<p> The distribution of Eisenia rosea, the main host of P. rudis, is influenced mainly by soil moisture and bulk density. Cluster-fly larvae locate hosts by random locomotion through the soil pores, whereupon penetration is induced by a substance present in the worm slime. Penetration occurs mainly on the upper surface of the worm, with fewer penetrations occurring towards either end of the worm. Several species of earthworm, including some which do not normally act as hosts, were infected in the laboratory. </p> <p> The encystment, surface casting, burrowing and autotomising behaviour of E. rosea varies with soil moisture and bulk density. The penetration rate of P. rudis larvae into E. rosea is affected by this behaviour, as well as by the soil pore morphology. The success of maintenance of infected worms is also affected by the worm behaviour, which in turn depends on the soil conditions. </p> / Thesis / Doctor of Philosophy (PhD)

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The development of potential genetically based resistance to cadmium (Cd) after long-term exposure to this metal at a sublethal concentration, was investigated in earthworm specimens belonging to the genus Eisenia. Adult (clitellate) earthworms from a long-term laboratory Cdexposed population (> 78 generations) and from other populations having no previous history of metal exposure were exposed to increasing concentrations (0; 2.5; 5; 10 and 20 mg/l) of Cd in the form of CdSO4. Different biomarkers and molecular markers were used to determine whether the specimens from the long-term Cd-exposed population had acclimatized or adapted to the metal contaminated environment. Acclimation was investigated at different physiological and biochemical levels using the following three biomarkers: the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay (MTT assay) measuring mitochondrial activity and cell viability; the single cell gel electrophoresis assay (comet assay) measuring DNA strand breaks and the biosynthesis of metallothioneins (MTs) that have the function of lowering metal toxicity. Earthworms from the long-term exposed substrate as well as specimens from populations not exposed to Cd were used. Adaptation was investigated by looking at both allozyme polymorphism at seven enzyme encoding loci and DNA polymorphism using chosen neutral and selectable genetic markers. The markers used were cytochrome c oxydase subunit I (COI) and metallothionein-2 (mt-2) respectively. This was done amongst the same pool of populations. Additionally, the DNA polymorphism study also aimed at genetically identifying the species utilized in this study thereby determining whether these earthworms belong to the species Eisenia fetida or Eisenia andrei. MTs biosynthesis did not generate the expected data mainly due to the fact that a suitable antibody could not be obtained (discussed in Chapter 5 section 5.3.3.). Similarly, the assessment of DNA polymorphism at the chosen selectable genetic marker mt-2 did provide information relevant to understanding the potential development of resistance to Cd in the long-term metal contaminated group. COI sequences generated in this study were compared to E. fetida and E. andrei COI sequences available on Genbank. Consequently, specimens used in this study were identified as possibly belonging to the species E. andrei. Allozyme polymorphism revealed no fixed genetic differences between the long-term Cd exposed laboratory culture and the rest of the populations. All the populations departed from Hardy-Weinberg equilibrium (χ2 > 5.9; p < 0.05), and showed a low mean heterozygosity per locus (Ho ≤ 0.21), probably due to inbreeding. Cell viability and proliferation as tested by the MTT assay revealed that coelomocytes, isolated from the long-term Cd-exposed group showed the highest viability (98.42%) compared to those from other groups (+/- 80%). Kruskal-Wallis ANOVA (H2, 225=109.7165 p < 0.001) revealed that the long-term Cd-exposed laboratory culture showed a better response to acute exposure to Cd, thus demonstrating that these worms have developed some kind of tolerance to Cd. Similarly, the comet assay showed that in the long-term Cd-exposed specimens, less DNA breaks occurred after Cd exposure than in the unexposed groups. Of all the comet parameters assessed in this study (comet tail length, tail moment and tail DNA percentage), tail DNA percentage seemed to be more sensitive although all three parameters indicated that long-term Cd-exposed specimens were more resistant than unexposed specimens as shown by the number of single strand DNA breaks induced by exposure to higher concentrations of Cd (p < 0.001). The comet and the MTT assays indicated that the earthworms with a previous history of Cd exposure have developed increased fitness towards higher doses of Cd, compared to previously unexposed groups. These findings mainly proved that several mechanisms could come into play at the physiological and