The global burden caused by dengue is estimated to be around 10000 deaths and 100 million symptomatic infections a year. Among all the dengue cases across the world. Asia accounts for 75% of them followed by Latin America and Africa. Aedes albopictus, one of the important vectors in the transmission of dengue and chikungunya, is native to the temperate and tropical parts of Southeast Asia and India. It is referred to as the “Asian tiger mosquito’’. For growth, flight, eclosure, and stress recovery mosquitoes rely on their stored sugar trehalose. These reserves in mosquitoes are accessed by a key enzyme known as trehalose. By the action of trehalase, a single molecule of trehalose is broken down into two molecules of glucose which is vital for the flight and survival of mosquitoes. The main objective of the study is to find out the correlation between plant extracts and their action on mosquitoes’ stored sugar trehalose. Treatment of lab-grown 3^rd and 4^th instar larvae with various concentrations (100 ppm, 250 ppm, 500 ppm, and 1000 ppm) of different plants (Prosopis juliflora, Calotropis porcera, and Azadirachta indica) crude extract was obtained using both methanol and ethanol as solvent. The larvicidal bioassay was performed following the World Health Organisation (WHO) 2005 protocol and the larval mortality was observed at a different time periods (24,48, and 72 hrs). Lethal Concentration (LC) values were predicted using the log-probit analysis. Emerged adults from the larvicidal bioassay were homogenized for the analysis of their trehalose concentration using the modified anthrone-sulfuric acid method. The methanolic extract of Prosopis juliflora had an excellent larvicidal efficacy (LC₅₀- 123.46 ppm and LC₉₀ – 423.56 ppm) after 72 hrs as well as a massive 23-fold increase of trehalose over control was observed with a 1000 ppm treatment of the extract. Further, exploration by GC-MS revealed the active components present in the extract. One or many of the compounds in the extract are responsible for the excessive build-up of trehalose in these mosquitoes. Additional docking studies would point out the main chemical compound involved in the desired trehalose accumulation. Pure isolation and optimization of this chemical would be a revelation in the field of vector control and management.
Keywords: Aedes albopictus, Trehalose, Larvicidal bioassay, Anthrone-Sulfuric acid method, GC-MS