Acute ecotoxicity of aqueous and ethanolic extract of leaves of Khaya senegalensis on chironomid larvae

John Ameh Adakole, J. B. Balogun

Resumo


Protection of aquatic habitat requires an understanding of both the sensitivity of invertebrates to contaminants and their ecological requirements. Phyto-chemical screening of the leaves of extract of Khaya senegalensis revealed the presence of active constituents. Acute ecotoxicities of aqueous and ethanolic extracts of leaves of Khaya senegalensis to Chironomid larvae were evaluated by static bioassay. Bioactivity of the ethanolic extract was found to be greater than the aqueous extract. The LC50 of aqueous and ethanolic extracts were 1.39g/l and 1.20g/l respectively. Stressful behaviors exhibited by the chironomids include deformity of mouthparts, certain body segments being filled with black particles and change in body coloration. All behaviors were dose-dependent. The larvae were not repelled by the extract, indicating that antifeedant activity was not a mortality factor. Mortality was probably due to the disappearance of the reddish coloration of the hemoglobin component and consequently impaired metabolism of the larvae. The results were discussed and compared with those of other studies.

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DOI: http://dx.doi.org/10.14210/bjast.v15n2.p41-45

(eISSN: 1983-9057, ISSN: 1808-7035)