In vitro larvicidal activity of Manihot esculenta, and Croton hirtus leaf extracts against Aedes aegypti (Diptera: Culicidae) Larvae

Praveen Krishnakumar, Shanooba S, Koshy PM

Abstract: Repeated use of synthetic insecticides for mosquito control or prevention has disrupted natural biological control systems and lead to the development of 3R phenomenon, namely resurgence, replacement and resistance in mosquito populations. This made scientists to think about human and environment friendly alternative control measures. Control of insect pests and vectors using eco-friendly botanical agents is need of the hour. Plants are considered as a rich source of bioactive chemicals. Plant metabolites and plant based pesticides appear to be one of the better alternatives as they are known to have minimal environmental impact and danger to consumers in contrast to synthetic pesticides. In the present work, an attempt has been made to evaluate the effect of Manihot esculenta, and Croton hirtus leaf extracts against 3rd instar Aedes aegypti larvae. The effectiveness ranged from Croton hirtus acetone extracts > Croton hirtus water extract > Manihot esculenta acetone extract > Manihot esculenta water extract. Croton hirtus acetone extract was most effective. In 1mg/ml concentration, mean mortality of 97% was observed after 24h of treatment. Later this mortality increased to 100%. Moderate concentration 0.5mg/ml of Croton hirtus acetone extract showed 100% mortality after 48h. Manihot esculenta water extract was found least effective exhibiting lowest mean percent mortality. Highest concentration of water extract of M.esculenta leaves could only exhibit a maximum mean percent mortality of 51% after 72h.