prairie communities. Arthropod diversity, abundance, and community composition may be modified by these factors either directly or by changes in plant community structure. Because arthropods provide essential ecosystem services and represent a large proportion of terrestrial biodiversity, understanding the responses of arthropod communities to disturbance is the central theme of this doctoral thesis. Land managers commonly utilize fire to control woody species encroachment into prairies and anthropogenic nutrient deposition increases plant productivity. The responses of arthropods to fire and fertilizer manipulations were examined. Fire maintained arthropod diversity by limiting woody plant cover. Path analysis indicated fertilization decreased arthropod diversity by promoting woody plant invasion. Direct negative effects of fire on the arthropod community were small compared to the indirect, positive effects. Arthropod abundance and species richness on the invasive species Chinese Tallow Tree (Sapium sebiferum) were compared to arthropods on three native tree species: Silver Maple (Acer saccharinum), Sycamore (Platanus occidentalis), and Sweetgum ( Liquidambar styraciflua). Although arthropod community composition differed on Sapium, species richness and abundance were similar to levels on native trees. Sapium experienced less chewing, fungal, and mining damage and supported relatively abundant predators and detritivores whilst there were relatively fewer herbivores. These observations are in accord with the Enemies Release Hypothesis that predicts low herbivore loads may contribute to Sapium's invasive success. When Sapium was compared to native plant dominated habitats, predators and detritivores were again relatively abundant while total arthropod diversity was comparatively low. This implies that Sapium has not acquired an insect fauna comparable to native plants in Texas. Insect assemblages on Sapium were examined along a geographical gradient, representing time since introduction. Sapium trees in Florida and Georgia (present longer) had higher insect loads compared to those in Louisiana and Texas (more recently introduced), but species richness did not differ. Herbivore and omnivore abundance and species richness were higher where Sapium has been present longer. This suggests that time since introduction is an important factor constraining herbivore diversity and abundance. Accumulation of herbivores may limit Sapium populations in the future.

My dissertation encompasses three studies of social behavior. Two explore the reproductive conflicts that occur between cooperating individuals. I examine conflict at two levels: within colonies of the social wasp, Eustenogaster fraterna, and within chimeric multicellular organisms formed by the social amoeba, Dictyostelium discoideum. The third project investigates the occurrence of sexual reproduction in a natural population of D. discoideum. Eustenogaster fraterna belongs to the basal eusocial family of stenogastrine wasps. Colonies are small averaging only 2.7 adult females but only one mated female. I examined the reproductive and genetic structure of 18 colonies by genotyping all within-colony individuals and assessing the ovarian development of females. My results show that 85% of females were potential reproducers. Adult females were not related as full sisters. Some brood could not be assigned to any of the adult females, suggesting that subordinate females could inherit the nest and replace the dominant female. D. discoideum live as free-living, single cells, but when starved they aggregate to form a multicellular fruiting body. Genetically distinct clones of D. discoideum co-aggregate to form genetic chimeras. 20% of cells form the stalk of the fruiting body and die, while others become reproductive spores. One clone can exploit the other by contributing less than its proportional share to the sterile stalk. I investigated whether cheating is a strategy dependent on the relative proportion of the clones aggregating. In a chimera, a rare clone could benefit by avoiding forming the stalk because it is less related to the reproductive part. My results do not support the frequency-dependence strategy. I investigated the occurrence of sexual reproduction in a natural population of D. discoideum, using the approach of estimating linkage disequilibrium in the population at one site. My results show that recombination does occur and is due to sexual reproduction not to parasexuality. In sum, conflicts within societies can be mitigated. E. fraterna workers gain insurance advantages by obtaining indirect genetic benefits or inheritance of work force. D. discoideum clones gain cheating advantages either when rare or common in the aggregation. Recombination yields novel genotypes; this might increase the complexity of interactions between co-aggregating clones.

