Operational use of neem oil as an alternative anopheline larvicide. Part A: laboratory and field efficacy

We conducted a study to determine the laboratory and field efficacy of neem oil towards anopheline larvae. No difference in LC50 was observed between laboratory and field strains for temephos, chlorpyriphos-methyl/fenitrothion and neem oil. No difference in susceptibility was found after 3 months of application every 2 weeks. Water treated with a single application of traditional larvicides was free of larvae after 4 weeks; neem oil-treated water, however, was free after 2 weeks but not at 4 weeks. Application of chlorpyriphos-methyl/fenitrothion and neem oil every 2 weeks for 7 rounds resulted in dramatic reduction in larval density with no statistically significant differences. An adult survey after larviciding also showed no significant difference. The efficacy of crude neem oil appears to be below that of conventional larvicides

Operational use of neem oil as an alternative anopheline larvicide. Part B: environmental impact and toxicological potential

This study was conducted to investigate the preliminary environmental and mammalian toxicology of neem oil, temephos and chlorpyriphos-methyl/fenitrothion. Culex pipiens, Daphnia magna and Gambusia affinis were used to study environmental impact. A high level of toxicity was observed, with slight differences between organisms. The emulsifiers individually also displayed toxicity towards the tested organisms. Up to 90 days daily oral crude neem oil treatment [5 g/kg body weight] of laboratory mice did not cause any significant changes in weekly body weight gain, nor in serum liver damage indicators, direct bilirubin or total bilirubin. Blood parameters of treated mice up to 90 days were not statistically different from those of control mice. Neem oil could be used as an environmentally friendly alternative to the traditional chemical anopheline larvicides