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Title: Ecology and control of tsetse at the interface of conservation and farming areas in northern Tanzania
Author: Lea, Rachel Sarah
ISNI:       0000 0004 8505 7988
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2019
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Rhodesian human African trypanosomiasis (r-HAT) and Animal African trypanosomiasis (AAT) are diseases caused by Trypanosoma spp. transmitted by tsetse (Glossina). In East and Southern Africa, the risk of r-HAT and AAT is greater in the vicinity of conservation areas where wild reservoir hosts and tsetse are abundant. The over-arching aim of this study was to analyse fine-scale variations in the abundance and distribution of tsetse at the interface of conservation and farming areas in northern Tanzania. Towards this aim, research was undertaken at the edges of the Serengeti and Saadani national parks to address four specific questions. First, what is the impact of natural environmental variables on the fine-scale (< 1 km) distribution and abundance of tsetse? Second, is the treatment of cattle with insecticides by livestock keepers having an impact on tsetse populations? Third, can satellite imagery be used to predict the fine-scale distribution and abundance of tsetse across different agro-ecological zones? Finally, does the molecular genetics of tsetse populations reflect the prior impact of natural and anthropogenic factors on population dynamics. Analyses of catches of Glossina pallidipes and Landsat imagery showed that the abundance of tsetse in conservation areas was correlated positively with normalised difference vegetation index (NDVI), tree cover, soil moisture (Band 7), land surface temperature (LST) and proximity to rivers. In nearby farming areas, the correlations were less marked or not significant, indicating that other factors were controlling tsetse populations. Questionnaire surveys of livestock keepers showed that in Serengeti district, ~70% of cattle owners reported treating their animals with pyrethroids at monthly intervals. Chemical analyses of hair from cattle using gas-chromatography with mass spectrometry, highperformance liquid chromatography and an insecticide quantification kit showed that ~30% of herds contained animals which had been recently treated with cypermethrin or alphacypermethrin. Previous literature suggests that treatment of cattle with pyrethroids at these levels will reduce the density of tsetse. Models based on satellite data, developed with data from Serengeti National Park, were successfully used to predict the relative abundance of tsetse in Saadani but were less useful in farming areas where abundance of tsetse was much less than predicted. The low numbers observed may be related to widespread treatment of cattle with insecticide in the farming areas of Tanga region surrounding Saadani. Analyses of the genetics of G. pallidipes populations in Serengeti and Saadani found no evidence for the impact of tsetse control operations. At Saadani, two cryptic and sympatric species of G. pallidipes were detected. The discovery of cryptic species may explain intraspecific variation in the behavioural responses of G. pallidipes and also makes the use of sterile insect technique a more difficult prospect. The results are discussed in relation to prospects for improved strategies and approaches to the control of r-HAT and AAT in Tanzania and elsewhere in East and Southern Africa.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral