scholarly journals Testing Configurations of Attractive Toxic Sugar Bait (ATSB) Stations in Mali, West Africa, for Improving the Control of Malaria Parasite Transmission by Vector Mosquitoes and Minimizing Their Effect on Non-target Insects

2020 ◽  
Author(s):  
Rabiatou A. Diarra A. Diarra ◽  
Mohamed M. Traore ◽  
Amy M Junnila ◽  
Sekou F. Traore ◽  
Seydou Doumbia ◽  
...  

Abstract Background Attractive Toxic Sugar Baits (ATSBs) successfully reduced Anopheles mosquito vector populations and malaria parasite transmission in Mali but application methods need to be improved for wide-scale use, and minimization of effects on non-target organisms (NTOs) must be assessed. The goals of this study were to determine on a village level the effect of different outdoor configurations of ATSB bait stations to 1) achieve > 25% Anopheles mosquito vector daily feeding rate for both males and females and 2) minimize the effect on non-target organisms. Methods Dye was added to Attractive Sugar Bait Stations (ASB – without toxin) to mark mosquitoes feeding on the sugar baits, and CDC UV light traps were used to monitor mosquitoes for the presence of the dye. Yellow plates, pitfall traps, Malaise traps, UV light traps, UV tray traps, and sweep nets were used to trap and sample non-target organisms (NTOs) for dye, indicating feeding on the ASB. ASB stations were hung on outer walls of village homes to determine the impact of different densities of ASBs (1,2, or 3 per home) as well as the impact of ASB height (1 m or 1.8 m above the ground on sugar feeding by anophelines. These experiments were carried out separately, on consecutive nights for mosquito and NTO monitoring. Eight villages in the Koulikoro province were chosen as the experimental locations Results The use of one ASB station per house marked 23.11% of female and 14.64% of male An. gambiae s.l. While two and three ASB stations per house gave feeding rates above the 25% goal, there was no statistical difference in the percentage of marked mosquitoes (p = 0.3141 females; p = 0.9336 males). There was no difference in sugar feeding on ASB stations when hung at 1.0 and 1.8 m and (p = 0.5170 females; p = 0.9934 males); however, ASBs at 1.8 m had less accidental damage from village residents and animals, and subsequent invasion of non-targets through rips or holes produced. ASB stations at 1.8 m above ground were fed on by three of seven monitored insect orders. Feeding rates were less than 0.015% of total trap catches and as low as 0.0001%. The monitored orders were: Hymenoptera [ants (Formicidae), bees (Apidae), and wasps (Vespidae)], Lepidoptera (Rhopalocera, Bombyces, Geometroidea, Noctuoidea, Sphingidae, Pyraloidea), Coleoptera (Carabidae, Tenebrionidae, Scarabaeidae, Cerambycidae, and Chrysomelidae), Diptera (Brachycera, Chironomidae), Hemiptera (Cicadomorpha and Heteroptera), Neuroptera (Myrmeleontiformia) and Orthoptera (Caelifera and Ensifera). Using one or two stations limited evidence of NTO feeding to ants (Hymenoptera), Brachycera, Heteroptera, Noctuiodea, Rhopalocera, wasps (Vespidae) and wild bees (Apidae) (both Hymenoptera) and had a significantly reduced percentage of stained individuals compared to three stations which produced the highest number of NTOs. The percentages of stained individuals were as follows: Brachycera accounted for 6.84 ± 2.03% of stained insects, wasps (Hymenoptera: Vespidae) for 5.32 ± 2.27%, and Rhopalocera for 2.22 ± 1.79%. Hanging the optimal number of stations per house for catching mosquitoes (two) 1.8 m above ground limited the groups of non-targets to Brachycera, Chironomidae, Noctuoidea, Rhopalocera, parasitic wasps and wasps (both Hymenoptera: Vespidae). The three most commonly stained non-target insect groups at this height were wasps (Vespidae) (1.65 ± 0.75%), Chironomidae (0.99 ± 0.37), and Brachycera (1.55 ± 0.69%). Feeding at this height only occurred when stations were damaged. Conclusions The goal of marking one quarter of the total Anopheles mosquito vector population per day was obtained using 2 bait stations at 1.8 m height above the ground on the outer walls of houses. This configuration of ATSB stations also had minimal effects on non-target insects: only 0.0001–0.013% of specimens (in three orders) were marked. Stations hung 1.8 m above the ground had less accidental damage from passing people and livestock. The minimal marking of non-target insects may be attributed to visual orientation of non-mosquito insects while mosquitoes, are mostly guided by olfactory cues. Furthermore, the bait stations have a membrane cover, which if intact, is impenetrable to most sugar feeding non-target insects but is pierced by the stylets of the mosquito proboscis. Thus, most non-target insects are not exposed to the toxin even if they approach the bait stations.

