Abdoulaye Niang - Academia.edu (original) (raw)

Papers by Abdoulaye Niang

Malaria Journal

Background Insecticides are currently the main tools used to reduce the transmission of malaria; ... more Background Insecticides are currently the main tools used to reduce the transmission of malaria; therefore, the development of resistance to insecticides in malaria vectors is of major concern for malaria control. The resistance level to pyrethroids is particularly high in the Western region of Burkina Faso and may affect the efficacy of insecticidal bed nets and indoor residual spraying. Adult mosquito swarming and other nocturnal behaviours exhibit spatial and temporal patterns that suggest potential vulnerability to targeted space spraying with effective insecticides. Indeed, targeted space-spraying against adult mosquito swarms has been used to crash mosquito populations and disrupt malaria transmission. Methods Prior to impact assessment of swarm killing, a baseline data collection was conducted from June to November 2016 in 10 villages divided into two areas in western Burkina Faso. The data considered both ecological and demographic characteristics to monitor the key entomolo...

The sibling species An. coluzzii and An. gambiae s.s. are major malaria vectors thought to be und... more The sibling species An. coluzzii and An. gambiae s.s. are major malaria vectors thought to be undergoing sympatric speciation with gene flow. In the absence of intrinsic post-zygotic isolation between the two taxa, speciation is thought possible through the association of assortative mating and genomic regions protected from gene flow by recombination suppression. Such genomic islands of speciation have been described in pericentromeric regions of the X, 2L and 3L chromosomes. Spatial swarm segregation plays a major role in assortative mating between sympatric populations of the two species and, given their importance for speciation, genes responsible for such pre-mating reproductive barriers are expected to be protected within divergence islands. In this study 2063 male and 266 female An. coluzzii and An. gambiae s.s. individuals from natural swarms in Burkina Faso, West Africa were sampled. These were genotyped at 16 speciation island SNPs, and characterized as non-hybrid individu...

Additional file 3: Table 1. Composition of the Culicidae fauna in ten villages of the Areas A (Sa... more Additional file 3: Table 1. Composition of the Culicidae fauna in ten villages of the Areas A (Santidougou, Kimidougou, Nastenga, Zeyama and Mogobasso) and Area B (Synbekuy, Ramatoulaye, Syndombokuy, Lampa, Syndounkuy) over a period of six months from June to November 2016.

Additional file 2. Location of the human dwelling compounds and swarms of Anopheles gambiae s.l. ... more Additional file 2. Location of the human dwelling compounds and swarms of Anopheles gambiae s.l. scattered through the villages in Area B (Synbekuy, Ramatoulaye, Syndombokuy, Lampa, Syndounkuy).

Background Reducing the burden of malaria requires better understanding of vector populations par... more Background Reducing the burden of malaria requires better understanding of vector populations particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the international airport of Yaoundé, the capital city of Cameroon, including species composition, abundance, Plasmodium infection rate; insecticide resistance profiles and underlying resistance mechanisms. Methods Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a village located 2km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F 1 adult progeny. WHO bioassays were performed to assess resistance profile to insecticides. The threshold of insecticide susceptibility was fixed above 98% mortality rate and mortality rates below 90% were considered indicative of confirmed insecticide resistance according to the WHO test procedures for insecticide resistance monitoring. Furthermore...

In the drive towards elimination of lymphatic filariasis, enhanced surveillance of vector mosquit... more In the drive towards elimination of lymphatic filariasis, enhanced surveillance of vector mosquitoes requires sound sampling methods which can be easily implemented and accepted by communities. Several tools have been validated as alternatives to human landing catches (HLC) for this purpose, but little is known about their effectiveness compared to HLC in terms of the vector density patterns. This study aimed at assessing the efficiency of four mosquitoes collecting tools (HLC, Center for Diseases Control (CDC) light trap, Double Net trap, Window Exit trap). These four sampling tools were evaluated in three different villages (Bapla, Ouessa and Koudjo) in Burkina Faso, when mosquito collection was managed by local people in each community. The results showed that HLC remained the most effective collection method in terms of vector abundance in all villages, followed by double net traps. Except in Bapla, the double net trap collected more Anopheles than CDC light traps. Across the st...

