Executive Summary : | Mosquitoes, in particular Aedes aegypti impose a serious global threat to human health as they act as vectors for the transmission of several deadly diseases namely dengue, chikungunya, yellow fever and Zika. Among all the vector-borne diseases, dengue is the fastest spreading disease (50-100 million infections every year worldwide and 1,36,422 dengue cases in 2019 and 14,044 cases recently in 2021 have been reported in India) for which so far neither a specific drug nor a vaccine is available for public use. Ae. aegypti is a day biter and primarily anthropophilic with preference for its breeding in small temporary water collections lying in urban and periurban areas. Current approaches to control Aedes rely generally on larvicding breeding habitats with synthetic larvicides like temephos. Such synthetic larvicides are effective in certain conditions only, but their application is beset with several technical, operational and administrative constraints. This scenario presses upon an urgent need for the development of ecofriendly and bio-effective larvicides with little impact to humans, other living non-target organisms and the environment. One of the promising ways is using non-chemical, safer, biodegradable and natural larvicides that are of botanical origin. In the recent years, plant based essential oils (EOs) are under much considerable attention as potential larvicides because they contain various bioactive secondary metabolites. Oils extracted from various plants like neem, eucalyptus, lemon, citronella, cinnamon, pine etc. show larvicidal characteristics, but very high concentration is required for these EOs to act as a potent larvicide. By making combined formulations of different EOs, larvicidal effectiveness can be enhanced, resulting in reduction of EO concentration, along with preventing the emergence of resistance. Although, the potential of many EOs have been studied as larvicidal agents against mosquitoes, but no such formulation based on EOs having no toxic effects to humans and environment is commercially available so far. Another, important feature regarding EOs is their short life due to their high volatility which reduces their bioavailability and efficacy in the larval breeding sites. To increase the sustainability of EOs in aquatic habitats, the technique of encapsulation using microcapsules (MCs) has been introduced as a delivery vehicle. For the production of MCs several protocols along with several carrier materials have been tried. Recently a new approach using yeast (Saccharomyces cerevisiae) for encapsulation of EOs has engrossed our scientific thoughts with logical approach that yeast (having EO inside) will be taken by mosquito larvae being their food and thus may result in their effective killing. So keeping this logical scientific idea in mind, the present study has been planned to prepare and test the larvicidal efficacy of essential oil based yeast microcapsules for the control of Ae. aegypti. |