Evaluation of ethanolic extracts of Piper guineense, Dennettia tripetala, and Capsicum frutescens as protectant of smoked fish, Clarias gariepinus (Pisces: Clariidea) against Dermestes maculatus (Coleoptera: Dermestidae)

Abstract Background Dermestes maculatus is a destructive pest of smoked-dried fish. Due to its implications, this research was aimed at investigating the insecticidal activities of edible plant extracts on smoked Clarias gariepinus as protectants against Dermestes maculatus. Result The extract of Piper guineense at 4%, 8%, and 12% concentrations recorded between 8–92% and 33–100% mortalities, respectively, for the first 4 weeks and 0% mortality was observed in weeks 5–8. The extracts of Capsicum frutescens and Dennettia tripetala at 4% concentration recorded between 8 and 92% mortalities in the first 4 weeks and 5 weeks, respectively, and no mortality was recorded in the remaining weeks. At 12% concentration for Dennettia tripetala extract, 8–100% mortality was recorded throughout the experimental period. At 12% concentration for Capsicum frutescens, 8–92% mortality was recorded in weeks 1–7 and 0% in week 8. Positive control recorded 33–67% mortality in weeks 1–4 and 0% mortality in weeks 5–8. Negative control recorded no mortality in the first 3 weeks, but few larvae were found dead in the remaining weeks. The mean value of 106, 36, and 96 progenies emerged at 4%, 8%, and 12% concentrations, respectively, in the smoked fish treated with Piper guineense. Mean value of 0.50 and 0.50 progenies were recorded at 4% and 8% concentrations, respectively, while no emergence was observed at 12% concentration of Dennettia tripetala extract. Extract of Capsicum frutescens recorded mean value of 1.00, 3.00, and 3.50 progenies at 4%, 8%, and 12% concentrations, respectively. Weight loss of 66.47%, 31.46%, and 56.25% at 4%, 8%, and 12% concentrations was observed for Piper guineense extract respectively. Extracts of Dennettia tripetala and Capsicum frutescens recorded weight loss of 3.46%, 2.11%, and 0.02% and 27.77%, 12.30%, and 22.90%, respectively, at 4%, 8%, and 12% concentrations. Positive and negative controls recorded 4.36% and 81.18% weight loss, respectively. Conclusion They can therefore serve as affordable substitutes for synthetic chemicals which had been proven to be detrimental to the health of its consumers.