In vivo Insecticidal Activity of Formulations Containing Essential Oils of Cymbopogon citratus Stapf and Eucalyptus globulus Labill

Background: National insecticide dipping program has been performed in Ethiopia for the last decade on sheep and goat to control ectoparasites. However, there is still high burden of ectoparasite in the country. On the other hand, the widespread use of chemical insecticides has significant drawbacks including increased cost, handling hazards, threat to human health and environment and insecticide resistance. These facts prompted the search for new alternative insecticides from plants for the control of ectoparasite. Objective: To determine insecticidal potency of essential oil formulations on sheep naturally infested by Melophagus ovinus (sheep ked). Method: A randomized block design studies were used on naturally ked infested sheep (n=6) as treatment and control (negative/Tween 80 and positive/diazinon) groups to evaluate insecticidal activity of two essential oils from Cymbopogancitratus and Eucalyptus globulus against Melophagus ovinus ectoparasite. Result: The essential oils showed promising insecticidal activity against sheep ked. C. citratus essential oil has higher antiparasitic activity than E. globulus essential oils. C. citratus oil showed 94.7%, 87%, and 90.2% parasite reduction of sheep ked parasite at a concentration of 0.6254%, 0.3125% and 0.1563%, respectively. The C. citratus essential oil has no differential (p>0.05) insecticidal activity compared to diazinon at a concentration of 0.6254% and 0.1563%.  Moderate antiparasitic activity was recorded in the groups of sheep treated by E. globulus essential oil. Conclusion: Essential oils from C. citratus and E. globulus are potential plant sources of insecticides that can substitute diazinon for the management of M. ovinus in sheep. It is recommended that essential oils from C. citratus and E. globulus can be potential bio-rational insecticides in eco-friendly control of ectoparasite in sheep.