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.

A study was conducted on the feeding behaviour of giraffe within the Bloemfontein vicinity, central Free State. Full-day field surveys were done on a monthly basis over a period of 12 months (March 2003 â February 2004) on four different study areas. Night observations were only conducted on a seasonal basis during full moon periods, to make use of maximum vision. Utilisation frequencies and âdurations for each plant species, as utilised by the giraffe, were carefully documented. The daily activity patterns of giraffe were determined by means of the momentary-scanning method. Plant surveys were conducted through circle, quadrants distributed in transects over each of the four study areas to determine the woody composition for each area. Approximately 100 g of leaf material of the most important food plants of giraffe were gathered on a monthly basis for subsequent chemical analyses (calcium and cru-protein). Prehistoric signs of giraffe by means of fossils and rock art have been noted by several writers since the nineteen thirties and forties. The first signs of the presence of giraffe in South Africa by whites were detected in rock art. The Limpopo Province lies in the savannah biome and therefore contains the best habitat for giraffe. It is thus self-evident that most conservation areas with giraffe can be found in the Limpopo Province. There is no earlier physical evidence of giraffe in the Free State. This province is also not part of the current range of giraffe. The biggest concentration of established giraffe presently occurs in the Boshof-district in the western Free State. This can be attributed to the vegetation which correlates with the savannah biome, namely the occurrence of Acacia trees. The extent of the adaptation of giraffe in the central Free State is mainly unknown. As a whole the active browsing of giraffe in this study was responsible for more than half (53 %) of the daily activities. Giraffe only spend 4 % of the total daily time in the lying position, usually when environmental temperatures are high. In contrast with the day-activities, browsing was responsible for less than a third (31 %) of their activity during night time. Peaks in the lying position where all individuals were involved, occurred long before and shortly after midnight alternating with browsing. During this study period giraffe in the central Free State browsed a total of 28 plant species. According to the utilization frequency and -time, the sweet-thorn, asparagus and buffalo-thorn are the most important components in the diet of giraffe. Collectively these three plant species constitute approximately 74 % of all observations and were consumed through out the year. Leaves of deciduous trees and shrubs are the staple food during the wet season but, as the plants shed their leaves and the food stock decrease, there is a change in the food preference. In this connection an increase in the utilisation of evergreen trees, woody- and offshoot fodder during the dry season, is significant. Unidentified grasses constitute nearly 2 % of the total diet of giraffe. Grasses were utilised mainly in August and September, the most critical time of the year which can possibly suggest an imbalance in the diet, which relates to calcium deficiencies. Osteophagia was detected in especially cows and younger individuals during the dry season, probably due to the fact that either cows in calf, nursing cows or growing individuals are more susceptible to mineral deficiencies in their diet. Although the availability of leaves in the dry season is limited, the asparagus leaves are available for utilization until late in this season. Sweet-thorn legumes and buffalo-thorn fruit are also available during the dry season and are utilised together with the sprigs. An increase occurred in the cru-protein contents for some of the leaves, including the sweet-thorn, during the dry season. There is a noticeable increase in the calcium content of the three dominant preferable plant species during the dry season. It seems as if the chemical composition and availability of the three dominant plant species per se play a less important role in the giraffeâs diet compared to the preference these animals show towards certain plant species. Giraffe are mainly browsers of thorny, deciduous trees, especially the Acacia species. Exotic plant species such as eucalyptus-, pine-, poplar- and willow trees as well as conyza weeds, cotoneaster and prickly pear are seasonally utilised in the central Free State. This phenomenon is more significant during the dry season when leaf materials of deciduous plants of the preference plants are absent and thus show a shortage. Critical periods for giraffe feeding in the central Free State are during the late dry- and early wet season (August â October), and not the dry season as a whole. The topography and composition of vegetation in the central Free State have to allow for seasonal habitat selection. Thus there is a correlation between the occurrence of the giraffe in the Free State and the occurrence of their preference food, namely Acacia-tree species.