biochemical level to allow the Cd exposed population to acclimatize to its chemically stressful environment. Clear genetic support for the differences found between the tested populations was not obtained, but needs to be investigated further using Cd selectable markers such as the mt-2 gene, in order to come to a more conclusive deduction. / AFRIKAANSE OPSOMMING: Die moontlike ontwikkeling van geneties gebaseerde weerstand teen kadmium (Cd) by erdwurms van die genus Eisenia, na langtermyn blootstelling aan die metaal by 'n subletale konsentrasie, is ondersoek. Volwasse (klitellate) erdwurms van 'n langtermyn laboratorium Cdblootgestelde bevolking (< 78 generasies) asook van ander bevolkings met geen voorgeskiedenis van metaal blootstelling nie, is blootgestel aan 'n reeks van Cd konsentrasies (0; 2.5; 5; 10; en 20 mg/l) in die vorm van CdSO4. Verskillende biomerkers en molekulêre merkers is gebruik om vas te stel of die erdwurms geakklimeer of aangepas het by die metaal in die gekontamineerde omgewing. Akklimasie is op verskillende fisiologiese en biochemiese vlakke getoets deur die volgende drie biomerkers te gebruik: Die 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromied toets (MTT toets), wat mitochondriale aktiwiteit en sel lewensvatbaarheid meet; die enkel sel elektroforese toets (Komeettoets) wat DNS string breuke meet; die biosintese van metallotioniene (MT's) wat metaalvergiftiging verlaag. Erdwurms van die langtermyn blootstellingsubstraat asook eksemplare van bevolkings wat nie aan kadmium blootgestel was nie, is gebruik. Aanpassing is ondersoek deur gebruik te maak van allosiem polimorfisme, waar 7 ensiem koderende lokusse gebruik is asook van DNS polimorfisme deur neutrale genetiese merkers te selekteer. Die merkers wat gebruik is, was sitochroom c oksidase, subeenheid I (COI) en metallotionien-2 (mt-2) respektiwelik. Hierdie toetse is met dieselfde groepe bevolkings uitgevoer. 'n Bykomende van die studie aspek waar ook van DNS polimorfisme gebruik gemaak is, was daarop gemik om die spesie wat vir die huidige studie gebruik is, geneties te identifiseer en om vas te stel of die erdwurms aan die spesie Eisenia fetida of Eisenia andrei behoort. Die MT biosintese het nie die verwagte data gegenereer nie, hoofsaaklik weens die feit dat geskikte teenligaampies nie beskikbaar was nie (bespreek in Hoofstuk 5 afdeling 5.3.3). Soortgelyk, het die waardebepaling van DNS polimorfisme by die geselekteerde genetiese merker mt-2 nie genoegsame informasie verskaf om die potensiaal van die ontwikkeling van weerstand teen Cd in die langtermyn blootgestelde groep te verstaan nie. COI geenvolgordes van E. fetida en E. andrei wat op Genbank beskikbaar was, is gebruik om met die resultate van die huidige studie te vergelyk. Die spesie wat tydens die huidige studie gebruik is, is op hierdie wyse geïdentifiseer as E. andrei. Allosiem polimorfisme het geen vaste genetiese verskille tussen die langtermyn blootgestelde laboratoriumkulture en die ander bevolkings getoon nie. Al die bevolkings het verskil van die Hardy-Weinberg ewewigstoestand (χ2 > 5.9; p < 0.05) en het 'n lae heterosigositeit per lokus getoon (Ho ≤ 0.21), moontlik as gevolg van inteling. Sellewensvatbaarheid en proliferasie soos getoets met die MTT toets, het getoon dat selomosiete, geïsoleer vanuit die langtermyn Cd blootgestelde groep, die hoogste lewensvatbaarheid (98.42%) gehad het in vergelyking met die ander groepe (+/- 80%). Kruksal-Wallis ANOVA (H2, 225=109.7165 p < 0.001) het getoon dat die langtermyn Cd blootgestelde laboratoriumkultuur 'n beter respons vir akute blootstelling aan Cd gehad het. Hierdeur is gedemonstreer dat hierdie wurms 'n soort toleransie teenoor kadmium ontwikkel het. Soortgelyk het die komeettoets aangetoon dat daar in die langtermyn blootgestelde eksemplare minder DNS breuke voorgekom het na verdere blootstelling aan Cd as in die ander groepe. Van al die komeet parameters wat tydens die studie gemeet is (komeet stertlengte, Olive stert moment en stert DNS persentasie), het die stert DNS persentasie geblyk om die mees sensitiefste te wees, alhoewel al drie parameters aangetoon het dat die langtermyn Cd blootgestelde eksemplare meer weerstandbiedend was teen induksie van DNS enkelstring breuke weens Cd blootstelling (p < 0.001), as die wat nie voorheen blootgestel was nie. Die komeet en MTT toetse het aangetoon dat erdwurms met 'n voorgeskiedenis van Cd blootstelling 'n toenemende fiksheid teen hoër dososse van Cd ontwikkel het as die wat nie voorheen aan kadmium blootgestel was nie. My bevindings kon hoofsaaklik toon dat verskeie meganismes op die fisiologiese en biochemiese vlak 'n rol sou kon speel om Cd blootgestelde bevolkings by 'n chemies stresvolle omgewing te laat akklimeer. Duidelike ondersteuning vir die verskille tussen die getoetsde bevolkings deur van Cd geselekteerde merkers soos die mt-2 geen gebruik te maak om 'n meer finale afleiding te kan maak is nie verkry nie en behoort verder ondersoek te word.

