Larvicidal activities of Biostop Moustiques®, a botanical insecticide on field collected malaria mosquito Anopheles gambiae sensu lato in Togo

The larvicidal activity of a botanical insecticide, Biostop Moustiques® (BM), was studied on field collected larvae of Anopheles gambiae s.l at the  concentrations of 1, 5, 10 and 20 mL/L of water. The samples were made based on three different localities of Togo: Lomé, Kovié and Kolokopé. BM had high mortality rates at 20 mL/L in all instars larvae. Specifically,  significant high mortality rates were recorded in L3 and L4 from field collected strain at a very low concentration (1 mL/L), compared to laboratory strain. In general, this study showed that the botanical insecticide tested has almost the same larvicidal effect no matter the strains of Anopheles gambiae used.Keywords: Biostop Moustiques®, Larvicidal activity, Anopheles gambiae, Togo

Vegetable production in Togo and potential impact of pesticide use practices on the environment

In West Africa, market gardening is considered one of the sectors in agriculture that consumes lots of pesticides. In order to study (i) the principal protection practices of vegetables and (ii) the inherent environmental risks to pesticide use practices, a survey was carried in Togo from 2010 to 2011. A random selection of 161 farmers were interviewed on their farms, which are distributed over the most important vegetable production sites located in dry Savanna, forests and littoral zones of Togo. The results showed that 88% of farmers interviewed responded that, insects are the most important vegetable pests in Togo. Crop protection  practices are primarily based on excessive use of synthetic pesticides which in most cases include organophosphates (27.3%) and pyrethroids (18.2%), known to be dangerous to human health and environment. Despite the excessive use of pesticides, farmers revealed that insect pests continue to cause serious damages, which is an indication that they have developed a resistance to pesticides. Moreover, about 80% of farmers did not have adequate materials for handling and  application of pesticides and are thus exposed to pesticide poisoning. An integrated pest management programme based on crop rotation, biological control and biopesticides is discussed.Keywords: Farmers, market gardening, crop protection, pests’ resistance

Susceptibility to DDT and pyrethroids, and detection of knockdown resistance mutation in Anopheles gambiae sensu lato in Southern Togo

Insecticides play an important role in malaria control programmes especially in Sub-Saharan Africa. However, the development of resistance by vectors to most commonly used public health insecticides has become a very crucial problem. DDT (Dichlorodiphenyltrichloroethane) was used worldwide to control malaria vectors and pyrethroids have been used in many vector control projects due to their known efficiency and lower toxicity to humans and non-target organisms. In West Africa, resistance to pyrethroid in the major malaria vector, Anopheles gambiae, had been reported in several countries. The last publication on this phenomenon in Togo was done in Togo in 2005. An update on the susceptibility of the malaria vector and characterization of its resistance mechanism becomes therefore crucial. Newly emerged female mosquitoes of two to five days old were selected and exposed to DDT 4%, Permethrin 1% and Deltamethrin 0.05%, the WHO diagnostic doses. These adult mosquitoes were from larvae of Anopheles gambiae sensu lato collected from rural and urban settings and reared in an insectary. A susceptible laboratory strain of An. gambiae sensu stricto was used as reference. Species identification was made using the morphological characteristics, PCR (polymerase chain reaction), and HhaI (Haemophilus haemoliticus) restriction digest. Knockdown resistance mutation screening was conducted on both living and dead mosquitoes. An. gambiae sensu stricto was the only sibling species of the complex present in Kovié and Lomé. The molecular M form was predominant in the two localities (almost 100%). High resistance level was observed in Lomé 1.19%, 56.45% and 41.17%; and in Kovié 0.91%, 55.55% and 67% mortality respectively to DDT 4%, Deltamethrin 0.05% and Permethrin 1% with a very high knockdown time (TKD50). Up to 70% of resistant individuals have been obtained in the two localities. It is important to inspect these localities through routine tests in order to decide on possible alternative strategies to be used. This study showed that An. gambiae is highly resistant to both DDT and pyrethroids in Lomé and Kovié, with the presence of kdr allele.Keyword: Anopheles gambiae s.s, DDT, pyrethroids, kdr, Southern Tog

Evaluation de l’efficacite des moyens de lutte antivectorielle utilisés dans les ménages au Togo

Une étude réalisée à Lomé (Togo) a porté sur l’évaluation de la sensibilité des femelles d’Anopheles gambiae à jeun, âgées de 2 à 5 jours, aux classes d’insecticides utilisées en santé publique, sur la caractérisation des mécanismes de résistance, sur l’évaluation de l’efficacité de nouvelle génération de moustiquaires imprégnées à longue durée d’action (MILDA) et des produits insecticides à usage domestique. Les tests de sensibilité ont révélé que les moustiques sont tous sensibles au Fénitrothion 1% (100% de mortalité). Les bombes aérosols utilisés dans les ménages sont efficaces sur les moustiques à l’exception d’ORO, de MOBIL et de TOTAL. Quant aux spirales, seul le BAYGON a été efficace. L’identification spécifique a permis de mettre en évidence Anopheles gambiae s.s, Anopheles coluzzii et Anopheles gambiae. Anopheles coluzzii prédomine (95,55% spécimens) sur Anopheles gambiae (4,44% spécimens). La mutation génétique homozygote Kdr/Kdr est observée chez 81% spécimens d’Anopheles coluzzii contre 50% chez Anopheles gambiae. Une activité enzymatique élevée a été observée chez les spécimens de la souche sauvage. Toutes les MILDA testées sont efficaces même après les 20 lavages sur la souche Kisumu.Mots clés: Anopheles gambiae s.s, Anopheles coluzzii et Anopheles gambiae, Kdr, MILDA, insecticidesEnglish Title: Evaluation of the efficacy of household vector management tools used in TogoEnglish AbstractSusceptibility trials with 2 to 5 days old females Anopheles have been conducted in Lome (Togo) on insecticides used in public health and households. These trials concerned also the resistance mechanisms and bio efficacy of new generations of long lasting insecticidal nets (LLINs). The results showed that the mosquitoes were fully susceptible to Fenitrothion 1% (mortality: 100%). They were also susceptible to the  only mosquito coil BAYGON and most of the spray insecticides were effective except ORO, MOBIL and TOTAL. The specific characterization revealed the presence of only An. gambiae s.s with Anopheles coluzzii and Anopheles gambiae. Anopheles coluzzii is predominant (95.55% specimens) over Anopheles gambiae (4.44% specimens). Homozygote Kdr/Kdr has been observed in 81% of Anopheles coluzzii versus 50% in Anopheles gambiae. High enzymatic activity was obtained in most of the wild strain. All the LLINs were effective on the susceptible Kisumu strain even after 20 washes.Keywords: Anopheles gambiae s.s, Anopheles coluzzii and Anopheles gambiae, Kdr, LLINs, insecticides