Search Results (40)

Malaria continues to affect millions of people around the world. Current control strategies have not been sufficient, and additional tools are required for malaria elimination. A promising approach is the use of bacteria from the mosquito microbiota, such as the Su_YN1 Serratia ureilytica bacterium, which is shown to strongly impair the development of P. falciparum and P. berghei in Anopheles mosquitoes. To evaluate the potential of using S. ureilytica Su_YN1 to block the Plasmodium parasite in South American vectors, we investigated its effects on mosquito fitness and survival. We found that this bacterium does not affect the longevity, blood feeding, fecundity and fertility of Anopheles aquasalis, an important South American vector. Overall, our results provide baseline support for the potential implementation of Su_YN1 for the control of malaria transmission in South America. Full article

The Asian tiger mosquito Aedes albopictus is a highly invasive species capable of transmitting human pathogens. For population management, the sterile insect technique (SIT) is considered an effective and sustainable alternative to conventional methods, such as insecticides and reducing or eliminating breeding sites. The use of symbiotic bacteria to improve the application of SIT or design combined SIT/incompatible insect technique (IIT) approaches is currently considered. In this context, exploring the microbiota of local mosquito populations is crucial for identifying interesting components. This study employed 16S rRNA sequencing and microbiological methods to characterize the diversity of laboratory and wild Ae. albopictus in Greece. Differences were recorded between wild and lab-reared mosquitoes, with laboratory samples exhibiting higher diversity. Laboratory treatment, sex, and developmental stage also resulted in variations between communities. Populations reared in the same facility developed mostly similar bacterial profiles. Two geographically distant wild populations displayed similar bacterial profiles, characterized by seasonal changes in the relative abundance of Pantoea and Zymobacter. Wolbachia was dominant in most groups (63.7% relative abundance), especially in field-caught mosquitoes. It was identified with two strains, wAlbA (21.5%) and wAlbB (42.2%). Other frequent taxa included Elizabethkingia, Asaia, and Serratia. Blood feeding favored an increase in Serratia abundance. Various Enterobacter, Klebsiella, Aeromonas, and Acinetobacter strains were isolated from larval and adult mosquito extracts and could be further characterized as diet supplements. These findings suggest that the microbiota of local populations is highly variable due to multiple factors. However, they retain core elements shared across populations that may exhibit valuable nutritional or functional roles and could be exploited to improve SIT processes. Full article

Serratia plymuthica, isolated from the midgut of Aedes aegypti, displays remarkable resilience to hemin, a toxic hemoglobin byproduct generated during blood digestion. This study explores its proteomic adaptations under oxidative stress induced by 5 mM hemin, mimicking midgut conditions. Growth assays demonstrated that S. plymuthica tolerated hemin concentrations ranging from 5 µM to 1 mM, reaching the stationary phase within approximately 10 h. Colonies exhibited morphological changes—darkened peripheries and translucent halos—suggesting heme accumulation and detoxification. Label-free quantitative proteomics identified 436 proteins, among which 28 were significantly upregulated—including universal stress proteins (USPs), ABC transporters, and flavodoxin—while 54 were downregulated, including superoxide dismutase and several ribosomal proteins. Upregulated proteins were associated with antioxidant defense, heme transport, and redox regulation, whereas downregulated proteins suggested metabolic reprogramming to conserve energy under stress. Functional enrichment analysis revealed significant alterations in transmembrane transport, oxidative stress response, and central metabolism. These findings suggest that S. plymuthica contributes to redox homeostasis in the mosquito gut by mitigating reactive oxygen species (ROS) and detoxifying excess heme, supporting its role as a beneficial symbiont. The observed stress tolerance mechanisms may influence mosquito physiology and vector competence, offering novel insights into mosquito–microbiota interactions and potential microbiota-based strategies for vector control. Full article

