48 research outputs found
Effects of pesticide residues in soil substrates on the biology cycle of Aedes aegypti from three different setting zones in Benin
No full text<p>In order to evaluate the effects of insecticides residues in soil substrates on the biology cycle of <i>Aedes aegypti</i>, we conducted a study in three ecological zones: urban areas (Dandji, southern Benin with few agriculture activities), peri urban areas (Awaya, central of Benin with agriculture practices), and forests (Kaoura, northern Benin with few agriculture activities). These areas were chosen because they provided an ideal environment for the development of <i>Aedes aegypti</i>. The purpose of this study is to look for insecticide residues that may have detrimental impacts on the biology cycle of <i>A. aegypti</i>. Indirect bioassays were used to investigate the factors affecting mosquito larvae's ability to develop normally at breeding sites, their rate of growth, and their ability to produce an adequate number of larvae. Due to the absence of an HPLC equipment for the direct detection of pesticide residues in samples, <i>A. aegypti</i> larvae at breeding sites were reconstituted using water and soil samples obtained at each study site. A comparison of the larval growth in test breeding locations was made using the reference strain SBE as a control. The different bioassays demonstrate the existence of inhibitory elements on test materials. In control samples, larval development was observed to be normal. However, when the breeding sites were established with just a few grams of soil samples from the three study sites, it was found that the <i>A. aegypti</i> eggs had a poor hatching rate, along with sluggish larval development and a low production of adult mosquitoes from hatched eggs. The findings of this study indicate that toxic substances that prevent <i>A. aegypti</i> eggs from hatching and larvae from growing are most likely leftover pesticides from agricultural operations. In order to quantify the toxic factors likely to affect the biology parameters of <i>A. aegypti</i> cited above, these results must be validated using HPLC techniques.</p><p>published by the <a href="https://innspub.net/journal-of-biodiversity-and-environmental-sciences/"><strong>Journal of Biodiversity and Environmental Sciences (JBES)</strong></a></p><p><br> </p>
Développement de la résistance d’Anopheles gambiae aux pyréthrinoïdes au Bénin : facteurs favorisants, mécanismes et impacts sur la transmission du paludisme
No full textAbstract and keywords provided in both French and EnglishBioMed Central articles attached in EnglishThe table of contents for this item can be shared with the requester. The requester may then choose one chapter, up to 10% of the item, as per the Fair Dealing provision of the Canadian Copyright ActLa lutte anti-vectorielle basée sur l’utilisation des matériaux imprégnés, notamment les moustiquaires imprégnées d'insecticides à longue durée d’action (MILD), considérées comme l’un des outils les plus efficaces de prévention contre les moustiques vecteurs, est en proie depuis quelques années, à une baisse d’efficacité. Cette baisse d’efficacité est due à l’émergence de la résistance des vecteurs du paludisme aux insecticides pyréthrinoïdes. Sans apporter des preuves concrètes, on cite l’utilisation des insecticides dans le domaine agricole comme principal facteur à l’origine de cette résistance. Dans le but de vérifier cette hypothèse, nous avons évalué la résistance des populations d’An. gambiae s.l issues des zones maraîchères (Houeyiho à Cotonou, Acron à Porto-Novo et Azèrèkè à Parakou), rizicoles (Malanville), céréalières (Kétou, Comè et Séhouè) et des zones cotonnières à programme calendaire (utilisation de fortes quantités d’insecticides), à Lutte Etagée Ciblée (LEC) avec très peu d’insecticide et des zones de programme biologique où aucun insecticide chimique n’est utilisé. Au début de l’étude, nous avons effectué une enquête sur la nature des pesticides utilisés contre les ravageurs des cultures, leur origine et les doses appliquées.Doctor of Philosoph
Insecticide resistance status in Anopheles gambiae in southern Benin.
