Evaluation of Ziziphora tenuior Essential Oil Repellency Effect Against Blood Feeding of Anopheles maculipennis in Zanjan District

Background and Objective: Anopheles maculipennis is one of the most important species of mosquito that can cause serious public health problems worldwide and applying insecticides and synthetic repellents are the current methods used for its control. The continuous application of these chemicals increases the probability of resistance, reduces insecticide efficiency and causes environmental problems. Therefore, introducing alternative substances (especially natural repellents) to control programs is necessary. The aim of this study was to compare the repellency effect of Ziziphoratenuior essential oil (EO) with DEET. Materials and Methods: Ziziphoratenuior was collected from Zanjan and its EO was extracted from dried leaves via a hydro-distillation process. The chief components of the essential oil were identified through the GC-mass method and serial dilutions of the essential oil and DEET were prepared. Adult An. Maculipennis’ were collected and kept in a laboratory. Contact bioassays were conducted by 9 volunteers, through a single-blind study where their arms were impregnated with repellent solutions. Non-blood fed female mosquitoes were exposed to different doses of repellents. The effective doses of 50% (ED50) and 90% (ED90) and duration of repellency were determined for each repellent. Results: Thymol, geraniol and carvacrol are the chief components of Ziziphora EO and form 36.2%, 11.16% and 4.9% of it, respectively. The ED50 and ED90 for this EO against An. Maculipennis were 1.7 and 3.67 mg/cm2, respectively. A 30% Ziziphorasolution prevented biting for 240 minutes. The response of An. Maculipennis to Ziziphora EO in high doses was similar to that of DEET, however, this response differed in doses lower than 1 mg/cm2. Conclusion: Ziziphora essential oil 30% solution has similar repellency effect to DEET and can prevent biting of An. Maculipennis for 240 minutes. Synergists could be added to increase its effectiveness and electrophysiologic studies could determine the mechanism of action of thymol and carvacrol at molecular levels.