Additional file 1: Table S1. Effects of time of the day (18 h, 19 h or 20 h), location (inside or... more Additional file 1: Table S1. Effects of time of the day (18 h, 19 h or 20 h), location (inside or outside the MERF) and their interaction on mean temperature and humidity. Table S2. Effects of MERF compartments on swarming rate, the height of swarm nucleus and the time at which the swarms started. Figure S1. Light stimuli used into the swarming room. a Ceiling light program with LED panels dimmed from 100% to 0% with the two C2 panels turning off 5 minutes after C1 panels. b Incandescent bulb light illuminating the bright wall during all the experiment. Figure S2: Monthly temperatures outside the MERF and in the MERF during experiments.

Communications Biology, 2021

Anopheles coluzzii females, important malaria vectors in Africa, mate only once in their lifetime... more Anopheles coluzzii females, important malaria vectors in Africa, mate only once in their lifetime. Mating occurs in aerial swarms with a high male-to-female ratio, where traits underlying male mating success are largely unknown. Here, we investigated whether cuticular hydrocarbons (CHCs) influence mating success in natural mating swarms in Burkina Faso. As insecticides are widely used in this area for malaria control, we also determined whether CHCs affect insecticide resistance levels. We find that mated males have higher CHC abundance than unmated controls, suggesting CHCs could be determinants of mating success. Additionally, mated males have higher insecticide resistance under pyrethroid challenge, and we show a link between resistance intensity and CHC abundance. Taken together, our results suggest that CHC abundance may be subject to sexual selection in addition to selection by insecticide pressure. This has implications for insecticide resistance management, as these traits m...

Wellcome Open Research, 2020

Background:Reducing the burden of malaria requires better understanding of vector populations, pa... more Background:Reducing the burden of malaria requires better understanding of vector populations, particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the Yaoundé international airport, Cameroon, including species composition, abundance,Plasmodiuminfection rate, insecticide resistance profiles and underlying resistance mechanisms.Methods:Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a locality situated 2 km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F1adults. Bioassays were performed to assess resistance profile to the four insecticides classes. The threshold of insecticide susceptibility was defined above 98% mortality rate and mortality rates below 90% were indicative of confirmed insecticide resistance. Furthermore, the molecular basis of resistance andPlasmodiuminfection rates were investigated.Results:Anopheles f...

The malaria parasite, which is transmitted by several Anopheles mosquito species, requires more t... more The malaria parasite, which is transmitted by several Anopheles mosquito species, requires more time to reach its human-transmissible stage than the average lifespan of a mosquito. Monitoring the species-specific age structure of mosquito populations is critical to evaluating the impact of vector control interventions on malaria risk. We developed a rapid, cost-effective surveillance method based on deep learning of mid-infrared spectra of mosquitoes’ cuticle that simultaneously identifies the species and the age of three main malaria vectors, in natural populations. Using over 40,000 ecologically and genetically diverse females, we could speciate and age grade An. gambiae, An. arabiensis, and An. coluzzii with up to 95% accuracy. Further, our model learned the age of new populations with minimal sampling effort and detected the impact of control interventions on simulated mosquito populations, measured as a shift in their age structures. We anticipate our method to be applied to ot...

Parasites & Vectors, 2019

Background The recent resurgence of interest in sterile insect techniques to control vector mosqu... more Background The recent resurgence of interest in sterile insect techniques to control vector mosquitoes has renewed interest in novel methods for observing mating behavior. Malarial vectors of the Anopheles gambiae complex are known to mate in swarms at specific locations at dawn and dusk. Most knowledge of mosquito swarming behavior is derived from field observations and a few experimental studies designed to assess critical parameters that affect mosquito swarming. However, such studies are difficult to implement in the field because of uncontrollable environmental factors and mosquito conditions. Here, we present two experimental setups specifically designed to analyze mosquito swarming behavior and provide evidence that swarming behavior of mosquitoes can be generated and accurately assessed under both semi-field and laboratory conditions. Methods The Mosquito Ecology Research Facility setup is a semi-field enclosure made of 12 compartments (10.0 × 6.0 × 4.5 m L × W × H each) exp...

Wellcome Open Research, 2019

Despite the global efforts made in the fight against malaria, the disease is resurging. One of th... more Despite the global efforts made in the fight against malaria, the disease is resurging. One of the main causes is the resistance that Anopheles mosquitoes, vectors of the disease, have developed to insecticides. Anopheles must survive for at least 10 days to possibly transmit malaria. Therefore, to evaluate and improve malaria vector control interventions, it is imperative to monitor and accurately estimate the age distribution of mosquito populations as well as their population sizes. Here, we demonstrate a machine-learning based approach that uses mid-infrared spectra of mosquitoes to characterise simultaneously both age and species identity of females of the African malaria vector species Anopheles gambiae and An. arabiensis. mid-infrared spectroscopy-based prediction of mosquito age structures was statistically indistinguishable from true modelled distributions. The accuracy of classifying mosquitoes by species was 82.6%. The method has a negligible cost per mosquito, does not r...

