Natural Mosquito Research Articles

Rapid age-grading and species identification of natural mosquitoes for malaria surveillance

The malaria parasite, which is transmitted by several Anopheles mosquito species, requires more time to reach its human-transmissible stage than the average lifespan of mosquito vectors. Monitoring the species-specific age structure of mosquito populations is critical to evaluating the impact of vector control interventions on malaria risk. We present a rapid, cost-effective surveillance method based on deep learning of mid-infrared spectra of mosquito cuticle that simultaneously identifies the species and age class of three main malaria vectors in natural populations. Using spectra from over 40, 000 ecologically and genetically diverse An. gambiae, An. arabiensis, and An. coluzzii females, we develop a deep transfer learning model that learns and predicts the age of new wild populations in Tanzania and Burkina Faso with minimal sampling effort. Additionally, the model is able to detect the impact of simulated control interventions on mosquito populations, measured as a shift in their age structures. In the future, we anticipate our method can be applied to other arthropod vector-borne diseases.

Trash to Treasure: How Insect Protein and Waste Containers Can Improve the Environmental Footprint of Mosquito Egg Releases.

Release and subsequent establishment of Wolbachia-infected Aedes aegypti in native mosquito populations has successfully reduced mosquito-borne disease incidence. While this is promising, further development is required to ensure that this method is scalable and sustainable. Egg release is a beneficial technique that requires reduced onsite resources and increases community acceptance; however, its incidental ecological impacts must be considered to ensure sustainability. In this study, we tested a more environmentally friendly mosquito rearing and release approach through the encapsulation of diet and egg mixtures and the subsequent utilization of waste containers to hatch and release mosquitoes. An ecologically friendly diet mix was specifically developed and tested for use in capsules, and we demonstrated that using either cricket or black soldier fly meal as a substitute for beef liver powder had no adverse effects on fitness or Wolbachia density. We further encapsulated both the egg and diet mixes and demonstrated no loss in viability. To address the potential of increased waste generation through disposable mosquito release containers, we tested reusing commonly found waste containers (aluminum and tin cans, PET, and glass bottles) as an alternative, conducting a case study in Kiribati to assess the concept’s cultural, political, and economic applicability. Our results showed that mosquito emergence and fitness was maintained with a variety of containers, including when tested in the field, compared to control containers, and that there are opportunities to implement this method in the Pacific Islands in a way that is culturally considerate and cost-effective.

A Survey on Native and Invasive Mosquitoes and Other Biting Dipterans in Northern Spain.

Haematophagous Diptera, such as mosquitoes (Culicidae), biting midges (Ceratopogonidae), and black flies (Simuliidae), are important insects for public and animal health due to their capacity to bite and transmit pathogens. Outdoor recreation areas are usually affected by biting species and provide suitable habitats to both adult and immature stages. This study aimed to determine the species diversity and larval sites of these Diptera groups in two golf courses. A multi-method collection approach using ultraviolet-CDC traps, human landing catches, collection in breeding sites, and ovitraps was implemented during summer 2020 in northern Spain. Insects were determined by morphological features accompanied by DNA barcoding. A total of ten native mosquito species were recorded either as adults or as larval stages. The invasive species Aedes japonicus was collected only at egg or pupa stage in ovitraps. Culex pipiens s.l. and Culex torrentium were both common mosquito species accounting for 47.9% of the total larval site collections and their larvae might be found in a wide range of natural and artificial sites. Culiseta longiareolata specimens were also prominent (30.1% of the total) and occurred exclusively in man-made water-filled containers. A total of 13 Culicoides species were identified, 10 of which were captured by ultraviolet-CDC traps, particularly members of the Obsoletus complex (Culicoides obsoletus/Culicoides scoticus, 74.9%) and seven species by emergence traps, being the two most abundant C. kibunensis (44.8%) and C. festivipennis (34.9%). Simulium cryophilum was also collected hovering around the operator under field sampling. A comprehensive representation of the blood-sucking Diptera fauna and their larval sites was obtained by the multi-method approach in two Spanish golf courses.

