Epsilon Archive for Student Projects

Abstract

Mosquitoes are medically the most important group of insects, transmitting a number of deadly diseases, including malaria. Female mosquitoes transmit them while feeding on human blood, which is required to mature eggs. It is important to understand vector population dynamics in
order to effectively control them. Sampling larval populations is one of the methods to estimate
mosquito requirements for site selection for oviposition and survival.

Our survey took place from 10th of June to 1st July in the area of village Chano, located in the Southern Nations, Nationalities and Peoples Region in Southern Ethiopia. Mosquito larvae were collected using standard dipping method once a week in three different land cover categories.
Water physical parameters were recorded on site and the chemical analysis was performed at the laboratory of The Institute of Health and Nutrition in Addis Ababa.

We found Anopheles arabiensis to be the only anopheline species present at the end of the rainy season in the surveyed area. There was no significant association detected between presence of Anopheles mosquito larvae and abiotic and landscape characteristics. However, we found that the density of early instar stages was increasing with increasing conductivity (p=0.01) and dissolved oxygen (p=0.02) and when habitats contained aquatic vegetation. Such habitats were associated with pastures. Late larval instars were positively associated with turbidity (p=0.003) and such habitats were more numerous in the settlement. We conclude that Anopheles arabiensis females were ovipositing more intensively in habitats that were more stable, but the survival in such habitats was lower. We suggest that water quality may be not the main factor influencing site
selection for oviposition when the climatic conditions are not favorable for the survival of the adult and immature stages. This knowledge could be applied in the development of vector control strategies, aiming at the mosquito populations when they are mostly vulnerable.