The resistance of malaria vectors to insecticides used in vector control is a major obstacle for national malaria control programs. It is in this context that an entomological study was conducted in urban, peri-urban and rural sites in the Oyem area (Northern Gabon). This study looks at species of the An. gambiae complex and the resistance mechanisms developed by Anopheles to escape to insecticides in Oyem, northern Gabon. To this end, Anopheles larvae were collected in the above-mentioned areas and reared to the adult stage in the field laboratory. Subsequently, the adult anopheles were subjected to sensitivity tests following the World Health Organization protocol. Seven insecticides (DDT 4%, Deltamethrin 0.05%, Permethrin 0.75%, Lambda-cyhalothrin 0.05%, Cyfluthrin 0.15%, Bendiocarb 0.1% and Malathion 5%) were used for these bioassays. The mosquitoes tested (live and dead) were analyzed using PCR to identify the species of the An. gambiae complex. The results obtained showed that the species Anopheles gambiae, the only species identified, has resistance to dichlorodiphenyltrichloroethane (DDT 4%) and Pyrethroids. However, this species is sensitive to Bendiocarb 0.1% and Malathion 5%. These statuses are confirmed by the presence of Kdr mutations (East and West) and the absence of the Ace-1R mutation in this vector.

In order to contribute to the knowledge of the culicidofauna of Loango national park, Gabon, an exploratory entomological survey was conducted in this area. Adult mosquitoes were captured in the vicinity of the Yatouga camp using CDC-light traps. These captures took place from February 20 to 27, 2020, from 5: 00 p.m. to 7: 00 a.m. and the captured mosquitoes were identified under binocular magnifying glass using morphological criteria. A total of 380 mosquitoes were collected. Morphological identifications of the captured specimens underlined the presence of 16 mosquito species especially Aedes circumluteolus (0.5%), Anopheles marshallii (15.5%), Anopheles obscurus (0.5%), Anopheles paludis (3.4%), Anopheles tenebrosus (0.5%), Coquilletidia aurites (0. 3%), Culex cinereus (1. 6%), Culex rubinotus (0. 5%), Culex decens (0. 5%), Ficalbia malfeyti (0. 5%), Mansonia africana (50. 5%), Uranotenia bilineata (1. 1%), Uranotenia cavernicola (13. 2%), Uranotenia caliginosa (0. 5%), Uranotenia mashonaensis (2. 1%), and Uranotenia nigromaculata (8. 7%). The genera Mansonia (50.5%), Uranotenia (25.6%) and Anopheles (20%) were the most abundant, while the genera Aedes, Coquilletidia, Ficalbia and Culex were very poorly represented with less than 3.9%. Most of the mosquitoes collected are known in other parts of Gabon and Africa for their vector role in the transmission of pathogens to humans and wildlife. There is an urgent need for a longitudinal study of the culicidofauna of this protected area, an habituation zone of ecotourism and great ape.