South Africa produces large amounts of solid mine waste, covering vast areas of land in the form of tailings dam facilities (TDF). Tailings material contains high levels of elements which poses potential risk for the environment and human health due to their potential toxic character. Agricultural practices such as tilling and chemical additions can also cause leaching of potentially harmful toxins into the surrounding environment. Both these soils are disturbed on a physical level, influencing the soil structure, chemical composition and soil biota present. This study analyzed in a comparative manner the chemical and physical properties of soils collected from gold mine tailings, agricultural areas and natural areas, and the consequences for soil life. Soil samples for the different land use types were taken in duplicate from the KwaZulu- Natal and North West provinces in South Africa. Topsoil layer formation was analyzed for all sites by sampling at depths of 0-5cm, 5-15cm and 15-25cm. Soil element content was assessed by means of metal indices. The physical and chemical characteristics of the soil were further analyzed by life cycle parameters of the oligochaete species Eisenia andrei and Enchytraeus doerjesi in gold mine tailings and agricultural soils. Ants were collected from all the land use types for species identification and analysis of element content. Soil layering regarding the vertical distribution of elements was observed in concentrations analyzed for the different land use types. Mining sites, especially in KwaZulu-Natal, indicated a decrease in element concentrations with increased depth. The opposite tendency was observed for the agricultural and natural soils, indicating increased concentrations with increased depth. Analysis of the elements indicated high levels of pollution in the mining sites which according to the metal indices were Co, Cd, and Ni. It was determined that tailings material from KwaZulu- Natal was more polluted than the tailings material from the mine in North West province, according to soil indices. Tailings material from both mining sites resulted in negative impacts on E. andrei and E. doerjesi, based on growth, hatching success, mortality and reproduction rate. A unique approach was taken during this study by exposing cocoons of E. andrei to soil samples. The negative effects of the mining samples on test species could be a result of the low organic matter, poor structure and high element content of the mining waste, compared to the agricultural and natural soil. Species numbers of ants were higher on the tailings material than agricultural and natural soils. Element analysis of ants collected, indicated high accumulation of elements such as Fe, Al, Cr, Cd, Pb, Cu and Zn in total body element content of one or more species, reflecting the combination of elements found in the different land use types. Accumulation levels were highest in Pheidole sp. compared to other species investigated. Ants are potential indicators of soil pollutants within a South African context. Risk assessment is necessary for analyzed soils to determine steps for sustainable re-use. A key system with regards to soil pollutant analyses should be incorporated in government policy for protection of South African soil. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

