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Cues involved in mate seeking and recognition prevent hybridization and can be involved in speciation processes. In malaria mosquitoes, females of the two sibling species Anopheles gambiae s.s. and An. coluzzii mate in monospecific male swarms and hybrids are rare. Long-range sex pheromones driving this behavior have been debated in literature but to date, no study has proven their existence or their absence. Here, we attempted to bring to light their existence. To put all the odds in our favor, we used different chemical ecology methods such as behavioral and electrophysiological assays as well chemical analyses, and we worked with mosquitoes at their optimal physiological mating state i.e. with swarming males during their natural swarming windows. Despite all our efforts, our results support the absence of long-range sex pheromones involved in swarm detection and recognition by females. We briefly discuss the implications of this finding in ecology, evolution and for control strategies.

The crude extracts of leaves of Aristolochia elegans Mast (Aristolochiaceae) collected from Rombo district in Kilimanjaro, Tanzania (3˚11ʹ15.4ʹʹS 37˚37ʹ05.5ʹʹE), were obtained by maceration of sample at room temperature followed by phytochemical analysis by GC-MS. The GC-MS analysis of the extracts showed that the main content was Caryophyllene among all extract investigated, followed by Calarene and Bicyclogermacrene. The crude extracts were then evaluated for larvicidal activity using World Health Organization (WHO) procedures against the third Instar larvae of Anopheles gambiae and monitored at an interval of 24 h, from 24 to 72 h and activity was recorded for various concentrations of the ranging from 25 to 200.0 μg/mL. Mortality effect of investigated extracts against laboratory-reared larvae had variations indicated by their LC50. LC50 for ethanol leaf extract were 165 µg/mL and 135 µg/mL after 48 and 72 h, respectively. LC50 for dichloromethane leaf extract were 145 µg/mL and 136 µg/mL after 48 and 72 h, respectively. For n-hexane extract, LC50 were 34 µg/mL and 33 µg/mL after 48 and 72 h, respectively. The remarkable differences in the larvicidal activity of crude extracts against the larvae of A. gambiae were due to qualitative and quantitative variations of the components, exemplified by the presence of sesquiterpenes with caryophyllene skeleton. The findings indicate that n-hexane leaf extract has potentials for use in the control of A. gambiae larvae and may be useful in the search for novel and effective natural compounds as larvicides.

Each year, over 200 million people are infected with the malaria parasite, nearly half a million of whom succumb to the disease. Emerging genetic technologies could, in theory, eliminate the burden of malaria throughout the world by intentionally eradicating the mosquitoes that transmit the disease. In this paper, we offer an ethical examination of the intentional eradication of Anopheles gambiae, the main malaria vector of sub-Saharan Africa. In our evaluation, we focus on two main considerations: the benefit of alleviating the malaria burden, and the loss of value that would accompany the eradication of the species. We outline a typology of the different ways in which species are valued or could be valuable, then use that typology to appraise the value of the species in question. We argue that Anopheles gambiae has minor (and redundant) instrumental value, little final subjective value and no objective final value.

This study was aimed to investigate thecurrent insecticide resistance status in malaria vector mosquitoes from Dogbo district in South-western Benin, West Africa. Larvae and pupae ofAnopheles gambiae s.l.populations were collected from the breeding sites from March to July 2020 during the first rainy season in Couffo department using the dipping method. WHO susceptibility tests were conducted on unfed female mosquitoes aged 2-5 days old. WHO bioassays were performed with impregnated papers of permethrin (0.75%), deltamethrin (0.05%), cyfluthrin (0.15%), lambdacyhalothrin (0.05%) and dichlorodiphenyltrichloroethane (DDT) (4%).An. gambiaes.l.populations from Dogbo district were resistant to permethrin, deltamethrin, cyfluthrin, lambdacyhalothrin and DDT. There is cross-resistance to both pyrethroid and DDT insecticides. However, the physical barrier of Long Lasting Insecticidal Nets (LLINs) which are regularly distributed free by Beninese National Malaria Control Programme throughout the entire country to increase coverage of LLINs is still important despite the insecticide resistance observed.

The current study was aimed to compare the susceptibility to deltamethrin in female adultAnopheles gambiae s.l.from Dogbo district with their F1 progeny susceptibility in South-Western Benin, West Africa. Larvae and pupae ofAnopheles gambiae s.l.populations were collected from the breeding sites in Couffo department in 2020 and reared up for obtaining F1 progeny. Female adultAn. gambiae s.l.mosquitoes were also collected from window traps put on windows of rooms in Dogbo district surveyed.An. gambiae s.l.mosquitoes were collected from March to July and August to November 2020 during the rainy season in the locations of Ayomi, Dévé, Honton, Lokogohoué, Madjrè and Totchangni. Female adultAn. gambiaespecies collected from window traps were morphologically identified using morphological keys and then transferred into mosquito cages for WHO bioassays performed with impregnated papers of deltamethrin (0.05%). WHO bioassays were also performed with F1 progeny. The physiological age of female adultAn. gambiae s.l.collected from window traps was determined through dissection using Detinova method. The results showed that the mortality rates recorded with female adultAn. gambiae s.l.mosquitoes collected from window traps were higher than those obtained with their F1 progenyAn. gambiae s.l.mosquitoes obtained after reproduction of parent mosquitoes. The current study clearly shows that changes in mosquito physiology occur with senescence.

Background Pyrethroids are the most widely used insecticides for the control of malaria transmitting Anopheles gambiae mosquitoes and rapid increase in resistance to this insecticide class is of major concern. Pyrethroids target the Voltage Gated Sodium Channels (VGSCs), that have a key role in the normal function of the mosquitoes' nervous system. VGSC mutations L995F and L995S have long been associated with pyrethroid resistance and screening for their presence is routine in insecticide resistance management programs. Recently, a VGSC haplotype containing two amino acid substitutions associated with resistance in other species, V402L and I1527T, was identified. These two VGSC mutations are found in tight linkage and are mutually exclusive to the classical L995F/S mutations. Results We identify the presence of the V402L-I1527 T haplotype in resistant An. coluzzii colonized strains and in field populations from Burkina Faso at frequencies higher than previously reported; in some cases almost reaching fixation. Functional validation of V402L in insecticide resistance using a CRISPR/Cas9 genome modified line showed that it confers reduced mortality after exposure to all tested pyrethroids and DDT, but at lower levels compared to L995F. In contrast however to L995F, no fitness costs were identified for mosquitoes carrying V402L under laboratory conditions. Conclusion The V402L substitution confers pyrethroid resistance in An. gambiae in the absence of any other VGSC substitution and/or alternative resistance mechanisms. The lower fitness cost associated with this kdr mutation may provide a selective advantage over the classical kdr in some settings and genotyping at this locus should be added in the list of resistant alleles for routine screening. This article is protected by copyright. All rights reserved.

The use of chemical insecticides causes important damages to environment and human health and there is a need to search for alternative solutions. This study aims to investigate on the effect of coconut oil onAnopheles gambiae sensu latolarvae tolerance in malaria vector control in Dogbo district in south-western Benin, West Africa. Larvae ofAnopheles gambiae s.l.mosquitoes were collected from breeding sites using the dipping method in May 2020 during the rainy season in Dogbo district. A batch of 25 larvae of fourth instar were exposed to a mixture of coconut oil with distilled water saturated with oxygen containing in each of five glass jars or test cups of same dimensions contained each 48 ml distilled water saturated with oxygen plus 2 ml of coconut oil and one control jar containing no trace of coconut oil. Larval mortality was recorded after 24 hours, 48 hours and 72hours exposure. The results show that the use of coconut oil causes full-grown Anopheles larvae to die by suffocation. After the application of this mixture, the larvae of four instars cannot breathe. The use of coconut oil is effective method for disturbing the siphonal respiration of mosquito larvae. Coconut oil is effective method for mosquito larvae control.

The use of chemical insecticides causes important damages to environment and human health and there is a need to search for alternative solutions. This study aims to investigate on the effect of aqueous extract of lemon inAnopheles gambiaes.l.larvae tolerance in couffo department in south-western Republic of Benin, West Africa. Larvae ofAnopheles gambiae s.lmosquitoes were collected from breeding sites using the dipping method in July 2020 during the rainy season in Dogbo district. A batch of 15 larvae of fourth instar were exposed to a mixture of aqueous extract of lemon with distilled water saturated with oxygen containing in each of five glass jars or test cups of same dimensions contained each 48 ml distilled water saturated with oxygen plus 2 ml of aqueous extract of lemon (Citrus limon)and one control jar containing no trace of aqueous extract of lemon. Larval mortality was recorded after 24hours, 48hours and 72hours exposure. The results show that the use of aqueous extract of lemon causes full-grown Anopheles larvae to die by suffocation. After the application of this mixture, the larvae of four instars cannot breathe. The use of aqueous extract of lemon is effective method for disturbing the siphonal respiration of mosquito larvae. Aqueous extract of lemon is effective method for mosquito larvae control.

Aim: In a view to determining the capacity of Clerodendrum polycephalum to control mosquitoes, the methanol extract of the leaf was investigated for insecticidal activities using three species of mosquitoes, Aedes aegypti, Anopheles gambiae and Culex quinquefasciatus. Methodology: The leaves of C. polycephalum were collected, dried and extracted with methanol. Mosquito larvae were exposed to different concentrations for 24/48h. and sublethal concentrations (L25, 50, 75) of the extract to determine larvicidal activity and monitor growth and development respectively. Twenty (20) blood-fed female Aedes aegyti mosquitoes were allowed to lay eggs on treated filter papers for antioviposition bioassay. The crude extract was separated into N-hexane, Dichloromethane, ethyl-acetate, ethanol fractions using Vacuum Liquid Chromatography to determine the active fraction. Results: Results showed that larval mortalities were in the order C. quiquefasciatus>A. gambiae>A. aegypti with effective concentration ranging from 250 – 8000 ppm. Mortalities at 48hr were significantly different (p

An evaluation of fly pests of cattle was conducted in Federal College of Animal Health and Production Technology (FCAH&PT) Farm, Chaha Village, Jos South Local Government Area, Plateau State, Nigeria between August and October, 2020. Samples were collected from the farm weekly for three months. A total of nine hundred and nineteen (919) adult dipterous flies comprising fifteen species in eight genera across the three sub-orders were caught and identified using aerial sweeping hand net, light trapping and aerial insecticide spray. Phlebotomus papaltasi (44.18%) was the most prevalent while Simulium damnosum (0.22%) was the least. Others were Musca domestica (17.73%), Stomoxys calcitrans (11.43%), Culicoides species (10.99%), Musca autumnalis (10.23%), mosquitoes – Anopheles gambiae/Culex quequinfasciatus (4.89%) and Tabanus species (0.33%). The haematophagous flies (72.04%) out-numbered the non-haematophagous flies (27.96%) and the number of females collected/caught 780 (84.87%) were higher than the males 139 (15.13%). The highest collections were made in October (353 representing 38.41%) while September had the lowest (263 /28.62%). The study established the presence of fly pests in the farm and recommends that appropriate control measures should be put in place to forestall any disease outbreak.

The objectives of this study were to determine the chemical composition and to evaluate the mosquito repellent property of essential oils extracted from the bark of the stem of Sterculia tragacantha Lindl on Anopheles gambiae, vector of malaria. The essential oil of the stem bark of S. tragacantha Lindl is extracted by hydrodistillation and their chemical compositions were identified by GC (Ir) and GC-MS. This oil has been tested on sensitive « kisumu » strains of A. gambiae adults, according to the World Health Organization (WHO) guidelines for laboratory testing of the repellency of chemicals. The extraction yield obtained from this oil is 0.12%. By means of GC (Ir) and GC-MS, 29 compounds representing 88.4% of the HE were identified. β-elemol (40.54%) is the major compound of this oil. It is rich in sesquiterpenes (79.47%) with a predominance of oxygenated sesquiterpenes (55.86%). As for the oxygenated monoterpenes, they represent 8.93%. The repellency test against adult female Anopheles, revealed that the EO of S. tragacantha (10%) has repellent properties against mosquitoes. Indeed, it induces an average reduction of 98.2% of the blood meal (TIRS) of mosquitoes on guinea pigs with a complete protection time (CPT) of 5 h compared to 3 h 30 min for the natural reference substance (Cymbopogon citratus). In view of its extractive value and prolonged repellent properties, S. tragacantha could be a good alternative in the vector borne diseases control if used as natural repellents for skin application. Key words: Anopheles gambiae, Sterculia tragacantha Lindl, essential oil, chemical composition, mosquito repellent.

The current study was aimed to investigate on dynamics of propoxur resistance inAnopheles gambiae s.l. populations from N’ dali district in northern Benin (West Africa) and also to investigate on dynamics of malathion resistance inAnopheles gambiae s. l. populations from Toffo district in southern Benin. Larvae and pupae ofAnopheles gambiae s. l .mosquitoes were collected from the breeding sites in Borgou and Atlantic departments in 2015 and 2019. WHO susceptibility tests were conducted on unfed female mosquitoes aged 2-5 days old. WHO bioassays were performed with impregnated papers with propoxur 0.1% and with malathion 5%. PCR techniques were used to detect species andAce-1mutations in 2015.Anopheles gambiaes. l. populations from N’dali were resistant to propoxur in 2015 and were still remained resistant to this product in 2019. RegardingAnopheles gambiaes. l. populations from Toffo, they were susceptible to malathion in 2015 whereas the malathion resistance status of these mosquitoes requires further investigation in 2019. PCR revealed that all specimens tested wereAnopheles gambiae s. s.The presence ofAce-1Rat very low frequency (0.01) was observed inAnopheles gambiaes. l. populations from both districts. This study shows that propoxur resistance detected inAn. gambiaes. l. populations from N’ dali needs to be monitored for insecticide resistance in this area.

Background Insecticide resistance has become a widespread problem causing a decline in the effectiveness of vector control tools in sub-Saharan Africa. In this situation, ongoing monitoring of vector susceptibility to insecticides is encouraged by the WHO to guide national malaria control programmes. Our study was conducted from April to November 2018 in Tchonka (Sud-Kivu, Democratic Republic of the Congo) and reported primary data on the resistance status of Anopheles funestus and Anopheles gambiae. Methods Insecticide susceptibility bioassays were performed on wild populations of A. funestus and A. gambiae using WHO insecticide-impregnated papers at discriminating concentration. In addition, PCR was performed to identify mosquito species and to detect kdr and ace-1R mutations involved in insecticide resistance. Results Bioassay results show resistance to all tested insecticides except pirimiphos-methyl, propoxur, fenitrothion and malathion with a mortality rate ranging from 95.48 to 99.86%. The addition of piperonyl butoxide (PBO) increased the susceptibility of vectors to deltamethrin and alpha-cypermethrin by exhibiting a mortality ranging from 91.50 to 95.86%. The kdr mutation was detected at high frequencies (approximately 0.98) within A. gambiae while ace-1R was not detected. Conclusions This study provides useful data on the insecticide resistance profiles of malaria vector populations to better manage vector control. Our results highlight that, despite the high level of resistance, organophosphorus compounds and pyrethroids + PBO remain effective against the vectors.

A cross sectional study on mosquito fauna of Anambra East Local Government Area was carried out between June 2017 and August 2018. Pyrethrum knockdown and Human Landing Catch Collection methods were used to collect adult mosquitoes from indoor and outdoor locations respectively, in four randomly selected towns in the LGA. The mosquitoes were identified using standard taxonomic keys. A total of 681 adult mosquitoes were collected: 182 (26.7%) in Aguleri, 135 (19.8%) in Umuleri, 273 (40.1%) in Igbariam and 91 (13.4%) in Nando. Out of these, 551 (80.9%) mosquitoes were collected from indoor location and 130 (19.1%) mosquitoes from outdoor location (P < 0.05). Six (6) Genera of mosquito collected were: Anopheles (39.4%), Aedes (3.7%), Culex (37.9%), Mansonia (18.4%), Eretmapodite (0.6%), and Coquilletidia (0.15%) (P < 0.05). Only Culex mosquitoes showed significant difference in indoor abundance, 43.6% and outdoor abundance 13.8% (P < 0.05). Sixteen species of mosquitoes were identified. The most abundant species of mosquito was Cx. quinquefasciatus, with 35.9% abundance and the least were Coquellettidia species and Cx. annuloris, 0.15% abundance each (P < 0.05). The most abundant Species of mosquito in indoor location was Anopheles gambiae s. l, with 42.3% abundance and the least were Ae. albopictus and Cx. annuloris, with 0.2% abundance each (P < 0.05). The most abundant species of mosquito in the outdoor locations was Mansonia uniformis, with 34.6% abundance and the least were An. funestus and Coquellettidia, with 0.80% abundance (P < 0.05). The presence of the different mosquito species found in this study area is of great medical importance. Most of the species are already known vectors of disease pathogens. Therefore, personal protection, provision of adequate mosquito management options, regular surveillance, and public health sensitizations are hereby recommended.

Culex quinquefasciatus, a member of the Culex pipiens complex, is widespread in Saudi Arabia and other parts of the world. It is a vector for lymphatic filariasis, Rift Valley fever, and West Nile virus. Studies have shown the deleterious effect of RNA interference (RNAi)-mediated knockdown of various lethal genes in model and agricultural pest insects. RNAi was proposed as a tool for mosquito control with a focus on Aedes aegypti and Anopheles gambiae. In this study, we examined the effect of RNAi of selected target genes on both larval mortality and adult emergence of Cx. quinquefasciatus through two delivery methods: soaking and nanoparticles. Ten candidate genes were selected for RNAi based on their known lethal effect in other insects. Disruption of three genes, chitin synthase-1, inhibitor of apoptosis 1, and vacuolar adenosine triphosphatase, resulted in the highest mortality among the selected genes using the two treatment methods. Silencing the other seven genes resulted in a medium to low mortality in both assays. These three genes are also active against a wide range of insects and could be used for RNAi-based mosquito control in the future.

A study of molecular characterization of Anopheles gambiae sensu lato, from three senatorial districts in Enugu State, was conducted between May, 2019 and June, 2020. The aim was to determine the siblings’ species of the mosquito complex and the distribution of the S (Savannah) and M (Mopti) molecular forms within the An. gambiae sensu stricto in the area. Three randomly selected communities; Awkunanaw (Enugu East), Obukpa (Enugu North) and Awgu (Enugu West senatorial districts) were used as sampling sites. Anopheles gambiae s.l. larvae were collected by dip method and reared to adult for the study. A total of 450(100%) An. gambiae s.l. mosquitoes were subjected to Polymerase Chain Reaction (PCR). Of this number, 150(33.33%) were randomly selected from bulk of An. gambiae s.l. mosquitoes collected from each of the three communities. All the 450(100%) were identified as An. gambiae s.s. The Restriction Fragment Length Polymorphism (RFLP) was done on the 450(100%) An. gambiae s.s. A total of 300(66.67%) from Awkunanaw and Obukpa Nsukka communities were An. gambiae S-form while 150(33.33%) from Awgu were identified as An. gambiae M-form. The study has revealed that An. gambiae s.s. is the dominant malaria vector within the complex in the area. Integrated vector control is recommended.

A study of insecticide resistant status and detection of G119S and L1014F mutation genes in Anopheles gambiae sensu lato. in Enugu State was conducted between May, 2019 and June, 2020. The aim was to investigate the resistance status of An. gambiae s.l. to four classes of insecticides used in vector control in the area and to identify the target site resistant genes present in resistant mosquitoes. Three randomly selected communities; Awkunanaw (Enugu East), Obukpa (Enugu North) and Awgu (Enugu West senatorial districts) were used as sampling sites. Anopheles gambiae s.l. larvae were collected by dip method and reared to adult for the study. WHO Tube Bioassay was used to determine resistance status. Polymerase Chain Reaction (PCR) was employed for detection of resistance mechanisms. The average mortality of An. gambiae s.l. tested with DDT was 28.3%, deltamethrin 63.53%, bendiocarb 88.33%, while malathion had the highest average mortality rate of 100%. The Acetycholinesterase Resistance Gene (GII9S Ace-1) mutation was detected at low frequencies in 75(100%) randomly selected An. gambiae s.l. from the three senatorial districts while the Knockdown Resistance Gene (LI0I4F kdr) mutation was not detected. Implementation of insecticide resistance management strategies in the state to control the spread of resistance is recommended.

Background Anopheles cell lines are used in a variety of ways to better understand the major vectors of malaria in sub-Saharan Africa. Despite this, commonly used cell lines are not well characterized, and no tools are available for cell line identification and authentication. Methods Utilizing whole genome sequencing, genomes of 4a-3A and 4a-3B ‘hemocyte-like’ cell lines were characterized for insertions and deletions (indels) and SNP variation. Genomic locations of distinguishing sequence variation and species origin of the cell lines were also examined. Unique indels were targeted to develop a PCR-based cell line authentication assay. Mitotic chromosomes were examined to survey the cytogenetic landscape for chromosome structure and copy number in the cell lines. Results The 4a-3A and 4a-3B cell lines are female in origin and primarily of Anopheles coluzzii ancestry. Cytogenetic analysis indicates that the two cell lines are essentially diploid, with some relatively minor chromosome structural rearrangements. Whole-genome sequence was generated, and analysis indicated that SNPs and indels which differentiate the cell lines are clustered on the 2R chromosome in the regions of the 2Rb, 2Rc and 2Ru chromosomal inversions. A PCR-based authentication assay was developed to fingerprint three indels unique to each cell line. The assay distinguishes between 4a-3A and 4a-3B cells and also uniquely identifies two additional An. coluzzii cell lines tested, Ag55 and Sua4.0. The assay has the specificity to distinguish four cell lines and also has the sensitivity to detect cellular contamination within a sample of cultured cells. Conclusions Genomic characterization of the 4a-3A and 4a-3B Anopheles cell lines was used to develop a simple diagnostic assay that can distinguish these cell lines within and across research laboratories. A cytogenetic survey indicated that the 4a-3A and Sua4.0 cell lines carry essentially normal diploid chromosomes, which makes them amenable to CRISPR/Cas9 genome editing. The presented simple authentication assay, coupled with screening for mycoplasma, will allow validation of the integrity of experimental resources and will promote greater experimental reproducibility of results. Graphical abstract

The performance of the three-part mosquito lure ATRAKTA (1-octen-3-ol, ammonium bicarbonate, and lactic acid) was evaluated in two DynaTrap commercial mosquito traps (models DT160 and DT700) as well as in one model of CDC trap (model 512). Lures were evaluated fresh from the factory, after being aged in functioning traps under field conditions, and after prolonged storage in the packaging (aged for 30 days aged in functioning traps before being tested in the DynaTrap models; and two years stored in the packaging before being tested in CDC traps). The primary study questions were whether the addition of lures would increase efficacy of various trap types and whether lures would retain effectiveness after a lengthy stay on the shelf or in traps. To do this, traps with no lures, new lures and old lures were used to trap three mosquito species (Aedes albopictus, Culex quinquefasciatus, and Anopheles gambiae) in the field in West Africa Mali, the first two species are also common North American nuisance mosquitoes. The addition of ATRAKTA lures aged 30 days to both DynaTrap® models, and ATRAKTA lures aged two years in the packaging to the CDC trap significantly increased catches of female Cx. quinquefasciatus and Ae. albopictus mosquitoes. Aged lures did not significantly lose their attraction in comparison to lures fresh from the factory. The addition of lures to traps resulted in slight increases in catches of An. gambiae, but these were not statistically significant. No effect of any lures on males was observed.

The prevalence, intensity and some vector dynamics of malaria in two communities of Anambra East Local Government Area LGA was carried out using standard parasitological and entomological techniques for rapid assessment of malaria infection, level of parasitaemia and morphological features of mosquitoes. Results showed an overall malaria RDT (Rapid Diagnostic Test) prevalence of 22% and community based prevalence of 13 (30%) and 22(24%) for Umuoba -Anam and Nando respectively. Overall, age related prevalence in the Anambra West LGA showed that the age bracket 35 to 42 years had the highest malaria prevalence 3(42.9 %). Overall sex related prevalence in Anambra East LGA showed no statistical significance in prevalence among males (12.0%) and females (10.0%) (P500-2000 parasites/µl) parasitaemia. There was no high parasitaemia recorded in Umuoba-Anam. Overall, a total of 225 mosquitoes were encountered with anopheles making up 61%. A hundred and twenty one (53.8% of the total mosquito population in the study was found to be unfed with blood meal whereas 54(24%) and 50 (22.2%) were freshly and previously fed respectively. One hundred and twenty one (53.8%) of the mosquitoes appeared non-gravid against 82(36.4%) that are gravid. The mosquitoes encountered wereAnopheles gambiae31(13.8%),Anopheles funestus77(34.22%), andCulexSpecie117(52%). The two communities recorded variations in prevalence, intensity and vector dynamics. There should be intensified effort to continuously educate the masses on all the strategies of malaria prevention.

Mosquitoes are responsible for transmission of illnesses of public health importance including malaria, lymphatic filariasis, dengue, chikungunya, and many other diseases caused by viruses. Vector control using synthetic insecticides has been the cornerstone for management of vector-borne diseases. However, the chemical based interventions have not been sustainable due to emergency of resistance against insecticides among disease vectors. Plant based mosquitocidal products can be potential alternative tools in vector control. Therefore, the present study aimed at exploring the larvicidal properties of Dioscorea sansibarensis leaf extract against malaria and lymphatic filariasis vectors; Anopheles gambiae s.s. and Culex quinquefasciatus. The larvicidal activities of Dioscorea sansibarensis were assessed following WHO test procedures. Ethanol leaf extract of Dioscorea sansibarensis was evaluated against all the four instar larvae stages of An. gambiae s.s and Cx. quinquefasciatus susceptible laboratory colonies. The highest larvicidal potency was shown against the 4th instar stages of both species with the LC50 values of 60.915 ppm and 80.700 ppm for Cx. quinquefasciatus and An. gambiae s.s., respectively. The respective LC95 values for Cx. quinquefasciatus and An. gambiae s.s. were 168.898 ppm and 249.295 ppm. This implies that the extract can be applied as mosquito larvicide should its impact on non-targeted species be established. Keywords: Dioscorea sansibarensis; vectors, mosquitoes, Zanzibar yams, Dar es Salaam, Tanzania

Assessment of geographical distribution of malaria vectors is essential to effective malaria parasite control. This study evaluated the influence of geographical locations on distribution of Anopheles mosquito species and malaria parasite vectorial efficacy in Enugu State, Nigeria. Mosquitoes were collected, using indoor resting pyrethrum spray collection (IRPSC) method. They were morphologically identified and molecularly (PCR) characterised. The M form (now called Anopheles coluzzii) and S form (now called nominotypical Anopheles gambiae s.s.), were identified using Restriction Fragment Length Polymorphism (RFLP). Plasmodium falciparum sporozoite rates of sampled mosquitoes and malaria status of households were evaluated microscopically and by using rapid diagnostic kits. An. gambiae Giles (sensu stricto), and bands resembling An. melas and An. arabiensisspecies complexes were observed. Out of 300 An. gambiae s.l. identified using PCR, 243 were An. gambiae Giles (sensu stricto), 6 were An. melas and 5 were An. arabiensis. Out of the 243 An. gambiae Giles (sensu stricto), 184 were M form (now An. coluzzii) and 59 were S form (now nominotypical An. gambiae s.s).The M form (now An. coluzzii) constituted 99% of Anopheles mosquitoes from southernmost part of the study area while northernmost part showed 100% S form (An. gambiae s.s.). The median location had the M form (An. coluzzii) and S form (An. gambiae s.s.) in sympatric. Sporozoite rate in northernmost area was highest when compared with median and southernmost parts. The S form (An. gambiae s.s.) was observed as more important malaria parasite vector, and the results revealed that geographical location affected species diversities which is an important consideration for malaria control programme. Keywords: Anopheles, distribution, sporozoite, malaria parasite

In Ethiopia, mosquito larva control interventions are given less emphasis due to a number of factors including lack of precise information on potential breeding habitats and complicated vector biology. Hence, the objective of this study was to assess the spatio-temporal variation and habitat characterization of Anopheline larvae in Bure district, Northwestern Ethiopia. Longitudinal larval sampling was done in 3 villages (Bukta, Workimdr and Shnebekuma) for a year (July 2015 - June, 2016). Sampling was done one time per month. Documentation of habitat type and environmental characteristics were done in each round of sampling. A total of 3490 Anophelines larvae were collected in a year. Seven larval species were identified morphologically: Anopheles gambiae s.l, An. funestus s.l, An. pharoensis. An. demeilloni, An. coustani, An. squamosus, An. cinereus. Of these, An. demeilloni (1.97 ± 0.03) and An. gambiae s. l (1.79 ± 0.06) were the predominant larvae, whereas An. pharoensis (0.18 ± 0.04) was the least representative (p

Anopheles mosquitoes are the main vectors of malaria. There is little information on the current entomological aspects of Anopheles mosquitoes in Amhara region of northwestern Ethiopia. Therefore, the aim of this study was to assess the prevailing species composition, parous rate, and infection rate of Anopheles mosquitoes in the Bahir Dar city administration. A community-based cross-sectional study was conducted from January through July 2020. For this, six Centers for Disease Control and Prevention light traps (three traps indoor and three traps outdoor) were used to collect adult female Anopheles mosquitoes. The species were morphologically identified, and the parous and infection rates were determined via dissection of ovaries and salivary gland, respectively. A total of 378 adult female Anopheles mosquitoes comprised of three species (Anopheles d’thali, Anopheles rhodesiensis, and Anopheles gambiae complex) were collected and identified at the study sites. Anopheles rhodesiensis was the predominant species accounting for 90% of all collections at the Zenzelima site, followed by An. gambiae complex (6.5%). In contrast, An. gambiae complex was the predominant species at the Tis Abay site, comprising 94% of captures. The overall parous and infection rates were 35 (62.5%) and 1 (2.9%), respectively.

Malaria larvae embrace unpredictable variable life periods as they spread across many stratospheres of the mosquito vectors. There are transcriptomes of a thousand distinct species. Ribonucleic acid sequencing (RNA-seq) is a ubiquitous gene expression strategy that contributes to the improvement of genetic survey recognition. RNA-seq measures gene expression transcripts data, including methodological enhancements to machine learning procedures. Scientists have suggested many addressed learning for the study of biological evidence. An enhanced optimized Genetic Algorithm feature selection technique is used in this analysis to obtain relevant information from a high-dimensional Anopheles gambiae dataset and test its classification using SVM-Kernel algorithms. The efficacy of this assay is tested, and the outcome of the experiment obtained an accuracy metric of 93% and 96% respectively.

The development of cryopreservation protocols for Anopheles gambiae could significantly improve research and control efforts. Cryopreservation of any An. gambiae life stage has yet to be successful. The unique properties of embryos have proven to be resistant to any practical cryoprotectant loading. Therefore, we have chosen to investigate early non-feeding first instar larvae as a potential life stage for cryopreservation. In order to determine an appropriate cryoprotective compound, larvae were treated with progressively better glass-forming cryoprotective mixtures. Toxicity evaluation in combination with calorimetry-based water content and supercooling point depression assessments were used to determine the cryoprotectants that could be used for cryostorage of viable larvae. Approximately 35–75% of the larvae were viable after reasonably high osmotic and biochemical challenge. This study provides ample evidence for an active osmoregulatory response in the Anopheles larvae to counter the permeation of cryoprotectants from the surrounding medium. The data show a strong correlation between the larval mortality and water content, indicating an osmoregulatory crisis in the larva due to certain cryoprotectants such as the higher concentrations of ethane diol (ED). The observations also indicate that the ability of the larvae to regulate permeation and water balance ceases at or within 20 min of cryoprotectant exposure, but this is strongly influenced by the treatment temperature. Among the compound cryoprotectants tested, 25% ED + 10% dimethyl sulfoxide (DMSO) and 40% ED + 0.5 M trehalose seem to present a compromise between viability, larval water content, supercooling point depression, and glass forming abilities.

Background: The efficacy of Bacillus thuringiensis var. israelensis (Bti) is affected by several factors including the species of the mosquito. Mosquito larvae of different species are found to coexist in larval breeding habitats. This study evaluated whether the coexistence between Anopheles gambiae and Culex quinquefasciatus affect the larvicidal activity of Bti. Methods: Two parallel larval bioassay experiments were conducted to test A. gambiae sensu stricto (s.s) and C. quinquefasciatus larvae susceptibility to Bti. They were followed by three parallel bioassays in which A. gambiae s.s and C. quinquefasciatus larvae were mixed in different proportions such that the earlier species contributed three quarters, half and a quarter of the larvae in each testing cup respectively. In each bioassay, six Bti concentrations were tested in four replicates and repeated on three different days. Larvae mortality was scored 24 hours after application of Bti and subjected to Probit analysis. Results: C. quinquefasciatus was significantly more susceptible to Bti than A. gambiae s.s at both lethal concentration values (LC50 and LC95). In coexisting scenario, LC50 of Bti was significantly lower when the proportion of C. quinquefasciatus exceeded 50%. No significant variation in susceptibility to Bti was observed at LC95 in any proportion of coexistence between the two species. Conclusion: The findings show that larvae of C. quinquefasciatus were significantly more susceptible to Bti than those of A. gambiae s.s. Moreover, when larvae of the two species coexisted, there was a general trend of increase in sensitivity to Bti with higher proportion of C. quinquefasciatus. Although this increase in sensitivity of coexisting larvae to Bti is worth noting, our findings suggest that it will not impact larval control where A. gambiae s.s and C. quinquefasciatus coexist.

The study was undertaken to evaluate the adulticidal efficacy of the methanolic leaf extracts and essential oils of Chenopodium ambrosioides, Hyptis suaveolens and Lippia adoensis against adults of Anopheles gambiae. A chemical profile of each plant extracts (qualitative phytochemical screening) and essential oil (GC/MS analysis) was also determined. Doses of 125, 250, 500 and 1000 mg/bottle of plant extracts and 25, 50, 100 and 200 mg/bottle of essential oils were prepared and tested using CDC bottles. In each plant extract, alkaloids, flavonoids, saponins, tannins, phenolic groups, terpenoids, fats and oils were presents. Major chemical constituents of essential oils were thymol (27.09%), sabinene (18.93%) and 4-carene (52.88%) in L. adoensis, H. suaveolens and C. ambrosioides, respectively. L. adoensis extract (at 1000 mg/bottle) and essential oil of H. suaveolens (at 200 mg/bottle) were the most potent causing 100% mortality of An. gambiae adults, 24 h post-exposure. Methanolic extract of L. adoensis (LC50= 20.20 mg/bottle) was the most effective compared to other extracts. Similarly, essential oil of H. suaveolens (LC50= 5.27 mg/bottle) was revealed as the most toxic on An. gambiae adults compared to other oils. Therefore, the extracts of L. adoensis and essential oil of H. suaveolens showed a high activity and should be recommended to be promoting as natural bioinsecticides to control mosquito adults.

Plants extracts have been used as alternative sources of mosquito control since the ancient time prior to the development of synthetic pesticides due to the presence of repellent properties against insects. Anopheles gambiae mosquito is the vectors of Malaria disease in Tropical and Subtropical Africa, and the present practice of using synthetic pesticides to control the vector have results in the development of resistance by the mosquitoes and the pesticides causes environmental pollution and damages the ecosystem. The aim of this study was to evaluate the adulticidal activities of some plant species against Anopheles gambiae. The results of the Phytochemical analysis showed that, Anthroquinones, Soluble Steroids and Tannis are present in Jatropha curcas while Adansonia digitata possesses Saponins, Flavonoids, Anthroquinones and Tannins. C. citrates was reported to be possessing Flavonoids, Soluble starch and Tannins and was mostly reported plants to be possessing higher insecticidal properties against mosquitoes. Zingiber officinale was found possessing Saponins, Alkaloids and Tannins and finally, the Lausonia inermis possessng only Anthroquinones and Alkaloids. The results of the adulticidal activities shows the Jatropha curcas causes the highest mortality at 87% of An. gambiae among the plant extracts tested in this study at the highest concentrations of 20mg/ml at the lowest LC50 value of 4.217mg/ml and LC90 of 15.76mg/ml respectively and the plant with the lowest was Z. officinale with the highest mortality of 21% and the highest LC50 of 6710.051mg/ml respectively. We conclude that, these plants extracts can be used as alternative bioinsecticides for An. gambiae, a Malaria vector control to reduce the Malaria burden in the study area that annually causes significant death and overwhelm the health facilities.

Summary The insect sex determination and the intimately linked dosage compensation pathways represent a challenging evolutionary puzzle that has been solved only in Drosophila melanogaster. Analyses of orthologs of the Drosophila genes identified in non-drosophilid taxa1,2 revealed that evolution of sex determination pathways is consistent with a bottom-up mode,3 where only the terminal genes within the pathway are well conserved. doublesex (dsx), occupying a bottom-most position and encoding sex-specific proteins orchestrating downstream sexual differentiation processes, is an ancient sex-determining gene present in all studied species.2,4,5 With the exception of lepidopterans, its female-specific splicing is known to be regulated by transformer (tra) and its co-factor transformer-2 (tra2).6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 Here we show that in the African malaria mosquito Anopheles gambiae, a gene, which likely arose in the Anopheles lineage and which we call femaleless (fle), controls sex determination in females by regulating splicing of dsx and fruitless (fru; another terminal gene within a branch of the sex determination pathway). Moreover, fle represents a novel molecular link between the sex determination and dosage compensation pathways. It is necessary to suppress activation of dosage compensation in females, as demonstrated by the significant upregulation of the female X chromosome genes and a correlated female-specific lethality, but no negative effect on males, in response to fle knockdown. This unexpected property, combined with a high level of conservation in sequence and function in anopheline mosquitoes, makes fle an excellent target for genetic control of all major vectors of human malaria., Highlights • fle is a new sex determination pathway element conserved in Anopheles mosquitoes • fle may have originated in the Anopheles lineage and is highly conserved in Anopheles • fle suppresses activation of dosage compensation in females • Depletion of fle transcripts is lethal or otherwise deleterious to females, Krzywinska et al. identify a new element of the sex determination pathway in Anopheles. femaleless (fle), in addition to controlling splicing of dsx and fru, is essential for suppression of dosage compensation and viability of females. Female-deleterious effects upon fle knockdown make fle a promising target for control of malaria mosquitoes.

The paper discusses the food supply of the vector of malaria – mosquitoes of the genus Anopheles , which are birds of tropical regions of West Africa. Birds, as distant migrants, penetrate high latitudes and contribute to the spread of malaria in Europe and other countries of the northern hemisphere. The results of the studies show that the main role in the choice of prey objects by female Anopheles gambiae mosquitoes – birds – is played by the nesting and forage biotopes of birds, which are comfortable for mosquito breeding. Probably, female mosquitoes use non-feathered parts of the body of adult birds for feeding unfeathered or weakly feathered chicks in nests. The circulation of Plasmodium falciparum includes populations of birds, primarily water, near-water and marsh complexes, as well as birds, the development of which takes place in specific conditions of a closed space – in holes, hollows and closed nests. The Anopheles gambiae mosquito in this system plays the role of a carrier of Plasmodium falciparum not only among populations of birds and mammals, but also among humans, which determines the range of tropical malaria, which is a natural focal vector-borne disease. The authors have identified 37 species of birds – carriers of malaria in natural and anthropogenic biocoenoses of Mali (West Africa). The most numerous during the migration and nesting period are birds of the aquatic, near-water and meadow-bog complexes (herons, herons, waders) – distant migrants on the territory of Russia and neighboring countries. The risk areas include, first of all, the southern regions – Astrakhan Region, Rostov Region and Krasnodar Region.

The global malaria burden has decreased substantially, but gains have been uneven both within and between countries. In Zambia, the malaria burden remains high in northern and eastern regions of the country. To effectively reduce malaria transmission in these areas, evidence-based intervention strategies are needed. Zambia’s National Malaria Control Centre conducted targeted indoor residual spraying (IRS) in 40 high-burden districts from 2014 to 2016 using the novel organophosphate insecticide pirimiphos-methyl. The Southern and Central Africa International Centers of Excellence for Malaria Research conducted an evaluation of the impact of the IRS campaign on household vector abundance in Nchelenge District, Luapula Province. From April 2012 to July 2017, field teams conducted indoor overnight vector collections from 25 to 30 households per month using Centers for Disease Control light traps. Changes in indoor anopheline counts before versus after IRS were assessed by species using negative binomial regression models with robust standard errors, controlling for geographic and climatological covariates. Counts of Anopheles funestus declined by approximately 50% in the study area and within areas targeted for IRS, and counts of Anopheles gambiae declined by approximately 40%. Within targeted areas, An. funestus counts declined more in sprayed households than in unsprayed households; however, this relationship was not observed for An. gambiae. The moderate decrease in indoor vector abundance indicates that IRS with pirimiphos-methyl is an effective vector control measure, but a more comprehensive package of interventions is needed with sufficient coverage to effectively reduce the malaria burden in this setting.

Malaria incidence is generally lower in cities than rural areas. However, reported urban malaria incidence may not accurately reflect the level of ongoing transmission, which has potentially large implications for prevention efforts. To guide mosquito net distribution, we assessed the extent of malaria transmission in Conakry, Guinea, in 2018. We found evidence of active malaria transmission.

Mosquitoes are vectors of pathogens affecting humans causing morbidity, mortality and significant economic losses. Insecticides provide main-protection against vector-mosquitoes. However, synthetic insecticides, cause environmental contamination and increase vector resistance. These effects make it a priority to search for alternative means that are not deleterious to the environment and are public health acceptable. Here, we report oviposition deterrence, blood-feeding inhibition, excito-repellent effect, and larvicidal activities by essential oils (EOs) from the leaves of Lantana. camara L., Hyptis. suaveolens Poit., Hyptis. spicigera Lam, and Ocimum. canum Sims against local laboratory strains of Anopheles. gambiae s. s. and Anopheles coluzzii. All bioassays followed WHO standard protocols including minor modifications to evaluate the oviposition deterrence of gravid females, inhibition of adult blood-feeding and mortality caused by EO (essential oils), and larval susceptibility to EO. All EO tested showed strong oviposition deterrence, and the oviposition activity index ranged from −1 to - 0.75. Using a tunnel, we showed that EO have excito-repellent and blood-feeding inhibitory activities, and induced adult mortality. Engorged females tested ranged from 10.58 to 26.40%. L. camara EO had the highest larvicidal activity on both mosquito strains, and LC50 values of 102.78 and 92.20 ppm (part per million) for An. coluzzii and An. gambiae, respectively. The two mosquito strains showed similar susceptibilities to EOs. Overall, our results show that the EO used in this study could be used in developing effective and environmentally friendly approach to deter oviposition, repel mosquitoes, and control larvae.

Introduction: Lymphatic filariasis (LF) and malaria are two vector-borne diseases which parasites can simultaneously infect human or mosquito. In Burkina Faso, studies mainly focused on the control of these diseases independently. Hence, there is a lack of information on their co-transmission of to both human and vector. The present study aimed at providing baseline data from endemic areas in Burkina Faso towards a successful integrated management of both diseases. Methods: The study was carried out in six sites distributed in the East, Center-East and South-West regions of Burkina Faso. Data were collected in August 2014 and September 2015. The infection rates in human and vector populations, vector diversity, trophic and resting behavior were investigated. To determine the disease prevalence nocturnal finger- prick blood sample and microscopic observations were performed. Vectors collected by human landing catches and pyrethrum spray collections. Biochemical and molecular analyses were performed to identify Anopheles gambiae sensu lato sibling species, and to determine vector infection rate and their blood meal origins. Results: Results indicate residual transmission of LF and malaria in human and vector populations. A low co-infection rate (Wuchereria bancrofti and Plasmodium falciparum was noted in both human and mosquito. Anopheles gambiae s.l. , An. funestus s.l. and An. nili were by order the main potential vectors encountered. It was in majority parous females and exhibited endophagic and exophagic behavior. Parasite’s co-infection was found with An. coluzzii and An. nili only. Conclusion: The present study has provided basic information on the (co-)transmission of both diseases in the study areas. These results will be useful for further investigations towards the development and implementation of a better integrated strategy to control these diseases.

The CH2Cl2-MeOH (30:70 v/v) extracts of the seeds of Mangifera indica (Mango), Persea americana (Avocado) and Dacryodes edulis (African plum) were evaluated for potential mosquito larvicidal activity against 3rd and 4th instar larvae of Aedes aegypti, Culex quinquefasciatus and Anopheles gambiae. Extracts were diluted with 1 mL of methanol and concentrations ranging from 1000 to 125 mg/L in 4 replicates each, were prepared in the volume of 100 mL in the plastic cups (250 mL). A volume of 1 mL of methanol added to 99 mL of tap water was prepared as negative control and Bi-one (1000 mg/L) constituted a positive control. In each test solution, 25 larvae of each mosquito species were separately transferred and larval mortality was recorded after 24 h post-treatment. As results, the three plant seed extracts applied at 1000 mg/L caused for at least 79% mortality of each mosquito species larvae assessed. The seed extract of P. americana (LC50 of 98.31, 129.24 and 136.26 mg/L, respectively against An. gambiae, Ae. aegypti and Cx. quiquefasciatus larvae) was the most potent followed by D. edulis (LC50 of 176.87 mg/L for An. gambiae, 198.68 mg/L for Ae. aegypti and 201.70 mg/L for Cx. quinquefasciatus) and M. indica (LC50 of 258.98 mg/L for An. gambiae, 297.35 mg/L for Ae. aegypti and 435.45 mg/L for Cx. quinquefasciatus). Globally, all the seed extracts were more toxic against An. gambiae larvae compared to other mosquito species and need further exploration for the development of a new botanical larvicide to reduce mosquito densities.

Mosquito control in Cameroon relies largely on the proper use of Long-Lasting Insecticidal Nets (LLINs). It is necessary to monitor their effectiveness in order to propose corrective measures to improve the strategy. The aim of this work was to determine the physical integrity and effectiveness of LLINs (Interceptor brand) on Anopheles gambiae s.l. populations in two urban and rural areas of the Ayos health district. The level of LLIN coverage and use was assessed through a population survey. The physical integrity of LLINs was assessed by measuring the holes according to the WHO method. Bio-efficacy testing of ITNs was carried out according to the cone test protocol using 2-5-day-old, non-blood fed Anopheles gambiae s.l. females from the natural field strain and the reference susceptible strain. Household LLIN coverage rates in urban and rural areas were 55.50% and 66.94%, respectively. On the other hand, the rates of use were 78.01% and 75.22% in urban and rural areas respectively. The proportion of nets that had lost their physical integrity after 36 months of use was 47.00% and 59.63% in urban and rural areas respectively. The size of holes ranged from 0.5 to 25 cm. Alphacypermethrin was found to be ineffective against both strains of Anopheles gambiae s.l. tested. Knockdown rates ranged from 8.5% to 73% for the reference susceptible strain and less than 2.5% for the natural field strain. Mortality rates for the natural strain of Anopheles gambiae s.l. ranged from 0% to 2.5% while they were between 29% and 70% for the susceptible strain. The results show a decrease in the effectiveness of LLINs against the mosquitoes tested. This may be due to the lower than expected WHO possession and use rates of LLINs, their relatively high degree of wear and tear, and the resistance of the vectors to alphacypermethrin.

Mosquitoes are the greatest animal threat to human health, causing hundreds of millions of infections and around one million deaths each year. All mosquito-borne pathogens must traverse the salivary glands (SGs) to be transmitted to the next host, making this organ an ideal target for interventions. The adult SG develops from precursor cells located in the larval SG duct bud. Characterization of the larval SG has been limited. We sought to better understand larval SG architecture, secretion, and gene expression. We developed an optimized method for larval SG staining and surveyed hundreds of larval stage 4 (L4) SGs using fluorescence confocal microscopy. Remarkable variation in SG cell and chromatin organization differed among individuals and across the L4 stage. Lumen formation occurred during L4 stage through secretion likely involving a coincident cellular apical lipid enrichment and extracellular vesicle-like structures. Meta-analysis of microarray data showed that larval SG gene expression is divergent from adult SGs, more similar to larval gastric cecae, but different from other larval gut compartments. This work highlights the variable cell architecture of larval Anopheles gambiae SGs and provides candidate targets for genetic strategies aiming to disrupt SGs and transmission of mosquito-borne pathogens.

Resistance of malaria vectors to synthetic chemicals with high operational cost and environmental pollution has been a great challenge to scientists. Alternative approaches such as the use of natural plant products which are environmentally friendly are put in place to control malaria vectors. This study was focused on testing the effectiveness of three solvent extracts of Lantana camara on the 3rd instar larvae and adults of Anopheles gambiae s. l. These extracts were obtained by maceration. Bioassays test were carried out by WHO’s method for determination of larvicidal and adulticidal efficacy. The results show that, larval mortality increased significantly with the concentration and exposure time. Lethal concentrations 50 (LC50) and 95 (LC95) after 24 hours of larvae exposure time are respectively 0.31 g/mL and 1.53 g/mL while within 48 h they are 0.27 g/mL and 0.79 g/mL for hexane extract; 1.45 g/mL and 2.0 g/mL (24 h exposure), 0.84 g/mL and 1.55 g/mL (48 h exposure) for acetone extract; 1.96 g/mL and no lethal concentration causing 95% mortality was determined; 0.40 g/mL and 2.20 g/mL (48 h) for aqueous extract. The efficacy of hexane and aqueous extract on the adult knock down and mortality were not significant even with the increasing extract concentrations and exposure time whereas with acetone extract, the adult LC50 after 24 h was 2.4 g/mL but with 95% mortality lethal concentration was not determined. According to the results, hexane extract showed high larvicidal efficacy of An. gambiae and acetone extract showed significant adult mortality. Those two extracts of L. camara can be used to fight against An. gambiae as alternative malaria vector control to replace conventional insecticides.

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). Moreover, a deficit of the Ace-1 resistance allele was observed (Fis

Insect systemic immune responses to bacterial infections have been mainly studied using microinjections, whereby the microbe is directly injected into the hemocoel. While this methodology has been instrumental in defining immune signaling pathways and enzymatic cascades in the hemolymph, it remains unclear whether and to what extent the contribution of systemic immune defenses to host microbial resistance varies if bacteria invade the hemolymph after crossing the midgut epithelium subsequent to an oral infection. Here, we address this question using the pathogenic Serratia marcescens (Sm) DB11 strain to establish systemic infections of the malaria vector Anopheles gambiae, either by septic Sm injections or by midgut crossing after feeding on Sm. Using functional genetic studies by RNAi, we report that the two humoral immune factors, thioester-containing protein 1 and C-type lectin 4, which play key roles in defense against Gram-negative bacterial infections, are essential for defense against systemic Sm infections established through injection, but they become dispensable when Sm infects the hemolymph following oral infection. Similar results were observed for the mosquito Rel2 pathway. Surprisingly, blocking phagocytosis by cytochalasin D treatment did not affect mosquito susceptibility to Sm infections established through either route. Transcriptomic analysis of mosquito midguts and abdomens by RNA-seq revealed that the transcriptional response in these tissues is more pronounced in response to feeding on Sm. Functional classification of differentially expressed transcripts identified metabolic genes as the most represented class in response to both routes of infection, while immune genes were poorly regulated in both routes. We also report that Sm oral infections are associated with significant downregulation of several immune genes belonging to different families, specifically the clip-domain serine protease family. In sum, our findings reveal that the route of infection not only alters the contribution of key immunity genes to host antimicrobial defense but is also associated with different transcriptional responses in midguts and abdomens, possibly reflecting different adaptive strategies of the host.

Many infectious diseases including malaria, lymphatic filariasis, chikungunya and dengue are transmitted by mosquitoes. Understanding the entomological diversity in a given area is critical for defining health risks, but also to design and evaluate control measures. Our study aimed to establish an entomological database of the Culicidae fauna in two clusters (Nyalla and Kambo) in the city of Douala in Cameroon. A longitudinal study was conducted from August to December in the Nyalla and Kambo neighbourhoods in the city of Douala. Culicidae larvae were weekly collected and reared until adult emergence. Adults were then morphologically identified using reference identification keys. A total of 20 breeding sites were productive out of an approximately 90 sites prospected. Water collections, pits, swamps and cinder blocks were main categories of larval habitats. In total, 2125 mosquito larvae were collected and reared during the survey. A total of 1790 mosquito adults emerged and were further identified and distributed among three genera: Culex (73.3%); Anopheles (22.6%) and Aedes (4.1%). Eleven Culicidae species were identified: Culex duttoni, Cx. descens, Cx. poicilipes, Cx. univittatus, Cx tigripes, Cx. antennatus, Cx. simpsoni, Cx. pipiens, Anopheles gambiae sl, Aedes aegypti and Ae. albopictus. Culex duttoni (39%) and An. gambiae s.l. (22.6%) were the main species recorded. The equitability, species richness and abundance of these genera was influenced by the nature of breeding sites and physical parameters including rainfall and temperature. The present study provides insights on the entomological diversity of the Culicidae fauna in the study area. Such information will help to orientate the fight against mosquito vectors in conjunction with the species and the types of breeding sites.

Genetic control strategies aimed to bias the sex of progenies towards males present a promising new paradigm to eliminate malaria-transmitting mosquitoes. A synthetic sex-ratio distortion (SD) system was successfully engineered in Anopheles gambiae by exploiting the meiotic activity of the I-PpoI endonuclease targeting ribosomal DNA (rDNA) repeats, exclusively located on the X chromosome. Males carrying the SD construct produce highly male-biased progenies without evident reduction in fertility. In this study, we investigated the fate of X and Y chromosomes in these SD males and found that ratios of mature X:Y-bearing sperm were comparable to wild-type insects, indicating absence of selection mechanisms during sperm maturation. We therefore tested the effect of meiotic cleavage of both X and Y chromosomes in a lab-generated SD strain carrying rDNA on both sex chromosomes, showing fertility comparable to wild-type and a reduced male-bias compared to SD males in which only the X is targeted. Exposure of Y-linked rDNA to I-PpoI cleavage for consecutive generations rapidly restored the male-bias to typical high frequencies, indicating a correlation between the number of cleavable targets in each sex chromosome and the sex-ratios found in the progeny. Altogether our results indicate that meiotic cleavage of rDNA repeats, located in the sex chromosomes of A. gambiae SD males, affects the competitiveness of mature sperm to fertilize the female oocyte, thereby generating sex-biased progenies. We also show that the presence of rDNA copies on the Y chromosome does not impair the effectiveness of engineered synthetic SD systems for the control of human malaria mosquitoes.

The current study was aimed to compare the susceptibility to deltamethrin in female adult Anopheles gambiae s.l. from Dogbo district with their F1 progeny susceptibility in South-Western Benin, West Africa. Larvae and pupae of Anopheles gambiae s.l. populations were collected from the breeding sites in Couffo department in 2020 and reared up for obtaining F1 progeny. Female adult An. gambiae s.l. mosquitoes were also collected from window traps put on windows of rooms in Dogbo district surveyed. An. gambiae s.l. mosquitoes were collected from March to July and August to November 2020 during the rainy season in the locations of Ayomi, D��v��, Honton, Lokogohou��, Madjr�� and Totchangni. Female adult An. gambiae species collected from window traps were morphologically identified using morphological keys and then transferred into mosquito cages for WHO bioassays performed with impregnated papers of deltamethrin (0.05%). WHO bioassays were also performed with F1 progeny. The physiological age of female adult An. gambiae s.l. collected from window traps was determined through dissection using Detinova method. The results showed that the mortality rates recorded with female adult An. gambiae s.l. mosquitoes collected from window traps were higher than those obtained with their F1 progeny An. gambiae s.l. mosquitoes obtained after reproduction of parent mosquitoes. The current study clearly shows that changes in mosquito physiology occur with senescence.

