Mosquitoes are of tremendous health importance because of their ability to host and transmit various disease pathogens and parasites including viruses, protozoa and nematodes (Onyido et al., 2010). Mosquitoes alone transmit diseases to more than 700 million people annually (Taubes, 1997). Various species ofmosquitoes have a world- wide distribution occurring throughout the tropical and temperate regions where theycause considerable annoyance due to their bites, and are important disease vectors due to the poor socio-economic conditions and favourable environmental and climatic conditions that favours the breeding of mosquito vectors (Appawu et al., 2001). Various species of mosquitoes have long been recognized as vectors of a number of numerous human infections both in sub Saharan Africa and in the tropics (Nwoke et al., 1993; Okogun et al., 2003; Lenhart et al., 2007; Adebote et al., 2008; Adeleke, 2008). Anopheles species is known to transmit human malaria parasite (Plasmodium), Aedes aegypti and some other species transmityellow fever and dengue, while Culex quinquefasciatus have been known to transmit lymphatic filariasis (Onyido et al., 2010). Blood sucking habits of adult mosquitoes makes them susceptible to acquiring pathogens and parasites from the vertebrate host.This is seen in the unique feeding habits of mosquitoes whereby only the females bite man and other animals, while the males feed on plant juices only. After feeding on their host, either outside or inside houses, mosquitoes seek resting place in which to shelter during digestion of their blood meals. Studies in various habitats (micro and macro) in Nigeria have demonstrated the abundance of various mosquito species. They include mosquitoes of the genera Anopheles,Culex, and Aedes (Nwoke et al., 1993; Ekanem, 2001; Usip and Ibenga, 2003). Tropical areas including Nigeria have the best combination of adequate rainfall, temperature and humidity allowing for breeding and survival of Anopheline mosquitoes. Mosquito vectors breed in any available aquatic environment and different species have different habitat preferences e.g. rice fields, tree holes, pools, puddles, borrow pits etc. It has been observed that correct identification of these local vectors was necessary for effective control measures to be employed. Oduola and Awe (2006) reported that the spatial distribution of mosquitoes will contribute to the design of malarial vector control which is a major component of the global malarial strategies and still remain the most general effective measure to prevent malarial transmission.Inadequate knowledge on disease vector has been a bane to malaria control in Nigeria. This study is therefore aimed at providing baseline information on mosquitovector species composition and the level of vector-host association using meal status in somerural communities of Abia State, Nigeria.
1 Material and Methods
Study area
The research work was carried out for a period of six weeks in a rural community of Asa Obingwu, Ukwa West L.G.A of Abia State whichis located on latitude 050451and50231North of latitude and 70371and 70191East of the longitude and at an altitude of 122-183m above sea level. The area has a tropical climate. The wet season usually is from April to October while the dry season begins in November and ends inMarch. Total annual rainfall ranges from 1,800-2,190mm, and a mean daily air temperature range of 220C to 310C. The average relative humidity is about 80 % with about 85 % occurring during the rainy season.The study area consists of about 60 houses with over 500 people.
Community mobilization
Prior to the study, the Eze of the community was visited and informed on what we intend to do in the community. He granted our request after hours of discussion.Announcements were made publicly in the community through the help of the village town crier .This facilitated both access and co-operation of the people. With their permission, public sensitization in the community was conducted.
Procedure of mosquito collection
In determining the distribution and abundance of mosquito in Asa- Obingwu community, thirty houses were randomly selected. A room occupied by residents the previous night was used where indoor collection using pyrethrum collection method was adopted and collections of adult mosquitoes were made in the morning before 8am. Prior to spraying, all animals were evacuated, all food covered and small furniture removed from the room. White sheets were then laid to completely cover the floor and also ensuring that the sheet is spread under the table. All windows and doors closed. The targeted room was sprayed from outside with pyrethrum-based Rambo through the openings below doors and later inside (clockwise) on ceiling and walls until the room was filled with the insecticidal mist.After 10 minutes the room was opened and the sheet were carefully picked up at the corners by about five individuals.
Mosquito preservation and labeling
All knockdown mosquitoes were collected in day-light with force and preserved in an eppendorf tube containing silica-gel with the collection date, village name and household number clearly labelled on the tube. Mosquitoes were put in the tube in order to prevent the delicate body parts of the insect such as palp, antenna, wings and legs which are of significant importance in identification. In the laboratory, mosquitoes collected were identified to species using dissecting— microscope.
Morphological identification of mosquitoes
The key of Gillies and Coetzee (1987) were used for the identification of Anopheles species, while the identification key of Gilleth (1972) was used for Culex identification andAedesmosquitoes. Anopheles mosquitoes were identified by the palp which is long as the proboscis and pointed and by the number, the length, and arrangement of the dark and pale scales in small blocks on the veins of the wings. Male and female Anopheles mosquitoes were identified by examination of antennae, in which those with feathery (plumose) appearance are males and those with only short and inconspicuous antennal hairs are females. Other mosquito species identified were Culex and Aedes.
