Entomocide effect of Alstonia boonei De wild on reproductive performance of Dermestes maculatus (Coleoptera: Dermestidae) infestation on smoked catfish Claria gariepinus (Pisces: Clariidea)

Abstract

Efficacy of Alstonia boonei powders and extracts against Dermestes maculatus (Coleoptera: Dermestidae) infesting stored smoked dried catfish (Claria gariepinus) were investigated in the laboratory. The products were tested at 2.5 g, 5.0 g, 7.5 g, 10 g, 12.5 g and 15 g and 1%, 2%, 5%, 10%, 15% and 20%/100 g of smoked catfish respectively. The ability of the plant to protect smoked catfish in terms of mortality rates, number of eggs laid and adult emergence were evaluated. All the tested plant parts caused significant mortality (P < 0.05) of adult D. maculatus. Alstonia boonei stem bark powder was the most potent, causing 100% mortality at 7.5 g of 8 days post exposure, followed by leaf powder which evoked 87.5% mortality after 10 days of exposure. For the extracts, adult mortality of D. maculatus was positively correlated with dose and exposure duration. Alstonia boonei product extracts significantly reduced the development of D. maculatus compared to the control. Stem bark extract significantly prevented oviposition. The use of A. boonei stem bark is advocated for the control of D. maculatus infestation. Further study is needed to characterize the chemical constituents and understand its mode of action with the likely formulation into herbal insecticide as alternative to synthetic insecticides.