| dc.description.abstract | Host preference in Aedes (Stegomyia) species mosquitoes was
investigated with special reference to the anthropophilic and
non-anthropophilic forms of Aedes (Stegomyia) simpsoni Theobald in
Uganda. Four aspects were studied; namely 1, the natural hosts
of A. simpsoni in an area where it is non-anthropophilic: 2, the
Genetic and environmental factors controlling host preference:
3, isolation of Bwamba anthropophilic populations: 4, the response
and stimuli involved in host preference.
Host preferences of anthropophilic and non-anthropophilic
strains of both A. simpsoni and Aedes aegypti are stable in culture and are predominantly genetic, not environmental, in origin.
The genotype of the male parent is the main determining factor.
The character is probably polygenic but at relatively few loci. In
the two strains of A. simpsoni there is at least partial genetic
isolation as measured by the hatchability of hybrid eggs.
Proximately, host selection appears to be based on response
by females to specific odours and the site of reception is the
antennae. The experimental measured response to odour alone
suffices to explain the observed host preference.
Rodents are the main hosts of A. simpsoni in the non-anthropophilic
population in Bwayise. The actual species used is probably
determined by interplay of innate preferences and host availability,
especially in relative synchrony of diurnal activity rhythm of the
rodent with that of the mosquito. Further data on this is required.
The non-anthropophilic population do occasionally bite man.
Non-anthropophily is merely one aspect of non-primatophilyi
the Bwayise strain does not normally feed upon wild primates
either. This explains the almost total absence of human yellow
fever in non-anthropophilic areas in Uganda, even though, in
non-anthropophilic areas reservoirs of disease are present in
monkeys and some A. simpsoni do bite man.
The anthropophilic.Bwamba strain is isolated from the non anthropophilic
Uganda strains by the geographical and ecological
barriers of the Ruwenzori mountains and the Semliki flats.
Recently established areas on the West (Bwamba) side of the
mountains were found to contain a population of anthropophilic
tendencies. Colonization of those areas may be either by direct
importation in Colocasia plants, or by dispersal along the new
cultivated tracts through former forest areas. Spread of the
anthropophilic form out of Bwamba is rendered less likely by the
partial genetic incompatibility between the two strains: but the
circumstances and possible hazard are worth serious considerations. | en |
