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

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\xa0g/100\xa0g of smoked catfish in 500\xa0ml 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 \u2009<\u20090.05) 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\xa0h 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\xa0h intervals of exposure to the plant powder. Tithonia diversifolia powder achieved 100% mortality at 9\xa0g dosage after 96\xa0h 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) .