Responses of two plant-derived bioinsecticides as protectants of smoke-dried catfish, Clarias gariepinus [Pisces: Clariidae] against hide beetle, Dermestes maculatus (De Geer) [Coleoptera: Dermestidae

Abstract

BackgroundToxicities of Vernonia amygdalina and Tithonia diversifolia leaf powders and extracts on larva and adult mortality of Dermestes maculatus on smoke-dried catfish were evaluated in the laboratory. The leaf powders were admixed at 1, 3, 6, 9 and 12 g/100 g of smoked catfish in 500 ml plastic container while plant extracts were tested at 1, 3, 6, 9 and 12% concentrations.ResultsThe toxicities of the plant products were concentrations and exposure time dependent. Significant difference (P < 0.05) existed between the toxicity of V. amygdalina and T. diversifolia leaf powders and control. Tithonia diversifolia powder evoked 27.5, 40, 52.7, 60 and 82.5% larval mortalities at the various concentrations after 24 h of exposure of the catfishes to the plant powder. Similarly, V. amygdalina leaf powders caused 20, 30, 42.5, 52.5 and 77.5% larval mortalities at varying concentrations of 24 h intervals of exposure to the plant powder. Tithonia diversifolia powder achieved 100% mortality at 9 g dosage after 96 h of treatment. Similar trend was achieved on the response of both plant leaf extracts as protectants of smoke-dried catfish against hide beetle.ConclusionTithonia diversifolia powder and extract were more lethal than bitter leaf (V. amygdalina) and could be integrated as smoked fish protectant against hide beetle (D. maculatus).