For better management of the use of insecticide in public health against Culex quinquefasciatus, an arboviral and filarial vector, a study was conducted at Natitingou, a town located in northern Benin, from October 2015 to March 2016, to evaluate the susceptible of this mosquito to insecticides and the mechanisms of resistance developed. The protocol was based on mosquito collection during both dry and rainy seasons across the four areas selected in northern Benin. Bioassays were performed on adult mosquitoes collected from the field to assess the susceptibility of filarial vectors to insecticide-impregnated papers (permethrin 0.75%, delthamethrin 0.05%, DDT 4%, and bendiocarb 0.1%) following WHOPES guidelines. Moreover, mosquitoes from the susceptible tests were used to search for the presence of the knock down resistance (Kdr) and the Acethylcholinesterase (Ace-1R) mutations. Finally, F1 generation of the wild population of Cx. quinquefasciatus were used for biochemical analysis to target Mixed Function Oxidase (MFO), non-specific esterase (NSE) and glutathione-S-transferases (GST) enzymes. This research showed: 1)- A wide spread of resistance to permethrin, delthamethrin and DDT was found in samples of Cx. quinquefasciatus despite the collection areas with 4%; 7% ; 19% and 60% as average of mortality respectively with DDT, permethrin, deltamethrin and bendiocarb; 2)- The kdr mutation was detected in all areas at various frequencies (0.8 to 0.88) whereas the Ace-1 mutation was found at a very low frequency (≤ 5%); 3)- Enzymes activities (oxidase, esterase and glutathion-S-transferases) were detected in all mosquito populations despite the areas of collection. This work has highlighted the high resistance of Cx. quinquefascitus to the 3 classes of insecticides used in public health. Moreover, the high frequency of kdr and the presence of enzyme activity in Cx. quinquefasciatus will augment the existing data on the insecticide resistance of filariasis vectors and will be useful for making decision to control this mosquito.

Background: Vegetable farming is developing fast in several cities in Benin. This study aims to assess the rapid expansion of this practice on the diversity of mosquito populations and malaria transmission in the Agbanto district, southern Benin. Methods: Firstly, socioeconomic data was collected by interviewing 100 vegetable farmers regarding the benefits obtained from the farming practices and possible disadvantages observed. Secondly, sampling of mosquitoes was conducted from June to December 2015 by Human Landing Catches (HLC) method in households at peri-urban areas close to the vegetable farms and in rural areas where there is no vegetable farming in order to investigate the differences in mosquito species and identify which of the species were responsible of malaria transmission. Finally, Enzyme-linked immunosorbent assay (ELISA), using monoclonal antibodies targeting the circumsporozoite protein (CSP), was used to estimate entomological parameters relative to malaria transmission. Results: This research showed that: 1)- The rapid development of urban agriculture is related to unemployment observed in cities, rural exodus and the search for a balanced diet by urban populations. This activity increases the farmers' household income and their living standard; 2)- During the six months sampling period, 24,449 mosquitoes were collected by HLC method, of which 26% (6,357/24,449) were Anopheles species. In the areas surveyed, the main malaria parasite, Plasmodium falciparum was transmitted by Anopheles gambiae s.s. Transmission was high during the two rainy seasons (June to July and October to November), but declined in the dry season (August to September); 3)- The Entomological Inoculation Rates (EIRs) and the Human Biting Rates (HBRs) were significantly higher (p < 0.05) during the dry season in the households from the peri-urban areas close to the vegetable farms than in the households from the rural areas where there is no vegetable farming. However, there was no significant difference (p > 0.05) in HBRs and EIRs between the two areas during the rainy seasons; Conclusion: This study showed the impact of vegetable farming activity in malaria transmission in the Agbanto district of southern Benin. Despite the advantages brought by this activity to urban populations, measure must be taken to decentralise this agriculture to rural cities.