A Search for Cheaper and Eco-Friendly Approaches to Reducing Mosquito Transmitted Diseases Using Smoke Extract of Fresh Shoot Systems of Cassia Obstusifolia, Hyptis Suaveolens and Striga Hermonthica

Plants have co-evolved with insects and are equipped with plethora of chemical defenses, which also tend be a powerful tools for reducing the burden of diseases caused by insects through vector control. In this research an ecofriendly approach to managing mosquitoes was studied. Fifteen (15) sucrose fed mosquitoes were subjected to repellence tests in a linear olfactometer. The stimuli were smoke extract from three plants, pyrethroid-based standard insecticide coil (Sasso mosquito coil) and fresh air as a negative control. Comparative repellence tests were also used to assess the repellent potency of the plants. The highest repellent potency due to Cassia obstusifolia, Hyptis suaveolens and Striga hermonthica were 38%, 85% and 65% respectively using equivalent volumes of smoke extract. Extracts of two of the plants were effectively repellent as the pyrethroid-based mosquito coil. In comparative tests, there were no significant differences (P>0.05) between the activity of smoke of both S. hermonthica and H. suaveolens compared to that of the pyrethroid-based coil. Extracts of Striga hermonthica maintained good repellence close to the synthetic coil for sixty minutes. Difference between the repellence of Cassia obstusifolia and Sasso was significant, indicating the lesser repellent potency of the plant sample. Major phytochemicals in fresh aerial parts of the three plants were; terpenes, alkaloids and phenolic compounds. Hyptis suaveolens and Striga hermonthica require toxicity studies and standardization to be recommended for management of mosquitoes in pro-poor settings.