Effects of selected phytochemicals as protectants of smoked catfish, Clarias gariepinus against Hide Beetle, Dermestes maculatus

Abstract

This study investigated the mortality and phytochemical constituents of Lemon, Pepper fruit, Black Pepper and African Nutmeg on smoked catfish infested with Hide Beetles. Disinfested dried catfish were thoroughly rubbed with the powder of the plants at 5.0 g, 7.5 g and 10.0 g per 100 g of dried fish; newly emerged adult Beetles were introduced and kept in separate muslin covered transparent containers. Each experimental set-up was in triplicate and carried out at ambient temperature of 28 °C and 32 °C, and 65-70% observed humidity. Adult mortalities and weights of the fish were monitored and recorded for 4 weeks. 0.5ml of ethyl acetate was introduced to 0.2 g of plant powders using micropipette in order to extract oil and left for 48 hours for total extraction. Phytochemical analyses were carried out on the extracted oil using Gas Chromatography/Mass Spectrometry. Nutmeg, Pepper fruit and Black Pepper powders caused significantly higher mortalities in both adults and larvae of the beetle at all concentrations than Lemon powder. The studies revealed the possible bioactive ingredients in the selected botanicals and showed that the plant products can be used as insecticides to effective protection against the insect pest of smoked fish during storage.