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

Abstract Background Toxicities 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. Results The 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. Conclusion Tithonia 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).