Ecology Of Man-Biting Mosquitoes In The Development Site Of Nnamdi Azikiwe University Awka, Anambra State Southeastern Nigeria

摘要

A study of man-biting mosquitoes at the permanent site hostels of Nnamdi Azikiwe University, Awka, was carried out between February and July 2008. Mosquito larvae were sampled from flood pools around the hostels using ladle. Indoor biting and resting adult mosquitoes were collected using pyrethrum knockdown collection method (PKC). Outdoor biting mosquitoes were collected using human volunteers as baits and collectors. 1265 mosquitoes made up of 5 mosquito species were collected as larvae. Culex quinquefasciatus 466(36.84%) and Aedes aegypti 400(31.62%) formed the bulk of the larval collection. 72 adult mosquitoes comprising 3 mosquito species were collected inside the university hostels. Anopheles gambiae, 50(69.45%), constituted the highest percentage of indoor biting and resting mosquitoes. A room density of 8.2 mosquitoes/roomight was recorded, 6 mosquitoes/roomight were A. gambiae. 132 outdoor biting adult mosquitoes were collected, A. aegypti 67(57.5%) and A. albopictus 38(28.79%) had the highest numbers. A biting rate of 5.97 mosquitoes/man/hour was observed, 3.04 mosquitoes/man/hour were A. aegypti. The students in the hostels are therefore exposed to mosquito bites and mosquito-borne diseases. Self-protection by the students and general provision of mosquito control strategies in the students hostels by the institution is hereby suggested Introduction Developmental projects, such as civil engineering constructions, mining and agricultural projects including deforestation, which are intended to improve the quality of life of the people often bring with it favorable conditions for the breeding of large populations of disease vectors and the associated disease burden. Sharma and Upreathy (1982) observed that dams, lakes, irrigation schemes and other developmental projects though essential for the economic growth of many countries, unfortunately cause increases in malaria and other vector-borne diseases such as filariasis, arboviruses and other health problems. Service (1991) noted that the policy, in the 1970s, of clearing forest in Enugu region of Nigeria for planting of the valuable timber trees, teaks and gmelina, increased the people’s exposure to the bites of forest mosquitoes. He noted that the situation was aggravated as a result of rot holes which developed in the tree stumps left behind after clearing operations which later became filled with water and formed ideal larval habitat for Aedes africanus – a yellow fever vector. WHO (1993) observed that schistosomasis infection has increased over the years due to large scale irrigation projects which created new habitats for the aquatic snails.The permanent site of Nnamdi Azikiwe University, Awka, in Anambra State of Nigeria is a relatively new project development site. Until March 2006, the institution was located at a temporary site within Awka metropolis but today all the departments have relocated to the permanent site. Most lecture halls, offices, research laboratories and access routes are still under construction. The new site is hitherto uninhabited. It was a vast expanse of agricultural land with such poor topographical features as sluggishly flowing streams, water logged land for the most part of the year, marshy terrain and ground water pools formed by collection of rain water in depressions near and around the hostels, lecture halls and administrative blocks. The land was primarily used for cultivation of rice, maize cassava, yam and vegetables. Wild palm trees and forest galleries punctuate the otherwise derived savannah vegetation. Occasionally monkeys are sited in some parts of the campus. Vectors such as tabanids sometimes fly through the windows into offices and lecture halls. Experience from personal interactions with the students and records from the University Medical Centre indicate that many students complain of malaria and other febrile illnesses suspected to be vector-borne. Large populations of people, students, lecturers, administrative