Despite the global efforts made in the fight against malaria, the disease is resurging. One of th... more Despite the global efforts made in the fight against malaria, the disease is resurging. One of the main causes is the resistance that Anopheles mosquitoes, vectors of the disease, have developed to insecticides. Anopheles must survive for at least 12 days to possibly transmit malaria. Therefore, to evaluate and improve malaria vector control interventions, it is imperative to monitor and accurately estimate the age distribution of mosquito populations as well as total population sizes. However, estimating mosquito age is currently a slow, imprecise, and labour-intensive process that can only distinguish under- from over-four-day-old female mosquitoes. Here, we demonstrate a machine-learning based approach that utilizes mid-infrared spectra of mosquitoes to characterize simultaneously, and with unprecedented accuracy, both age and species identity of females of the malaria vectors Anopheles gambiae and An. arabiensis mosquitoes within their respective populations. The prediction of t...

Parasites & Vectors, 2015

Malaria Journal, 2020

BackgroundIt is assumed that malaria vectors feed on locally available nectar sources to obtain e... more BackgroundIt is assumed that malaria vectors feed on locally available nectar sources to obtain energy. Sugar feeding is energetically critical for theAnophelesmale swarming and mating activities. However, little is known about the impact of local nectar feeding on male physiological development and its consequences on male mosquito life traits in the malaria control context. This study aimed to evaluate the influence of local fruit juices on the life traits of malesAnopheles coluzzii.MethodsSwarming characteristics (number of males in swarm, number of mating pairs, and swarm duration) in semi-field conditions; mating rate and longevity in a laboratory setting were compared between malesAn. coluzziifed exclusively with mango, papaya or banana juices. The trophic preference was investigated in semi-field conditions.ResultsThe results of this study showed that in the laboratory, mosquitoes fed with papaya juices lived on average longer (10 days) than those fed with banana or mango jui...

Malaria Journal

Background Insecticides are currently the main tools used to reduce the transmission of malaria; ... more Background Insecticides are currently the main tools used to reduce the transmission of malaria; therefore, the development of resistance to insecticides in malaria vectors is of major concern for malaria control. The resistance level to pyrethroids is particularly high in the Western region of Burkina Faso and may affect the efficacy of insecticidal bed nets and indoor residual spraying. Adult mosquito swarming and other nocturnal behaviours exhibit spatial and temporal patterns that suggest potential vulnerability to targeted space spraying with effective insecticides. Indeed, targeted space-spraying against adult mosquito swarms has been used to crash mosquito populations and disrupt malaria transmission. Methods Prior to impact assessment of swarm killing, a baseline data collection was conducted from June to November 2016 in 10 villages divided into two areas in western Burkina Faso. The data considered both ecological and demographic characteristics to monitor the key entomolo...

The sibling species An. coluzzii and An. gambiae s.s. are major malaria vectors thought to be und... more The sibling species An. coluzzii and An. gambiae s.s. are major malaria vectors thought to be undergoing sympatric speciation with gene flow. In the absence of intrinsic post-zygotic isolation between the two taxa, speciation is thought possible through the association of assortative mating and genomic regions protected from gene flow by recombination suppression. Such genomic islands of speciation have been described in pericentromeric regions of the X, 2L and 3L chromosomes. Spatial swarm segregation plays a major role in assortative mating between sympatric populations of the two species and, given their importance for speciation, genes responsible for such pre-mating reproductive barriers are expected to be protected within divergence islands. In this study 2063 male and 266 female An. coluzzii and An. gambiae s.s. individuals from natural swarms in Burkina Faso, West Africa were sampled. These were genotyped at 16 speciation island SNPs, and characterized as non-hybrid individu...

Additional file 3: Table 1. Composition of the Culicidae fauna in ten villages of the Areas A (Sa... more Additional file 3: Table 1. Composition of the Culicidae fauna in ten villages of the Areas A (Santidougou, Kimidougou, Nastenga, Zeyama and Mogobasso) and Area B (Synbekuy, Ramatoulaye, Syndombokuy, Lampa, Syndounkuy) over a period of six months from June to November 2016.