Laboratory study on larval competition between two related mosquito species: Aedes (Stegomyia) albopictus and Aedes (Stegomyia) cretinus

Aedes albopictus (Asian tiger mosquito) and Aedes cretinus are closely related mosquito species with similar morphological and bio-ecological characteristics. These species have been detected in specific areas of Athens, Greece, with Ae. albopictus developing significantly higher population densities than the native mosquito Ae. cretinus. In a laboratory factorial experimental design, we investigated the potential of interspecific and intraspecific competition between larvae of these species under various food and population density conditions. Duration of larval development, survival rate from the first larval instar until adulthood and the wing length of females were measured. When these two species developed on their own, larvae developed faster and the females were larger at high food provision, indicating intraspecific competition. When the two species developed in the same environment and food provision was low, Ae. albopictus outcompeted Ae. cretinus. In particular, the larval developmental time when these species competed with each other was 1.3 to 2.4 days shorter for Ae. albopictus and 0.9 to 1.4 days longer for Ae. cretinus, compared with single species development. Interspecific competition resulted to larger Ae. albopictus females at limited food availability and low density of individuals. Our findings indicate that Ae. albopictus is a superior competitor to Ae. cretinus, primarily at limited larval food resources, and this may account for the expansion of Ae. albopictus and the limited presence of Ae. cretinus in areas of Athens, Greece, where these related species co-exist.

Why did theWolbachiatransinfection cross the road? drift, deterministic dynamics, and disease control.

Maternally inherited Wolbachia transinfections are being introduced into natural mosquito populations to reduce the transmission of dengue, Zika, and other arboviruses. Wolbachia-induced cytoplasmic incompatibility provides a frequency-dependent reproductive advantage to infected females that can spread transinfections within and among populations. However, because transinfections generally reduce host fitness, they tend to spread within populations only after their frequency exceeds a critical threshold. This produces bistability with stable equilibrium frequencies at both 0 and 1, analogous to the bistability produced by underdominance between alleles or karyotypes and by population dynamics under Allee effects. Here, we analyze how stochastic frequency variation produced by finite population size can facilitate the local spread of variants with bistable dynamics into areas where invasion is unexpected from deterministic models. Our exemplar is the establishment of wMel Wolbachia in the Aedes aegypti population of Pyramid Estates (PE), a small community in far north Queensland, Australia. In 2011, wMel was stably introduced into Gordonvale, separated from PE by barriers to A. aegypti dispersal. After nearly 6 years during which wMel was observed only at low frequencies in PE, corresponding to an apparent equilibrium between immigration and selection, wMel rose to fixation by 2018. Using analytic approximations and statistical analyses, we demonstrate that the observed fixation of wMel at PE is consistent with both stochastic transition past an unstable threshold frequency and deterministic transformation produced by steady immigration at a rate just above the threshold required for deterministic invasion. The indeterminacy results from a delicate balance of parameters needed to produce the delayed transition observed. Our analyses suggest that once Wolbachia transinfections are established locally through systematic introductions, stochastic "threshold crossing" is likely to only minimally enhance spatial spread, providing a local ratchet that slightly-but systematically-aids area-wide transformation of disease-vector populations in heterogeneous landscapes.

Mosquito-bacteria interactions during larval development trigger metabolic changes with carry-over effects on adult fitness.

In animals with distinct life stages such as holometabolous insects, adult phenotypic variation is often shaped by the environment of immature stages, including their interactions with microbes colonizing larval habitats. Such carry-over effects were previously observed for several adult traits of the mosquito Aedes aegypti after larval exposure to different bacteria, but the mechanistic underpinnings are unknown. Here, we investigated the molecular changes triggered by gnotobiotic larval exposure to different bacteria in Ae.aegypti. We initially screened a panel of 16 bacterial isolates from natural mosquito breeding sites to determine their ability to influence adult life-history traits. We subsequently focused on four bacterial isolates (belonging to Flavobacterium, Lysobacter, Paenibacillus, and Enterobacteriaceae) with significant carry-over effects on adult survival and found that they were associated with distinct transcriptomic profiles throughout mosquito development. Moreover, we detected carry-over effects at the level of gene expression for the Flavobacterium and Paenibacillus isolates. The most prominent transcriptomic changes in gnotobiotic larvae reflected a profound remodelling of lipid metabolism, which translated into phenotypic differences in lipid storage and starvation resistance at the adult stage. Together, our findings indicate that larval exposure to environmental bacteria trigger substantial physiological changes that impact adult fitness, uncovering a possible mechanism underlying carry-over effects of mosquito-bacteria interactions during larval development.

Dynamics of an impulsive reaction-diffusion mosquitoes model with multiple control measures.

