An individual-based model of tsetse fly populations dynamics : modelling an extensive mark-release-recapture experiment

Ferreira, Roux-Cil (2015-04)

Thesis (MComm)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: Tsetse flies (Glossina spp), native to mid-continental Africa, are the vectors of trypanosomes that causes human (sleeping sickness) and animal (nagana) trypanosomiasis. Vector control plays a major role in alleviating the burden of the disease. Mathematical models of tsetse population dynamics provide insights into how best to manage these control efforts. A major mark-recapture experiment, carried out in Zimbabwe, provided valuable information on tsetse population dynamics, but the analyses so far published could be improved on because not all of the information available on the marking procedure was used. We have constructed an individual-based model that follows the life of individual tsetse flies, their progeny and, in particular, the sequence of occasions on which individual flies were captured and given distinctive marks. We have access to comprehensive data from the tsetse fly mark-release-recapture experiment carried out on Antelope Island, Lake Kariba, Zimbabwe. In order to calibrate or validate the model, we model both the growth of the introduced tsetse population and the mark-recapture process. We have compared the model outputs to the original data and recommend processes that may be followed for model calibration. It is possible to construct an individual-based model that adequately models tsetse fly populations. Whereas the focus of this study has been on modelling the mark-recapture study, the individual-based model could also be used in more general settings to model the growth, and reduction in fly numbers, changes in age structure, species and gender ratios and the acquisition of trypanosome infections by individual flies. This model can thus be used to investigate the effect of various factors on tsetse fly and trypanosome, population dynamics as well as on the performance of various control techniques effecting fly mortality and disease transmission.

AFRIKAANSE OPSOMMING: Tsetsevlieë (Glossina spp), inheems aan sentraalkontinentale Afrika, is die draers van trypanosomen wat trypanosomiasis by die mens (slaapsiekte) en by diere (nagana) veroorsaak. Die beheer van draers speel 'n belangrike rol om die las wat die siekte veroorsaak, te verlig. Wiskundige modelle van tsetse bevolkingsdinamika bied insigte oor hoe om beheerpogings die beste te bestuur. 'n Belangrike merk-hervang eksperiment, wat in Zimbabwe uitgevoer is, bevat waardevolle inligting oor tsetse bevolkingsdinamika. Die ontleding daarvan, wat tot dusver gepubliseer is, kan egter verbeter word aangesien nie al die inligting beskikbaar in die merkprosedure, gebruik is nie. Ons het 'n individu-gebaseerde model saamgestel wat die lewens van individuele tsetsevlieë en hul nageslagte volg, in besonder die volgorde waarop individuele vlieë gevang en herkenbaar gemerk is. Ons het toegang tot omvattende data van die tsetsevlieg merk-vrylaat-hervang eksperiment wat uitgevoer is op Antelope Eiland, Karibadam, Zimbabwe. Ten einde die model te kalibreer of om die model se geldigheid te bevestig, modelleer ons beide die groei van die ingevoerde tsetse bevolking en die merk-hervangs metode. Ons vergelyk die modeluitsette met die oorspronklike data en beveel prosesse aan wat gevolg kan word om die model te kalibreer. Dit is moontlik om 'n individu-gebaseerde model saam te stel wat tsetsevliegbevolkings voldoende moduleer. Terwyl hierdie studie die modellering van die merk-hervang data bestudeer, kan die individueel-gebaseerde model ook gebruik word in meer algemene gevalle vir die modellering van die vermeerdering en vermindering in vlieë getalle, veranderinge in die ouderdomstruktuur, spesies en geslagverhoudings en die verwerwing van trypanosomen infeksies deur individuele vlieë. Hierdie model kan dus gebruik word om die effek te ondesoek van verskeie faktore op die tsetsevlieg en trypanosomen, populasiedinamiek sowel as die prestasie van verskillende beheertegnieke rakende vliegsterftes en siekte-oordrag.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/96685
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