Adult Mosquitoes Research Articles

Gaps in protection to Anopheles exposure in high malaria endemic regencies of Papua Province, Indonesia.

Malaria in eastern Indonesia remains high despite significant reductions and local elimination in other parts of the country. Malaria control activities that have been implemented include early diagnosis and prompt treatment, provision of Long-lasting insecticide-treated nets (LLINs), and indoor residual spraying (IRS). To expedite malaria elimination in this region, a rapid entomological assessment combined with human behaviour observations (HBOs) were conducted in eight high malaria endemic regencies in Papua Province, Indonesia. The present study focuses on identifying gaps in protection against mosquito biting indoors and outdoors that may contribute to the sustained transmission and persistently high endemicity. This research was carried out alongside a rapid entomological assessment across 48 villages in all eight regencies over 150 days. It included human landing catches (HLCs) of adult mosquitoes, with human behavior recorded through direct observation during these HLCs. The human behavior observation (HBO) data concentrated on temporal (overnight) and spatial (domestic or peri-domestic) presence, in addition to bed net usage and sleeping patterns. Household surveys, which were also conducted during the entomological collections, gathered information on house construction materials, mosquito bite prevention practices, livestock presence, and other intervention usage. Behavior-adjusted exposure for unprotected individuals in 14 villages shows gaps in protection of ITN usage before sleeping. Meanwhile, an analysis of household survey in each regency identified several gaps in protection against mosquito bites. Human exposure to mosquito bites was driven by ITN usage, IRS coverage, indoor presence without protection prior to sleeping, the absence of mosquito house screens, and outdoor presence without protection. The data reveals several gaps in protection against mosquito exposure across all eight regencies of Papua assessed. There is a need to optimize indoor interventions, as current vector control efforts do not adequately address outdoor exposure. Assessing spatial and temporal exposure can help identify effective protective vector strategies for these areas while highlighting persistent exposure risks. Community-based larval source management could enhance overall exposure reduction. Additionally, innovative measures like spatial repellents may address some protective gaps, together with improved case detection and treatment. The findings indicate that the existing strategy may not suffice to eradicate malaria in the region, necessitating a reconsidered, evidence-based, and adaptive approach.

The effect of the egg storage time on the hatching success, morphometrics of larvae, and adult emergence of Aedes aegypti and Aedes albopictus

AbstractAedes aegypti (L.) and Aedes albopictus (Skuse) are important vectors that transmit arboviruses such as Dengue virus (DENV), Yellow fever virus (YFV), Chikungunya virus (CHIKV), and Zika virus (ZIKV). Focusing on the unique characteristics of their eggs to withstand dry conditions, this study aimed to elucidate the viability of dry‐stored eggs and the subsequent morphometric changes in larvae and adult mosquitoes upon rehydration. Experiments were carried out using ovitrap‐collected eggs, which were reared in the laboratory until adult emergence. The resulting mosquitoes were fed on cattle blood and sugar solution and allowed to lay eggs on the paper strips, which were air‐dried and stored for 6 months. The viability of these eggs was tested monthly. The head length and total length of fourth‐instar larvae and head, thorax, abdomen, wing length, wing width, and total length of adults were measured, including the days needed for adult emergence. The results imply that the prolonging of the egg storage period led to a decline in viability, delayed emergence of adults, and a negative impact on the morphometrics of fourth‐instar larvae in both Ae. aegypti and Ae. albopictus. Nonetheless, the morphometrics of the adults did not exhibit any significant differences compared to those of fresh eggs.

Impacts of ground-based ULV pyrethroid sprays on abundance and age structure of the Zika vector, Aedes aegypti (Diptera: Culicidae), in urban Arizona.

Aedes aegypti (L.), the primary mosquito vector of arboviruses such as dengue and Zika, has a global distribution that includes the southern United States. Control of this peridomestic mosquito is challenging. Ultra-low volume (ULV) pyrethroid sprays are commonly used against adult mosquitoes to break transmission during a disease outbreak, although efficacy data are limited. This study examined the impacts of ULV sprays on Ae. aegypti vectorial capacity as measured by vector abundance and age structure in two cities in Maricopa County, AZ with robust Ae. aegypti populations and a well-developed vector management program. We assessed impacts of routine ULV applications conducted by Maricopa Vector Control Division during the summer rainy seasons of 2017 to 2019 to determine whether existing practices mainly targeting Culex spp. also suppressed Ae. aegypti. The insecticide formulations applied for Culex spp. control (Duet and Permanone 30-30) did not affect Ae. aegypti abundance, but Duet applications slightly reduced female mosquito age. Deltagard, the insecticide product used specifically against Ae. aegypti, was only applied three times in 2018 over small areas, so efficacy assessment was difficult. Deltagard was associated with a small decline in Ae. aegypti abundance. CDC bottle bioassays of Ae. aegypti collected in the study area showed resistance to permethrin and deltamethrin. Overall, the lack of significant mosquito population suppression or age structure changes after insecticide applications suggest that current tools used by Maricopa Vector Control Division are unlikely to effectively control Ae. aegypti populations in the event of a disease outbreak.

