Human onchocerciasis in Nigeria is spread from person to person by infected adult female flies of the genus Simulium, a complex of verifiably real species. This study was designed to determine the specific vector species composition of the areas using the morphological and cytotaxonomic identification techniques. Adult female flies were collected from four sites using human landing collection method and used for morphological identification. Larval samples were obtained from breeding sites in two of the four communities and were used for cytotaxonomic species identification. A total of 3,118 flies collected for morphological studies were identified as forest flies, thus: Agbokim, 582 (18.6 %), Aningeje, 1224 (39.2 %), Ekong Anaku, 978 (31.3 %), and Orimekpang 334 (10.7 %). A total of 243 larvae, 97 (39.9 %) from Anigeje and 146 (60.1 %) from Ekong Anaku were cytologically studied. Clear and distinctive chromosomal bands were obtained from a total of 31 (12.7 %), 11 (35.5 %) from Anigeje and 20 (64.5 %) from Ekong Anaku. Among the Anigeje samples, 1 (9.1 %) was identified as S. damnosum s.s., another 1 (9.1 %) was identified as S. sirbanum. The remaining 9 (81.8 %) of the samples were identified as S. squamosum. In Ekong Anaku, 3 (15.0 %) out of the 20 karyotyped larvae were S. damnosum s.s., 1 (5.0 %) was S. sirbanum and 14 (70.0 %) were S. squamosum while2 (10.0 %) were of a fourth species, S. yahense. The results of this study showed only members of the forest species group were identified using morphological identification but cytotaxonomic studies indicated both forest and savannah species groups were present. The severe savannah and the mild forest strains of ochocerciasis could be endemic in these areas and requires improved control and elimination efforts.
Friday Maduka Chikezie, Kenneth Nnamdi Opara, Peace Mayen Edwin Ubulom, Mike Yaw Osei-Atweneboana. Simulium vectors of the lower cross river basin: A morphometric and cytotaxonomic identification. International Journal of Entomology Research, Volume 7, Issue 2, 2022, Pages 72-80