Buffalo-adapted Theileria parva causes Corridor disease in cattle. Strict control measures therefore apply to the movement of buffalo in South Africa and include mandatory testing of buffalo for the presence of T. parva. The official test is a real-time hybridization PCR assay that amplifies the V4 hypervariable region of the 18S rRNA gene of T. parva, T. sp. (buffalo) and T. sp. (bougasvlei). The effect that mixed T. parva and T. sp. (buffalo)-like infections have on accurate T. parva diagnosis was investigated. In-vitro mixed infection simulations indicated PCR signal suppression at 100 to 1000-fold T. sp. (buffalo) excess at low T. parva parasitaemia. Suppression of PCR signal was found in field buffalo with mixed infections. The T. parva-positive status of these cases was confirmed by selective suppression of T. sp. (buffalo) amplification using a locked nucleic acid clamp and independent assays based on the p67, p104 and Tpr genes. Conventional and SYBR® Green touch-down PCR methods were developed for each protein coding gene and buffalo from the endemic Kruger National Park were screened. The protein gene assays compared well with the negative and T. parva positive samples diagnosed on the current real-time assay however, they did detect additional positive samples diagnosed as negative on the real-time hybridization. These samples were all T. sp. (buffalo) positive. This confirmed the suppressive effect on PCR signal due to template competition in the current real-time PCR assay. Some positive samples were not detected by the protein genes, possibly due to sequence variation in the primer regions. These independent markers proved useful as supplementary assays in the accurate diagnosis of T. parva infections where mixed infections occur in the buffalo host. The development of the Hybrid II assay, a real-time hybridization PCR method, which compared well with the official hybridization assay in terms of specificity and sensitivity revolutionized the diagnosis of the disease for the main reason that it is not influenced by mixed infections of T. sp. (buffalo)-like parasites and is as such a significant improvement on the current hybridization assay. While the incidence of mixed infections in the Corridor disease endemic region of South Africa is significant, little information is available on the specific distribution and prevalence of T. sp. (buffalo) and T. sp. (bougasvlei). Specific real-time PCR assays were developed and a total of 1211 samples known to harbor these parasites were screened. Both parasites are widely distributed in southern Africa and the incidence of mixed infections with T. parva within the endemic region is similar (~25-50%). However, a significant discrepancy exists with regard to mixed infections of T. sp. (buffalo) and T. sp. (bougasvlei) (~10%). Evidence for speciation between T. sp. (buffalo) and T. sp. (bougasvlei) is supported by phylogenetic analysis of the COI gene, and their designation as different species. This suggests mutual exclusion of parasites and the possibility of hybrid sterility in cases of mixed infections.

African animal trypanosomiasis (AAT) is a disease caused by haemoparasites of the genus Trypanosoma and its vectors are tsetse flies of the genus Glossina which are endemic to the African continent. In South Africa the disease is restricted to the north eastern parts of KwaZulu-Natal Province and it is transmitted to susceptible vertebrate hosts by Glossina brevipalpis and G. austeni. The current study aimed at determining the prevalence, genetic diversity and the phylogenetic position of the South African trypanosome species in the north eastern KwaZulu-Natal as well as determining preferred feeding host by tsetse flies from their blood meal. A total of 296 blood samples were collected from the north eastern parts of KwaZulu-Natal Province whereby 137 were from cattle; 101; 9; 49 were from goats, sheep and dogs respectively and 376 tsetse flies (375 G. brevipalpis and 1 G. austeni) were also collected. PCR with universal KIN primers was used to detect the trypanosome parasites in both blood and tsetse flies. From 137 cattle samples 23.4% (32/137) were positive for the presence of trypanosome infections whilst none were positive for sheep, goat and dog samples. A total of 15.4% (54/375) G. brevipalpis tested positive for trypanosomes. Detected trypanosome species with KIN primers were Trypanosoma congolense (Savannah) and T. theileri for blood samples and for tsetse flies T. congolense (Savannah and Kilifi) types were detected. Nested PCR targeting 18S rRNA gene detected T. congolense (Savannah) and T. theileri species. The sequences from this gene revealed great genetic diversity within these Trypanosoma species. Amplification of gGAPDH gene detected T. congolense (Savannah) and T. brucei brucei species when subjected to BLAST. Sequences obtained from this gene also revealed great genetic diversity and showed that the detected trypanosomes are different genotypes from the known species in other countries outside South Africa. Phylogenetic analysis revealed that South African Trypanosoma species were more genetically related to east African trypanosomes however, they formed isolated clusters with each other indicating that indeed they are different genotypes from the trypanosome species on the NCBI database. Blood meal analysis showed that G. brevipalpis preferred to feed on small mammals, birds and humans in the absence of livestock or other large wild reservoir hosts. This study showed that there are active trypanosomes circulating amongst livestock and tsetse flies in KwaZulu-Natal Province as well as the prevalence of T. theileri and T. b. brucei which were never documented in previous studies. Further research is needed to investigate the pathogenicity of these detected Trypanosoma parasites in domestic animals.