No full textBACKGROUND: The emergence of pyrethroid resistance in Anopheles gambiae has become a serious concern to the future success of malaria control. In Benin, the National Malaria Control Programme has recently planned to scaling up long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) for malaria prevention. It is, therefore, crucial to monitor the level and type of insecticide resistance in An. gambiae, particularly in southern Benin where reduced efficacy of insecticide-treated nets (ITNs) and IRS has previously been reported. METHODS: The protocol was based on mosquito collection during both dry and rainy seasons across forty districts selected in southern Benin. Bioassay were performed on adults collected from the field to assess the susceptibility of malaria vectors to insecticide-impregnated papers (permethrin 0.75%, delthamethrin 0.05%, DDT 4%, and bendiocarb 0.1%) following WHOPES guidelines. The species within An. gambiae complex, molecular form and presence of kdr and ace-1 mutations were determined by PCR. RESULTS: Strong resistance to permethrin and DDT was found in An. gambiae populations from southern Benin, except in Aglangandan where mosquitoes were fully susceptible (mortality 100%) to all insecticides tested. PCR showed the presence of two sub-species of An. gambiae, namely An. gambiae s.s, and Anopheles melas, with a predominance for An. gambiae s.s (98%). The molecular M form of An. gambiae was predominant in southern Benin (97%). The kdr mutation was detected in all districts at various frequency (1% to 95%) whereas the Ace-1 mutation was found at a very low frequency (<or= 5%). CONCLUSION: This study showed a widespread resistance to permethrin in An. gambiae populations from southern Benin, with a significant increase of kdr frequency compared to what was observed previously in Benin. The low frequency of Ace-1 recorded in all populations is encouraging for the use of bendiocarb as an alternative insecticide to pyrethroids for IRS in Benin
Bendiocarb, a potential alternative against pyrethroid resistant <it>Anopheles gambiae </it>in Benin, West Africa
No full textAbstract Background Anopheles gambiae, the main malaria vector in Benin has developed high level of resistance to pyrethroid insecticides, which is a serious concern to the future use of long-lasting insecticidal nets (LLIN) and indoor residual spraying (IRS). In this context, one of the pathways available for malaria vector control would be to investigate alternative classes of insecticides with different mode of action than that of pyrethroids. The goal of this study was to evaluate under field conditions the efficacy of a carbamate (bendiocarb) and an organophosphate (fenitrothion) against pyrethroid-resistant An. gambiae s.s. Methods Wild populations and females from laboratory colonies of five days old An. gambiae were bio-assayed during this study. Two pyrethroids (deltamethrin and alphacypermethrin), an organophosphate (fenitrothion), a carbamate (bendiocarb) and a mixture of an organophosphate (chlorpyriphos + a pyrethroid deltamethrin) were compared in experimental huts as IRS treatments. Insecticides were applied in the huts using a hand-operated compression sprayer. The deterrency, exophily, blood feeding rate and mortality induced by these insecticides against An. gambiae were compared to the untreated control huts. Results Deltamethrin, alphacypermethrin and bendiocarb treatment significantly reduced mosquito entry into the huts (p An. gambiae (in the first month) and 77.8% (in the fourth month). Bendiocarb and the mixture chlorpyriphos/deltamethrin mortality rates ranged from 97.9 to 100% the first month and 77.7-88% the third month respectively. Conclusion After four months, fenitrothion, bendiocarb and the mixture chlorpyriphos/deltamethrin performed effectively against pyrethroid-resistant Anopheles. These results showed that bendiocarb could be recommended as an effective insecticide for use in IRS operations in Benin, particularly as the mixture chlorpyriphos/deltamethrin does not have WHOPES authorization and complaints were mentioned by the sleepers about the safety and smell of fenitrothion.</p
The impact of the expansion of urban vegetable farming on malaria transmission in major cities of Benin.
No full textBACKGROUND: Urban agricultural practices are expanding in several cities of the Republic of Benin. This study aims to assess the impact of such practices on transmission of the malaria parasite in major cities of Benin. METHOD: A cross sectional entomological study was carried out from January to December 2009 in two vegetable farming sites in southern Benin (Houeyiho and Acron) and one in the northern area (Azèrèkè). The study was based on sampling of mosquitoes by Human Landing Catches (HLC) in households close to the vegetable farms and in others located far from the farms. RESULTS: During the year of study, 71,678 female mosquitoes were caught by HLC of which 25% (17,920/71,678) were Anopheles species. In the areas surveyed, the main malaria parasite, Plasmodium falciparum was transmitted in the south by Anopheles gambiae s.s. Transmission was high during the two rainy seasons (April to July and October to November) but declined in the two dry seasons (December to March and August to September). In the north, transmission occurred from June to October during the rainy season and was vehicled by two members of the An. gambiae complex: Anopheles gambiae s.s. (98%) and Anopheles arabiensis (2%).At Houeyiho, Acron and Azèrèkè, the Entomological Inoculation Rates (EIRs) and the Human Biting Rates (HBRs) were significantly higher during the dry season in Households Close to Vegetable Farms (HCVF) than in those located far from the vegetable areas (HFVF) (p 0.05).The knock-down resistance (kdr) mutation was the main resistance mechanism detected at high frequency (0.86 to 0.91) in An. gambiae s.l. at all sites. The ace-1R mutation was also found but at a very low frequency (< 0.1). CONCLUSION: These findings showed that communities living close to vegetable farms are permanently exposed to malaria throughout the year, whereas the risk in those living far from such agricultural practices is limited and only critical during the rainy seasons. Measures must be taken by African governments to create awareness among farmers and ultimately decentralize farming activities from urban to rural areas where human-vector contact is limited
Contribution de L’agriculture dans la Sélection et la Distribution de la Résistance d’Anopheles Gambiae (Diptera, Culicidae) aux Insecticides le Long du Transect Sud-Nord en République du Beninn
No full textAbstractA study carried out along the South-North transect in Benin has shown the impacts of the use of chemical pesticides in agricultural for crop protection in the selection and spread of resistance of Anopheles gambiae s.l. to insecticidesIndeed, the knock-down resistance frequency found in An. gambiae populations from the cotton and vegetable farming fields where farmers used a high dose of chemical pesticides, is significantly higher than the one from areas with low or no use of pesticides (food crop and rice growing areas).The acetylcholinesterase mutation was also found, but only in An. gambiae populations from the areas where high dose of pesticides were used for pests controlThese findings confirm once again the role of agriculture in the selection and spread of resistance of Anopheles gambiae s.l. to insecticidesKey words: agriculture; Insecticides; Resistance; Anopheles gambiae; Benin
DOES THE INTENSIFICATION OF URBAN AND RURAL AGRICULTURE IN BENIN CONTRIBUTE TO THE EMERGENCE OF ENZYMATIC ACTIVITY IN ANOPHELES GAMBIAESENSULATO?