EVIDENCE OF ANOPHELES RESISTANCE TO PYRETHROID PESTICIDES: REPORT FROM GADAU KATAGUM ENDEMIC REGION BAUCHI STATE, NIGERIA

Malaria continues to pose a significant health issue negatively. The high number of cases requires prevention, including controlling the Anopheles gambiae s.l., mosquito. One of the control methods is the use of insecticides containing pyrethrin. WHO tube Bioassays in Anopheles gambiae s.l., to determine resistance from pyrethroids expose in F1 adult mosquitoes to insecticides and a sensitivity test to temephos, measuring the activity of non-specific alpha and beta esterase enzymes. This study determined Anopheles gambiae s.l., resistance from larvae to adult. The bioassay was used for the temephos sensitivity of Anopheles larvae. The LC99 value was analyzed using probit and compared with the diagnostic. WHO susceptibility test was conducted to determine pyrethroid resistance from adult mosquitoes. A mortality of less than 90% was declared as resistant. Measurement of alpha and beta esterase levels used Lee's microplate assay technique based on visual identification and absorbance value. Anopheles gambiae s.l., were resistant to both class of pyrethroids. Adult mosquitoes have recorded resistant to both class of type i and ii pyrethroid with increase in time reaching about 60% with cypermethrin. At 24 hours Mortality Rates showed Cypermethrin with the highest at 90% followed by Permethrin (80%), Deltamethrin (75%), and Tetramethrin (70%). Based on the alpha esterase activity test, it was found that most of the mosquitoes showed very sensitive meanwhile, most of the mosquitoes were moderate resistance. This study suggests that Anopheles gambiae s.l., the population from the endemic region in Bauchi, Nigeria are indicated to develop resistance to the pyrethroids insecticides.

Repellent activities of ethanolic extract of Cymbopogon citratus (Poaceae) and Ocimum basilicum L. (Lamiaceae) leaves against Culex quinquefasciatus mosquitoes (Diptera: Culicidae) in Dogbo district in south-western Benin, West Africa

The alteration of mosquito life cycle using larvicides is key in the control of diseases transmitted by mosquitoes. The residual and environmental effect of some of these synthetic larvicides has given an opportunity to search for a potent larvicide as an alternate control measure against mosquitoes. The current study was aimed to evaluate the repellent activities of ethanolic extract of Cymbopogon citratus (Poaceae) and Ocimum basilicum L. (Lamiaceae) leaves against Culex quinquefasciatus adult mosquitoes in lymphatic filariasis vector control in Dogbo district in south-western Republic of Benin. Larvae of Culex quinquefasciatus mosquitoes were collected from breeding sites using the dipping method from September to November 2023 during the small rainy season in Dogbo district of Couffo department. Then, these larvae were reared in insectary until became adult mosquitoes. Repellent activities of ethanolic extract of both plant leaves were measured on adult mosquitoes with different concentrations of 1mg/cm2, 2mg/cm2, 3mg/cm2, 4mg/cm2 and 5mg/cm2. The results showed that the leaves of both plant had repellent effects against Culex quinquefasciatus adult mosquitoes. However, the repellent effect of Cymbopogon citratus leaves was higher than that of Ocimum basilicum L. leaves. Both ethanolic extracts of Cymbopogon citratus and Ocimum basilicum L leaves are found to be effective in the repellency against the bites of Culex quinquefasciatus adult mosquitoes.

