CYTOTAXONOMIC STUDY OF THE LARVAE OF BLACKFLY (DIPTERA: SIMULIIDAE) FROM RIVER OSE, ONDO STATE, NIGERIA.

Abstract

A study of the cytotaxonomy of the larvae of blackfly was undertaken at three (3) sites, Imeri A, Imeri B, and Ose-oba, along River Ose in Ondo State, Nigeria. The collected larvae were fixed, sorted, and dissected. Their salivary glands were removed and stained with formic-lacto propanoic (FLP) orcein. Based on morphology of the larvae and the pupae, three (3) species were identified. These include; Simulium damnosum complex, S. alcocki, and a yet to be identified species (YI). Investigations on the polytene chromosomes from the salivary glands of each of these species revealed that the S. damnosum comprises of three cytospecies which were S. squamosum, S. damnosum s.s, and S. sirbanum. Meanwhile the S. alcocki was also found to be complex of sibling species but the YI remained as a single species. There was no difference between the distribution of S. damnosum complex and S. alcocki; however these two species were different from the yet to be identified species (YI) in occurrence. Significant difference between the population of male and female flies was observed among S. damnosum s.s and S. alcocki while their population showed no differences in the remaining species. The results of the present study which conform with earlier reports suggest that the study area (River-Ose) has been, and is still a good breeding site for S. damnosum and S. alcocki species of black flies. Efforts should therefore be directed at controlling these flies due to their medical, veterinary and economic importance.