Vol. 3, Issue 2, Part A (2021)

Insecticidal effects of methanol, acetone and hexane extracts from dried leaves of Azadirachta indica have been assessed on stage 4 larvae of Anopheles gambiae s.s Giles, 1902 at the laboratory of Zoology of the University of Ngaoundere. Biological tests carried out according to the WHO protocol revealed that the extracts obtained from the various organic solvents have larvicidal activities. The acetone extract was the most effective. The LC₅₀ values were 51.34 ppm, 56.54 ppm and 65.37 ppm for acetone, methanol and hexane extract respectively. The LH₅₀ values were 4 h 06 min 36 sec, 3h 34 min 59 sec and 4 h 29 min 34 sec respectively for the three extracts. Phytochemical screening revealed the presence of terpenoids, sterols, saponins, flavonoids, and tannins; secondary metabolites responsible for the insecticidal activity. Each of these extracts showed low toxicity compared to Temephos (positive control) at the WHO Recommended concentration of 0,012 mg/L.