Aedes albopictus is one of the most important vectors of Dengue, which poses a serious threat to public health. The bacterial microbiota has an effect on the parameters of mosquitos, such as larval development and fecundity, and it has emerged as a promising field to be explored for novel environmentally friendly control strategies. Rahnella sp. are present in many insects, including Ae. Albopictus, and play a role in bacterial–insect interactions; however, the role of the bacteria in mosquito biology has not yet been characterized. In this study, we characterized the Rahnella isolate RAeA1 obtained from Ae. albopcitus, and its colonization stability in Ae. albopictus was investigated by generating GFP-tagged bacteria. The influences of the bacteria on larval development and mosquito reproductive capacity were evaluated by inoculating RAeA1 in axenic larvae and antibiotic-treated adult mosquitoes, respectively. The results indicated that RAeA1, which is widespread in the field population of Ae. albopictus, can be transmitted directly from the parental strain to the progeny and can rescue axenic larvae developing into adults with a prolonged development time to pupation. RAeA1 inoculation can impair egg production and ovary maturation, as well as reducing the synthesis of ecdysteroids and vitellogenin in Ae. albopictus females. Overall, our results provide a thorough study of bacterium function characterization that will facilitate the development of potential strategies in relation to the design of microbiomes for vector control. Full article

The Aedes aegypti mosquito serves as a vector for several diseases, including dengue, Zika, chikungunya, and yellow fever. This species is well adapted to urban environments and poses a significant threat to public health. Some studies suggest that the gut bacteria of insect vectors may play a crucial role in developing resistance to insecticides. This study assessed the resistance of Ae. aegypti from Florencia, Caquetá, to temephos and deltamethrin and analyzed the diversity of gut bacteria in resistant larvae and adult females. Larvae exhibited resistance to temephos at a lethal concentration 50 (LC₅₀) of 0.034 µg/mL, while females showed resistance to deltamethrin at a discriminant concentration of 10 µg/mL. The bacterial load in the guts of deltamethrin-treated females (3.42 × 10⁶ CFU/mL) was significantly higher compared to temephos-treated larvae (9.4 × 10⁵ CFU/mL) and untreated females (8 × 10⁴ CFU/mL). A total of sixty-eight bacterial strains were isolated from the guts of both larval and resistant females Ae. aegypti, with 31 strains identified through 16S rRNA gene analysis and 11 confirmed by gyrB gene sequencing. In untreated females, Bacillus comprised 12.55% of the gut bacteria and was identified as an exclusive genus. In resistant larvae, Serratia was the most abundant and exclusive genus, accounting for 35.29%, while in resistant females, Cedecea was the predominant genus, representing 66.67%. These findings suggest that gut bacteria may influence the resistance of Ae. aegypti to temephos and deltamethrin. Furthermore, this research provides valuable information that can be considered for the design of local vector control strategies. The results highlight new research focused on the study of insecticide tolerance and degradation within the gut microbiota of insect vectors of arboviruses. Full article

Rhamnolipids, biosurfactants synthesized from natural resources, demonstrate significant applications, including notable insecticidal efficacy against Aedes aegypti L., the primary vector for numerous arboviruses. The global spread of A. aegypti poses substantial public health challenges, requiring innovative and sustainable control strategies. This research investigates the use of andiroba (Carapa guianensis Aubl.) biomass waste as a substrate for synthesizing a rhamnolipid biosurfactant (BSAW) produced by Pseudomonas aeruginosa and evaluates its insecticidal activity against A. aegypti. The findings indicate a biosurfactant yield of 4.42 mg mL⁻¹, alongside an emulsification index approaching 60%. BSAW successfully reduced both surface and interfacial tensions to below 30 mN/m and 4 mN/m, respectively. Characterization revealed that BSAW is a di-rhamnolipid, consisting of two rhamnose units covalently linked to a saturated C₁₀ fatty acid chain. At a concentration of 1.0 mg mL⁻¹, BSAW exhibited notable larvicidal activity, leading to structural impairments and cellular dysfunctions in A. aegypti larvae while also disrupting their associated bacterial microbiota. Moreover, BSAW effectively deterred oviposition in adult mosquitoes. These findings underscore BSAW’s potential to compromise various developmental stages of A. aegypti, supporting integrated arbovirus management approaches. Furthermore, this research emphasizes the feasibility of utilizing agro-industrial waste as substrates for microbial rhamnolipid production. Full article

