Larvicidal activities of ethanolic extracts of Hyptis suaveolens Linn (Lamiaceae) and Azadirachta indica (Meliaceae) leaves and their phytochemical properties in malaria vector control in Dogbo district in South-western Benin, West Africa

Abstract

The use of chemical insecticides causes important damages to environment and human health and there is a need to search for alternative solutions. This study aims to investigate on phytochemical properties of Hyptis suaveolens Linn (Lamiaceae) and Azadirachta indica (Meliaceae) leaves and to evaluate their larvicidal activities in the malaria vector control in couffo department in south-western Republic of Benin. Larvae of Anopheles gambiae s.l mosquitoes were collected from breeding sites using the dipping method from April to July 2022 during the great rainy season in Dogbo district. A batch of twenty (20) larvae of fourth instar were exposed to ethanolic extracts of Hyptis suaveolens Linn and Azadirachta indica leaves with different concentrations of 1 mg/liter, 2mg/liter, 3 mg/liter, 4 mg/liter and 5 mg/liter in some glass jars or plastic test cups of same dimensions covered with small cutting untreated net and in some control jars containing no trace of these ethanolic extracts. Larval mortality was recorded after 24 hours, 48 hours and 72hours exposure. The results showed that the optimal concentration of ethanolic extract of Hyptis suaveolens Linn which kills 100% of Anopheles gambiae s.l. larvae was 4 mg/liter whereas the optimal concentration of ethanolic extract of Azadirachta indica which kills 100% of Anopheles gambiae s.l. larvae was 2 mg/liter. Hyptis suaveolens Linn and Azadirachta indica leaves possess some phytochemical properties with larvicidal activities on larvae of Anopheles gambiae sensu lato.