Development of a Gravid Trap for Collecting Live Malaria Vectors Anopheles gambiae s.l.

Malaria parasites are transmitted to humans by infectious female Anopheles mosquitoes. Chemical-insecticide-based mosquito control has been successful in reducing the burden of malaria. However, the emergence of insecticide resistance in malaria vectors and concerns about the effect of the chemicals on the environment, human health, and non-target organisms present a need for new or alternative vector control intervention tools. Biocontrol methods using aquatic invertebrate predators have emerged as a potential alternative and additional tool to control mosquito populations. Ecological control specifically makes use of species insights for improving the physical habitat conditions of competitors and predators of vectors. A first step towards this is to gain knowledge on the predation potential of several typically present macroinvertebrates. Hence, this study aimed at (1) examining the influence of the predation of hemipterans on the number of emerging adult mosquitoes and (2) detecting Anopheles mosquito DNA in the gut of those predators. The prey and predators were collected from a range of water bodies located in the Gilgel Gibe watershed, southwest Ethiopia. A semi-field study was carried out using mesocosms which were constructed using plastic containers mimicking the natural aquatic habitat of immature Anopheles mosquitoes. Adult mosquitoes that emerged from the mesocosms were collected using a mechanical aspirator. At the end of the experiment, predators were withdrawn from the mesocosms and identified to genus level. Polymerase Chain Reaction (PCR) was employed to identify sibling species of Anopheles gambiae s.l. and to detect Anopheles mosquito DNA in the gut of the predators. Data were analysed using R software. Giant water bugs (belostomatids) were the most aggressive predators of Anopheles larvae, followed by backswimmers (notonectids) and water boatmen (corixids). All female Anopheles gambiae s.l. emerged from the mesocosms were identified as Anopheles arabiensis. Anopheles arabiensis DNA was detected in the gut content of hemipteran specimens analysed from the three families. The number of the adult mosquitoes emerging from the mesocosms was affected by the presence of predators. The findings of this study provide evidence of the potential use of aquatic macroinvertebrate predators as biocontrol agents against immature Anopheles mosquitoes and their potential to be considered as a component of integrated vector management for insecticide resistance and the combined restoration of aquatic ecosystems via smart ecological engineering.

Download Full-text

Insecticide resistance in indoor and outdoor-resting Anopheles gambiae s.l. in Northern Ghana

10.21203/rs.3.rs-17402/v1 ◽

2020 ◽

Author(s):

Majidah Hamid-Adiamoh ◽

Alfred Amambua-Ngwa ◽

Davis Nwakanma ◽

Umberto D’Alessandro ◽

Gordon A. Awandare ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Gambiae ◽

Blood Meal ◽

Northern Ghana ◽

Malaria Vectors ◽

Glutathione S Transferase ◽

Metabolic Resistance ◽

Anopheles Gambiae S.L ◽

Outdoor Resting ◽

Resting Behavior

Abstract Background Selection pressure from continued exposure to insecticides drives the development of insecticide resistance and changes in resting behavior of malaria vectors, which may support residual transmission in several endemic settings. There is a need to understand how resistance drives changes in resting behavior within vector species. Here, we examined the association between insecticide resistance and resting behavior of Anopheles gambiae s.l. in Northern Ghana. Methods Adult mosquitoes were collected both indoors and outdoors from two communities using mouth aspirators and pit shelters. F1 progenies from a subset of mosquitoes were exposed to dichloro diphenyl trichloroethane (DDT), deltamethrin, malathion and bendiocarb using WHO insecticide susceptibility tests. Insecticide resistance markers including voltage-gated sodium channel (Vgsc)- 1014F, Vgsc-1014S, Vgsc-1575Y, glutathione-S-transferase epsilon 2 (GSTe2)-114T and acetylcholinesterase (Ace1)-119S, as well as blood meal sources were investigated using PCR methods. Activities of metabolic enzymes, acetylcholine esterase (AChE), non-specific β-esterases, glutathione-S-transferase (GST) and monooxygenases (oxidases) were measured from unexposed F1 progenies using microplate assays. Results Susceptibility of An. coluzzii to deltamethrin 24hr post-exposure was significantly higher in indoor (mortality=5%) than the outdoor (mortality=2.5%) populations (P=0.02). The mosquitoes were fully susceptible to malathion (mortality: indoor=98%, outdoor=100%). Susceptibility to DDT was significantly higher in outdoor (mortality=9%) than indoor (mortality=0%) mosquitoes (P=0.006). Mosquitoes were also found with suspected resistance to bendiocarb but mortality was not statistically different (mortality: indoor=90%, outdoor=95%. P=0.30). The frequencies of all resistance alleles were higher in F1 outdoor (0.11-0.85) than indoor (0.04-0.65) mosquito populations, while Vgsc-1014F in F0 An. gambiae s.s significantly associated with outdoor-resting behavior (P=0.01). Activities of non-specific β-esterase enzymes were significantly higher in outdoor than indoor mosquitoes (Mean enzyme activity: Outdoor=: 1.70/mg protein; Indoor=1.35/mg protein. P<0.0001). AChE activity was also more elevated in outdoor (0.62/mg protein) than indoor (0.57/mg protein) mosquitoes but this was not significant (P=0.08). Human blood index (HBI) was predominantly detected in indoor (18%) than the outdoor mosquito population (3%).Conclusions These findings revealed higher phenotypic resistance in indoor than outdoor-resting mosquitoes, but genotypic and metabolic resistance levels were higher in outdoor than the indoor mosquito populations. However, the overall results did not establish that there was a significant preference of resistant malaria vectors to solely rest indoors or outdoors, but varied depending on the resistant alleles present. Indication that human and animal blood meal indices were more prevalent in indoor-resting mosquitoes was also shown. Continued monitoring of changes in resting behavior within An. gambiae s.l. populations is recommended.