The midgut microbiota of Aedes aegypti is crucial for the mosquito’s development, nutrition, and immunity. However, its communities are also distinctively influenced by the colonization of different microorganisms, influencing its susceptibility to pathogens and transmission capacity. In this study, we investigated the effects of infections with Escherichia coli, Staphylococcus aureus, and Beauveria bassiana on the midgut microbial composition of Ae. aegypti. These microorganisms were inoculated into the midguts of third-instar larvae using a soaking method. Midgut samples were then analyzed through high-throughput 16S rDNA sequencing to assess bacterial load and microbiota composition of fourth-instar larvae and female adult mosquitoes. The results reveal that E. coli-colonized fourth-instar larvae (CO_4W) exhibited 20 unique genera, whereas the S. aureus-colonized group (S_4W) had operational taxonomic units assigned to 194 bacterial taxa, including a notable decrease in Elizabethkingia. In addition, B. bassiana infection led to a significant reduction of Elizabethkingia meningoseptica in larvae, decreasing from 42.9% in the control group (CK_4W) to 0.9% in the B. bassiana-infected group (B_4W). Distinct microbial profiles were also compared between adult mosquitoes and fourth-instar larvae. Significant abundance changes were found in Firmicutes, Bacteroidota, and Proteobacteria among different groups. Metabolic pathway predictions using PICRUSt suggested that microorganism invasion enriched the pathways involved in carbohydrate metabolism and amino acid metabolism. This enrichment suggests that the microbiota may undergo specific adaptive responses to pathogen presence. Overall, our results provide new insights into the relationship between the invasion of microorganisms and midgut bacterial communities in mosquitoes. Full article

Anopheles arabiensis is a highly adaptable member of the An. gambiae complex. Its flexible resting behaviour and diverse feeding habits make conventional vector control methods less effective in controlling this species. Another emerging challenge is its adaptation to breeding in polluted water, which impacts various life history traits relevant to epidemiology. The gut microbiota of mosquitoes play a crucial role in their life history, and the larval environment significantly influences the composition of this bacterial community. Consequently, adaptation to polluted breeding sites may alter the gut microbiota of adult mosquitoes. This study aimed to examine how larval exposure to metal pollution affects the gut microbial dynamics of An. arabiensis adults. Larvae of An. arabiensis were exposed to either cadmium chloride or copper nitrate, with larvae reared in untreated water serving as a control. Two laboratory strains (SENN: insecticide unselected, SENN-DDT: insecticide selected) and F₁ larvae sourced from KwaZulu-Natal, South Africa, were exposed. The gut microbiota of the adults were sequenced using the Illumina Next Generation Sequencing platform and compared. Larval metal exposure affected alpha diversity, with a more marked difference in beta diversity. There was evidence of core microbiota shared between the untreated and metal-treated groups. Bacterial genera associated with metal tolerance were more prevalent in the metal-treated groups. Although larval metal exposure led to an increase in pesticide-degrading bacterial genera in the laboratory strains, this effect was not observed in the F₁ population. In the F₁ population, Plasmodium-protective bacterial genera were more abundant in the untreated group compared to the metal-treated group. This study therefore highlights the importance of considering the larval environment when searching for local bacterial symbionts for paratransgenesis interventions. Full article

