Abstract
Ph.D. (Biodiversity and Conservation)
The House Sparrow (Passer domesticus) is an invasive species that has been
established in South Africa since the 1960s. This birds’ close association with
humans makes it a reliable bio-indicator of environmental change. The birds were
collected in the Limpopo- and Free State Provinces. In the Limpopo Province the
sites were in the area of Thohoyandou an endemic malaria region, while in the Free
State the site was close to the town of Clarens a non-endemic malaria region. In
accordance with the Stockholm convention which regulates its use, DDT can still be
used in malaria control programmes. The sites were chosen according to the spray
history in the Limpopo Province. Two sites per site category were chosen: a) those
last sprayed 30 years ago (Tshakuma and Muledane), b) two areas that were last
sprayed five years ago (Makonde and Mangondi) and, c) two areas that were
recently sprayed (sprayed within the years of sampling) (Makula and Lefule).
The mosquitoes in this area have developed resistance against pyrethroids, the
alternative pesticide used for malaria vector control. The main aim of this study, was
to determine the impact of DDT and its metabolites on the histology of selected body
tissues, reproductive success and the overall health of the House Sparrow. This was
done by determining the concentrations of p,p’-DDT, o,p’-DDT, p,p’-DDE, o,p’-DDE,
p,p’-DDD and o,p’-DDD in House Sparrow tissues (kidney, liver, brain and testis),
hatchlings, eggs and eggshells from the various sites using extraction of
contaminants and gas chromatography- mass spectrometry. Concentrations of DDT
congeners were also analyzed in soil. The eggshell structure was examined. Special
attention was given to the shell thickness, pore numbers, pore sizes and hatching
success of the eggs. The eggshell structures were examined using a scanning
electron microscope and X-ray micro-computed tomography. The bone density...