The mango seed weevil (MSW), Sternochetus mangiferae (Fabricius) (Coleoptera: Curculionidae), generally causes few problems on early-season cultivars, since the fruit are marketed and consumed before adult emergence from the fruit. Adult emergence from late-hanging cultivars, however, results in unattractive lesions that influence the marketability of the fruit. There is little evidence that MSW influences yield, although some authors argue that MSW development in the seed may lead to premature fruit drop. The economic impact of the MSW is primarily based on the fact that it is a major phytosanitary pest, restricting access to new foreign markets and contributing to substantial rejections of fruit destined for existing export countries. The MSW has no natural enemies, is monophagous on mango and completes its entire life cycle within the mango seed. The impact of this pest can, therefore, be greatly reduced by orchard sanitation. Sanitation practices, however, are labour intensive, necessitating producers to rely on alternative or additive control measures. Several semi-penetrant and contact pesticides are registered for MSW control. However, with trans-laminar products it is imperative that treatments coincide with, or are applied just after, the onset of weevil oviposition. This requires intensive and accurate scouting programmes, with an in-depth knowledge regarding the duration of oviposition necessary to ensure seasonal control. When using contact insecticides, applications should coincide with seasonal and daily activity peaks to ensure direct contact. Since adult weevils are extremely inactive, this necessitates an in-depth knowledge of MSW activity patterns. It is also imperative to understand the development cycle and life strategies of the insect in order to know at which time intervention would prove to be the most effective. The product most generally used for MSW control in the Hoedspruit magisterial district of the Limpopo Province is fenthion (Lebaycid® EC 500g/â a.i.). This product is very effective, but does not provide 100% control and can lead to secondary infestations of mango scale, Aulacaspis tubercularis (Newstead) (Hemiptera: Diaspididae), and mealybug (various species). The use of organophosphates on fruit destined for certain overseas markets is also under investigation by the EU. It is for this reason that Westfalia Technological Services, over the past four years, investigated various aspects of MSW general biology, reproduction and control. The investigation into the activity patterns of adult weevils indicated that MSW were crepuscular â nocturnal insects. For this reason, applications with contact insecticides aimed at controlling the adult weevil would be expected to be more efficacious when applied at dusk. During the study investigating MSW development, it was found that the majority of MSW eggs hatched between 7 and 14 days, with some of the first instar larvae already having penetrated into the seeds between 7 and 14 days after oviposition, depending on whether the eggs were laid early or late in the season. This implies that chemical control with contact and semi-penetrant chemicals, aimed at controlling the MSW larvae, should preferably not commence later than 7 days after observing the first eggs in the orchards. However, it was found during the course of this study that MSW oviposition commenced during the latter part of September and continued up to the latter part of January, a period considerably longer than previously stated in the literature. For this reason, more than one chemical application would be warranted. While investigating alternative chemical control measures, it was found that a single application with the systemic insecticide, thiamethoxam (Actara⢠SC 240g/â a.i.), applied during flowering in the root zone, rendered seasonal MSW control. The use of this product, therefore, negates the necessity of tedious fruit inspections and an in-depth understanding of the pest in order to determine the most appropriate time for chemical intervention.

The efficacy of the Bt-genes (the cry1Ac and cry2Ab2 genes) were evaluated for bollworms (i.e. the american or âafricanâ bollworm, Helicoverpa armigera, the red bollworm Diparopsis castanea and the spiny bollworm species, Earias biplaga and E. insulana) on cotton under normal spraying conditions in different field trials in South Africa. Differences that were found in bollworm efficacy and yields are explained by comparison in various field trials. Bt-cottons (Genetically Modified Cotton) exhibiting either only bollworm resistance (NuOPAL), or cotton exhibiting both bollworm resistance and herbicide tolerance (NuOpal RR)-, or cotton exhibiting only herbicide tolerance (DeltaOpal RR) were compared with non-Bt-cotton (DeltaOPAL). At the same time the effect of the Bt-gene on non-target organisms, such as secondary pests and predator numbers was monitored. Since most of the small-scale farmers in South Africa cultivate Bt-cotton and they are required to plant a refuge as part of a Resistance Management Programme, the abundance of alternative host plants for bollworms was evaluated in the largest small-scale production region, the Makhathini Flats (KwaZulu-Natal). Finally, the acceptance of Bt-technology amongst growers are discussed. This study was undertaken over a number of years and the repetition of a number of the trials at different localities has showed that Bt-technology has proved to be not only effective against the target pests, which are the african bollworms on cotton, but it is also beneficial to farmers in the form of a higher yield production and improved crop protection. The effect of the Bt-gene on non-target organisms is minimal if present and the Bt-gene has no detrimental effect on predator numbers, especially in the presence of an increase in insect host numbers, irrelative of the cotton type planted. The increase in predator numbers and secondary pests is a result of the decrease in the number of bollworm sprays applied on Bt-cottons to control bollworm, as bollworms are effectively controlled by the Bt-gene. In some instances when additional sprays for secondary pests were applied, the benefit for the grower to plant Bt-cottons, is reflected in the higher yields and lower input costs as a result of the absence or fewer bollworm sprays. The host plant study showed that alternative host plant abundance in an area where cotton is cultivated, can provided evidence for a possible alternative refuge to conventional cotton. The fact that very little, of the cotton planted by South African farmers are conventional cotton (non-Bt-cotton) varieties, confirms the acceptance of Bt-technology amongst cotton growers, with full acceptance of the requirements of planting this cotton, while obtaining higher yields per surface area than in the case of non-Bt-cottons. The benefits of planting Bt-cotton that have been illustrated in this study, clearly demonstrates the acceptance of Bt-cotton in South Africa, especially amongst, the commercial and the small-scale farmer, by enabling cotton growers to farm more cost-effectively.