Mosquito-borne diseases are responsible for hundreds of thousands of deaths per year. The identification and control of the vectors that transmit pathogens to humans are crucial for disease prevention and management. Currently, morphological classification and molecular analyses via DNA barcoding are the standard methods used for vector identification. However, these approaches have several limitations. In the last decade, matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-TOF MS) profiling has emerged as an innovative technology in biological sciences and is now considered as a relevant tool for the identification of pathogens and arthropods. Beyond species identification, this tool is also valuable for determining various life traits of arthropod vectors. The purpose of the present systematic review was to highlight the contribution of MALDI-TOF MS to the surveillance and control of mosquito-borne diseases. Published articles from January 2003 to August 2024 were retrieved, focusing on different aspects of mosquito life traits that could be determinants in disease transmission and vector management. The screening of the scientific literature resulted in the selection of 54 published articles that assessed MALDI-TOF MS profiling to study various mosquito biological factors, such species identification, life expectancy, gender, trophic preferences, microbiota, and insecticide resistance. Although a large majority of the selected articles focused on species identification, the present review shows that MALDI-TOF MS profiling is promising for rapidly identifying various mosquito life traits, with high-throughput capacity, reliability, and low cost. The strengths and weaknesses of this proteomic tool for vector control and surveillance are discussed. Full article

Mosquitoes are vectors of many important human diseases. The prolonged and widespread use of insecticides has led to the development of mosquito resistance to these insecticides. The gut microbiota is considered the master of host development and physiology; it influences mosquito biology, disease pathogen transmission, and resistance to insecticides. Understanding the role and mechanisms of mosquito gut microbiota in mosquito insecticide resistance is useful for developing new strategies for tackling mosquito insecticide resistance. We searched online databases, including PubMed, MEDLINE, SciELO, Web of Science, and the Chinese Science Citation Database. We searched all terms, including microbiota and mosquitoes, or any specific genera or species of mosquitoes. We reviewed the relationships between microbiota and mosquito growth, development, survival, reproduction, and disease pathogen transmission, as well as the interactions between microbiota and mosquito insecticide resistance. Overall, 429 studies were included in this review after filtering 8139 search results. Mosquito gut microbiota show a complex community structure with rich species diversity, dynamic changes in the species composition over time (season) and across space (environmental setting), and variation among mosquito species and mosquito developmental stages (larval vs. adult). The community composition of the microbiota plays profound roles in mosquito development, survival, and reproduction. There was a reciprocal interaction between the mosquito midgut microbiota and virus infection in mosquitoes. Wolbachia, Asaia, and Serratia are the three most studied bacteria that influence disease pathogen transmission. The insecticide resistance or exposure led to the enrichment or reduction in certain microorganisms in the resistant mosquitoes while enhancing the abundance of other microorganisms in insect-susceptible mosquitoes, and they involved many different species/genera/families of microorganisms. Conversely, microbiota can promote insecticide resistance in their hosts by isolating and degrading insecticidal compounds or altering the expression of host genes and metabolic detoxification enzymes. Currently, knowledge is scarce about the community structure of mosquito gut microbiota and its functionality in relation to mosquito pathogen transmission and insecticide resistance. The new multi-omics techniques should be adopted to find the links among environment, mosquito, and host and bring mosquito microbiota studies to the next level. Full article

The overuse of synthetic insecticides has led to various negative consequences, including insecticide resistance, environmental pollution, and harm to public health. This may be ameliorated by using insecticides derived from botanical sources. The primary objective of this study was to evaluate the anti-mosquito activity of the essential oil (EO) of Citrus reticulata Blanco cv. Chachiensis (Chachi) (referred to as CRB) at immature, semi-mature, and mature stages. The chemical compositions of the CRB EO were analyzed using GC-MS. The main components were identified to be D-limonene and γ-terpinene. The contents of D-limonene at the immature, semi-mature, and mature stages were 62.35%, 76.72%, and 73.15%, respectively; the corresponding contents of γ-terpinene were 14.26%, 11.04%, and 11.27%, respectively. In addition, the corresponding contents of a characteristic component, methyl 2-aminobenzoate, were 4.95%, 1.93%, and 2.15%, respectively. CRB EO exhibited significant larvicidal activity against Aedes albopictus (Ae. albopictus, Diptera: Culicidae), with the 50% lethal doses being 65.32, 61.47, and 65.91 mg/L for immature, semi-mature, and mature CRB EO, respectively. CRB EO was able to inhibit acetylcholinesterase and three detoxification enzymes, significantly reduce the diversity of internal microbiota in mosquitoes, and decrease the relative abundance of core species within the microbiota. The present results may provide novel insights into the utilization of plant-derived essential oils in anti-mosquitoes. Full article