2021 ◽  
Author(s):  
Rabiatou A. Diarra ◽  
Mohamed M. Traore ◽  
Amy M Junnila ◽  
Sekou F. Traore ◽  
Seydou Doumbia ◽  
...  

Abstract Background Attractive Toxic Sugar Baits (ATSBs) successfully reduced Anopheles mosquito vector populations and malaria parasite transmission in Mali, but application methods need to be improved for wide-scale use, and effects on non-target organisms (NTOs) must be assessed. The goals of this study were to determine on a village level the effect of different outdoor configurations of ATSB bait stations to 1) achieve > 25% Anopheles mosquito vector daily feeding rate for both males and females and 2) minimize the effect on non-target organisms. Methods Dye was added to Attractive Sugar Bait Stations (ASB – without toxin) to mark mosquitoes feeding on the sugar baits, and CDC UV light traps were used to monitor mosquitoes for the presence of the dye. Yellow plates, pitfall traps, Malaise traps, UV light traps, UV tray traps, and sweep nets were used to trap and sample non-target organisms (NTOs) for dye, indicating feeding on the ASB. ASB stations were hung on outer walls of village homes to determine the impact of different densities of ASBs (1,2, or 3 per home) as well as the impact of ASB height (1 m or 1.8 m above the ground on sugar feeding by anophelines. These experiments were carried out separately, on consecutive nights for mosquito and NTO monitoring. Eight villages in the Koulikoro province were chosen as the experimental locations. Results The use of one ASB station per house marked 23.11% of female and 7.11% of male An. gambiae s.l. While two and three ASB stations per house gave feeding rates above the 25% goal, there was no statistical difference in the percentage of marked mosquitoes (p=0.3141 females; p=0.9336 males). There was no difference in sugar feeding on ASB stations when hung at 1.0 and 1.8 m and (p=0.5170 females; p=0.9934 males); however, ASBs at 1.8 m had less accidental damage from village residents and animals, and subsequent invasion of non-targets through rips or holes produced. ASB stations at 1.8 m above ground were fed on by three of seven monitored insect orders. Feeding rates were less than 0.015% of total trap catches and as low as 0.0001%. The monitored orders were: Hymenoptera [ants (Formicidae), bees (Apidae), and wasps (Vespidae)], Lepidoptera (Rhopalocera, Bombyces, Geometroidea, Noctuoidea, Sphingidae, Pyraloidea), Coleoptera (Carabidae, Tenebrionidae, Scarabaeidae, Cerambycidae, and Chrysomelidae), Diptera (Brachycera, Chironomidae), Hemiptera (Cicadomorpha and Heteroptera), Neuroptera (Myrmeleontiformia) and Orthoptera (Caelifera and Ensifera). Using one or two stations limited evidence of NTO feeding to ants (Hymenoptera), Brachycera, Heteroptera, Noctuiodea, Rhopalocera, wasps (Vespidae) and wild bees (Apidae) (both Hymenoptera) and had a significantly reduced percentage of stained individuals compared to three stations which had the highest feeding rates amongst NTOs. The percentages of stained individuals were as follows: 6.84 ± 2.03% Brachycera were stained followed by wasps (Hymenoptera: Vespidae) 5.32 ± 2.27%, and Rhopalocera 2.22 ± 1.79%. Hanging the optimal number of stations per house for catching mosquitoes (two) 1.8 m above ground, limited the groups of non-targets to Brachycera, Chironomidae, Noctuoidea, Rhopalocera, parasitic wasps and wasps (both Hymenoptera: Vespidae). The three most commonly stained non-target insect groups at this height were wasps (Vespidae) (1.65 ± 0.75%), Chironomidae (0.99 ± 0.37), and Brachycera (1.55 ± 0.69%). Feeding at this height only occurred when stations were damaged.Conclusions The goal of marking one quarter of the total Anopheles mosquito vector population per day was obtained using 2 bait stations at 1.8 m height above the ground on the outer walls of houses. This configuration of ATSB stations also had minimal effects on non-target insects: only 0.0001% to 0.013% of specimens (in three orders) were marked. Stations hung 1.8 m above the ground had less accidental damage from passing people and livestock. The minimal marking of non-target insects may be attributed to visual orientation of non-mosquito insects while mosquitoes, are mostly guided by olfactory cues. Furthermore, the bait stations have a membrane cover, which if intact, is impenetrable to most sugar feeding non-target insects but is pierced by the stylets of the mosquito proboscis. Thus, most non-target insects are not exposed to the toxin even if they approach the bait stations.