Repellent activities of ethanolic extract of Cymbopogon citratus (Poaceae) and Ocimum basilicum L. (Lamiaceae) leaves against Aedes aegypti mosquitoes in Dogbo district in south-western Benin, West Africa

The use of chemical insecticides causes important damages to environment and human health and there is a need to search for alternative solutions. The current study was aimed to evaluate the repellent activities of ethanolic extract of Cymbopogon citratus (Poaceae) and Ocimum basilicum L. (Lamiaceae) leaves against Aedes aegypti adult mosquitoes in dengue vector control in Dogbo district in south-western Republic of Benin. Larvae of Aedes aegypti mosquitoes were collected from breeding sites using the dipping method from September to November 2023 during the small rainy season in Dogbo district of Couffo department. Then, these larvae were reared in insectary until became adult mosquitoes. Repellent activities of ethanolic extract of both plant leaves were measured on adult mosquitoes with different concentrations of 1mg/cm2, 2mg/cm2, 3mg/cm2, 4mg/cm2 and 5mg/cm2. The results showed that the leaves of both plants had repellent effects against Aedes aegypti adult mosquitoes. However, the repellent activity of Cymbopogon citratus was higher than that of Ocimum basilicum L. Both ethanolic extracts of Cymbopogon citratus and Ocimum basilicum L leaves are found to be effective in the repellency against the bites of Aedes aegypti adult mosquitoes.

Surveillance of Wolbachia infection in mosquito species in Ota, Ogun State, Nigeria

IntroductionIn light of climate change, proliferation of mosquito-borne diseases like dengue and malaria is a mounting concern, driven by expanding mosquito populations as a result of favorable environment for their survival. Addressing public health challenges caused by mosquitoes demands constant innovation and sustainable solutions.ObjectiveThis study responds to recent reports of Wolbachia infections in West African mosquito species, suggesting their potential as biocontrol agents for disease vectors. We seek to detect the presence of Wolbachia pipientis in different mosquito species in Ota and identify mosquito species present in the area.MethodWe conducted a comprehensive mosquito larval surveillance in Ota, Ogun State, Nigeria using a systematic stratified random sampling method from November 2022 to March 2023 to assess mosquito species distribution and Wolbachia infection. During this period, we surveyed mosquito larvae in various sites, rearing them to adulthood. We meticulously identified species, sex, and collection locations then, stored specimens at − 20 °C. Sodium chloride precipitation protocol was employed to extract DNA from the mosquitoes individually. Polymerase chain reaction (PCR) analysis was carried out using one to one point five microliter of DNA, with distilled water as negative control.ResultsOut of 1265 emerging young adult mosquitoes, 62.1% were females, while 37.1% were males. Aedes species constituted 22.2%, Anopheles 37.2%, and Culex 40.6% of the population. DNA analysis identified Wolbachia infection in Ae. albopictus and Ae. aegypti, with wsp gene sizes ranging from 590 to 632 bp, confirming Wolbachia presence by sequencing.ConclusionOur study is the first report on Wolbachia presence in Aedes sp within this region, which suggests that this mosquito species is a less likely vector for dengue virus and other related infectious agents. The study highlights the importance of continuous mosquito population and breeding site monitoring for potential biocontrol interventions against disease vectors.

Evaluation of DENV‐Mediated Potential of Aedes albopictus (KDCA Strain) Through Comparative Experiments With Aedes aegypti

ABSTRACTAedes albopictus is an important vector of various arboviruses, including dengue virus (DENV). The vector capacity for DENV has been studied in various geographical regions, but information on Korean Ae. albopictus strains are limited. This study aimed to investigate the vector capacity of the Korean Ae. albopictus strain (Korea Disease Control and prevention Agency, KDCA) for DENV‐2. Adult mosquitoes were orally infected with DENV‐2 and dissected on days 3 and 7 post‐infection. Viral RNA was extracted from midgut and carcass tissues and detected by RT‐PCR. The results showed that the KDCA strain could acquire and transmit DENV‐2, although with lower efficiency compared with Ae. aegypti. These findings highlight the potential risk of DENV transmission by Ae. albopictus strain (KDCA) and emphasize the need for effective vector control strategies.