The mosquito microbiota is a critical determinant of mosquito life history. It is therefore a target for novel vector control strategies like paratransgenesis. However, the microbiota in Anopheles funestus, a major African malaria vector, is poorly characterized. Thus, the study aimed to investigate the overall bacterial landscape in the salivary glands, ovaries and midguts of three laboratory strains of An. funestus differing in insecticide-resistant phenotype by sequencing the V3–V4 hypervariable region of bacterial 16S rRNA genes. When examining alpha diversity, the salivary glands harbored significantly more bacteria in terms of species richness and evenness compared to ovaries and midguts. On the strain level, the insecticide-susceptible FANG strain had significantly lower bacterial diversity than the insecticide-resistant FUMOZ and FUMOZ-R strains. When looking at beta diversity, the compositions of microbiota between the three tissues as well as between the strains were statistically different. While there were common bacteria across all three tissues and strains of interest, each tissue and strain did exhibit differentially abundant bacterial genera. However, overall, the top five most abundant genera across all tissues and strains were Elizabethkingia, Acinetobacter, Aeromonas, Cedecea and Yersinia. The presence of shared microbiota suggests a core microbiota that could be exploited for paratransgenesis efforts. Full article

Microbial communities play an important role in the fitness of mosquito hosts. However, the factors shaping microbial communities in wild populations, with regard to interactions among microbial species, are still largely unknown. Previous research has demonstrated that two of the most studied mosquito symbionts, the bacteria Wolbachia and Asaia, seem to compete or not compete, depending on the genetic background of the reference mosquito host. The large diversity of Wolbachia–Asaia strain combinations that infect natural populations of mosquitoes may offer a relevant opportunity to select suitable phenotypes for the suppression of pathogen transmission and for the manipulation of host reproduction. We surveyed Wolbachia and Asaia in 44 mosquito populations belonging to 11 different species of the genera Anopheles, Aedes, and Culex using qualitative PCR. Through quantitative PCR, the amounts of both bacteria were assessed in different mosquito organs, and through metagenomics, we determined the microbiota compositions in some selected mosquito populations. We show that variation in microbial community structure is likely associated with the species/strain of mosquito, its geographical position, and tissue localization. Together, our results shed light on the interactions among different bacterial species in the microbial communities of mosquito vectors, and this can aid the development and/or improvement of methods for symbiotic control of insect vectors. Full article

The flavivirus West Nile virus (WNV) naturally circulates between mosquitoes and birds, potentially affecting humans and horses. Different species of mosquitoes play a role as vectors of WNV, with those of the Culex pipiens complex being particularly crucial for its circulation. Different biotic and abiotic factors determine the capacity of mosquitoes for pathogen transmission, with the mosquito gut microbiota being recognized as an important one. Here, we review the published studies on the interactions between the microbiota of the Culex pipiens complex and WNV infections in mosquitoes. Most articles published so far studied the interactions between bacteria of the genus Wolbachia and WNV infections, obtaining variable results regarding the directionality of this relationship. In contrast, only a few studies investigate the role of the whole microbiome or other bacterial taxa in WNV infections. These studies suggest that bacteria of the genera Serratia and Enterobacter may enhance WNV development. Thus, due to the relevance of WNV in human and animal health and the important role of mosquitoes of the Cx. pipiens complex in its transmission, more research is needed to unravel the role of mosquito microbiota and those factors affecting this microbiota on pathogen epidemiology. In this respect, we finally propose future lines of research lines on this topic. Full article