Assessment of Physico-Chemical and Ecological Variables in Selected Natural Breeding Sites of Mosquitoes in Ibadan, Oyo State, Nigeria

Larval habitats have been described as important determinants of adult distribution and abundance. Mosquitoes employ aquatic environment for growth and development, thus, a study of the factors that determine their habitat selection and preference is important for their occurrence. It also makes it possible to predict the type of disease, offer a precise prevention and suggest a likely control measure in combating mosquitoes in an area. The data required was obtained through field and laboratory works. The physico-chemical parameters considered were; temperature, pH, conductivity. Dissolved Oxygen, Biochemical Oxygen Demand and Chemical Oxygen Demand, and the ecological sites were; road puddle, sunlit pool, gutter, swamp and small drains. The temperature, pH and conductivity were recorded in situ while water sample from the sites were fixed and taken to the laboratory. Eleven Local Government Areas were visited, two locations each were picked at random from the areas and three sites were selected in each locations from the possible sites examined. A total number of 66 breeding sites examined consisted of 27 Culex sp., 25 Anopheles sp and 14 for both. Gutter had the highest percentage (55.56%) occurrence of Culex sp., while it was least encountered in sunlit pool. Road puddle had the highest (56%) for Anopheles sp. but was least in small drain and swamp. The temperature of the breeding sites ranged from 25 to 35°C with a mean value of 30°C, the pH ranged from 2.5 to 9.5 with a mean value of 6.0, the conductivity ranged from 010 to 1620 with a mean of 815, the Dissolved Oxygen ranged from 1.02 to 11.18, the Biochemical Oxygen Demand ranged from 5.40 to 22.96 and the Chemical Oxygen Demand ranged from 76.45 to 320.15. The implication of these observations was discussed in relation to the success of the species in the habitats.

Keywords: Anopheles; Culex; Breeding sites; Preference; Ecological variables; Sunlit pool; Occurrence