Adult-capture assays as a tool to measure insecticide resistance in Anopheles malaria vectors: a modeling comparison with larval-capture assays

Systematic, long-term, and spatially representative monitoring of insecticide resistance in mosquito populations is urgently needed to quantify its impact on malaria transmission, and to combat failing interventions when resistance emerges. Resistance assays on wild-caught adult mosquitoes (known as adult-capture) offer an alternative to the current protocols, which recommend larval capture. Adult-capture assays can be done in a shorter time frame, in more locations, and in the absence of an insectary. However, unlike insectary-raised mosquitoes, a group of adults captured in the wild represents different ages and may have previous exposure to insecticides. Since age and prior exposure are critically important in determining the likelihood of death during the assay, taking these factors into account is important for assessing the relative utility of the assay. Currently such quantitative assessments are lacking. We developed a discrete-time deterministic model to simulate the mosquito life cycle, including insecticide exposure due to insecticide-treated bed nets. We incorporated non-lethal effects of insecticide exposure demonstrated in laboratory experiments and the impact of multiple exposure to insecticides on mosquito death rates during the assay. We then sampled from this population using both larval-captured and adult-captured mosquito collection and simulated insecticide resistance assays. To quantify possible biases in adult-capture assays, we compared the results of these assays to the true resistance allele frequency in the population. In simulated samples of 100 test mosquitoes, reflecting WHO-recommended sample sizes, we found that adult-capture samples had a 94% positive predictive value (PPV) for resistance at the WHO’s 10% resistance cutoff, and a 97% negative predictive value (NPV), compared to 98% PPV and 19% NPV for larval-captured samples. Bias in the adult-capture assays was primarily dependent on the level of insecticide resistance rather than coverage of bed nets or exposure heterogeneity. Using adult-captured mosquitoes for resistance assays may have advantages over larval-capture collection in many settings, and in our model does not appear to be significantly less accurate than larval-capture, especially when used to categorize resistance under the binary WHO criteria. These results suggest that adult-captured assays could be deployed for resistance monitoring programs at a more widespread scale.

Lysinibacillus sphaericus exposure impedes Anopheles dirus’s oviposition via downregulating vitellogenin

BackgroundVector control using Lysinibacillus sphaericus is an effective strategy for preventing the transmission of mosquito-borne diseases. Our previous study demonstrated that exposure to L. sphaericus during the larval stage of Anopheles dirus significantly reduced the fecundity of surviving adult mosquitoes. However, the underlying mechanisms driving this reduction remain unclear. Sublethal doses of L. sphaericus, often resulting from insufficient or delayed application, can still impact mosquito populations. Therefore, this study aimed to investigate how sublethal doses of L. sphaericus inhibit the reproductive capacity of An. dirus mosquitoes.MethodsFirst, the staining method was used to detect L. sphaericus in surviving adult mosquitoes that had been exposed to sublethal doses during the larval stage. Second, adult mosquitoes were fed a sucrose solution containing L. sphaericus, and the effects on the reproductive capacity were observed. Third, transcriptome sequencing and qPCR were employed to identify and validate genes associated with oviposition suppression in An. dirus following treatment with sublethal doses of L. sphaericus. Finally, we assessed the effects of sublethal doses and direct feeding of L. sphaericus on vitellogenin (Vg) expression and activation of the target of rapamycin (TOR) signaling pathway using qPCR and Western blotting.ResultsOur findings demonstrated that L. sphaericus persists in adult An. dirus mosquitoes that survived larval exposure to sublethal doses. Additionally, feeding adult female mosquitoes with L. sphaericus significantly suppressed their oviposition ability. Transcriptome analysis revealed substantial alterations in gene expression profiles among surviving mosquitoes exposed to sublethal doses of L. sphaericus. Notably, L. sphaericus inhibit lysosomal function and lipid metabolism, which are critical for mosquito physiology. Furthermore, L. sphaericus significantly downregulated the Akt-TOR signaling pathway and Vg expression in adult mosquitoes.ConclusionsExposure An. dirus larvae to L. sphaericus resulted in the persistence of L. sphaericus in surviving adult mosquitoes and significantly suppressed female oviposition by downregulating Vg expression via inhibition of lysosomal function and the TOR signaling pathway. This study offers novel insights into the interaction between L. sphaericus and its mosquito host and identifies potential molecular targets for controlling mosquito population density by modulating oviposition behavior.Graphical

Water sources selected for immature development of some African rainforest dwelling mosquitoes under different landscapes in Cameroon.

