LYOPHILISATEOF PHYTOPLANKTONSCENEDESMUS QUADRICAUDAFOR MALARIA VECTORSANOPHELES GAMBIAE LARVAE CONTROL IN BENIN: PRELIMINARY STUDY UNDER LABORATORY

For malaria control, the phytoplankton Scenedesmus quadricaudause is an alternative because it has a deleterious effect on vector larvae. This phytoplankton species can be used in several forms (live or formulated). The aim of this study was to assess the effect of Scenedesmus quadricaudalyophilisate on Anopheles gambiae mosquito larvae in the laboratory.Large-scale culture trials of phytoplankton of Scenedesmus quadricaudawas carried out in a semi-controlled environment. The phytoplankton cells obtained were harvested by centrifugation at 1,500 rpm for 15 min. The biomass obtained was lyophilised and its deleterious effect on stage 3 larvae of Anopheles gambiae was evaluated. For this assessment, 25 larvae were exposed to different concentrations 10 mg/l, 20 mg/l, 50 mg/l, 100 mg/l, 150 mg/l, 200 mg/l, 250 mg/l and 300 mg/l) of lyophilisate. The results showed that after two months of culture, the number of Scenedesmus quadricauda cells increased from 5,000 cells/ml to 14250000 cells/ml. The mortality rate of the larvae 10 days after exposure to the lyophilisate was 100% with concentrations 20 mg/l, 50 mg/l and 100 mg/l. With concentrations 10 mg/l, 150 mg/l, 200 mg/l, 250 mg/l and 300 mg/l, mortality rates were 88%, 98.4%, 86.4%, 84% and 67.2% respectively 11 days after exposure. The present study showed that Scenedesmus quadricauda lyophilisate could be integrated in control vector tool.