Download Full-text

Human biting rhythm of Anopheles gambiae s.l. and sleeping behaviour of pregnant women in a lagoon area in Southern Benin

10.21203/rs.3.rs-396314/v1 ◽

2021 ◽

Author(s):

Armel DJENONTIN ◽

Aziz BOURAÏMA ◽

Christophe SOARES ◽

Seun EGBINOLA ◽

Gilles COTTRELL

Keyword(s):

Plasmodium Falciparum ◽

Pregnant Women ◽

Anopheles Gambiae ◽

Early Morning ◽

Allelic Frequency ◽

Malaria Vectors ◽

Mosquito Nets ◽

Anopheles Gambiae S.L ◽

Almost All ◽

Southern Benin

Abstract ObjectiveIn the framework of EVALMOUS study aiming to assess the use and effectiveness of mosquito nets by pregnant women and other members of their household in a lagoon area in southern Benin, the behaviour of pregnant women relative to the time they go to bed using the net were recorded. Malaria vectors biting rhythm, Plasmodium falciparum infection and insecticide resistance genes in malaria vectors were also determined.ResultsOverall, 3848 females of Anopheles gambiae s. l. were collected and 280 pregnant women responded to the survey. Almost all Anopheles gambiae s. l. tested were Anopheles coluzzi with the exception of two, which were Anopheles melas. The CSP index in malaria vector was 1.85% and the allelic frequency of kdr gene was 74.4%. Around 90% of bites and Plasmodium falciparum transmission occurred between 10 p.m. and 6 a.m., which coincides with the period when more than 80% of pregnant women were under bednet. Despite a slight early evening and early morning biting activity of malaria vectors in the study area, the good use of nets might remain a useful protection tool against mosquito biting and malaria transmission.

Download Full-text

Hétérogénéité génétique et résistance des vecteurs du paludisme (Anopheles gambiae s.l) aux insecticides en zone cotonnière au Benin

International Journal of Biological and Chemical Sciences ◽

10.4314/ijbcs.v14i8.6 ◽

2020 ◽

Vol 14 (8) ◽

pp. 2724-2736

Author(s):

Rock Aikpon ◽

Antoine Missihoun ◽

Antoine Lokossou ◽

Gorgias Aikpon ◽

Sahidou Salifou ◽

...

Keyword(s):