Little is known about the behaviors of African equatorial rain forest mosquito species and their potential role as sylvatic and bridge-vectors of various pathogens of animal and public health. In 2016 and 2017, the diversity and sources of water supporting immature development of mosquitoes in Talangaye Rainforest (South West Cameroon) before, during and after deforestation were investigated. Mosquito eggs, larvae and pupae were collected from 12 natural, seminatural, and artificial water sources and reared to adults. A total of 595 adult mosquitoes belonging to seven genera and at least 43 species were identified. Culex was the most abundant (56.3%) and was encountered in the majority in bamboo pots. Aedes and Uranotaenia species were mostly found in rock pools, while Anopheles and Hodgesia species solely prefer stream pools. In terms of mosquito abundance, rock pools were the most productive (29.91%) followed by bamboo pots (24.7%). Natural sites such as rock pools, tree holes, and stream pools recorded a greater number of species (S = 21, 14 and 12 respectively). During the rainy season, rock pools (46.23%) and bamboo pots (18.7%) were the most productive water bodies, while in the dry season, bamboo pots (35.71%) and stream pools (35.71%) harbored the most mosquitoes. The disturbed and pristine-like habitats had the greatest number of mosquitoes and breeding sites compared to palm plantation. This study provides some useful data on water sources used for immature development of forest mosquito species in Southwest Cameroon and how some species might adapt to changing landscapes, especially due to deforestation.

Bionomics and distribution of malaria vectors in Kisumu city, Western Kenya: implications for urban malaria transmission

BackgroundIncreasing unplanned urbanization in tropical Africa may create new niches for malaria vectors, raising transmission risk, yet control efforts focus on rural ecosystems. Understanding mosquito diversity, ecology and biting behaviour in urban areas is crucial for effective control. This study assessed Anopheles diversity, abundance, behaviour, and Plasmodium infection rates in Kisumu city, Kenya.MethodsIndoor and outdoor host-seeking and resting adult mosquitoes were collected using CDC miniature light traps (CDC-LT) and Prokopack aspirators along an urban–rural transect. Anophelines were identified morphologically, with Anopheles gambiae sensu lato (s.l.) and Anopheles funestus group further distinguished to siblings using polymerase chain reaction (PCR). Sporozoite infection rates were determined using a multiplexed real-time quantitative PCR (qPCR) assay.ResultsA total of 3,394 female Anopheles mosquitoes were collected: An. gambiae s.l. (68%), An. funestus s.l. (19.8%), Anopheles coustani (7.8%), Anopheles pharoensis (2.6%), Anopheles maculipalipis (1.6%), and Anopheles leesoni (0.2%). All six species were found in urban zone, but only three were in peri-urban and rural sites. Overall, urban collection accounted for 55.5% of mosquitoes, followed by peri-urban (30%) and rural sites (14.5%). Anopheles arabiensis dominated urban (84.3%) and peri-urban (89%) sites, while An. gambiae sensu stricto (s.s.) was predominant in rural zone (60.2%) alongside An. arabiensis (39.7%). Anopheles funestus was predominant in peri-urban (98.4%) and rural (85.7%) areas, while An. leesoni accounted for 1.6% and 14.3%, respectively. In urban areas, all An. funestus s.l. samples were An. funestus s.s.. Most (55.5%) of Anopheles mosquitoes were collected indoors, while secondary vectors were mainly outdoors. Overall, sporozoite rates were higher outdoors (3.5%) than indoors (1.45%) in rural areas. Indoor rates were 2.5% (An. funestus), 1.4% (An. gambiae s.s.), and 1% (An. arabiensis). Outdoors, An. gambiae had 5.3%, and An. arabiensis 2.1%. In peri-urban areas, An. gambiae had 2.3%. No sporozoites were found in urban samples.ConclusionThe study highlights a shift in Anopheles diversity towards urban areas with increased outdoor activity and outdoor malaria transmission in rural and peri-urban areas, underscoring the need for tools targeting outdoor-biting mosquitoes. The presence of An. funestus in urban settings emphasizes the need for sustained entomological surveillance to inform integrated vector control.

Higher abundance of the vector Aedes aegypti in rural areas than in urban areas in Managua, Nicaragua.

