Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Age and temperature are two factors that affect mortality in adult tsetse flies. Both are found
to be very important, but the simultaneous effect of these factors on the mortality rate have
not been studied. This study seeks to address this, with an application to a population of
female tsetse, using a model based on partial differential equations. Adult mortality is agedependent
and is modelled as the sum of two exponentials, with four parameters (coefficients
of each exponential): numerical analysis of a population model with this mortality structure
predicts exponential growth. Analysis of each of the parameters through parameter variation
shows that two of these parameters control the mortality of the nulliparous (ages 0 − 10
days) flies only while the other two only take care of flies of mature ages. Measurement of
the impact of these parameters on the mortality of tsetse of different ages by the normalized
forward sensitivity index method is also carried out. This is followed by fitting the model
based on the age-dependent mortality along with a constant tsetse birth rate to data representing
the catches of female Glossina pallidipes at Rekomitjie Research station, Zimbabwe.
Considering a three parameter adult tsetse mortality, parameter analysis shows the effect of
one of the parameters to affect the mortality of flies of all ages while a second controls only the
mature tsetse flies of reproductive ages. A further analysis resulted in the estimate of these
parameters as functions of temperature, thereby leading to the establishment of an age and
temperature-dependent adult tsetse mortality. Using data for the daily average temperature
records obtained in 1981 on Antelope Island, Lake Kariba, Zimbabwe, daily changes in the
pupal duration (adult tsetse birth rate) changes negatively with temperature change. Incorporating
this (temperature-dependent ) birth rate into the model, together with the established
age and temperature-dependent adult mortality, the adult tsetse population dynamics is explored
numerically. The latter model is then fitted to population data of female Glossina
morsitans morsitans obtained from the same Island and for the same period as used for
the temperature data. The data suggests peak tsetse population to be in the month of July
and lowest in the month of December. The first quarter of the year is predicted to be most
favorable for breeding tsetse while the second, showed a period of stable growth rate and a
time of tsetse abundance. In addition, the dynamics with both age and temperature showed a
non-uniform daily population growth contrary to that with age effect only. This study has enhanced
our understanding of tsetse population dynamics for age and temperature-dependent
adult mortality with temperature-dependent pupal duration and suggests the period of tsetse
abundance on Antelope Island. / AFRIKAANSE OPSOMMING: Geen opsomming in Afrikaans.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/18101 |
| Date | 12 1900 |
| Creators | Elama Ameh, Josephine, Ochigbo, Josephine Elanma |
| Contributors | Ouifki, Rachid, Hargrove, John W., Stellenbosch University. Faculty of Science. Dept. of Mathematical Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 83 p. : ill. |
| Rights | Stellenbosch University |
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