2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Rabiatou A. Diarra ◽  
Mohamed M. Traore ◽  
Amy Junnila ◽  
Sekou F. Traore ◽  
Seydou Doumbia ◽  
...  

Abstract Background Application methods of |Attractive Toxic Sugar Baits (ATSB) need to be improved for wide-scale use, and effects on non-target organisms (NTOs) must be assessed. The goals of this study were to determine, at the village level, the effect of different configurations of bait stations to (1) achieve < 25% Anopheles mosquito vector daily feeding rate for both males and females and (2) minimize the effect on non-target organisms. Methods Dye was added to Attractive Sugar Bait Stations (without toxin) to mark mosquitoes feeding on the baits, and CDC UV light traps were used to monitor for marked mosquitoes. An array of different traps were used to catch dye marked NTOs, indicating feeding on the ASB. Stations were hung on homes (1, 2, or 3 per home to optimize density) at different heights (1.0 m or 1.8 m above the ground). Eight villages were chosen as for the experiments. Results The use of one ASB station per house did not mark enough mosquitoes. Use of two and three stations per house gave feeding rates above the 25% goal. There was no statistical difference in the percentage of marked mosquitoes between two and three stations, however, the catches using two and three bait stations were both significantly higher than using one. There was no difference in An. gambiae s.l. feeding when stations were hung at 1.0 and 1.8 m. At 1.8 m stations sustained less accidental damage. ASB stations 1.8 m above ground were fed on by three of seven monitored insect orders. The monitored orders were: Hymenoptera, Lepidoptera, Coleoptera, Diptera, Hemiptera, Neuroptera and Orthoptera. Using one or two stations significantly reduced percentage of bait-fed NTOs compared to three stations which had the highest feeding rates. Percentages were as follows: 6.84 ± 2.03% Brachycera followed by wasps (Hymenoptera: Vespidae) 5.32 ± 2.27%, and Rhopalocera 2.22 ± 1.79%. Hanging the optimal number of stations per house for catching mosquitoes (two) at 1.8 m above ground, limited the groups of non-targets to Brachycera, Chironomidae, Noctuoidea, Rhopalocera, parasitic wasps and wasps (Hymenoptera). Feeding at 1.8 m only occurred when stations were damaged. Conclusions The goal of marking quarter of the total Anopheles population per day was obtained using 2 bait stations at 1.8 m height above the ground. This configuration also had minimal effects on non-target insects.


Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2590
Author(s):  
David S. Guttery ◽  
Abhinay Ramaprasad ◽  
David J. P. Ferguson ◽  
Mohammad Zeeshan ◽  
Rajan Pandey ◽  
...  

The meiotic recombination 11 protein (MRE11) plays a key role in DNA damage response and maintenance of genome stability. However, little is known about its function during development of the malaria parasite Plasmodium. Here, we present a functional, ultrastructural and transcriptomic analysis of Plasmodium parasites lacking MRE11 during its life cycle in both mammalian and mosquito vector hosts. Genetic disruption of Plasmodium berghei mre11 (PbMRE11) results in significant retardation of oocyst development in the mosquito midgut associated with cytoplasmic and nuclear degeneration, along with concomitant ablation of sporogony and subsequent parasite transmission. Further, absence of PbMRE11 results in significant transcriptional downregulation of genes involved in key interconnected biological processes that are fundamental to all eukaryotic life including ribonucleoprotein biogenesis, spliceosome function and iron–sulfur cluster assembly. Overall, our study provides a comprehensive functional analysis of MRE11′s role in Plasmodium development during the mosquito stages and offers a potential target for therapeutic intervention during malaria parasite transmission.


mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Viswanathan Lakshmanan ◽  
Matthew E. Fishbaugher ◽  
Bob Morrison ◽  
Michael Baldwin ◽  
Michael Macarulay ◽  
...  

