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-speci?c 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: Aedes aegypti is present year round in several cities of the Republic of Benin. This study aims to assess the seasonal distribution of this mosquito at Dandji, in southern Benin.
Method: A cross seasonal entomological study on larvae and adults of Ae. aegypti was carried out from May 2013 to April 2014 in southern Benin (Dandji). The study was based on sampling Ae. aegypti immature stages (larvae/pupae) from domestic, peri-domestic and natural water sources and were reared to adults. The collections were made during the dry and rainy seasons. Addional Ae. aegypti were collected by Human Landing Catches (HLC), Indoor Pyrethrum Spray Catches (PSC), Biogents (BG) sentinel trap and Gravid traps (GT).
Results: During the year of study, a total number of 18,658 mosquitoes were collected where 15,204 were collected by HLC; 303 with BG trap, 3,038 with PSC, 48 with the GT. Among the 18, 593 of Ae. aegypti collected, the female populations (13,834) was significantly higher than the male populations (p<0.05). From the 13,834 females, 1,380 were blood-fed.
Adult's collection was high during the two rainy seasons (June to July and October to November) but declined in the two dry seasons (December to March and August to September).
At Dandji, the average of Human Biting Rates (HBR) obtained during the rainy seasons (79.6 bites/p/n) was significantly higher than those obtained during the dry seasons (58.62 bites/p/n) (p < 0.05).
Conclusion: These findings showed the presence of Aedes aegypti year round at Dandji in southern Benin. This presence is strengthening with the trade of second hand tires which are good breeding sites for the development of Ae. aegypti. Data on blood feeding patterns of Ae. aegypti collected during this study will certainly provide valuable information about potential Dengue virus (DENV) hosts others than humans and will help to get a greater understanding about DENV ecology in Benin. It is therefore crucial for health authorities of Benin to develop a program to fight against this mosquito in order to avoid an outbreak of DENV as it was the case in many sub Saharan Africa countries recently.