Host plant resistance and biological control by means of natural enemies are becoming more favourable as high potential alternatives for chemical control of insect pests. Tritrophic studies (plantâherbivore-natural enemy) indicated that the application of host plant resistance and biological control to a particular pest could give significantly better or worse results than expected from each component respectively. Russian wheat aphid Diuraphis noxia (Kurdjumov) is a serious pest of wheat in South Africa since 1978. Plant resistant cultivars are being used against D. noxia since 1992. The introduction of parasitoids and predators for biological control of this pest automatically led to the development of an integrated pest control programme involving both control strategies. Nothing is known about interactions between resistant cultivars, D. noxia and natural enemies in South Africa. These interactions could have substantial influence on the efficacy of the control programme. The parasitoid Aphelinus hordei (Kurdjumov), introduced from the Ukraine, established in the Lesotho highlands after being released in the wheat production areas of the Free State Province. This parasitoid together with a native parasitoid Diaeretiella rapae (McIntosh), also parasitising D. noxia in South Africa, was included in a study on tritrophic interactions. A. hordei and D. rapae respectively have narrow and wide host ranges. Field studies on the interaction between A. hordei and resistant and susceptible cultivars indicated reduction in aphid population growth on each of the cultivars. Diuraphis noxia was highly parasitised on a susceptible cultivar Betta, while a positive interaction on resistant Gariep occurred, resulting in the enhancement of the resistance. A slightly lower percentage control was found on SST 333 in the presence of A. hordei. Volatile profiles emitted by infested Betta plants and resistant Elands and SST 333 plants, differed qualitatively (different volatiles) and quantitatively (concentration of volatiles). These differences caused behavioural differences between parasitoid species e.g. A. hordei could not distinguish infested from clean Elands, while D. rapae did. Diaeretiella rapae could not distinguish infested from clean SST 333 while A. hordei did. Aphelinus hordei could not distinguish between infested Betta and Elands, while D. rapae significantly preferred Betta to Elands. Parasitoids therefore responded to different volatiles from the same cultivars. This means that both A. hordei and D. rapae, use different volatiles or volatile combinations from the same plant-herbivore combination in host habitat location. Semiochemicals e.g. methyl salicylate, that act as insect behaviour-modifying chemicals, was tested in the laboratory and the field as potential control options against D. noxia. Volatile compounds released by plants could serve as signals attracting beneficial insects and induce a variety of responses in plants. A slow release wax pellet formulation named OX54 releasing methyl salicylate, menthol and 1,8-cineole was tested. Olfactometric studies showed that D. noxia and R. padi was repelled by each of the compounds although not released by their alternate host plants in South Africa. Both parasitoid species were repelled by some of the semiochemicals tested, but differences occurred between the two species. Aphelinus hordei did not respond to 1,8 -cineole, while D. rapae was not responding to menthol indicating that the different parasitoids differ in sensitivity to other semiochemicals. The repellence of the parasitoids by methyl salicylate indicated that these volatiles are not induced by D. noxia when feeding on wheat. Different host range of the parasitoids may be a reason for this reaction. OX54 and methyl salicylate respectively caused a delay in the immigration of D. noxia into resistant cultivar Elands during field trials, but on susceptible Betta an increase in infestation was found. Lower infestation on treated Elands resulted in a slight increase in yield compared to the control. The positive integration of host plant resistance and biological control can have two objectives namely synergistic reduction of pest densities and the protection of durability of resistance. Some resistant wheat cultivars to D. noxia seem to be highly resistant and the efficacy of natural enemies in these wheat fields is of utmost importance. The application of semiochemicals in these cases should also be investigated . Where resistant cultivars are less effective and hence have more durable resistance, the value of biological control is to enhance the effect of plant resistance on the reduction of the pest population in such a way that the effects of plant resistance and biological control are sufficient to prevent damage. The understanding and effective manipulation of agro -ecosystems in the wheat production areas of the Free State Province is therefore essential for the successful establishment of a successful integrated pest control programme.