Anopheles Gambiae ◽

Genetic Resistance ◽

Malaria Vectors ◽

Human Landing Catch ◽

Anopheles Coluzzii ◽

Resistance Allele ◽

Two Samples ◽

Mosquito Collection ◽

Anopheles Gambiae S.L ◽

Mutation Kdr

La résistance des vecteurs du paludisme aux insecticides utilisés dans la lutte anti vectorielle est un obstacle majeur pour les programmes nationaux de lutte contre le paludisme. La présente étude avait pour but d’évaluer la diversité génétique des populations de Anopheles gambiae et la résistance aux insecticides (mutation Kdr et Ace-1) en zone cotonnière au Bénin. Deux méthodes de capture ont été utilisées pour la collecte d’échantillon. La capture sur appât humain et la récolte de la faune résiduelle matinale par spray. La PCR SINE a permis de distinguer deux espèces jumelles et d’obtenir les différents génotypes pour les deux gènes. Deux espèces du complexe An. gambiae s.l ont été trouvées en sympatrie (Anopheles coluzzii et Anopheles gambiae). La résistance kdr et Ace-1 connaissent un flux saisonnier. L’allèle résistant du gène kdr est fixé dans la population de vecteurs (Fis>0). Par contre, un déficit de l’allèle résistant est noté au niveau du gène Ace-1 (Fis<0).Mots clés : Hétérogénéité, génétique, résistance, vecteur, paludisme. English Title: Genetic heterogeneity and resistance to insecticides in malaria vector Anopheles gambiae s.l in the cotton growing area in Benin Resistance of malaria vectors to insecticides used in vector control is a major threat for national malaria control programs. The purpose of this study was to assess the genetic diversity of Anopheles gambiae populations and resistance to insecticides (Kdr Ace-1 mutation) in the cotton growing area in Benin. Two samples methods were used for mosquito collection: Human Landing catch (HLC) and the residual fauna collection by spray. The SINE PCR allow to identify species the different genotypes resistance genes. Two species of the An. gambiae s.l complex have been found in sympatry (Anopheles coluzzii and Anopheles gambiae). kdr and Ace-1 resistance had seasonal variation trend. The kdr resistance allele is fixed in the vector population (Fis> 0). Moreover, a deficit of the Ace-1 resistance allele was observed (Fis <0). Keywords: Heterogeneity, genetic, resistance, vector, malaria.

Download Full-text

Anopheles gambiae (s.l.) exhibit high intensity pyrethroid resistance throughout Southern and Central Mali (2016–2018): PBO or next generation LLINs may provide greater control

10.21203/rs.2.24378/v4 ◽

2020 ◽

Author(s):

Arthur Sovi ◽

Chitan Keita ◽

Youssouf Sinaba ◽

Abdourhamane Dicko ◽

Ibrahim Traore ◽

...

Keyword(s):

Anopheles Gambiae ◽

High Intensity ◽

Pyrethroid Resistance ◽

Fold Increase ◽

Malaria Vectors ◽

Effective Control ◽

Pirimiphos Methyl ◽

Anopheles Gambiae S.L ◽

Agricultural Use ◽

Rotation Strategy

Abstract Background: Millions of pyrethroid LLINs have been distributed in Mali during the past 20 years which, along with agricultural use, has increased the selection pressure on malaria vector populations. This study investigated pyrethroid resistance intensity and susceptible status of malaria vectors to alternative insecticides to guide choice of insecticides for LLINs and IRS for effective control of malaria vectors. Methods: For 3 years between 2016 and 2018, susceptibility testing was conducted annually in 14–16 sites covering southern and central Mali. Anopheles gambiae (s.l.) were collected from larval sites and adult mosquitoes exposed in WHO tube tests to diagnostic doses of bendiocarb (0.1%) and pirimiphos-methyl (0.25%). Resistance intensity tests were conducted using CDC bottle bioassays (2016–2017) and WHO tube tests (2018) at 1×, 2×, 5×, and 10× the diagnostic concentration of permethrin, deltamethrin and alpha-cypermethrin. WHO tube tests were conducted with pre-exposure to the synergist PBO followed by permethrin or deltamethrin. Chlorfenapyr was tested in CDC bottle bioassays at 100 µg active ingredient per bottle and clothianidin at 2% in WHO tube tests. PCR was performed to identify species within the An. gambiae complex. Results: In all sites An. gambiae (s.l.) showed high intensity resistance to permethrin and deltamethrin in CDC bottle bioassay tests in 2016 and 2017. In 2018, the WHO intensity tests resulted in survivors at all sites for permethrin, deltamethrin and alpha-cypermethrin when tested at 10× the diagnostic dose. Across all sites mean mortality was 33.7% with permethrin (0.75%) compared with 71.8% when pre-exposed to PBO (4%), representing a 2.13-fold increase in mortality. A similar trend was recorded for deltamethrin. There was susceptibility to pirimiphos-methyl, chlorfenapyr and clothianidin in all surveyed sites, including current IRS sites in Mopti Region. An. coluzzii was the primary species in 4 of 6 regions. Conclusions: Widespread high intensity pyrethroid resistance was recorded during 2016–2018 and is likely to compromise the effectiveness of pyrethroid LLINs in Mali. PBO or chlrofenapyr LLINs should provide improved control of An. gambiae (s.l.). Clothianidin and pirimiphos-methyl insecticides are currently being used for IRS as part of a rotation strategy based on susceptibility being confirmed in this study.

Download Full-text

Insecticide resistance status of malaria vectors Anopheles gambiae s.l of southwest Burkina Faso and residual efficacy of indoor residual spraying with microencapsulated pirimiphos-methyl insecticide

10.1101/2020.07.13.200865 ◽

2020 ◽

Author(s):

Dieudonné D. Soma ◽

Barnabas M. Zogo ◽

François D. Hien ◽

Aristide S. Hien ◽

Didier P.A. Kaboré ◽

...

Keyword(s):

Insecticide Resistance ◽

Burkina Faso ◽

Anopheles Gambiae ◽

Local Population ◽

Indoor Residual Spraying ◽

Susceptible Strain ◽

Malaria Vectors ◽

Pirimiphos Methyl ◽

Anopheles Gambiae S.L ◽

Residual Efficacy

AbstractThe rapid spread of insecticide resistance in malaria vectors and the rebound in malaria cases observed recently in some endemic areas underscore the urgent need to evaluate and deploy new effective control interventions. A randomized control trial was conducted with the aim to investigate the benefit of deploying complementary strategies, including indoor residual spraying (IRS) with pirimiphos-methyl, in addition to long-lasting insecticidal nets (LLINs) in Diébougou, southwest Burkina Faso. We measured the susceptibility of Anopheles gambiae s.l. population from Diébougou to conventional insecticides. We further monitored the efficacy and residual activity of pirimiphos-methyl on both cement and mud walls using a laboratory susceptible strain (Kisumu) and the local An. gambiae s.l. population. An. Gambiae s.l. from Diébougou was resistant to pyrethroids (deltamethrin, permethrin and alphacypermethrin) and bendiocarb but showed susceptibility to organophosphates (pirimiphos-methyl and chlorpyrimiphos-methyl). A mixed-effect generalized linear model predicted that pirimiphos-methyl applied on cement or mud walls was effective for 210 days against the laboratory susceptible strain and 247 days against the local population. The residual efficacy of pirimiphos-methyl against the local population on walls made of mud was similar to that of cement (OR=0.792, [0.55-1.12], Tukey’s test p-value =0.19). This study showed that one round of IRS with pirimiphos-methyl CS has the potential to control the multi-resistant An. gambiae s.l. population from Southwest Burkina Faso for at least 7 months, regardless of the type of wall.

Download Full-text

Insecticide resistance status of three malaria vectors, Anopheles gambiae (s.l.), An. funestus and An. mascarensis, from the south, central and east coasts of Madagascar

Parasites & Vectors ◽

10.1186/s13071-017-2336-9 ◽

2017 ◽

Vol 10 (1) ◽

Cited By ~ 9

Author(s):

Jean-Desire Rakotoson ◽

Christen M. Fornadel ◽

Allison Belemvire ◽

Laura C. Norris ◽

Kristen George ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Gambiae ◽

Malaria Vectors ◽

The South ◽

South Central ◽

Anopheles Gambiae S.L

Download Full-text

Insecticide resistance in indoor and outdoor-resting Anopheles gambiae s.l. in Northern Ghana

10.21203/rs.3.rs-17402/v2 ◽

2020 ◽

Author(s):

Majidah Hamid-Adiamoh ◽

Alfred Amambua-Ngwa ◽

Davis Nwakanma ◽

Umberto D’Alessandro ◽

Gordon A. Awandare ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Gambiae ◽

