No description available.

Wolbachia are bacteria that infect and induce reproductive alterations in a large number of arthropods. The present study was undertaken to improve our understanding of the effects that Wolbachia have on the reproductive biology of the leaf beetle Chelymorpha alternans Boh, in Panama. Two strains of Wolbachia occur in C. alternans, both of which induce some degree of cytoplasmic incompatibility (CI), a reproductive problem occurring when individuals bearing different infection status are mated together resulting in lowered levels of egg fertility. I attempted to localize where Wolbachia occurs in highest density in male reproductive tissues and to see if variation in Wolbachia density was associated with levels of CI in crossing experiments involving males (1) differing in age, (2) carrying different strains and (3) belonging to different populations previously known to vary in their levels of CI. Wolbachia were found to occur only in the somatic cells surrounding the testis, rather than in the germ cells, and yet were capable of inducing strong CI. Male age, infection status and provenance all were factors affecting the level of CI induced.

No description available.

No description available.

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Thesis (M. Ag. Sci.)--University of Adelaide, Dept. of Entomology, 1966. / Includes bibliographical references.

Thesis (Ph.D.) - University of Glasgow, 1996. / Ph.D. thesis submitted to the Environmental Sciences Department, Scottish Agricultural College, 1996. Includes bibliographical references. Print version also available.

Thesis (Ph.D.) - Carleton University, 2006. / Includes bibliographical references (p. 88-121). Also available in electronic format on the Internet.

Thesis (M.Sc.)(Entomology)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

The number of people on our planet is projected to rise to between 9.4 and 10 billion by 2050. Some estimates suggest that current levels of food production will need to double to feed this population. Increasing the intensity of food production on existing agricultural land will be a crucial element in meeting this goal, but practices associated with intensive management can cause biodiversity declines and erode the ecosystem functions that underpin production. My work explores agricultural intensification within the context of pasture-based cattle production. I focus on a variety of ecosystem functions supported by dung beetles (Coleoptera: Scarabaeoidea) and other dung-associated invertebrates. I investigate how variations in diversity, and chemical perturbations of veterinary anthelmintics affect the delivery of multiple ecosystem functions. I show that maintaining species-rich dung beetle assemblages has inconsistent benefits in providing multiple ecosystem functions. While dung beetles play an important role in supporting functioning in the short term, my work also reveals that their contributions may be less evident when considered over longer periods. Chemical perturbations caused by anthelmintic residues represent a significant threat to some invertebrate groups, but my experiments show that exposure does not always translate into an immediate reduction in ecosystem functioning. While use of anthelmintic products with relatively low toxicological risk did not cause obvious reductions in function, my work shows exposure can have significant consequences for the conservation of sensitive species. Overall, my work highlights the need for multigenerational studies, mathematical modelling, and careful consideration of sublethal effects to assess fully the risks of anthelmintic residues in the pasture environment. Furthermore, the emphasis on dung beetles (rather than other dung-associated invertebrates) in the existing literature neglects potentially important functional benefits provided by other taxa, such as earthworms. As the global human population continues to expand, it is important that we find sustainable ways to produce food while simultaneously conserving biodiversity. As loss of biodiversity in agricultural ecosystems does not always have functional consequences, it is important that wider justifications for conservation remain integrated into agricultural policy and practice.