Background Ae. aegypti is the primary vector of dengue, chikungunya, and Zika viruses, traditionally associated with urban environments. However, its presence and abundance in rural settings remain understudied. This study compares Ae. aegypti populations between rural and urban communities in Managua, Nicaragua, across different seasons over multiple years. Methods Entomological surveys were conducted in 500 randomly selected households (250 rural, 250 urban) during the rainy and dry seasons of 2022 and 2023. Immature mosquitoes were collected from water-holding containers, and adult mosquitoes were sampled using aspirators. Entomological indices, including Stegomyia , pupal, and adult indices, were compared across seasons and localities. Results All entomological indices were significantly higher in rural communities than in urban areas across both years and seasons. Rural households had greater mosquito densities, with pupal productivity concentrated in large water storage containers. Adult mosquito collections confirmed a greater Ae. aegypti presence in rural areas, suggesting sustained transmission risk. We observed pupal thresholds in water-holding containers for female adult collections. Discussion Contrary to the conventional view of Ae. aegypti as an urban mosquito, our findings highlight its substantial presence in rural settings, likely driven by water storage practices and environmental conditions. These results align with findings from other regions reporting high mosquito abundance in rural areas, challenging assumptions about urban dominance. Conclusion Rural areas play a crucial role in sustaining Ae. aegypti populations. Vector control strategies should target both rural and urban communities, with seasonally tailored interventions to mitigate disease transmission risks.

Resting habitat, blood meal source and viral infection rate of Aedes aegypti (Diptera: Culicidae) in the Southern Afar Region of Ethiopia

BackgroundKnowledge of Aedes species distribution, preference to feed on humans, and susceptibility to viruses is crucial in preventing transmission of Aedes-transmitted viruses. This study aimed to determine resting behavior, blood sources, and viral infection status of Aedes aegypti in Awash Sebat, Awash Arba, and Werer towns of Afar Region.MethodsAdult mosquitoes were collected using a Prokopack aspirator between 8:00–14:00 and 15:00–18:00 h both indoor and outdoor of the house. The mosquitoes were sorted by sex, date of collection, collection places, and abdominal status and identified by species/genus using standard keys. Blood meal sources and dengue virus and chikungunya virus infection status of Ae. aegypti were determined using ELISA and RT-qPCR respectively.ResultA total of 2,745 adult mosquitoes comprising the genera Aedes (1433; 52.2%) Culex (1292; 47.1%) and Anopheles (20; 0.7%) were collected. The proportion of female Ae. aegypti in Awash Sebat (611; 36%) was highest as compared to females Ae. aegypti in Awash Arba (172; 33.8%), and in Werer (59; 11%). A higher proportion of outdoor resting of Ae. aegypti was caught from tyres rather than other indoor and outdoor locations (314; 37.29%) (X2 27.374, df = 12; p = 0.007). Seasonal and monthly variation was observed in Ae. aegypti collection, where the wet season and the months of August 2022, September 2022, and October 2022 had high Ae aegypti density. The overall human blood and bovine blood indices of Ae. aegypti were 53/145 (36.6%) and 18/145 (12.4%), respectively. Furthermore, dengue and chikungunya viruses were not detected from the Ae. aegypti examined.ConclusionThe majority of Ae. aegypti collections were made during the wet season from outdoor resting sites, particularly from tyres. Thus, outdoor targeted management of Ae. aegypti is recommended as a strategy particularly tyre removal during the wet season, to reduce resting and proliferation of Ae. aegypti and hence prevent the risks of Aedes-borne disease transmission.

Preimaginal development of Aedes aegypti L. (Diptera: Culicidae) in brackish water gives rise to adult mosquitoes with thicker cuticles and greater insecticide resistance.

Aedes aegypti L. and Aedes albopictus Skuse mosquitoes (Diptera: Culicidae), the principal vectors of many human arboviral diseases, lay eggs and undergo preimaginal development in fresh water. They have recently been shown to also develop in brackish water in coastal areas. Previous findings showed that Ae. aegypti larvae developing in brackish water possessed thicker cuticles and greater larvicide resistance than larvae developing in fresh water. The present study compared cuticle ultrastructure, resistance to adulticides, and the activities of adulticide detoxifying enzymes in female mosquitoes emerging from fresh and brackish water-developing Ae. aegypti preimaginal stages. The results showed that brackish water-derived females possessed significantly thicker tarsal and abdominal cuticles compared to fresh water-derived females. Brackish water-derived Ae. aegypti females were also significantly more resistant to three different types of pyrethroids and malathion compared to fresh water-derived females. Corresponding reversal of cuticle changes and adulticide resistance when preimaginal salinity was reversed showed that preimaginal salinity determined both procuticle structure and adulticide resistance in brackish water-derived females. Compared with fresh water-derived Ae. aegypti females, brackish water-derived females had similar activities of the adulticide-detoxifying enzyme families of esterases and glutathione S-transferases and a modest increase in the activity of monooxygenases, all of which were lower than the threshold values attributed to resistance in field populations of Ae. aegypti. Reduced permeability of the thicker and remodelled cuticles in brackish water-derived Ae. aegypti females to adulticides is proposed to be mainly responsible for their greater resistance to different types of adulticides. Greater salinity tolerance of preimaginal stages, adult cuticle changes and higher larvicide and adulticide resistance are inherited properties of brackish water-developing Ae. aegypti that reverse in a few generations after transfer to fresh water. This is compatible with a role for epigenetic changes in the adaptation of Ae. aegypti to brackish water. Greater resistance of salinity-tolerant Ae. aegypti to adulticides and larvicides poses a hitherto unappreciated problem for controlling arboviral diseases, with attendant implications also for other mosquito-borne diseases.