Blood Meal ◽

Northern Ghana ◽

Malaria Vectors ◽

Glutathione S Transferase ◽

Metabolic Resistance ◽

Anopheles Gambiae S.L ◽

Outdoor Resting ◽

Resting Behavior

Abstract Background: Selection pressure from continued exposure to insecticides drives the development of insecticide resistance and changes in resting behavior of malaria vectors, which may support residual transmission in several endemic settings. There is a need to understand how resistance drives changes in resting behavior within vector species. Here, we examined the association between insecticide resistance and resting behavior of Anopheles gambiae s.l. in Northern Ghana. Methods: Adult mosquitoes were collected both indoors and outdoors from two communities using mouth aspirators and pit shelters. F1 progenies from a subset of mosquitoes were exposed to dichloro diphenyl trichloroethane (DDT), deltamethrin, malathion and bendiocarb using WHO insecticide susceptibility tests. Insecticide resistance markers including voltage-gated sodium channel (Vgsc)- 1014F, Vgsc-1014S, Vgsc-1575Y, glutathione-S-transferase epsilon 2 (GSTe2)-114T and acetylcholinesterase (Ace1)-119S, as well as blood meal sources were investigated using PCR methods. Activities of metabolic enzymes, acetylcholine esterase (AChE), non-specific β-esterases, glutathione-S-transferase (GST) and monooxygenases (oxidases) were measured from unexposed F1 progenies using microplate assays. Results: Susceptibility of An. coluzzii to deltamethrin 24hr post-exposure was significantly higher in indoor (mortality=5%) than the outdoor (mortality=2.5%) populations (P=0.02). The mosquitoes were fully susceptible to malathion (mortality: indoor=98%, outdoor=100%). Susceptibility to DDT was significantly higher in outdoor (mortality=9%) than indoor (mortality=0%) mosquitoes (P=0.006). Mosquitoes were also found with suspected resistance to bendiocarb but mortality was not statistically different (mortality: indoor=90%, outdoor=95%. P=0.30). The frequencies of all resistance alleles were higher in F1 outdoor (0.11-0.85) than indoor (0.04-0.65) mosquito populations, while Vgsc-1014F in F0 An. gambiae s.s significantly associated with outdoor-resting behavior (P=0.01). Activities of non-specific β-esterase enzymes were significantly higher in outdoor than indoor mosquitoes (Mean enzyme activity: Outdoor=: 1.70/mg protein; Indoor=1.35/mg protein. P<0.0001). AChE activity was also more elevated in outdoor (0.62/mg protein) than indoor (0.57/mg protein) mosquitoes but this was not significant (P=0.08). Human blood index (HBI) was predominantly detected in indoor (18%) than the outdoor mosquito population (3%). Conclusions: These findings revealed higher phenotypic resistance in indoor than outdoor-resting mosquitoes, but genotypic and metabolic resistance levels were higher in outdoor than the indoor mosquito populations. However, the overall results did not establish that there was a significant preference of resistant malaria vectors to solely rest indoors or outdoors, but varied depending on the resistant alleles present. Indication that human and animal blood meal indices were more prevalent in indoor-resting mosquitoes was also shown. Continued monitoring of changes in resting behavior within An. gambiae s.l. populations is recommended.

Download Full-text

Effect of Bacillus thuringiensis var. israelensis Sugar Patches on Insecticide Resistant Anopheles gambiae s.l. Adults

Journal of Medical Entomology ◽

10.1093/jme/tjz058 ◽

2019 ◽

Vol 56 (5) ◽

pp. 1312-1317 ◽

Cited By ~ 2

Author(s):

Sévérin N’do ◽

Koama Bayili ◽

Bazoma Bayili ◽

Moussa Namountougou ◽

Roger Sanou ◽

...

Keyword(s):

Bacillus Thuringiensis ◽

Guinea Pig ◽

Anopheles Gambiae ◽

Indoor Residual Spraying ◽

Malaria Vectors ◽

Bed Nets ◽

Sugar Solution ◽

Bed Net ◽

Anopheles Gambiae S.L ◽

Large Tunnel

AbstractBackgroundLarge distribution of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) contributed to a significant decrease in malarial mortality. Unfortunately, large insecticide resistance in malaria vectors occurred and is a threat to the future use of these control approaches. The purpose of this study was to explore a new approach for vector control. Patches containing Bacillus thuringiensis var. israelensis (Bti) solubilized Cry toxins mixed with sugar were developed and tested in the laboratory with pyrethroid-resistant Anopheles gambiae s.l. using tunnel tests.MethodsMosquitoes were released at 6:00 p.m. into a large tunnel separated by a bed net, perforated with nine holes, from a smaller chamber with a guinea pig. Nine Bti sugar patches (BSPs) were attached to the bed net between the nine holes. Fourteen hours later (8:00 a.m.), mosquitoes were collected from the tunnel and the guinea pig chamber. Live females were kept in cups and were fed a sugar solution (5%) for 72 h and delayed mortality was followed. The results were reported as passing, blood fed and mortality rates.ResultsMosquito populations that are resistant to the insecticides in the bed net, exhibited high mortality (60%) in the presence of the BSPs. Untreated bed nets with patches in the tunnel test killed 66–95% of the mosquitoes that landed and untreated bed nets were superior to treated bed nets.ConclusionBSPs efficiently kill resistant mosquitoes that land on treated and untreated bed nets and thus could ultimately reduce the number of vector-borne malarial mosquitoes.

Download Full-text