ABSTRACT Transmission of malaria occurs during Anopheles mosquito vector blood meals, when Plasmodium sporozoites that have invaded the mosquito salivary glands are delivered to the mammalian host. Sporozoites display a unique form of motility that is essential for their movement across cellular host barriers and invasion of hepatocytes. While the molecular machinery powering motility and invasion is increasingly well defined, the signaling events that control these essential parasite activities have not been clearly delineated. Here, we identify a phosphodiesterase (PDEγ) in Plasmodium, a regulator of signaling through cyclic nucleotide second messengers. Reverse transcriptase PCR (RT-PCR) analysis and epitope tagging of endogenous PDEγ detected its expression in blood stages and sporozoites of Plasmodium yoelii. Deletion of PDEγ (pdeγ−) rendered sporozoites nonmotile, and they failed to invade the mosquito salivary glands. Consequently, PDEγ deletion completely blocked parasite transmission by mosquito bite. Strikingly, pdeγ− sporozoites showed dramatically elevated levels of cyclic GMP (cGMP), indicating that a perturbation in cyclic nucleotide balance is involved in the observed phenotypic defects. Transcriptome sequencing (RNA-Seq) analysis of pdeγ− sporozoites revealed reduced transcript abundance of genes that encode key components of the motility and invasion apparatus. Our data reveal a crucial role for PDEγ in maintaining the cyclic nucleotide balance in the malaria parasite sporozoite stage, which in turn is essential for parasite transmission from mosquito to mammal. IMPORTANCE Malaria is a formidable threat to human health worldwide, and there is an urgent need to identify novel drug targets for this parasitic disease. The parasite is transmitted by mosquito bite, inoculating the host with infectious sporozoite stages. We show that cellular signaling by cyclic nucleotides is critical for transmission of the parasite from the mosquito vector to the mammalian host. Parasite phosphodiesterase γ is essential for maintaining cyclic nucleotide balance, and its deletion blocks transmission of sporozoites. A deeper understanding of the signaling mechanisms involved in transmission might inform the discovery of novel drugs that interrupt this essential step in the parasite life cycle.


2016 ◽  
Vol 113 (26) ◽  
pp. 7183-7188 ◽  
Author(s):  
Jorge M. Santos ◽  
Neuza Duarte ◽  
Jessica Kehrer ◽  
Jai Ramesar ◽  
M. Cristina Avramut ◽  
...  

Transmission of the malaria parasite from the mammalian host to the mosquito vector requires the formation of adequately adapted parasite forms and stage-specific organelles. Here we show that formation of the crystalloid—a unique and short-lived organelle of the Plasmodium ookinete and oocyst stage required for sporogony—is dependent on the precisely timed expression of the S-acyl-transferase DHHC10. DHHC10, translationally repressed in female Plasmodium berghei gametocytes, is activated translationally during ookinete formation, where the protein is essential for the formation of the crystalloid, the correct targeting of crystalloid-resident protein LAP2, and malaria parasite transmission.


2020 ◽  
Author(s):  
David S. Guttery ◽  
Abhinay Ramaprasad ◽  
David J. P. Ferguson ◽  
Mohammad Zeeshan ◽  
Rajan Pandey ◽  
...  

AbstractThe Meiotic Recombination 11 protein (MRE11) plays a key role in DNA damage response and maintenance of genome stability. However, little is known about its function during development of the malaria parasite Plasmodium. Here, we present a functional, ultrastructural and transcriptomic analysis of Plasmodium MRE11 during its life-cycle in both mammalian and mosquito vector hosts. Genetic disruption of Plasmodium berghei mre11 (PbMRE11) results in significant retardation of oocyst development in the mosquito midgut associated with cytoplasmic and nuclear degeneration, along with concomitant ablation of sporogony and subsequent parasite transmission. Further, absence of PbMRE11 results in significant transcriptional downregulation of genes involved in key interconnected biological processes that are fundamental to all eukaryotic life including ribonucleoprotein biogenesis, spliceosome function and iron-sulphur cluster assembly. Overall, our study provides a comprehensive functional analysis of MRE11’s role in Plasmodium development during the mosquito stages and offers a potential target for therapeutic intervention during malaria parasite transmission.


2021 ◽  
Author(s):  
Floriane Almire ◽  
Sandra Terry ◽  
Melanie McFarlane ◽  
Agnieszka M. Sziemel ◽  
Selim Terhzaz ◽  
...  