Data analysis
Mosquito abundance was depicted in tables and difference in the weekly relative abundances were subjected to statistical analysis using student’ s t-test and Analysis of Variance (ANOVA) to determine their levels of significance. All statistical tests were performed at 5% (0.05) level of significance
2 Results
2.1 Mosquito’s identification
A total of 613 mosquitoes were sampled in Asa- Obingwu community, Ukwa West L.G.A of Abia State, Nigeria, comprising of 3 genera namely Anopheles, Culex, and Aedes. The higher proportion is the Anophelines 485 (79.1%) compared to the Culex 51(8.3%), and Aedes 77 (12.6 %) The result is presented inTable 1 and Table 2.
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Table 1 Species composition of all mosquitoes in Asa Obingwu community of Abia State
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Table 2 Density of mosquito collected in Asa -Obingwu community of Abia State
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2.2 Blood meal status
The numerical proportion of fed and unfed of Anopheles was 324 and 171 respectively as shown in Table 3. The Table 4 and Table 5 also revealed the blood meal status of Culexand Aedes mosquito collected where 32 unfed and 19 fed were recorded for Culx.9 Aedes were fed while 68 were unfed.
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Table 3 Blood meal status of Anopheles mosquito
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Table 4 Blood meal status of Culex mosquitoes
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Table 5 Blood meal status of Aedes mosquitoes
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2.3Average indoor resting density of mosquitoes in Asa Obingwu
The average indoor resting density of Anopheline mosquitoes in the study area per night was 4 (four). Culex and Aedes show a resting density of 0.4 and 0.6 respectively, as shown in Table 6.
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Table 6 Average indoor resting density of mosquitoes in Asa-Obingwu
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3 Discussion
The result of the present study have demonstrated the relative abundance and blood meal status of Anopheles gambiae, Culex quinquefasciatus and Aedes aegypti encountered in Asa- Obingwu community, Ukwa West L.G.A, Abia State. This is the first time such report is being studied in this study area. All species of mosquitoes reported in this study have also been reported by different studiesin other parts of Nigeria (Ekanem, 2001; Okogun et al., 2003; Usip and Ibenga, 2003; Oduola and Awe, 2006; Lenhart et al., 2007; Adebote et al., 2008; Onyido et al., 2010). The higher proportion of Anopheles 485(79.1%) when compared to Culex 51 (8.3 %) and Aedes 77 (12.6 %) in this study area is in accordance with the findings of Onyidoet al.,2010 andis in contrast with the report of Usip and Ibanga where Culex was the most abundance. Abundance of Anopheline is as a result of suitable environmental and climatic breedingconditions which favours their breeding of larva of the vectors. This was also reported in the findings of Minakaw et al., (2002). The high indices of Anopheles gambiae in Asa Obingwu was due to the close proximity of residential areas to their farm lands which was most often a water logged area. The insurgence of Aedes and Culex may be as a result of water storage practice of individual in Asa Obingwu.The people of Asa Obingwu had the practice of storing water in earthen pots in a corner of their house. Adebote et al, (2008) suggested that the presence of earthen pot may facilitate the emergence of Aedes.
Man-made malaria in the study area may also be due to unavailability of pipe- borne water in the study area.Poverty and dearth of knowledge on the dangers posed by mosquitoes to man may also have played its role in the abundance of the mosquitoes in the study area. 85% of the villagers are farmers, and so illiterates. Inadequate information, on the risk posed to them by the vector (mosquito), has worsened their nonchalant attitude towards the management of malaria vector.Poor road network has made accessibility a problem which is quite discouraging for health workers and may have been the reason for the inadequate level of awareness and consequently the abundance of mosquitoes in the study area.
The blood meal status shows that the percentage of fed Anopheles mosquitoes is greater than that of the unfed which is in contrast with the findings of Mukabana et al, (2002) where unfed dominate over the fed Anopheles. This is an indication of the fact that the inhabitants of Asa Obingwu are prone to malaria infection since Anopheles has been incriminated as an efficient vector of malaria (Adeleke et al., 2010).
The people in this study area are less prone to disease transmitted by Culex and Aedes mosquitoes because in this study the percentage of unfed Culex (67.7%) and Aedes (88.3 %) is significantly greater than the fed Culex (37.3%) and fed Aedes (88.3%). A. gambiae is the most abundant of the three groups of mosquitoes collected in Asa Obingwu community but further Molecular characterization of An. gambiae s.l is necessaryin order to determine sibling species in the complex.Conversely, Aedes aegypti has the lowest abundance. Average Indoor resting density of Anopheles was four .This shows that 4Anopheles mosquitoes would be found in one house per night in Asa Obingwu.This is quite a significant number which also indicates the rate at which the inhabitants of every house will be infected with malaria parasite. The identification ofAnophelesgambiae: the major vector of malaria in Africa and high host-vector association in Asa Obingwu community suggest possibilities of high malaria transmission risk indices in the community. This calls for all stakeholders involved in the concerted effort to promote malaria vector control tools such as long lasting insecticide treated bed nets that will reduce risk of exposure to malaria.
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Carmelita C. OHAERI2 
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Onyinye M. UKPAI2 