No full textTo explore the contribution of agricultural practices on enzymatic activity in Anopheles gambiae populations, collections of Anopheles gambiaelarve were done in cotton vegetable farming (famers use for both,insecticides for pest control) and in subsistence farming (no insecticide) from the district of Banikoara, located in Benin. Enzymatic activities such as total protein, monooxygenase P450, Glutathione-S-Transferase and esterasewere investigated on F1 generation females aged 3-5 days. Results from this study showed a significant high level of Glutathione-S-Transferase and monooxygenase P450 activities from the wild populations of An. gambiae particularly in cotton and vegetable farming areas compared to the susceptible Kisumu strain (control) (P0.05). These findings confirmed the contribution of agricultural practices on theemergence of enzymatic activity in Anopheles gambiaes.l particularly on Glutathione-S-Transferase, and monooxygenase P450. However, the same level of the wild populations activity in esterase compared to the control could be explained by the involving of many insecticide resistance mechanisms of An. gambiae associated to the level of enzymatic activity in An. gambiae populations in this locality
Impact of the Use of Long-Lasting Insecticide-Treated Nets (Llins) on the Rate of Malaria Parasitaemia Among Children Aged Between 0- 5 Years Old at Natitingou, Northern Benin
No full textThe use of Long-Lasting Insecticide-treated Nets (LLINs) is one of the preventive methods against malaria in sub-Saharan Africa. The current study was conducted from May- July 2015 on 300 Agbanto hospital patients aged between 0-5 years old to investigate the impact of LLINs use on the prevalence of malaria parasitaemia density in the district of Natitingou in the West –North of Benin.Firstly, KAP (Knowledge Attitude, Practice) survey was conducted on the target population to understand the practices of the people in the use of LLINs. Secondly, blood samples were taken from the patients for malaria parasitaemia density analysis using the thick and thin blood films technique.The results showed that 97% of patients surveyed own at least one LLIN and knew the preventive importance of using the nets against malaria. However, less than 50% of children aged between 0-5years old do not sleep under the LLIN. Ironically, the parents of these children used the nets to protect vegetable seedlings against.In parallel, parasitological results showed the children 0-5 year olds who didn’t sleep under LLINs were significantly affected by malaria with malaria parasitaemia than those who slept under the LLINs.This study showed a high prevalence of parasitaemia associated with malaria parasitaemia, especially in children aged 0-5 years who do not sleep under LLINs. It’s therefore crucial the Ministry of Health through the National Malaria Control Program to put more emphasis on information, education and communication (IEC) techniques on the use of the LLINs. This will reduce the parasitic density and consequently the infant mortality rate due to malaria
Sensibilité des Populations de Anopheles Gambiae aux Pyréthrinoïdes, Principal Vecteur du Paludisme dans la Région de Natitingou au Nord -Ouest du Bénin
No full textVector control programme based on deployment of insecticide treated nets (ITNs) has become the main method for malaria prevention in many endemic countries across Africa. However, the threat of pyrethroid resistance in West Africa is increasingly becoming a serious concern for the future usefulness of ITNs.Without sufficient evidence, the emergence of insecticide resistance in insect vectors has been partly attributed to the abusive use of insecticides against household and agricultural pests.To explore this hypothesis further, Knowledge Attitude-Practice (KAP) surveys were organized in the study sites (urban and rural areas) from july to October 2017. In each site, leaders of farmers organizations were interviewed using semi-structured questionnaires that focused on the treatment strategies, and the use of insecticides in the farms. Furthermore, qualitative data were collected through direct observations, in-depth interviews and focus group discussions. This was complemented by bioassay tests to assess the susceptibility of An. gambiae to various insecticides such as deltamethrin (0.05 %), permethrin (0.75%), DDT (4%), and lambdacyhalothrine (0.05%).Results from this study showed that: i)- More than 90% of the farmers interviewed used pesticides which were not registered for pest control; ii)- most of the farmers did not respect the dose recommended for treatment; iii)- An. gambiae populations developed a high resistance against pyrethroids and organochlorine regardless the areas of collection. This study confirms once again that the use of insecticide in an improper manner to control vegetable pests in agriculture is one of the factors responsible for the selection of insecticide resistance in malaria vectors.Measure must be taken by agriculture authorities to the management of pesticides in agriculture hence reducing the selection pressure of insecticides on An. gambiae populations
Emerg Infect Dis
No full textLassa virus has been identified in 3 pygmy mice, Mus baoulei, in central Benin. The glycoprotein and nucleoprotein sequences cluster with the Togo strain. These mice may be a new reservoir for Lassa virus in Ghana, Togo, and Benin