Chemical targeting of prolyl-tRNA synthetase stalls ovarian development and kills malaria vectors.

Along with rising resistance to antimalarials, the emergence of insecticide resistance in Anopheles mosquito species also remains a serious concern. Here, we reveal two potent compounds that show larvicidal and endectocidal activity against malaria vectors, Anopheles culicifacies and Anopheles stephensi, respectively. We investigated larvicidal activity of two inhibitors against III-instar larvae of Anopheles culicifacies. The survival and fertility of adult female Anopheles stephensi mosquitoes were assessed. Additionally, we purified recombinant prolyl-tRNA synthetase of Anopheles culicifacies and performed enzyme-based assays and structural analysis with the two inhibitors. Our study reveals that the Anopheles culicifacies prolyl-tRNA synthetase (AcProRS) is potently inhibited by halofuginone (HFG) and an ATP mimetic (L95). The evaluation of larvicidal activity of HFG against Anopheles culicifacies III-instar larvae showed a dose-dependent increase in mortality. In adult female Anopheles stephensi mosquitoes, ingestion of HFG via artificial blood feeding resulted in impaired ovary development, reduced egg laying, and decreased overall survival. The potent enzymatic inhibition of AcProRS thus drives the killing of larvae. The co-crystal structure of AcProRS with inhibitors provides a structural basis for improving their potency as future larvicides. Our data suggest the potential for repositioning halofuginone (HFG) and pyrrolidine-based ATP-mimetics (L95) as larvicides. Targeting the vector-encoded aminoacyl-tRNA synthetases provides a new focus for developing effective agents that can control multiple mosquitoe-borne infectious diseases like malaria and dengue.

Asian tiger mosquito in the oil-producing city of Soyo: the first report of Aedes (Stegomyia) albopictus (Skuse, 1894) in Angola

BackgroundThe Asian tiger mosquito, Aedes albopictus (Skuse, 1894), is a highly invasive species that has successfully colonized many tropical and temperate regions worldwide. Its rapid global spread is strongly associated with human activities and has created favorable conditions for the emergence of human arboviruses in new geographic areas.MethodsMosquito larvae were collected by community health workers from different breeding sites and reared to adults in a field insectary. Adult mosquitoes were morphologically identified to species level. Species identification was confirmed by cytochrome oxidase subunit I DNA barcoding.ResultsWe report the first detection of Aedes albopictus in Angola during an Anopheles stephensi survey conducted in Soyo, Zaire Province. Phylogenetic analysis indicated that the Angolan Ae. albopictus population clusters with sequences from Central African countries, suggesting an introduction from within the continent.ConclusionsThe presence of Ae. albopictus in Angola highlights the need for enhanced vector surveillance and control measures to prevent the emergence of arboviral diseases. This finding emphasizes the relevance of collaboration between local health authorities, communities, and international organizations in monitoring the spread of invasive mosquito species.

In-depth physiological study on the sustainable application of a botanical insecticide with low mammalian toxicity against Aedes aegypti (Diptera: Culicidae).

In-depth physiological study on the sustainable application of a botanical insecticide with low mammalian toxicity against Aedes aegypti (Diptera: Culicidae).

Insights into spatio-temporal dynamics of Anopheles vectors while approaching malaria elimination along the Thailand-Cambodia border.

Insights into spatio-temporal dynamics of Anopheles vectors while approaching malaria elimination along the Thailand-Cambodia border.

Implications for malaria transmission: a cross-sectional study on the bionomics and susceptibility of local malaria vectors in urban and periurban settings of Ndola district

ObjectivesTo assess vector behaviour and phenotypic resistance for effective vector control programming.DesignThis was a cross-sectional study.SettingThis study was conducted in the urban and periurban areas of Ndola district, Zambia.Participants/study unitsA...