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.

The navel orangeworm, Amyelois transitella (Pyralidae) (Walker), is the most damaging Lepidoptera larva found on pistachio nuts (Pistacia vera L., Anacardiaceae). Pistachios have only relatively recently been planted in South Africa at Green Valley Nuts, a division of the Industrial Development Corporation, near Prieska in the Northern Cape Province. The navel orangeworm causes direct damage to pistachio nut clusters by feeding on individual nut kernels and contaminating nuts with their faecal excretions. In the process the quality of the nuts is reduced and the nuts are rendered more susceptible to fungal infection. After harvest, navel orangeworm larvae overwinter inside fallen nuts on the orchard floor, as well as inside nuts left behind on trees. The prevalence of navel orangeworm in mummy nuts was studied from May to September in 2008 and 2009 at Green Valley Nuts. The potential survival of the larvae in these nuts was estimated from nuts sampled under trees of three different pistachio cultivars (Ariyeh, Sirora and Shufra). Orchard row management practices were investigated to determine the effect of cover crops, mulch and hydro-cooling on navel orangeworm survival. This was done by monitoring emergence cages and light traps for the presence of navel orangeworm adults emerging from mummy nuts. In both years, navel orangeworm was noted overwintering in mummy nuts. The highest occurrence of navel orangeworm over the two year study period was recorded in nuts from Sirora, a cultivar planted in an orchard lacking inter-tree row cover crops, mulch and hydro cooling. The results support the assumption that these orchard row management practices have a suppressing effect on navel orangeworm development, causing high mortality rates due to mummy nut decomposition. Research was also conducted to observe the life cycle and behaviour of the pest under laboratory conditions. The complete life cycle duration of the navel orangeworm ranged from 50 to 84 days. A single life cycle which gave rise to a next generation was successfully tracked.

The first insects attracted to a decomposing body are usually representatives of the Diptera, in particular members of the families Calliphoridae (blow flies) and Sarcophagidae (flesh flies). These flies will deposit their eggs (or often larvae in the case of sarcophagids) on the body, within a few hours after death, depending on environmental conditions. The immature stages will complete their developmental cycle on and around the body. As a consequence, these insects are of great importance in forensic entomology; the main area of application being the determination of the postmortem interval (PMI). One of the key pieces of information needed to calculate the PMI is the correct species identification of the immature stages. The aim of this study was to provide diagnostic descriptions for the immature stages of forensically important calliphorids and sarcophagids in central South Africa. Forensically important calliphorids prevalent in this region are Lucilia cuprina (Wiedemann), Lucilia sericata (Meigen), Chrysomya chloropyga (Wiedemann), Chrysomya marginalis (Wiedemann), Chrysomya albiceps (Wiedemann) and Calliphora vicina Robineau-Desvoidy. The sarcophagid prevalent in the region is Sarcophaga cruentata Meigen. A range of characteristics was evaluated by means of light and scanning electron microscopy and the most pertinent of these were identified for diagnostic purposes. The eggs were evaluated in terms of nine characteristics; six of which were of no diagnostic use, while three could be used to identify some of the species. The eggs of C. chloropyga and C. albiceps were indistinguishable from each other. Twelve features were identified for their possible diagnostic value in larvae. In first instar larvae five of these characteristics were of no diagnostic value, while six were useful to identify some of the species. All species could, however, be identified with the aid of the cephalopharyngeal skeleton. For second instar larvae, four of the characteristics were of no diagnostic use, but seven were useful to identify some of the species. All the species could be identified using the cephalopharyngeal skeleton. In the third instar larvae four characteristics were of no diagnostic use, but by using three other characteristics some of the species could be identified. All the species could be identified by means of five morphological characteristics (labrum, cephalopharyngeal skeleton, posterior spiracles, spiracular plate and anal area). Seven characteristics were identified for their possible diagnostic values in puparia. Five of these characteristics were useful to identify some of the species, but all the species could be identified with the aid of two of the characteristics (frontal field and bubble membrane). The ultimate aim of the study was to construct keys for use during the identification of specimens found at the crime scene. The keys that were constructed not only mapped out the pertinent diagnostic characteristics, but also considered what characteristics could be combined when a specimen was viewed from a specific angle. Since specimens often reach the forensic laboratory in less than optimal condition, it is essential that a wide range of characteristics and keys be available during identification. This will also enable the forensic entomologist to give priority to specimen preparation and the method of observation when rapid analysis is needed or where very few good specimens are available for identification. With these tools (descriptive diagnostic characteristics and keys) the identification of immature stages of calliphorids and sarcophagids found at the crime scene should be an uncomplicated exercise.

Conflict between livestock farmers and predators has been an ongoing battle since the breeding of domestic animals were first attempted by man. Insufficient data on the dynamics of predators, especially in regions outside formal protected areas where they are perceived as problem animals, make control methods almost impossible. Due to complaints of predation by cattle farmers in the unspoiled Roodewalshoek Conservancy, the dynamics of livestock predation was investigated. Specific emphasis was placed on the relationship between the ecological traits of leopard, brown hyaena and natural prey species and the consequences thereof on livestock losses. Investigations were carried out by means of motion-sensing camera traps, combined with seasonal field observations of all physical signs of animals. The presence of recorded prey species showed a monthly variation, with some prey species present all year round while others showed definite periods of occurrence. Rainfall seemed to have some influence on the occurrence of such species. Most small potential prey species was observed continuously during the winter months and only sporadically during the summer. Medium sized potential prey species that occurred on a constant basis throughout the year in the study area included bushbuck, Chacma baboons and common grey duikers. Sporadic occurrence of impala and mountain reedbuck were encountered mostly during the mid-summer months, especially during December. All species classified as large prey were continuously present throughout the year, except for the aardvark which showed a sporadic presence and were mostly observed during mid-summer. Large predators were continually observed in the conservancy except in late summer during the month of January and reached highest numbers during early autumn, mid-winter and in the height of summer. All the other predators, including small and medium-sized predators, were present on a frequent basis except during late summer and only reached a high in mid-winter and early spring. It was also evident that, when the presence of large predators in the study area increased, the presence of other predators diminished. The majority of calves (59%) were killed by predators during the wet summer months, while only 41% of calves were predated upon during winter months with low precipitation. Lunar cycles seem to play a distinctive role in livestock predation with almost two thirds of calves lost to predators when moonlight intensity was low. Even though sufficient occurrences of natural prey could be found in the Roodewalshoek Conservancy, predation on livestock persists during the calving season. Regarding the key predator of livestock in the conservancy, both leopards and brown hyaenas were almost equally accountable and displayed alternating periods of calf predation. Instances of predation where the problem animal could be identified, implicated brown hyaenas in 48% and leopards in 52% of livestock losses. During times when brown hyaenas were responsible for the most calf losses, predation caused by leopards was low. High incidences of leopard predation consequently resulted in lowered brown hyaena predation. This could be due to inter-predator competition for shared resources. The behaviour of surplus-killing by both predator species is indicative of the ability to fully exploit all the available resources in their area. The relatively large number of livestock lost to predation each year may be due to a combination of several factors. These include the lack of predator control in adjacent game farms and other protected areas, continuous presence of livestock, leopards and brown hyaenas as well as the open, unattended system in which livestock is kept in the Roodewalshoek Conservancy.