Research in Zoology 2013, 3(2): 62-65 DOI: 10.5923/j.zoology.20130302.03 Spatial and Temporal Distribution of Tabanids (Diptera: Tabanidae) in Akwa Ibom State, Nigeria Veronica I. Itina, Aline M. E. Noutcha, Samuel N. Okiwelu * Department of Animal and Environmental Biology, University of Port Harcourt, Port Harcourt, Nigeria Abstract Rapid Assessment Surveys confirmed the endemicity and widespread occurrence of the tabanid-transmitted human disease, Loiasis in Akwa-Ibom State, Nigeria, but data on the species composition, seasonal abundance and distribution of tabanids in the State was non-existent. A study was therefore undertaken over a 12-month period, covering wet and dry seasons, at rural and urban sites to determine the occurrence, seasonal abundance of known and potential tabanid species across the eco-vegetational zones (Mangrove Swamp Forest, Freshwater Swamp Forest, Lowland Rainforest, Moist Savanna Woodland) in the State. The Malaise trap was the sampling tool. Distribution of tabanids was across all eco-vegetational zones; however, most were collected from the mangrove swamp forest. The mangrove and fresh water swamp forests yielded more than 90% of all tabanids. The total number of tabanids was 2,790; eleven species in four genera (Tabanus, Chrysops, Haematopota, Hippocentrum). The genus Chrysops was dominant, constituting 65.4% of all tabanids; Chrysops silacea, a known vector of Loiasis was the most abundant and widespread species, 32.4% of all tabanids. More than 80.0% were collected in the wet season. Most species occurred in both seasons, with the exception of Tabanus atratus and Chrysops pikei recorded in the wet season only. More than 60.0% of all tabanids were from rural locations. The endemicity and widespread occurrence of loiasis in the State ie: probably maintained by the widely distributed C. silacea and other factors. The rainy season can be considered as the period of potentially higher risk of transmission, particularly in the rural mangrove and fresh water swamp forests. Keywords Tabanids, Loiasis, Distribution, Eco-vegetational zones, Akwa-Ibom State, Nigeria 1. Introduction Loiasis is a tabanid-transmitted helminth disease of Central and Western Africa[1, 2]. The diurnally periodic microfilariae are usually absent from peripheral blood of people at night, but appear during the day, particularly in the morning. The microfilariae are therefore readily picked up by the primary tabanid vectors which bite during the day[3]. Loiasis has been established as endemic and widespread in Akwa-Ibom State, Nigeria[4-6]. There have been anecdotal records of tabanids in the State. A study was therefore undertaken over a 1-year period to determine variations in species composition, relative abundance and distribution of tabanids in rural and urban locations across the eco-vegetational zones in the State. 2. Materials and Methods * Corresponding author: okiwelu2003@yahoo.com (Samuel N. Okiwelu) Published online at http://journal.sapub.org/zoology Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved 2.1. Study Area Akwa Ibom State is located in the south eastern region of Nigeria, 4.32 0 -5.33 0 N and 7.25 0 - 8.25 0 E. There are four vegetation zones: mangrove swamp forest, fresh water swamp forest, Lowland rainforest and moist savanna woodland. The mean annual rainfall is 2000-2500mm and the temperature range, 27 - 32℃. There are two seasons: rainy (April - October) and dry (Nov - March). 2.2. Study Sites Two Local Government Areas (LGAs), each from an urban and a rural location were randomly selected in each of the four eco-vegetational zones; the LGAs were: Eket, Onna, Etinan, Nsit Atai, Uyo, Ibesikpo Asutan, Ikot Ekpene and Ibiono-Ibom. The geographical coordinates of the study towns and villages appear in Table 1. 2.3. Vector Collection, Handling and Identification The Malaise trap, effective for the collection of tabanids[7] was used. Tabanids were collected fortnightly, 07.00-19.00hrs; data were pooled to obtain monthly relative abundance.