Mellese, Berhan (2008) The Effect of Water Physical Quality and Water Level Changes on the Abundance and Occurrence of Anopheles Larvae (Diptera:Culicidae) around the Shoreline of the Koka Reservoir, Central Ethiopia. Masters thesis, Addis Ababa University.
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Abstract
Entomological studies on the effect of water physical quality and water level change on the occurrence of Anopheles mosquito larvae and the formation of larval breeding habitats were conducted in two villages (Ejersa and Kuma) at the Koka Reservoir in Central Ethiopia between August and December 2007. Data on the type and number and physical characteristics of Anopheles larval breeding habitats, species composition and densities were recorded. Meteorological and reservoir water level data were compared with availability of Anopheles larval breeding sites and densities. Four-year retrospective clinical data indicated that the pattern of malaria transmission in the village at close proximity of the Koka reservoir is strongly associated with reservoir water level change during the peak malaria transmission season. Data from adult and larval collection showed that Anopheles pharoensis, An. gambiae s.l., An. coustani and An. squamosus were found in the study area in different proportions. An. pharoensis larvae were dominant at the village close by the reservoir while An. gambiae s.l. more common at the second village away from reservoir in the short breeding interval during the study periods. The total count of An. pharoensis larvae at the reservoir site was significantly higher than at the control village (X2 = 942.8, df = 1, p < 0.05). This indicates that this species prefers breeding sites created in association with shoreline puddles that provide ideal turbid breeding pools with much floating aquatic vegetation. The total count of An. gambiae s.l. at the reservoir site was also significantly higher (X2=200.5, df=1, p < 0.05) than at a the nearby control village. Generally, mean larval density of An. gambiae s.l. was higher in slightly turbid and shallow aquatic habitats (F=16.97, p<0.05 and F=6.03, p<0.05 respectively) than that of turbid and deep aquatic habitats. The density of An. pharoensis in breeding habitats with floating vegetation and with relatively shady condition was significantly higher than that of the aquatic habitats with much light and greater emergent vegetation (F=15.75, p < 0.05 and F=10.56, p < 0.05 respectively). There was also a positive correlation between the occurrence of larvae, water temperature of the breeding habitats and daily minimum atmospheric temperature (r= 0.541 and, r= .0.604, respectively p <0.05). Similar comparison indicated a positive correlation between water level changes resulting in subsequent recession of the reservoir and the number of positive breeding habitats during the sampling period in the reservoir village (r = 0.605, p < 0.05). Results in this study clearly showed that water physical characteristics such as water temperature, turbidity, depth and vegetation cover play an important role in the species composition, total count and density of Anopheles mosquitoes in the vicinity. Reservoir water level change is also associated with the proliferation of ideal mosquito breeding habitats.
| Item Type: | Thesis (Masters) |
|---|---|
| Subjects: | G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > QH Natural history > QH301 Biology Q Science > QL Zoology R Medicine > RA Public aspects of medicine > RA0421 Public health. Hygiene. Preventive Medicine |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 18 Sep 2018 09:13 |
| Last Modified: | 18 Sep 2018 09:13 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/5274 |
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