It is well-known that mosquito control is one of the effective methods to reduce and prevent the transmission of mosquito-borne diseases. In this paper, we formulate a reaction-diffusion impulsive hybrid model incorporating Wolbachia, impulsively spraying of insecticides, spatial heterogeneity, and seasonality to investigate the control of mosquito population. The sufficient conditions for mosquito extinction or successful Wolbachia persistence in a population of natural mosquitoes are derived. More importantly, we give the estimations of the spraying times of insecticides during a period for achieving the mosquito extinction and population replacement in a special case. A global attractivity of the positive periodic solution is analyzed under appropriate conditions. Numerical simulations disclose that spatial heterogeneity and seasonality have significant impacts on the design of mosquitoes control strategies. It is suggested to combine biological control and chemical pulse control under certain situations to reduce the natural mosquitoes. Further, our results reveal that the establishment of a higher level of population replacement depends on the strain type of the Wolbachia and the high initial occupancy of the Wolbachia-infected mosquitoes.

Diversity and distribution of larval habitats of mosquitoes (Diptera: Culicidae) in northern Spain: from urban to natural areas.

Studies of the biodiversity of mosquito larval habitats are important for vector-borne disease control programs and help to improve vector distribution maps. This study was designed to investigate the geographical distribution of mosquito species and their larval habitats in urban, rural, and natural areas in northern Spain. Pre-imaginal stages were collected over two sampling periods (spring and summer) in 2019. In the laboratory, immature specimens were reared to the adult stage for species identification by morphological taxonomy and/or molecular methods. In total, 2,182 specimens belonging to 13 different native mosquito species of five genera were collected from 135 sampling points of which 59.2% harbored larvae. Culex pipiens s.l. was the most abundant species (45.1%), followed by Culex torrentium (12.3%), Anopheles maculipennis s.l. (10.2%), Culex hortensis (9.5%), and nine other species with lower frequencies that accounted for less than 25%. By molecular identification, An. maculipennis s.s. was identified as the only species within the An. maculipennis species complex and Cx. pipiens pipiens as the predominant subspecies of the Cx. pipiens species complex. Margins in large sunlit water bodies were the most suitable sites for An. maculipennis s.l., whereas Cx. pipiens s.l. was present in both natural and artificial habitats. The larval site index, species richness, and relative abundance of the mosquitoes were determined based on the characteristics of the sites where they were collected. The public health importance and ecology of some identified mosquitoes is also discussed.

Wolbachia detection in Aedes aegypti using MALDI-TOF MS coupled to artificial intelligence

The mosquito Aedes aegypti is the major vector of arboviruses like dengue, Zika and chikungunya viruses. Attempts to reduce arboviruses emergence focusing on Ae. aegypti control has proven challenging due to the increase of insecticide resistances. An emerging strategy which consists of releasing Ae. aegypti artificially infected with Wolbachia in natural mosquito populations is currently being developed. The monitoring of Wolbachia-positive Ae. aegypti in the field is performed in order to ensure the program effectiveness. Here, the reliability of the Matrix‑Assisted Laser Desorption Ionization‑Time Of Flight (MALDI‑TOF) coupled with the machine learning methods like Convolutional Neural Network (CNN) to detect Wolbachia in field Ae. aegypti was assessed for the first time. For this purpose, laboratory reared and field Ae. aegypti were analyzed. The results showed that the CNN recognized Ae. aegypti spectral patterns associated with Wolbachia-infection. The MALDI-TOF coupled with the CNN (sensitivity = 93%, specificity = 99%, accuracy = 97%) was more efficient than the loop-mediated isothermal amplification (LAMP), and as efficient as qPCR for Wolbachia detection. It therefore represents an interesting method to evaluate the prevalence of Wolbachia in field Ae. aegypti mosquitoes.

Reactions

OPINION Reactions ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2021, 99 (40), p 3November 1, 2021Cite this:C&EN 99, 40, 3Mosquito repellentI’m in the process of reading through this week’s C&EN and was looking forward to the article “A Better Natural Mosquito Repellent’’ (Oct. 4, 2021, page 8). Since I work in a forestry organization, our field crews are exposed to mosquitoes and, more worrisome these days, ticks.While my career vastly differs from what I researched during my PhD, working with insect attractants and such over the past decade has opened my eyes to how badly the cause-and-effect way of thinking adds blinders to peripheral vision, aka thinking outside the box. This is a great example: put out a citronella candle, see fewer mosquitoes. We accept the outcome, but are we missing steps with the mechanism? In the end, does this knowledge even matter? Perhaps yes, perhaps no.Given that p-menthane-3,8-diol (PMD) can be made at elevated temperatures, who’s to say the citronella candles are not producing PMD as the flame burns wax and generates the activation energy to convert citronellal. There would be ambient moisture in the air, and the proton could come from a number of sources. I have not taken the time yet to peruse the literature to see if any publications are out there that link PMD with a burning citronella candle, but it should be an easy connection to make with real-time mass spectrometry such as selected ion flow tube.I’ve always wondered about insect lures. Once we deploy them, they are at the mercy of the elements, and what we believe is the attractant could merely be an intermediate where a decomposition or rearrangement product is the true active compound, since the same could be happening with the insect that naturally produces these compounds. We know they work only because we catch specimens, but if we found out the attractant was a smaller degradation product, it would possibly save us time and effort at the bench level with fewer synthetic steps.Gaetan LeClairFredericton, New Brunswick CorrectionsOct. 11, 2021, page 35: The ACS Comment incorrectly says the Loconti Scholarship awarded by the Project SEED Committee was $20,000. It was $5,000.Oct. 18, 2021, page 21: The feature story on the conference of the National Organization for the Professional Advancement of Black Chemists and Chemical Engineers has the incorrect year for the 50th anniversary celebration. It is tentatively scheduled for 2023, not 2022.Oct. 25, 2021, page 7: The news article on jellyfish’s diets incorrectly describes the food in the experiment. The brine shrimp were live, not frozen. The krill were frozen, not live. And the moon jellies rejected the krill, not the brine shrimp.

Detection of Knockdown-Resistance Mutations (V1016G and F1534C) in Dengue Vector from Urban Park, Surabaya, Indonesia

An urban park is potentially a source of vector-borne disease transmission due to it being a natural and artificial mosquito breeding habitats combined with people's continuous presence. Thus, this study aims to screen the occurrence of knockdown-resistance (kdr) mutant alleles (V1016G and F1534C) in mosquito populations collected from urban parks in Surabaya, Indonesia. Cross sectional study was conducted in July 2019. A total of 28 ovitraps were installed in seven urban parks, having four ovitraps installed in each park. In total, 1,662 eggs were collected, and only 187 emerged into adult mosquitoes, consisting of 97 Aedes (Stegomyia) aegypti and 90 Aedes (Stegomyia) albopictus. All-female adult mosquitoes (n=55) were tested using allele-specific polymerase chain reaction assay (AS-PCR) to detect voltage gated sodium channel (VGSC) gene mutations. This study found no mutations in Valine to Glysine mutation in point 1016 (V1016G) and Phenylalanine to Cysteine in point 1534 (F1534C) alleles in both two species. All of mosquito samples have wild type genotype of kdr alleles (V1016V and F1534F). Data were analysed using R Studio 1.4 Version by Genetics package. Results showed that the frequency of resistant alleles (G1016 and C1534) was zero, and the frequency of susceptible allele was 1 (V1016 and F1534). Insecticide bioassay could not be established due to the limited number of adult mosquitoes, so insecticide resistance status could not be determined. However, this study can be used as preliminary monitoring for the vector control program.

Genetic Diversity and Population Structure of the Asian Tiger Mosquito (Aedes albopictus) in Vietnam: Evidence for Genetic Differentiation by Climate Region.

Aedes albopictus is a native mosquito to Southeast Asia with a high potential for disease transmission. Understanding how Ae. albopictus populations that develop in the species’ native range is useful for planning future control strategies and for identifying the sources of invasive ranges. The present study aims to investigate the genetic diversity and population structure of Ae. albopictus across various climatic regions of Vietnam. We analyzed mitochondrial cytochrome oxidase I (COI) gene sequences from specimens collected from 16 localities, and we used distance-based redundancy analysis to evaluate the amount of variation in the genetic distance that could be explained by both geographic distance and climatic factors. High levels of genetic polymorphism were detected, and the haplotypes were similar to those sequences from both temperate and tropical regions worldwide. Of note, these haplotype groups were geographically distributed, resulting in a distinct population structure in which northeastern populations and the remaining populations were genetically differentiated. Notably, genetic variation among the Ae. albopictus populations was driven primarily by climatic factors (64.55%) and to a lesser extent was also influenced by geographic distance (33.73%). These findings fill important gaps in the current understanding of the population genetics of Ae. albopictus in Vietnam, especially with respect to providing data to track the origin of the invaded regions worldwide.

