Utilizing larvicidal and pupicidal efficacy of Eucalyptus and neem oil against Aedes mosquito: An approach for mosquito control

BACKGROUND AND OBJECTIVES: Plant-based products can provide safe and biodegradable mosquito control agents. The essential oils have a strong odor due to complex secondary metabolites and exhibit lower density than that of water, which renders them suitable to form a thin layer above the water surface. The present study was designed to evaluate the larvicidal, pupicidal activity of Eucalyptus and neem oils against Aedes aegypti and Aedes albopictus. MATERIALS AND METHODS: We evaluated the activity of commercially available Eucalyptus (Eucalyptus globulus) and neem (Azadirachta indica) oils against larvae and pupae of A. aegypti and A. albopictus for their larvicidal and pupicidal activity, stability in different water types, dependence on volume and surface area of the water body, and residual efficacy. RESULTS: Eucalyptus oil was found to be more effective against larvae and pupae at lower concentrations, i.e., concentration at which 50% is observed (LC50) for larvae and pupae was 93.3 and 144.5 parts per million (ppm) and concentration at which 90% is observed (LC90) was 707.9 and 741.3 ppm, respectively, while for neem oil, LC50 for larvae and pupae was 7852 and 19,054 ppm and LC90 was 10,092 and 19,952 ppm, respectively. The efficacy of Eucalyptus oil depended on surface area rather than volume of water, and the residual efficacy of Eucalyptus oil was up to 8 days. CONCLUSIONS: Eucalyptus oil was more effective against mosquito larvae at lower concentration as compared to neem oil. It can, therefore, be utilized in the community in artificial and small temporary water bodies as an eco-friendly vector control measure in the era of increasing resistance to chemical insecticides.