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.

Cotyledon orbiculata, Hermannia depressa and Nicotiana glauca are widely used plants in traditional medicine for treatment of various infections and diseases. C. orbiculata is mostly used in treatment of epilepsy, earache and the removal of warts while H. depressa is used to relieve toothache, nerves and diarrhoea. Lastly, N. glauca has been mostly used as pain killer in relieving earache, toothache and seldom applied on body in treatment of soreness and inflammation. Traditional usages of these plants by indigenous people and local traditional healers have not yet been scientifically reported, that is why the current study was aimed at determining the anthelmintic and anticancer activity of these plants. The anthelmintic activity of acetone and water extracts from the shoots of Cotyledon orbiculata, Hermannia depressa and Nicotiana glauca were investigated using the egg hatch, larval development and larval mortality assays. In all extracts tested, C. orbiculata water extract at 7.5 mg/ml prevented nematode eggs from hatching with 82.63% success rate. Other extracts exhibited egg hatch inhibition in a degree of less than 50%. Similarly, C. orbiculata water extracts suppressed nematode larval development with 85.32% at the concentration of 2.5 mg/ml followed by 66.69% of H. depressa extract at 7.5 mg/ml concentration. However, N. glauca water and all acetone extracts induced the 100% larval development inhibition. The in vitro larval mortality rate revealed that the water extracts from all the plants were able to kill all larvae at 2.5 mg/ml within 48 to 96 h. The results from this study have shown that the extracts from the three plants have the potential to prevent and ameliorate diseases associated with gastrointestinal nematodes. The anticancer activity of the above mentioned plants was tested on two cancer cell lines, the MCF-7 and HeLa cells. All plants possessed anticancer activity at different durations and concentrations. The N. glauca demonstrated an activity against both cell lines, however, the plant acetone extracts were much effective on the MCF-7 line at 48 hours with inhibition percentages > 80% at all concentrations. The N. glauca acetone extracts were effective at 24 hours. The H. depressa acetone extracts also possessed much activity than water extracts at 24 hours, whereas C. orbiculata showed no activity at all on this cell line. The C. orbiculata acetone extracts followed by the water extracts were the most effective on the HeLa line ranging from 12 to 84% and 0 to 77% inhibition. H. depressa activity was observed at 48 hours of experimentation at all concentrations in both extracts. N. glauca exhibited significant inhibition percentages at 24 hours of water extracts and 48 hours of acetone extracts. This study has showed that the three plants are potential candidates for cancer treatment. Brine shrimp lethality test was conducted on the nauplii stage of the shrimps. Furthermore, two assays, MTT and LDH cytotoxicity assays were conducted on the MDBK cells. None of the plants was toxic on the brine shrimps as most of them survived through 24 and 48 hours. C. orbiculata and H. depressa brine shrimp larval mortality was observed at 96, 72, 72, 96 and 96 h at 0.2, 0.4, 0.6, 0.8, and 1.0 mg/ml of water extracts respectively and 72 h at all concentrations of acetone extracts while N. glauca larval mortality was observed at 120 and 96 hours at all concentration of both extracts. There was a cell survival decrease of 50% at 0.65 mg/ml and 50-60% in C. orbiculata water and acetone extracts treated wells, respectively. No significant cell decrease was observed from both H. depressa and N. glauca water and acetone extracts except for N. glauca acetone extract at 2.50 mg/ml. None of the plants induced a significant toxicity on both the brine shrimps and the bovine cells. Alkaloids, saponins, tannins and phenols were the constituents tested for in order to identify constituents responsible for observed activity of the whole study. No alkaloids were detected from all plants for both extracts, only saponins, tannins and phenols were present even though N. glauca acetone extracts possessed none of the tested constituents. Tested plants are therefore good candidates in treating parasitic gastrointestinal nematodes and cancer disease. Potassium permanganate (KMnOâ) is a widely used chemical substance in the rural communities as prophylaxis or in treatment of various infections and diseases; however, there is no scientific validation of its usage. Anthelmintic activity of potassium permanganate was tested against parasitic gastrointestinal nematodes in comparison to anthelmintic commercial drugs, Tramisol®, Noromectin® and Valbazen®. There was no egg hatch inhibition induced (<10%) by potassium permanganate at all concentrations as compared to >80% inhibition of commercial drugs, however, 85.24, 98.10 and 90.91% of larval development was induced at 0.5, 1.0 and 1.5 mg/ml, respectively. Larval mortality was observed at 216, 144 and 144 hours at 0.5, 1.0 and 1.5 mg/ml, respectively. The cytotoxicity of this chemical was tested on the brine shrimps and MBDK cells as well. Within 24 hours all the brine shrimps larvae treated with KMnOâ died. A significant decrease in MDBK cell survival was observed at 0.65 mg/ml at 24, 48 and 72 hours. This study has therefore showed that potassium permanganate have anthelmintic activity and concentration dependent cytotoxicity on the mammalian cell lines. In conclusion Cotyledon orbiculata, Hermannia depressa, Nicotiana glauca and potassium permanganate have the potential to supress the aggressiveness of parasitic gastrointestinal nematode and cancer diseases. These substances are therefore potential candidates in treatment of tested pathogens.

