International Journal of Mosquito Research 2019; 6(1): 12-18 ISSN: 2348-5906 CODEN: IJMRK2 IJMR 2019; 6(1): 12-18 Current sensitivity status of Anopheles gambiae © 2019 IJMR Received: 05-11-2018 (s.l.) (Culicidae) to DDT and pyrethroids in two Accepted: 10-12-2018 agricultural sites of Mouila, Gabon Aubin Armel Koumba A. Research Institute in Tropical Ecology (IRET), P.O. Box: 13354, Libreville, Gabon Aubin Armel Koumba, Christophe Roland Zinga-Koumba, Rodrigue B. University of Abomey-Calavi (UAC), Mintsa Nguema, Pearl Comlan, Ghislaine Nkone Asseko, Abdou Razack 05 P.O. Box: 1604, Cotonou, Benin C. Regional Institute of Public Health Safiou, Marie-Pascale Gneingui, Guillaume Koffivi Ketoh, Luc Salako (IRSP), P.O. Box: 918, Ouidah, Benin Djogbenou and Jacques François Mavoungou Christophe Roland Zinga-Koumba Research Institute in Tropical Ecology (IRET), P.O. Box: 13354, Libreville, Abstract Gabon The present study was conducted during the rainy season of 2017 in Mboukou and Moutassou, two palm Rodrigue Mintsa Nguema oil concessions located in the suburbs of Mouila city. It aimed at determining the susceptibility status of Research Institute in Tropical Ecology Anopheles gambiae s.l. to organochlorines and pyrethroids. The larvae and pupae of An. gambiae s.l. (IRET), P.O. Box: 13354, Libreville, were collected from different breeding sites by the dipping method and reared to the adult stage in the Gabon field laboratory. The adult females were exposed to various insecticides: Organochlorine (DDT 4%) and Pearl Comlan Pyrethroids (Permethrin 0.75%, 3.75% and 7.75%; Deltamethrin 0.05%, 0.25% and 0.50%; University of Health Sciences of Lambdacyhalothrin 0.05%, 0.25% and 0.50%). The sensitivity of An. gambiae s.l. populations to Libreville (USS), P.O. Box: 4009, Libreville, Gabon insecticides was assessed following WHO protocol. All tested mosquitoes were identified by PCR method. An. gambiae s.s. and An. coluzzii were the only anopheline species identified in all the Ghislaine Nkone Asseko prospected sites. The results of the susceptibility tests revealed that the malaria vectors of the surveyed World Health Organization Country Office Gabon, P.O. Box: 820, Libreville, sites were susceptible or resistant to the tested insecticides depending on the type and the dose of Gabon insecticide. These Anopheles were resistant to DDT 4% and low doses of pyrethroids (Permethrin 0.75%, Deltamethrin 0.05%, Lambdacyhalothrin 0.05%). But they were sensitive to all pyrethroids at high doses Abdou Razack Safiou National Malaria Control Program (98 to 100% mortality). (PNLP), P.O. Box : 14426, Libreville, Gabon Keywords: sensitivity, Anopheles gambiae s.l., DDT, pyrethroids, mouila, gabon Marie-Pascale Gneingui National Malaria Control Program 1. Introduction (PNLP), P.O. Box : 14426, Libreville, Gabon For several decades, humanity has faced several dangerous diseases and one of them is malaria. Malaria is a parasitic disease caused by a protozoan parasites belonging to the genus Guillaume Koffivi Ketoh [1] Unit of Research in Ecotoxicology, Plasmodium and transmitted to humans via a bite of infected female anopheline mosquitoes . University of Lomé, P.O. Box: 1515, It occupies a significant position in terms of endemic diseases [2, 3] and remains the major cause Lomé 01, Togo [4] of morbidity and mortality in the world, particularly in Africa . In 2016, we estimated about Luc Salako Djogbenou 216 million, the number of people living with the disease worldwide, of which 90% of malaria A. University of Abomey-Calavi (UAC), [5] 05 P.O. Box: 1604, Cotonou, Benin cases and 92% of malaria deaths occurred in sub-Saharan Africa . Globally, this parasitosis B. Regional Institute of Public Health caused about 445, 000 deaths in 2016, and the most affected being children aged under 5 years (IRSP), P.O. Box: 918, Ouidah, Benin [6] and pregnant women . Jacques François Mavoungou Faced with this major public health problem, the countries concerned are developing strategic A. Research Institute in Tropical [7, 8] Ecology (IRET), P.O. Box: 13354, plans for the prevention and the control of vectors as well as in the management of patient . Libreville, Gabon The main entomological control methods against malaria transmission are the massive B. Institute of Technological Research distribution of long-lasting insecticidal nets (LLINs) and the indoor residual spraying (IRS). (IRT), P.O. Box: 9154, Libreville, Gabon However, the massive use of synthetic antimalarials (chloroquine, amodiaquine) and residual insecticides (DDT) after the Second World War led unfortunately to the development of [9] Correspondence antimalarial resistance and the rapid emergence of insecticide resistance . It is therefore Aubin Armel Koumba essential to know the efficacy of insecticides towards Anopheles malaria vector to better guide A. Research Institute in Tropical [10-12] Ecology (IRET), P.O. Box: 13354, malaria control strategies . Libreville, Gabon In Gabon, a tropical African country, malaria