Efficacy of Glycosmis pentaphylla (Retz.) DC. Leaf Extract for Controlling Aedes aegypti (L.) larvae

Abstract

     Although, the use of synthetic chemical insecticides to control mosquito vectors has short-term effectiveness, the chemical resistance in many target insects can be developed and environment can also be contaminated. Natural phytochemicals isolated from herbal plants applied as insecticides to control those vectors are considered as good alternatives. In this study, hexane and ethanolic leave extracts of Glycosmis pentaphylla were estimated for their toxicity of 3^rd-4^th instar larvae of Aedes aegypti. Percentage larval mortality was evaluated after 24, 36, 48 and 72 h exposure at different concentrations (0, 1,250, 2,500, 5,000 and 10,000 mg/L). It was found that G. pentaphylla leaf hexane extract exhibited median lethal concentrations to kill 50% (LC₅₀) of the treated larvae in 24, 36, 48 and 72 h of 3,242.13, 1,920.62, 1,329.07 and 1,251.32 mg/L, respectively. Meanwhile, G. pentaphylla leaf ethanolic extract displayed LC₅₀ of the treated larvae in 24, 36, 48 and 72 h of 2,493.59, 1,204.88, 1,534.69 and 1,099.50 mg/L, respectively. With regard to the mortality rate, the concentration at 10,000 mg/L of G. pentaphylla leave extracts in both solvents showed high effectiveness in killing Ae. aegypti larvae with 100% mortality after exposure for 24 h. No mortality of the insects was observed in any of the controls. The mortality increased when exposed to a higher concentration in all trials. Further, the results of the independent t-test demonstrated no significant difference in the mean total mortality of Ae. aegypti between the hexane and ethanolic extracts in all times of exposure (P ≥ 0.05). From these results, both extracts trended to be further utilized in preventing this Ae. aegypti larvae and other arthropods of medical and veterinary importance in the area.