This study investigates insect-fungal-plant interactions on tree-nut crops (pistachio, walnut and pecan) in South Africa. The main aim was to determine whether insects occurring in tree-nut crop orchards are assocaited with fungal phytopathogens and whether they have the capability to harbour and dissiminate them. Isolations from Atelocera raptoria (powdery stink bug) on pistachio showed that the largest proportion of fungi associated with these insects are pathogenic, some serious pathogens of the crop. Isolations from Coenomorpha nervosa (grey-brown stink bug) and Empoasca citricola (green citrus leafhopper) on walnut showed that the insects were associated with fungi but the presence of pathogens was minimal. The isolation of fungi associated with insects occurring in pecan orchards showed that the most abundant fungal species from Empoasca sp. (leafhoppers) and the Sciobius cf. granosus (citrus snouted weevil) were pathogenic. Pathogens were also isolated from Panafrolepta dahlmani, however, a large proportion of the fungi isolated from these specimens were non-pathogenic. Fungi from the grey-brown stink bug, collected through a pecan nut production season and comparing it to other ways of dispersal (air, soil, leaf & nut samples), showed that the greatest diversity of fungi was found to be associated with the stink bug specimens. This indicates that stink bugs, most likely insects in general, play an important role in the dynamics of fungal populations within pecan orchards. As a result the isolation of fungi from insects in tree-nut crop orchards may give an indication of the mycoflora in the environment. Overall, the two most abundant fungal species isolated from stink bugs and other niches were Alternaria tenuissima and Cladosporium cladosporioides. The incidence of these two species on stink bugs followed a similar trend to the incidence of these two species in the air and soil. However, the incidence of these two species on the stink bugs differed from their incidence in the leaves and nuts. This indicates that the fungi occurring on the stink bugs are from their environment and that the presence of fungal species such as A. tenuissima and C. cladosporioides in the leaves and nuts cannot necessarily be attributed to vectoring by stink bugs. Neofusicoccum parvum was only isolated from the nuts and from the stink bugs. It was completely absent from all the other samples taken throughout the whole season. This suggests an association between the stink bugs and N. parvum, where the stink bugs act as disseminators spreading this fungus between developing nuts as they feed. Pathogenicity trials indicated that A. tenuissima and N. parvum are pathogenic on pecan nuts and leaves, while C. cladosporioides cannot be considered a pathogen of this crop. It was also found that wounding of pecan nuts increases disease incidence on nuts inoculated with A. tenuissima and is a necessity for both A. tenuissima and N. parvum to be able to infect, colonise and cause symptoms on pecan leaves. Wounding does not increase the rate of disease development, but it reduces the time required by N. parvum to infect and colonise pecan nuts. In contrast, wounding does not provide the same benefit to A. tenuissima. Overall, the study has shown that insects occurring in tree-nut orchards have the capability to harbour and disseminate fungal phytopathogens. These insects feed on various parts of the trees causing damage and, in addition, provide suitable entry points into the trees through which pathogens gain entry to infect, colonise and cause disease.