South Africa produces large amounts of solid mine waste, covering vast areas of land in the form of tailings dam facilities (TDF). Tailings material contains high levels of elements which poses potential risk for the environment and human health due to their potential toxic character. Agricultural practices such as tilling and chemical additions can also cause leaching of potentially harmful toxins into the surrounding environment. Both these soils are disturbed on a physical level, influencing the soil structure, chemical composition and soil biota present. This study analyzed in a comparative manner the chemical and physical properties of soils collected from gold mine tailings, agricultural areas and natural areas, and the consequences for soil life. Soil samples for the different land use types were taken in duplicate from the KwaZulu- Natal and North West provinces in South Africa. Topsoil layer formation was analyzed for all sites by sampling at depths of 0-5cm, 5-15cm and 15-25cm. Soil element content was assessed by means of metal indices. The physical and chemical characteristics of the soil were further analyzed by life cycle parameters of the oligochaete species Eisenia andrei and Enchytraeus doerjesi in gold mine tailings and agricultural soils. Ants were collected from all the land use types for species identification and analysis of element content. Soil layering regarding the vertical distribution of elements was observed in concentrations analyzed for the different land use types. Mining sites, especially in KwaZulu-Natal, indicated a decrease in element concentrations with increased depth. The opposite tendency was observed for the agricultural and natural soils, indicating increased concentrations with increased depth. Analysis of the elements indicated high levels of pollution in the mining sites which according to the metal indices were Co, Cd, and Ni. It was determined that tailings material from KwaZulu- Natal was more polluted than the tailings material from the mine in North West province, according to soil indices. Tailings material from both mining sites resulted in negative impacts on E. andrei and E. doerjesi, based on growth, hatching success, mortality and reproduction rate. A unique approach was taken during this study by exposing cocoons of E. andrei to soil samples. The negative effects of the mining samples on test species could be a result of the low organic matter, poor structure and high element content of the mining waste, compared to the agricultural and natural soil. Species numbers of ants were higher on the tailings material than agricultural and natural soils. Element analysis of ants collected, indicated high accumulation of elements such as Fe, Al, Cr, Cd, Pb, Cu and Zn in total body element content of one or more species, reflecting the combination of elements found in the different land use types. Accumulation levels were highest in Pheidole sp. compared to other species investigated. Ants are potential indicators of soil pollutants within a South African context. Risk assessment is necessary for analyzed soils to determine steps for sustainable re-use. A key system with regards to soil pollutant analyses should be incorporated in government policy for protection of South African soil. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

The nutritional and chemical characteristics of five earthworm species: Lumbricus terrestris; Allolobophora longa; Eisenia foetida; Dendrobaena veneta and Dendrodrilus subrubicundus were assessed on the basis of crude protein and amino acid composition, lipid and fatty acid composition, and ash and mineral composition. Analyses indicated that all the earthworm species evaluated possessed a high quality protein and lipid fraction suitable for use in fish feeds which was somewhat similar in composition to that of fish meal. During experimental feeding trials (50-84 days in duration) each earthworm species was nutritionally evaluated, on the basis of fish growth performance, feed utilization efficiency and gross carcass composition, as a complete feed (frozen slices of whole worm) for rainbow trout· (Salmo gairdneri) A dried 'earthw9rm meal' derived from each of the species E.foetida, D.veneta and D.subrubicundus was similarly evaluated as a potential replacement for fish meal in trout diets. Fish fed frozen slices of earthworm, with the exception of fish fed E.foetida, achieved growth rates and feed utilization efficiency comparable to. fish fed a control, fish meal based ration. Fish fed solely on frozen slices of E.foetida achieved little or no growth over the experimental period. The possible reasons for the reduced palatability of frozen E.foetida to the fish are discussed, pre-treatment processes applied and a significant improvement in the palatability of frozen E.foetida was achieved by blanching. High dietary inclusion levels of earthworm meal (replacing ~ 50% of the fish meal protein) resulted in depressed feed intake and growth of the fish. At reduced levels of inclusion, dried E.foetida meal (constituting 5-30% of a production salmonid diet) and dried D.subrubicundus meal (constituting 7-36% o~ a semi-synthetic trout diet) adequately replaced the dietary fish meal component without loss in fish growth and feed utilization efficiency. The possible uptake of potentially toxic trace elemeots (Fe, Zn, Mn, Pb, Cu, Cr, Ni, Co and Cd) into the fish carcass through the ingestion of contaminated earthworm diets was also investigated and the levels of certain elements, in particular Pb, were observed to increase in the carcass of fish fed high levels of earthworm in the diet. However, in no instance did the results indicate any harmful or toxic effect of including earthworms in the diets of rainbow trout.

