Abstract

Contact activities of Piper guineense (Schum and Thonn) and Eugenia aromaticum (L). (Merril and Perryl) extracts in the control of Dermestes maculatus larvae infesting stored fish (Clarias gariepinus) were investigated under laboratory condition (28±3°C and 65±5% RH). The extracts were tested by application of 2.0 µL each to ten third instars larvae using micro pipette at a concentration of 6.00, 10.00 and 20.00% each of the plant extracts (methanol, n-hexane and ethyl acetate). Mortality was recorded at 1, 2, 3 and 7 days of post treatments. The observed mortality was dose and exposure-dependent. All the extracts significantly enhanced larval mortality (P>0.05) when compared with the control. The n-hexane and ethyl-acetate extracts of P. guineense at 20% concentration induced the highest mortality of 86.66%, lowest mortality of 56.66% was observed on methanol fraction treated larvae after 7 days of post treatments. The n-haxane of E. aromaticum extracts recorded highest mortality (80.0%), followed by ethyl-acetate (76.66%) and methanolic (7.00%) fractions treated larvae at 20% concentration after 7 days of post-treatments. The results showed strong insecticidal activity in control of larvae of hide beetles infesting dried fish.

Key words: Plant extracts, Piper guineense, Eugenia aromaticum, Dermestes maculatus.