A practical investigation into factors influencing the success of catfish (Clarias gariepinus) farming in the Vaalharts Irrigation Scheme was undertaken. These factors were production, nutrition, disease, disease treatment, processing and marketing. Flow-through tarpaulin ponds in the Vaalharts Irrigation Scheme were used very successfully for the propagation and rearing of Clarias gariepinus. The growth rate of Clarias gariepinus fingerlings stocked in an irrigation dam and a tarpaulin flow-through pond was determined and compared. The highest specific growth rate (1.61% bw/day) of fish in the irrigation dam coincided with the highest average monthly water temperature (26°C) recorded during the month of January 2005. The specific growth rate of fish in the flow-through ponds was lower (<1.27% bw/day) than that of fish in the irrigation dam. Fingerlings stocked at an average size of 8.9 g in the irrigation dam reached a size of 450 g within 216 days. The nutritional value and feed conversion rates (FCR) of two feed formulations were determined and compared. The percentage protein of these two feeds was 22.07% and 33.50%, respectively. Higher percentage feed protein levels coincided with better feed conversion rates. Except for an outbreak of white spot disease (Ichthyophthirius multifiliis) in one hatchery pond, no significant mortalities of fish were recorded as a result of parasite infestations. Parasitic infestations were successfully treated in the Vaalharts hatchery using prophylactic formalin bath treatments. Fish processed yielded a fillet dressout percentage of 40%. Consumer resistance for catfish products were found in urban markets. In the semi-urban informal settlements, however, catfish were readily accepted.

Owing to the increase of complaints in the city of Bloemfontein concerning the damage being caused to buildings by birds, different aspects of the biology of feral pigeons (Columba livia) was investigated. Close to 400 pigeons, which included nearly 50 lost racing pigeons, were collected on a regular basis within the city boundaries over a period of one year (March 2005 - February 2006). Although slightly more male birds were obtained, no significant variance from a balanced sex ratio in the population structure was distinguished. Feral pigeons moult continuously throughout the year at a relatively low intensity rate. Conspicuous peaks in the moulting of primary, secondary and tail feathers were observed for both sexes, however, the period for replacement was slower for females. Leucism was displayed by more than a quarter of the birds. Feral pigeons are more frequently infected with parasitic louse flies compared to local rock pigeons (Columba guinea), with the highest infection occurring during the summer months. Apart from measurements of the beak, the standard body measurements of adult males are significantly larger compared with their female counterparts. A similar trend applies in the different sexes of juvenile feral pigeons as well as racing pigeons. The seasonal variation in the body weight and visible fat deposits of adult feral pigeons probably coincides with the birds' breeding activity and the temporary availability of abundant food supplies. A prominent peak in the activity of the ovarian cycle of female birds, based on the weight and diameter of macroscopic follicles, coincides with the gonad cycle of male feral pigeons which occurs during the early winter months, followed by a smaller peak during spring. Based on the presence of nests, eggs and chicks, feral pigeons breed throughout the year with a decrease in breeding activity during the wetter summer months. Nest types vary from dried droppings on which eggs are laid to firmly-built, dry stick nests. After hatching from a typical clutch of two eggs the weight of the chicks increase daily on a linear scale. Both parents are involved in the hatching and raising of the chicks. Second or subsequent clutches are laid regularly throughout the year at the same nesting site. Rock and feral pigeons may interbreed, however this phenomenon is rarely documented. Agricultural crops including maize (Zea mays), sunflower (Helianthus annuus) and wheat (Triticum aestivum) are the most important components of the diet of feral pigeons living at the SASOL library on the campus of the University of the Free State. The diet of birds living within the city centre consists mainly of natural vegetation of which seeds of the Camdeboo stinkwood (Celtis africana) constitutes the most important component. The low percentage of animal matter consists largely of pupae of Diptera and egg cocoons of unidentified earthworms, while grit constitutes the largest component of inorganic matter. No significant statistical difference was found in the composition of the different sexes' diet. Under experimental conditions feral pigeons show a definite affinity towards maize in comparison with sorghum (Sorghum almum), sunflower and wheat. Associated with the latter, yellow food items are preferred above blue, green and red coloured items. Single birds eat on average more over a short term (10 minutes) than individuals which feed in groups, but almost equal amounts of food are ingested by individuals over a longer period (2 hours). Feral pigeons living on the university campus leave their nesting sites daily just after sunrise to go and feed on agricultural crops on the surrounding farmlands, returning approximately two hours later. Birds feeding in the city were mainly found on the ground during the early morning hours and to a lesser extent during the afternoon. The birds usually spend the hot midday hours in the shade. Lost racing pigeons regularly join local feral populations in urban areas. With the consideration of appropriate national and/or municipal laws, the shooting of feral pigeons with airguns and/or the provision of alpha-chloralose treated bait seems to be the most effective way in which their numbers in urban areas may be controlled. The introduction of natural enemies such as owls and/or falcons into urban areas could also be considered as a method of control of feral pigeon numbers.

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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 bodyâs 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.