Principal objectives of my research were to: (1) report for the first time that coelomocytes are able to reduce NBT dye and confirm the presence of lysozyme-like activity in earthworm; (2) develop a standard methodology for determination of NBT reduction and lysozyme-like activity in earthworms; (3) compare NBT reduction and lysozyme-like activity in earthworms with those of murine and human cells and fluids; and (4) demonstrate the sensitivity of earthworm NBT reduction and lysozyme-like activity as the assays using matrics in refuse-derived fuel fly ash (RDFF) and CuSO4.

Earthworms are well known for their casting and burrowing activities which improve soil structure and soil fertility. However, earthworm populations in temperate regions exhibit patchy distribution in space and time. This makes it difficult to predict how earthworm activities may influence paedogenesis and nutrient cycling processes at the ecosystem level. The main objective of this study was to determine the spatiotemporal dynamic of surface cast production of two earthworm species, Aporrectodea turgida and Lumbricus terrestris, on the row-interrow scale in a temperate soybean agroecosystem. Our observations demonstrated that casting activity was synchronous with plant growth. More casts were also found in the row intercepts compared to the interrow ones. Both the spatial and temporal variations are thought to be caused by the microclimate found under the plant canopy, verifying results from controlled laboratory studies that show casting activity to be controlled by soil temperature and moisture. These results suggest a possible mutualism between earthworm and plants in cultivated temperate soybean agroecosystems, but this remained to be confirmed.

As Charles Darwin first noted in 1881, earthworms through their burrowing and casting activities, play an important role in the creation and maintenance of soil structure. Burrowing activity leads to the reorganisation of voids and creation of macropores within the soil. This has implications for aeration and the flow properties of water through soils. Casting activity affects the structural stability of soil through the stabilisation of aggregates. The overall aim of this research project has been to investigate the effects of earthworm activity and diversity on void space and aggregation in an upland soil. This research has been carried out as part of NERC's Thematic Programme on Soil Biodiversity. The field site was located on the Macaulay Land Use Research Institute's experimental farm at Sourhope in the Scottish Borders. Three experiments were designed to investigate the impact of earthworms on soil fabric, with each experiment representing an increased level of system complexity. The simplest experiment took place in a controlled environment and used an artificial soil and different earthworm treatments. The second level of system complexity used soil from Sourhope which had its structure removed, and then earthworm and liming treatments applied. The most complex experiment also used Sourhope soil and liming and earthworm treatments, except in this case the soil was undisturbed. The effects of earthworms and liming on void space were characterised using saturated hydraulic conductivity to measure macroporosity, and image analysis to quantify total porosity and void size distribution. Aggregation was assessed through aggregate stability and point counts of earthworm excremental features. The effect of earthworm inoculation in the simplest experiment led to the reorganisation of voids through increased abundance of voids &gt; 2 mm2 in area, and decreases in the proportion of voids with an area &lt; 2 mm2. No significant effects were observed on aggregate stability. The effect of liming in the experiment using disturbed soil was to increased abundance of voids &gt; 2 mm2. No significant effects were observed on aggregation due to either liming or earthworm inoculation. In the most complex experiment, neither liming nor earthworm inoculation led to changes in void space or aggregation, except for an increase in saturated hydraulic conductivity and therefore macroporosity due to earthworm inoculation. The overall conclusions from this research were that as system complexity increased, then the effects of the treatments on void space and aggregation became more difficult to isolate. Nevertheless, it was clear that liming significantly affected void space through increased abundance of earthworms. Out of the two treatments applied to the Sourhope soil, liming had the strongest effect on both earthworm abundance and void space.

Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1996. / Copy of author's previously published work inserted. Includes bibliographical references (leaves 261-306).

Thesis (Ph.D.)--University of Adelaide, Faculty of Agricultural Science, 1958. / Includes bibliographical references.