Etude comparative de deux produits de neem (huile et poudre) sur les stades préimaginaux du moustique Culex quinquefasciatus(Diptera : Culicidae)

Comparative study of two neem products (oil and powder) on preimaginal stages of  Culex quinquefasciatus mosquito (Diptera: Culicidae)Neem (Azadirachta indica) products (neem oil formulated 1 % and neem powder 0.3 %), manufactured by a Senegalese industry (SENCHIM), were applied to mosquito (Culex quinquefasciatus) larvae and nymphs. The doses products were from 0.02 to 0.038 %  (neem oil) and 0.2 to 2 % (powder). In laboratory conditions, results showed that neem powder was more toxic at larval stage (mortalities between 86.1 and 100 %) than nymphal stage (between 14.5 and 95.9 % adults flow away). Neem oil formulated was effective as well as larval stage (mortality between 52.1 and 80 %) than nymphal stage (between 0 and 14 % adults flown away). The histopathological study  reveals that neem products act upon larval digestive system after ingestion, whereas for nymphs only contact effects are showed. Neem oil formulated 1 % appears more effective than neem powder 0.3 % for mosquitoes control in aquatic environment

Toxic effects of neem products (Azadirachta indica A. Juss) on Aedes aegypti Linnaeus 1762 larvae

Treatment and comparative analysis of the properties of aqueous extracts of seed kernel of Azadirachta indica A. Juss (neem) was carried out on Aedes aegypti larvae. The aim of this work was to evaluate lethal effects of neem products (1% Suneem, formulated neem oil and neem powder) on A. aegypti larvae. Assays showed that A. indica was toxic to larvae of A. aegypti. For 1% Suneem, 1% formulatedneem oil and neem powder, the lethal concentrations and lethal time at 50% (LC50 and LT50) for A. aegypti were 2 and 8 mg/l after 24 h and 3 mg/l after 120 h, respectively. Assays showed that Suneemand Formulated neem oil were more toxic to A. aegypti than Neem powder. Both products of the neem (A. indica, A. juss) have a remarkable influence on the development of A. aegypti larvae, causing an inhibition of nymphs and adults emergency. The Histopathological results revealed a serious damage on the epithelial columnar cells, a perturbation of alimentary flow, slightly hypertrophied cells, abeginning of vacuolisation on apical level, and a bursting of some cells in posterior part of the gut. However, nuclei, adipose tissue and muscles seem to keep normal appearance