Bio-insecticidal Potential of Lemongrass (Cymbopogon citratus) Essential Oils on Smoke-dry Fish Against Weevils within Storage

Abstract

This study aims to test the insecticidal effect of two Lemongrass Essential oils (EOs) on two weevils attacking smoke-dry fish within the storage. Fasting capacity, larvicidal and adulticidal properties of EOs on weevils, and the sensorial analysis of fish within storage will be assessed. smoke-dry Clarias gariepinus were purchased from the smoker and carried to the laboratory for the study. weevils and EOs were from the Soil Microbiology Laboratory of the University of Yaoundé I. Two species of weevil, and two EOs at three concentrations were used. Fasting capacity was evaluated by exposure of larvae to Eos. Larvicidal and insecticidal capacity was evaluated by exposure of larvae and insect to Eos against control treatment. Emerged insects were count for each treatment after the test. Sensorial property was tested using a panel who scored attributes. The results show that both insects fasted for up to 4 days without death. By contact or fumigation, significant kills of weevil larvae were record in the presence of EOs depending on the exposure time and concentration, with a better efficiency at 5%. Mycorrhizal plant EO causes 83% of death by contact on both insects than none mycorrhizal plant EO causing 75 and 65% of death respectively for Necrobia rufipes (N. rufipes) and Dermestes. Maculatus (D. maculatus). Adulcidal test within 42 days shows a significantly greater efficiency of mycorrhizal plant EO accounting for 97% and 92.5% respectively for N. rufipes and D. maculatus than none mycorrhizal plant EO accounting for 92.5% and 87.5% respectively for N. rufipes and D. maculatus. EOs have better lavicidal and insecticidal capacity than control treatments (p < 0.05). After 42 days, a significantly less emergence rate of larvae was recorded with mycorrhizal plant EO than none mycorrhizal plant EO (p < 0.05). sensorial properties of stored fish were significantly good under EOs treatment and bad under control treatments (p < 0.05). AM fungi inoculation impact plant metabolism with the accumulation of metabolites geraniol, neral, isoneral and isogeranial which may be responsible for the better biological activities record in this study.