is hyperendemic and mainly caused by B. University of Abomey-Calavi (UAC), 05 P.O. Box: 1604, Cotonou, Benin Plasmodium falciparum and its major vectors consist of Anopheles gambiae s.l. and Anopheles C. Regional Institute of Public Health funestus s.l. [13]. This disease continues to be the main cause of morbidity and mortality in the (IRSP), P.O. Box: 918, Ouidah, Benin ~ 12 ~ International Journal of Mosquito Research country. According to the National Malaria Control Program, gambiae s.l. population were collected at their larval stage nearly 45% of children and 71% of pregnant women from natural (ponds) and artificial (water reservoirs, pits and consulted were hospitalized because of severe forms of tires) breeding sites present in 11 sampling stations, malaria [14, 15]. To effectively roll back malaria, Gabon distributed all over the study area. These stations were promote vector control based on the mass distribution of represented by Pk19, Moutassou camp (Estate 13, Estate impregnated bed nets and indoor residual insecticide spraying 13Bis, Estate 15), Moutambe Sane Foumou village, Doubou and the management of environment as main control camp, Mboukou village, Doubou village, Mavassa camp, strategies [16]. However, insecticide resistance of Anopheles Ngounié camp and Mboukou camp. Anopheline larvae and gambiae has been reported for a few years in Libreville and pupae were collected from breeding sites [21] using the dipping Port-Gentil by Pinto et al. (2006) [17] and Mourou et al. (2010) method [22], transferred to trays using pipettes and transported [14]. These resistance phenomena can seriously hinder control to the field laboratory for rearing [23]. These larvae were efforts. reared in water from the respective breeding sites and fed In Mouila, Koumba et al. (2018) [16] revealed that in the dry every second day with ornamental fish meal (Sera Vipagran) season, the populations of An. gambiae s.l. in the agricultural [24]. The adults obtained were fed using 10% sugar solution ad areas of this region were resistant to 4% DDT, 0.05% libitum. They were identified morphologically using the Deltamethrin and 0.75% Permethrin. Also, in order to know identification key of Baldacchino & Paupy (2010) [25] and the the sensitivity status of Anopheles gambiae s.l. to females were subjected to sensitivity tests. Organochlorines and Pyrethroids of various doses, a study was conducted in the agricultural sites of Mouila in the rainy 2.3 Adult sensitivity tests season. The aim of this study was to determine the The WHO sensitivity tests kits (WHO tubes and accessories) susceptibility status of An. gambiae sensu lato populations to and insecticide impregnated papers (DDT 4%, Permethrin one organochlorine and different pyrethroids in Mouila. 0.75%, 3.75% and 7.75%, Deltamethrin 0.05%, 0.25% and 0.50%, Lambdacyhalothrin 0.05%, 0.25% and 0.50%) were 2. Materials and Methods provided by WHO country office Gabon (Table 1). 2.1 Study area The present study was conducted in the rainy season of 2017 Table 1: Insecticides used for ssensitivity test in two agricultural sites, in the suburbs of Mouila city, notably Insecticide Tested Insecticide Mboukou and Moutassou. (Fig. 1). The Mboukou site family concentration (%) (1°39'06 "S and 10°49'42.6" E) is located in the Tsamba- Permethrin 0.75 – 3.75 – 7.75 Magotsi department about 35 kilometers from the town of Pyrethroids Deltamethrin 0.05 -0.25 – 0.50 Mouila. It is limited to the East by river Ngounié and Saint- Lambdacyhalothrin 0.05 – 0.25 – 0.50 Martin and Migabe villages and to the West by the Douya, Organochlorines DDT 4 Doubou, Mboukou and Rembo villages [18, 19]. The Moutassou site (1°59'33.8 "S and 11°02'25.2" E) is located in the Douya- Bioassays were carried out using WHO test kits for adult Onoye division about 13 kilometers from the town of Mouila mosquitoes and WHO procedures [26]. The insecticide [20]. It is limited to the north by the city of Mouila, to the East susceptibility tests were conducted using 2-4 days old, by the Moulandoufouala, Mbengui and Mbadi villages then to glucose-fed but non-blood-fed female Anopheles mosquitoes, the West by the Moutassou, Koumbanou, Ikolo-Ikolo and from larvae collected from the various breeding sites of the Digabosse villages. It is an ecosystem dominated by savannas, study sites. Each test on a batch of 25 mosquitoes was forests and forest-savanna mosaics occupying 75% of the replicated four times. They were exposed to impregnated exploitation permit [20]. papers with different insecticides for 60 minutes. Controls made up of wild mosquitoes were exposed to paper treated with olive oil only. The number of Knocked-down mosquitoes was first recorded every 5 minutes during the first 20 minutes of exposure and then every 10 minutes until 60 minutes of exposure. After 1 hour of exposure, the mosquitoes were transferred into WHO observation insecticide free tubes and maintained on sugar solution (10%). Mortality was recorded 24 hours post-exposure.