AbstractAs mosquito females require a blood meal to reproduce, they can act as vectors of numerous pathogens, such as arboviruses (e.g. Zika, dengue and chikungunya viruses), which constitute a substantial worldwide public health burden. In addition to blood meals, mosquito females can also take sugar meals to get carbohydrates for their energy reserves. It is now recognised that diet is a key regulator of health and disease outcome through interactions with the immune system. However, it has been mostly studied in humans and model organisms. So far, the impact of sugar feeding on mosquito immunity and in turn, how this could affect vector competence for arboviruses has not been analysed. Here, we show that sugar feeding increases and maintains antiviral immunity in the digestive tract of the main arbovirus vector Aedes aegypti. Our data demonstrate that the gut microbiota does not mediate the sugar-induced immunity but partly inhibits it. Importantly, sugar intake prior to an arbovirus-infected blood meal further protects females against infection with arboviruses from different families, highlighting a broad antiviral action of sugar. Sugar feeding blocks arbovirus initial infection and dissemination from the gut, lowers infection prevalence and intensity, thereby decreasing transmission potential of female mosquitoes. Overall, our findings uncover a crucial role of sugar feeding in mosquito antiviral immunity and vector competence for arboviruses. Since Ae. aegypti almost exclusively feed on blood in some natural settings, our findings suggest that this could increase the spread of mosquito-borne arboviral diseases.


2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Joseph M. Wagman ◽  
Kenyssony Varela ◽  
Rose Zulliger ◽  
Abuchahama Saifodine ◽  
Rodaly Muthoni ◽  
...  

Abstract Background The need to develop new products and novel approaches for malaria vector control is recognized as a global health priority. One approach to meeting this need has been the development of new products for indoor residual spraying (IRS) with novel active ingredients for public health. While initial results showing the impact of several of these next-generation IRS products have been encouraging, questions remain about how to best deploy them for maximum impact. To help address these questions, a 2-year cluster-randomized controlled trial to measure the impact of IRS with a microencapsulated formulation of pirimiphos-methyl (PM) in an area with high ownership of long-lasting insecticidal nets (LLINs) was conducted in a high-transmission district of central Mozambique with pyrethroid resistant vectors. Presented here are the results of the vector surveillance component of the trial. Methods The 2 year, two-armed trial was conducted in Mopeia District, Zambezia Province, Mozambique. In ten sentinel villages, five that received IRS with PM in October–November 2016 and again in October–November 2017 and five that received no IRS, indoor light trap collections and paired indoor-outdoor human landing collections catches (HLCs) were conducted monthly from September 2016 through October 2018. A universal coverage campaign in June 2017, just prior to the second spray round, distributed 131,540 standard alpha-cypermethrin LLINs across all study villages and increased overall net usage rates in children under 5 years old to over 90%. Results The primary malaria vector during the trial was Anopheles funestus sensu lato (s.l.), and standard World Health Organization (WHO) tube tests with this population indicated variable but increasing resistance to pyrethroids (including alpha-cypermethrin, from > 85% mortality in 2017 to 7% mortality in 2018) and uniform susceptibility to PM (100% mortality in both years). Over the entire duration of the study, IRS reduced An. funestus s.l. densities by 48% (CI95 33–59%; p < 0.001) in indoor light traps and by 74% (CI95 38–90%; p = 0.010) during indoor and outdoor HLC, though in each study year reductions in vector density were consistently greatest in those months immediately following the IRS campaigns and waned over time. Overall there was no strong preference for An. funestus to feed indoors or outdoors, and these biting behaviours did not differ significantly across study arms: observed indoor-outdoor biting ratios were 1.10 (CI95 1.00–1.21) in no-IRS villages and 0.88 (CI95 0.67–1.15) in IRS villages. The impact of IRS was consistent in reducing HLC exposures both indoors (75% reduction: CI95 47–88%; p = 0. < 0.001) and outdoors (68% reduction: CI95 22–87%; p = 0.012). While substantially fewer Anopheles gambiae s.l. were collected during the study, trends show a similar impact of IRS on this key vector group as well, with a 33% (CI95 7–53%; p = 0.019) reduction in mosquitoes collected in light traps and a non-statistically significant 39% reduction (p = 0.249) in HLC landing rates. Conclusion IRS with PM used in addition to pyrethroid-only LLINs substantially reduced human exposures to malaria vectors during both years of the cluster-randomized controlled trial in Mopeia—a high-burden district where the primary vector, An. funestus s.l., was equally likely to feed indoors or outdoors and demonstrated increasing resistance to pyrethroids. Findings suggest that IRS with PM can provide effective vector control, including in some settings where pyrethroid-only ITNs are widely used. Trial registrationclinicaltrials.gov, NCT02910934. Registered 22 September 2016, https://www.clinicaltrials.gov/ct2/show/NCT02910934.


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