EFFET INSECTICIDE ET ANTICHOLINESTERASE DE L’EXTRAIT AQUEUX FOLIAIRE DE L’ORTIE Urtica dioica L. (Urticaceae) SUR LES LARVES L4 DU Culex pipiens L. (Diptera, Culicidae)

Abstract

This study focuses on the toxicity of the aqueous leaves extract of Nettle Urtica dioica, collected from El-Golea in the septorienal Algerian Sahara, on Culex pipiens L. larvae L4. The study shows that the percentage of cumulative mortality is proportional to the applied dose; the extract at dilutions 100%, 80%, 60%, 40% and 20% caused 100% larval mortality after 9h, 11h, 12h, 48h and 72h, respectively. The estimated lethal times 50 (LT50) are 1min 8', 35min, 1h65 min, 9h79 min and 21h60 min recorded in larvae treated with 100%, 80%, 60%, 40% and 20% doses respectively. The estimated lethal dose 50 (LD50) was 0,0446 mg/ml. The treatment of Culex pipiens larvae L4 with increasing doses of Urtica dioica extract significantly decreased cholinesterase activity. The most noticeable inhibition is that of 100% dilution which decreased the activity to 2,89 ± 0,48 nano-mol/ml/min. The study of the biological effect of the aqueous leaf extract of Nettle provides interesting insecticidal and anticholinesterase properties to nettle against Culex pipiens larvae.