Isolation and Characterization of Eugenia Aromatica Oil Extract Against Tropical Warehouse Moth Ephestia cautella (Lepidoptera: Pyralidae) In Cocoa Beans

Abstract

Akinneye JO, Akinyemi MI, Akinwotu SS and Owoeye JA

Cocoa bean is a raw material used for the production of chocolate and other confectionaries. Ephestia cautella is the major pest of dried cocoa beans in storage and synthetic insecticide like organochlorides and organophosphates are the major insecticides used to control this pest in storage which further post health hazard to man and his environment. This then necessitate the search for insecticide of plant origins which are bio-degradable and non-toxic to man. This study investigates the contact and fumigant efficacy of the powder and oil extract of Eugenia aromatica on the developmental stages of E. cautella. Powders of E. aromatica were administered at different concentrations (0.5g, 1.0g, 1.5g, 2.0g, and 2.5g). The oil from E.aromatica was extracted with ethanol using soxhlet extractor and redistilled using rotary evaporator and tested as fumigant insecticidal against development stages of E. cautellaat 0.5ml, 1.0ml, 1.5ml, 2.0ml, and 2.5ml. Egg hatchability, adult emergence, larvae and adult mortality of E.cautella were used as indices of insecticidal activities at 24hrs, 48hrs, 72hrs, and 96hrs post-treatment. Essential oil obtained from the plant was purified using thin layer chromatography and analysed by Gas Chromatography -Mass Spectrometer (GC-MS). Result obtained shown that E. aromatica powder and oil completely inhibited egg hatchability and adult emergence both as contact and fumigant. Except the 0.5g of E. aromatica powder that recorded 50.00% larva mortality and 51.67% adult mortality, other treatment concentrations recorded 90-100% larva and adult mortality. At 2.5ml oil extract tested as contact and fumigant larvicides after 96hrs recorded 92.98% and 98.23% mortality respectively. Results from phytochemical analysis of the oil showed that the major components were eugenol (82.044%) and Caryophyllene (11.716%). These findings suggested that E aromatica extract could be a potential source of insecticide which may be used for the production of biopesticide.

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