FORMULATION AND EVALUATION OF OVIPOSITION DETERRENT ACTIVITY OF TABERNAEMONTANA DIVARICATA LEAF EXTRACT-BASED MOSQUITO REPELLENT SPRAY

Mosquitoes, especially Aedes aegypti, are major vectors of dengue, chikungunya, malaria, and Zika virus, contributing to global morbidity and mortality. Conventional repellents such as DEET and pyrethroids, although effective, are associated with toxicity, insecticide resistance, and environmental concerns. Thus, natural plant-based repellents represent a promising alternative. This study aimed to formulate a mosquito repellent spray using ethanolic leaf extract of Tabernaemontana divaricata (Crepe Jasmine) and to evaluate its oviposition deterrent activity against Aedes aegypti. Leaves of T. divaricata were shade-dried, powdered, and subjected to ethanolic extraction. Phytochemical screening confirmed the presence of alkaloids, flavonoids, tannins, steroids, glycosides, and amino acids. A solvent-based spray formulation was prepared and evaluated for stability and safety (flammability, combustibility, leakage tests). Oviposition deterrent activity was assessed by cage experiments and egg count assays under controlled laboratory conditions. The Oviposition Activity Index (OAI) and Effective Repellency (ER %) were calculated.The phytochemical analysis confirmed bioactive constituents responsible for repellent properties. In egg count assays, repellency increased with concentration: 14.08% at 100 ppm, 25.12% at 200 ppm, and 48.48% at 400 ppm. Corresponding OAI values (−0.07 to −0.31) indicated significant oviposition deterrent activity. Spray formulations were safe, stable, and effective in disrupting the oviposition stage of the mosquito life cycle.Ethanolic leaf extract of Tabernaemontana divaricata demonstrated strong oviposition deterrent activity and can be successfully formulated into a stable mosquito repellent spray. By interrupting egg-laying, the formulation provides an eco-friendly and biodegradable alternative to synthetic repellents, offering potential pharmaceutical application in vector control and public health.