Additional file 2. Location of the human dwelling compounds and swarms of Anopheles gambiae s.l. ... more Additional file 2. Location of the human dwelling compounds and swarms of Anopheles gambiae s.l. scattered through the villages in Area B (Synbekuy, Ramatoulaye, Syndombokuy, Lampa, Syndounkuy).

Background Reducing the burden of malaria requires better understanding of vector populations par... more Background Reducing the burden of malaria requires better understanding of vector populations particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the international airport of Yaoundé, the capital city of Cameroon, including species composition, abundance, Plasmodium infection rate; insecticide resistance profiles and underlying resistance mechanisms. Methods Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a village located 2km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F 1 adult progeny. WHO bioassays were performed to assess resistance profile to insecticides. The threshold of insecticide susceptibility was fixed above 98% mortality rate and mortality rates below 90% were considered indicative of confirmed insecticide resistance according to the WHO test procedures for insecticide resistance monitoring. Furthermore...

In the drive towards elimination of lymphatic filariasis, enhanced surveillance of vector mosquit... more In the drive towards elimination of lymphatic filariasis, enhanced surveillance of vector mosquitoes requires sound sampling methods which can be easily implemented and accepted by communities. Several tools have been validated as alternatives to human landing catches (HLC) for this purpose, but little is known about their effectiveness compared to HLC in terms of the vector density patterns. This study aimed at assessing the efficiency of four mosquitoes collecting tools (HLC, Center for Diseases Control (CDC) light trap, Double Net trap, Window Exit trap). These four sampling tools were evaluated in three different villages (Bapla, Ouessa and Koudjo) in Burkina Faso, when mosquito collection was managed by local people in each community. The results showed that HLC remained the most effective collection method in terms of vector abundance in all villages, followed by double net traps. Except in Bapla, the double net trap collected more Anopheles than CDC light traps. Across the st...

Additional file 1: Table S1. Effects of time of the day (18 h, 19 h or 20 h), location (inside or... more Additional file 1: Table S1. Effects of time of the day (18 h, 19 h or 20 h), location (inside or outside the MERF) and their interaction on mean temperature and humidity. Table S2. Effects of MERF compartments on swarming rate, the height of swarm nucleus and the time at which the swarms started. Figure S1. Light stimuli used into the swarming room. a Ceiling light program with LED panels dimmed from 100% to 0% with the two C2 panels turning off 5 minutes after C1 panels. b Incandescent bulb light illuminating the bright wall during all the experiment. Figure S2: Monthly temperatures outside the MERF and in the MERF during experiments.

Communications Biology, 2021

Anopheles coluzzii females, important malaria vectors in Africa, mate only once in their lifetime... more Anopheles coluzzii females, important malaria vectors in Africa, mate only once in their lifetime. Mating occurs in aerial swarms with a high male-to-female ratio, where traits underlying male mating success are largely unknown. Here, we investigated whether cuticular hydrocarbons (CHCs) influence mating success in natural mating swarms in Burkina Faso. As insecticides are widely used in this area for malaria control, we also determined whether CHCs affect insecticide resistance levels. We find that mated males have higher CHC abundance than unmated controls, suggesting CHCs could be determinants of mating success. Additionally, mated males have higher insecticide resistance under pyrethroid challenge, and we show a link between resistance intensity and CHC abundance. Taken together, our results suggest that CHC abundance may be subject to sexual selection in addition to selection by insecticide pressure. This has implications for insecticide resistance management, as these traits m...

Wellcome Open Research, 2020

Background:Reducing the burden of malaria requires better understanding of vector populations, pa... more Background:Reducing the burden of malaria requires better understanding of vector populations, particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the Yaoundé international airport, Cameroon, including species composition, abundance,Plasmodiuminfection rate, insecticide resistance profiles and underlying resistance mechanisms.Methods:Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a locality situated 2 km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F1adults. Bioassays were performed to assess resistance profile to the four insecticides classes. The threshold of insecticide susceptibility was defined above 98% mortality rate and mortality rates below 90% were indicative of confirmed insecticide resistance. Furthermore, the molecular basis of resistance andPlasmodiuminfection rates were investigated.Results:Anopheles f...

