A Onyido, V Ezike, N Ozumba, E Nwosu, O Ikpeze, M Obiukwu, E Amadi
arboviruses, man-biting mosquitoes, reservoir hosts, zoological garden
A Onyido, V Ezike, N Ozumba, E Nwosu, O Ikpeze, M Obiukwu, E Amadi. Crepuscular Man-Biting Mosquitoes Of A Tropical Zoological Garden In Enugu, South-Eastern Nigeria. The Internet Journal of Parasitic Diseases. 2008 Volume 4 Number 1.
Ovitraps and human baits methods were used in sampling crepuscular man-biting mosquitoes of the Zoological Garden Enugu which were studied between February and July 2005.
Mosquitoes are small slender-bodied insects which viciously hunt their hosts, especially man, for blood meals. They have worldwide distribution and are found in both tropics and temperate regions of the world. The mosquitoes breed in a variety of habitats where there is stagnant water including swamps, edges of river, slow flowing streams, tree holes, plant axils, crab holes, broken bamboo stems, tin cans, plastic containers of all sorts, water holding cisterns and tanks, coconut shells, foot prints of animals and man, sand excavation ditches, stone quarry sites, motor vehicle tyre prints, sunlit or shaded quiescent water, scoops in concrete slabs used in feeding animals and cassava fermentation pots (Onyido
Mosquitoes are regarded as public enemies because of their biting annoyance, noise nuisance, sleeplessness, allergic reactions and disease transmission due to their bites. They transmit human diseases such as malaria, yellow fever, dengue haemorrhagic fever and encephalitis (Onyido
Zoological gardens are simulated natural ecological habitats for keeping animals in captivity. They form important tourist attraction centers that bring large populations of adults and children together for sight-seeing and recreation. It is pertinent that mosquito populations should be controlled to protect the public and the animals from mosquito-borne diseases and prevent the zoological gardens from being centers for the dissemination of vector-borne infections. Surveillance of mosquito population and their biting activities is therefore a bold step towards providing the baseline information for the control of the mosquitoes and mosquito-borne diseases. This work is aimed at studying the man-biting mosquitoes of Enugu zoological garden with a view to providing data for their control. Specifically the man-biting species will be identified and their biting activities elucidated.
Materials And Methods
Enugu has many tertiary institutions of higher learning including the Institute of Management and Technology, Enugu State University of Science and Technology, University of Nigeria Enugu Campus, Biggard Memorial Seminary, School of Dental Therapy and Technology, Federal School of statistics, Federal Training School, Our Savior’s Institute of Technology, the Nigerian Law School Campus, and Caritas University. It also has many secondary and primary schools. Also found in Enugu are many tertiary and specialist hospitals like University of Nigeria Teaching Hospital, National Orthopaedic Hospital, National Neuropsy–psychiatric hospital and Parklane General Hospital. In Addition there are many health centers, polyclinics and private hospitals, maternities and clinics.
Enugu metropolis also serves as the commercial nerve centre of Enugu State and the administrative headquarters of many National and State institution. It has a branch of the Central Bank of Nigeria, many commercial banks and departmental stores, the famous Ogbette and Aria markets with many lock-up and open stalls. It is the Zonal headquarters of Nigerian Telecommunications, Nigerian Postal Services, Power Holding of Nigeria (formerly, National Electric Power Authority), Project Development Agency, Industrial Training Fund and Federal Secretariat.
Geographically Enugu is located between latitudes 6o and 7o North of Equator and Longitude 7o and 8o East of Greenwich. It has an undulating topography and is situate in the valley of Udi Hills. It has 8 months of (April - October) rainy season and 4 months (November - March) of dry season. It has derived savannah vegetation with tall grasses and few trees. It is located within the transitional zone between the guinea savannah in the north and rain forest belt in the south.
The Zoological Garden is a small strip of Land between Government Reserved Area – a low density area and Abakpa Nike – a high density area (Ikpeze, 2005). It is bounded in the North by Army barracks of the 82 Division, Nigerian Army and in the south by the Air Force Quarters. It is separated from Abakpa Nike by Enugu – Onitsha Express way and bounded by the Government reserved Area in the East. The animals are kept under the simulated natural conditions provided by the forest and giant trees. Common animals in the Zoo include lions, elephants, chimps, snake, crocodiles, antelopes and birds such as peacocks. People from all walks of life come in with their families to watch the animals.
Biting rate = Total number of individual mosquitoes collected divided by the number of man hours used in collection
Man hours = The product of the number of volunteer workers employed and the number of hours used in catching the mosquitoes.
The result of
Table 2 shows the mosquitoes identified from the eggs collected. Five
Table 3 shows the number of different species of mosquitoes collected in each month with human bait method. A total of 1112 mosquitoes consisting of 14 species were collected of which seven species were
From the monthly totals, the highest number of mosquitoes was collected between April and June. The collections in June topped the list with 328 mosquitoes (29.49%). Except in April when only three mosquitoes species were collected, between six and eight species were collected each month from May to September. From the biting rates, a total of 9.5 mosquitoes bit each worker every hour (i.e. 9.5 mosquitoes per man per hour). Approximately 6 out of every nine mosquitoes that bit man per hour were
Figure 1 shows a graph of quarter-hourly collections of different man-biting mosquito species from the Zoo. The plots of three most abundant species,
Most of the collections from the ovitraps were between April and July; no eggs were collected in the month of February. This could be due to harsh dry season weather prevalent at the time (Iloeje, 2001) and because most mosquitoes especially the
Out of the 14 species of mosquito collected with human bait method, 7 were
With the exception of the