Bioefficacy of plant essential oils for the ovicidal, larvicidal and pupicidal activities against the Dengue vector Ae. aegypti
Asma Mirza and Amtuz Zehra
The present study was conducted to investigate the bioefficacy of three commercially obtained plant essential oils viz. Neem, Eucalyptus and Clove for the control of the medically important dengue vector Ae.aegypti. A standard solution was used to make 50 ml solutions ranging from 50 to 1000 ppm. Twenty five eggs as a batch were added to each essential oil solution and a mortality count was conducted 48hrs post treatment. Essential oils LC50 and their confidence limits at 95% probability were calculated according to the methods of Reed-Muench and Pizzi, respectively to assess the toxicity levels.Maximum bioefficacy was observed in Neem and Clove oil, probably due to the action of minor compounds present in the plant oils. A 1000ppm concentration of all the oils was found to be 80-95% larvicidal. Overall, the three oils achieved over 80% larval and pupal mortality within 48hrs of treatment and there was no significant difference in lethal doses. Also, none of the oils were effective at 5% or 10% concentration at all developmental stages. The study highlighted that the ideal method of controlling mosquitoes is by targeting them at the stage at which they are vulnerable i.e., the oval/larval or pupal stage.