The malaria parasite, which is transmitted by several Anopheles mosquito species, requires more t... more The malaria parasite, which is transmitted by several Anopheles mosquito species, requires more time to reach its human-transmissible stage than the average lifespan of a mosquito. Monitoring the species-specific age structure of mosquito populations is critical to evaluating the impact of vector control interventions on malaria risk. We developed a rapid, cost-effective surveillance method based on deep learning of mid-infrared spectra of mosquitoes’ cuticle that simultaneously identifies the species and the age of three main malaria vectors, in natural populations. Using over 40,000 ecologically and genetically diverse females, we could speciate and age grade An. gambiae, An. arabiensis, and An. coluzzii with up to 95% accuracy. Further, our model learned the age of new populations with minimal sampling effort and detected the impact of control interventions on simulated mosquito populations, measured as a shift in their age structures. We anticipate our method to be applied to ot...

Parasites & Vectors, 2019

Background The recent resurgence of interest in sterile insect techniques to control vector mosqu... more Background The recent resurgence of interest in sterile insect techniques to control vector mosquitoes has renewed interest in novel methods for observing mating behavior. Malarial vectors of the Anopheles gambiae complex are known to mate in swarms at specific locations at dawn and dusk. Most knowledge of mosquito swarming behavior is derived from field observations and a few experimental studies designed to assess critical parameters that affect mosquito swarming. However, such studies are difficult to implement in the field because of uncontrollable environmental factors and mosquito conditions. Here, we present two experimental setups specifically designed to analyze mosquito swarming behavior and provide evidence that swarming behavior of mosquitoes can be generated and accurately assessed under both semi-field and laboratory conditions. Methods The Mosquito Ecology Research Facility setup is a semi-field enclosure made of 12 compartments (10.0 × 6.0 × 4.5 m L × W × H each) exp...

Wellcome Open Research, 2019

Despite the global efforts made in the fight against malaria, the disease is resurging. One of th... more Despite the global efforts made in the fight against malaria, the disease is resurging. One of the main causes is the resistance that Anopheles mosquitoes, vectors of the disease, have developed to insecticides. Anopheles must survive for at least 10 days to possibly transmit malaria. Therefore, to evaluate and improve malaria vector control interventions, it is imperative to monitor and accurately estimate the age distribution of mosquito populations as well as their population sizes. Here, we demonstrate a machine-learning based approach that uses mid-infrared spectra of mosquitoes to characterise simultaneously both age and species identity of females of the African malaria vector species Anopheles gambiae and An. arabiensis. mid-infrared spectroscopy-based prediction of mosquito age structures was statistically indistinguishable from true modelled distributions. The accuracy of classifying mosquitoes by species was 82.6%. The method has a negligible cost per mosquito, does not r...

Despite the global efforts made in the fight against malaria, the disease is resurging. One of th... more Despite the global efforts made in the fight against malaria, the disease is resurging. One of the main causes is the resistance that Anopheles mosquitoes, vectors of the disease, have developed to insecticides. Anopheles must survive for at least 12 days to possibly transmit malaria. Therefore, to evaluate and improve malaria vector control interventions, it is imperative to monitor and accurately estimate the age distribution of mosquito populations as well as total population sizes. However, estimating mosquito age is currently a slow, imprecise, and labour-intensive process that can only distinguish under- from over-four-day-old female mosquitoes. Here, we demonstrate a machine-learning based approach that utilizes mid-infrared spectra of mosquitoes to characterize simultaneously, and with unprecedented accuracy, both age and species identity of females of the malaria vectors Anopheles gambiae and An. arabiensis mosquitoes within their respective populations. The prediction of t...

Parasites & Vectors, 2015

Malaria Journal, 2020

BackgroundIt is assumed that malaria vectors feed on locally available nectar sources to obtain e... more BackgroundIt is assumed that malaria vectors feed on locally available nectar sources to obtain energy. Sugar feeding is energetically critical for theAnophelesmale swarming and mating activities. However, little is known about the impact of local nectar feeding on male physiological development and its consequences on male mosquito life traits in the malaria control context. This study aimed to evaluate the influence of local fruit juices on the life traits of malesAnopheles coluzzii.MethodsSwarming characteristics (number of males in swarm, number of mating pairs, and swarm duration) in semi-field conditions; mating rate and longevity in a laboratory setting were compared between malesAn. coluzziifed exclusively with mango, papaya or banana juices. The trophic preference was investigated in semi-field conditions.ResultsThe results of this study showed that in the laboratory, mosquitoes fed with papaya juices lived on average longer (10 days) than those fed with banana or mango jui...