author(s)
Armand Akpo, Luc Didolanvi, Dieudonné Kpoviessi, Armel Djènontin, Daniel Chougourou and Martin Akogbéto

abstract
The dynamism of the resistance of malaria vectors over time, in space and through the generation implies monitoring the susceptibility of available insecticides with respect to these vectors. This study aims to update the data on the susceptibility of An. gambiae to pyrethroids in the Cotonou city, a town endemic to malaria. Sensitivities tests for permethrin and deltamethrin were carried out at the CREC on stage 2, 3 and 4 larvae of the reference Kisumu, Kis-kdr and Wild strains according to the protocol recommended by WHO. The Kisumu strain served as a control. Mortalities were read 24 hours after exposure. Diagnostic doses were determined using the log-probit method of dose determination corresponding to proportion. The high doses are determined with larvae of the Wild and Kis-kdr strains. The weak ones refer to the reference Kisumu strain. However, the wild-type strain appears less sensitive than the Kis-kdr strain. The ratios determined are well above 2, for the larvae of the wild populations compared to the Kis-kdr strain, indicating the low sensitivity of the vectors to the pyrethroids tested, hence the limits of permethrin and deltamethrin in malaria control in areas of high resistance. Larvae of the wild strain An. gambiae appear to be less sensitive to permethrin and deltamethrin than to the laboratory strain Kis-kdr. These results show the involvement of other factors in the resistance of malaria vectors in Cotonou city which deserve to be elucidated.