Anopheles gambiae complex mosquitoes comprise different morphologically identical species and the most medically important malaria vectors in Africa. Understanding An. gambiae complex mosquitoes’ mating behaviour is a clue for prevention and control of malaria. The factors affecting the mating behavior of An. gambiae complex are age, body size, food finding, type of food, host availability and environmental temperature. An. gambiae complex passes through different and unique mating strategies. The fundamental mechanisms underlying mating behavior of An. gambiae complex are male aggregation before copulation which is called swarming, finding female and insemination. Male in the swarm detects the wing beat of female with which he mates by auditory system. The wing beat frequencies of opposite sex of the same genetic form simply harmonize indicating possible hybridization while that of different genetic forms do not harmonize. The successive mating behavior of female An. gambiae mosquitoes includes, locating a male among the swarm for cupola, friend selection and storage of sperm. Successful female An. gambiae complex mosquitoes mating is accomplished by host seeking, blood feeding and digestion, egg development and oviposition. The sequential process of host finding and blood feeding followed by blood digestion and simultaneously egg maturation and accomplished by searching of oviposition site and oviposition is referred to as gonotrophic cycle. The time period between two successive blood feedings or two successive ovipositions is said to be gonotrophic period. The length of gonotrophic period depends on temperature, number of previous gonotrophic cycle, host and breeding site availability. In addition to population net reproduction of the colony, gonotrophic cycle is also used to estimate female mosquitoes’ age by determining the parity. Finally, understandings of mating behavior and gonotrophic cycle of An. gambiae complex mosquitoes help in malaria vector control strategies and their vector competence.

Nocturnal Anopheles mosquitoes exhibit strong behavioral avoidance to blue-light while diurnal Aedes mosquitoes are behaviorally attracted to blue-light and a wide range of other wavelengths of light. To determine the molecular mechanism of these effects, we expressed light-sensing Anopheles gambiae (AgCRY1) and Aedes aegypti (AeCRY1) Cryptochrome 1 (CRY) genes under a crypGAL4-24 driver line in a mutant Drosophila genetic background lacking native functional CRY, then tested behavioral and electrophysiological effects of mosquito CRY expression relative to positive and negative CRY control conditions. Neither mosquito CRY stops the circadian clock as shown by robust circadian behavioral rhythmicity in constant darkness in flies expressing either AgCRY1 or AeCRY1. AgCRY1 and AeCRY1 both mediate acute increases in large ventral lateral neuronal firing rate evoked by 450 nm blue-light, corresponding to CRY's peak absorbance in its base state, indicating that both mosquito CRYs are functional, however, AgCRY1 mediates significantly stronger sustained electrophysiological light-evoked depolarization in response to blue-light relative to AeCRY1. In contrast, neither AgCRY1 nor AeCRY1 expression mediates measurable increases in large ventral lateral neuronal firing rates in response to 405 nm violet-light, the peak of the Rhodopsin-7 photoreceptor that is co-expressed in the large lateral ventral neurons. These results are consistent with the known action spectra of type 1 CRYs and lack of response in cry-null controls. AgCRY1 and AeCRY1 expressing flies show behavioral attraction to low intensity blue-light, but AgCRY1 expressing flies show behavioral avoidance to higher intensity blue-light. These results show that nocturnal and diurnal mosquito Cryptochrome 1 proteins mediate differential physiological and behavioral responses to blue-light that are consistent with species-specific mosquito behavior.

The use of botanical insecticides in place of synthetic ones is gradually gaining traction in mosquito control. This research examined the potency of Clerodendrum volubile and Petivera alliacea ethanolic leaf extracts against different life stages of Anopheles gambiae. Each plant extracts were formulated into concentrations of 50, 100, 200, 400 and 800 mg/l. Mosquito bioassays namely oviposition deterrent, larvicidal, pupicidal, adulticidal and repellency effect were investigated. The highest concentrations of C. volubile and P. alliacea had oviposition active index of −0.60 and − 0.76 respectively. Larval mortality of 58.33 and 100% were recorded for 800 mg/l concentration of C. volubile and P. alliacea after 24 h of exposure. However, the same concentration for both plant extracts recorded 100% after 48 and 72 h. The pupicidal activity of 800 mg/l of C. volubile were 51.67, 71.67 and 100%, and for P. alliacea 85, 100, 100% after 24, 48 and 72 h respectively. The adult mortality for both plant extracts were 16.67% at the highest used concentration after 30 min of exposure. Nevertheless, after 120 min, the same concentration of C. volubile and P. alliacea extracts recorded mortalities of 75 and 100% separately. Clerodendrum volubile extract provided protection of 100% against An. gambiae bites for 90 min while P. alliacea lasted for about 120 min. Petivera alliacea recorded the lowest LC50 and LC90 values for all the various life stages. The efficacies of these plant extracts imply that they can be incorporated into the integrated management of mosquitoes.

Malaria is a longstanding public health problem in sub-Saharan Africa, while arthropod-borne viruses (arboviruses) like dengue and chikungunya cause an underrecognized burden of disease. While many human and environmental drivers affect the dynamics of vector-borne diseases, here we argue that the direct effects of warming temperatures are likely to promote greater environmental suitability for dengue and other arboviruses transmitted by Aedes aegypti while reducing the suitability for malaria transmitted by Anopheles gambiae. Environmentally-driven changes in disease dynamics will no doubt be complex and heterogeneous, but given that current public efforts are targeted to malaria control, we encourage the public health community to consider Aedes aeypgti and dengue, chikungunya, and other arboviruses as potential emerging public health threats in sub-Saharan Africa.

Chromosomal inversion polymorphisms have special importance in the Anopheles gambiae complex of malaria vector mosquitoes, due to their role in local adaptation and range expansion. The study of inversions in natural populations is reliant on polytene chromosome analysis by expert cytogeneticists, a process that is limited by the rarity of trained specialists, low throughput, and restrictive sampling requirements. To overcome this barrier, we ascertained tag single nucleotide polymorphisms (SNPs) that are highly correlated with inversion status (inverted or standard orientation). We compared the performance of the tag SNPs using two alternative high throughput molecular genotyping approaches versus traditional cytogenetic karyotyping of the same 960 individual An. gambiae and An. coluzzii mosquitoes sampled from Burkina Faso, West Africa. We show that both molecular approaches yield comparable results, and that either one performs as well or better than cytogenetics in terms of genotyping accuracy. Given the ability of molecular genotyping approaches to be conducted at scale and at relatively low cost without restriction on mosquito sex or developmental stage, molecular genotyping via tag SNPs has the potential to revitalize research into the role of chromosomal inversions in the behavior and ongoing adaptation of An. gambiae and An. coluzzii to environmental heterogeneities.

Wuchereria bancrofti has been reported to cause 90% of all cases of lymphatic filariasis in Africa. wolbachia endosymbiot infect a wide range of insects and nematodes. This study was conducted in 48 settlements (8 from each division). A total of 2003 mosquitoes was pooled into 120 clusters from the 48 settlements in The Gambia. Polymerase chain reaction (PCR) was used to detect the presence of Wolbachia and filarial nematode and further differentiate Wolbachia into super groups among the positive samples. The level of association between Wolbachia and the genera of anthropophilic mosquitoes in The Gambia was also determined. Microscopic results showed 64.9% Anopheles, 32.0% Culex, 3.0% Aedes. PCR showed that, 34.17% of Wolbachia in the mosquito obtained varied among the three mosquito genera, with highest being among Anopheles. Only Wolbachia super group B was identified in Culex and Aedes. The purpose of this study carried out in The Gambia was to describe the most common mosquito species and to identify, by means of PCR, their association with the Wolbachia bacteria and the presence of nematodes responsible for filiariasis, in order to understand the role that this bacterium plays in the chain of filarial transmission. Key words: Wuchereria bancrofti, Filariasis, Anopheles gambiae, Culex quinquefasciatus, elephantiasis.