COMPOSITION OF SIMULIUM DAMNOSUM COMPLEX IN AGBA VILLAGE (EBONYI STATE): A MORPHOLOGICAL DELINEATION OF FOREST AND SAVANNAH SPECIES

The study was carried out to determine the species composition of Simulium damnosum complex around Asu River, situated in Agba village, Ishielu, L.G.A of Ebonyi state, Nigeria; using morphological characteristics. A total of 91 flies were collected and observed for morphological characteristics; the thorax length/ antenna length ratio. Human baits were used for the collection. The flies were identified morphometrically using ocular microscope; and the body parts measured in millimetres using the ocular and stage micrometer. The thorax length/ antenna length ratios were determined according to published protocols. These were used to separate the flies into savannah and forest types. Any Simulium damnosum that had the thorax/antenna length ratio above 2.25 were identified as savannah dwellers, while those with TL/AL ratio of less than 2.25 were identified as forest dwellers. Of the 91 adult female black flies collected, 73 were forest dwellers representing (80.22%) of the sample population. The number identified as savannah dwellers was 18, representing (19.78%) of the entire sample population. The mean thorax length obtained for the forest and savannah dwellers were (0.8267±0.0404) and (0.9400±0.0529) respectively, while the mean antenna length were (0.4200±0.0346) for the forest dwellers and (0.3833±0.0306) for the savannah flies. The mean TL/AL ratios obtained in the study were 1.9683 and 2.4524 for the forest and savanna dwellers respectively. Sequel to the above, it can be concluded that the savannah and forest “types” of S. damnosum are coexisting in the area as suggested by pockets of earlier epidemiological studies. This coexistence has a potential implication on the dynamics of transmission in the area