Bioefficacy of Nerium oleander Linnaeus (Apocynaceae) floral extracts on the larva of three vector mosquitoes of medical importance

摘要

Mosquitoes are the major vectors of many pathogens which cause diseases like dengue, chikungunya,yellow fever, Zika virus fever, filariasis, Japanese encephalitis and malaria. Vector mosquito control ormanagement is important in order to prevent mosquito-borne diseases as well as to improve publichealth. Repeated use of synthetic insecticides induces ecological imbalance, affects non-target organismsand poses severe health risk to humans. Plant extracts are believed to be a good alternative to chemicalinsecticides. In the present study, Nerium oleander flower (pink, red and white) extracts were evaluatedfor its bioefficacy on the larvae of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatusmosquitoes. The larvae of each species were exposed to different concentrations viz., 62.5, 125, 250, 500and 1000mg/L and larval mortality was assessed 24 hours after exposure and LC50 and LC90 values werecalculated. Amongst the different floral extracts tested, the acetone extract of Nerium oleander redflowers exhibited the highest larvicidal activity against all the three mosquito species and their LC50values were 94.60, 101.21 and 121.79mg/L against Anopheles stephensi, Culex quinquefasciatus andAedes aegypti respectively. Identifying plant based insecticides that are efficient as well as suitable andadaptive to local ecological conditions, biodegradable and having wide spread mosquito larvicidalchattels will work as a new weapon in the arsenal of insecticides and in the future may add to a suitablealternative tool to fight against mosquito-borne diseases.