A better natural mosquito repellent

Found in lemon eucalyptus, p -menthane-3,8-diol (PMD) is the only natural chemical on the US Centers for Disease Control and Prevention’s list of recommended mosquito repellents. Scientists have now discovered that one form of PMD may repel certain types of mosquitoes nearly as well as the benchmark synthetic mosquito repellent, DEET, while being significantly less toxic to people ( J. Agric. Food Chem. 2021, DOI: 10.1021/acs.jafc.1c03897 ). DEET is commonly used to fend off mosquitoes, but it can irritate the skin and be neurotoxic . Many natural alternatives are less toxic but evaporate quickly, limiting their effectiveness. In contrast, PMD lasts longer. In nature, PMD can be found as a mix of four diastereomers, so organic chemist Marc Lemaire of Claude Bernard University Lyon and colleagues in France and Madagascar tested how well each of the diastereomers repelled the Aedes albopictus mosquito . On human skin, one diastereomer, (1 R

A natural mosquito repellent’s most active form found

A natural mosquito repellent’s most active form found

How do noncompetent hosts cause dilution of parasitism? Testing hypotheses for native and invasive mosquitoes.

Parasite dilution occurs in varied systems, via multiple potential mechanisms. We used laboratory manipulation and field surveys to test for invader-induced parasite dilution via two specific mechanisms: host-host competition and encounter reduction. In the laboratory, single Aedes triseriatus larvae were exposed to one of eight combinations of: parasitic Ascogregarina barretti, +/-1 cohabiting Aedes albopictus larva during parasite exposure, and +/-1 cohabiting A. albopictus larva after infectious parasite removal. Larval infection intensity (predicted to decrease via dilution by encounter reduction) was not significantly affected by A. albopictus. Adult infection prevalence and intensity (predicted to decrease via dilution by host-host competition) were significantly greater with A. albopictus, suggesting parasite amplification by interspecific competition, an effect potentially mediated by competition increasing A. triseriatus development time. In the field, we tested for effects of potential dilution host abundances on prevalence and abundance of A. barretti in A. triseriatus larvae. Piecewise path analysis yielded no evidence of host-host competition impacting parasitism in the field, but instead indicated a significant direct negative effect of Aedes spp. abundance on parasite abundance in A. triseriatus, which is consistent with dilution via encounter reduction in the field, but only in tree holes, not in man-made containers. Our results are consistent with the hypothesis that a noncompetent invader can alter the native host-parasite relationship, but our laboratory and field data yield differing results. This difference is likely due to laboratory experiment testing for per capita effects of dilution hosts on parasitism, but field analysis testing for effects of dilution host abundance on parasitism. Individually, host-host competition with the invader amplifies, rather than dilutes, parasite success. In contrast, our path analysis is consistent with the hypothesis that dilution of parasitism results from increased abundance of noncompetent hosts in the field.

Extraction, identification and molecular docking studies evaluation of Momordica tuberosa (Roxb) against Anopheles

Objectives: This study aimed to identify phytochemicals from Momordica tuberosa (M. tuberosa) leaves and it’s in silico larvicidal potential compounds against Anopheles. Further, to analyze their inhibitory mechanisms against the Anopheles angiotensin-converting enzyme (ACE). In view of the above fact, we made an attempt to discover potential and novel natural mosquito larvicidal compounds with least impact on human health. Method: The GC-MS analysis confirmed the phytoconstituents from the methanol extracts of M. tuberosa through GC-MS and selected compounds were submitted to docking studies on Anopheles angiotensin-converting enzyme as possible targets. Findings: GC-MS analysis of the extract showed the presence of 20 compounds with Limonene dioxide, Neophytadiene and Palmitic acid as main constituents. Three Selected compounds (Limonene dioxide, Neophytadiene and palmitic acid) specifically binds the binding site of an angiotensin-converting enzyme (ACE). The binding energy Limonene dioxide (- 6 kcal/mol), Neophytadiene (- 6.5 kcal/mol), Palmitic acid (- 5.7 kcal/mol) and interaction were analyzed. The present study displays better docking binding energy in the selected compounds. The results further substantiate that the 3 compounds of the M. tuberose found to be model candidates for the design and development of potential larvicidal. Novelty: The study helps to pave the first way to develop the promising larvicidal compound from plants. This result visibly suggests that compounds (Limonene dioxide, Neophytadiene and Palmitic acid) from M. tuberosa could act as potential larvicidal agents – to control Anopheles. Keywords: Phytochemical; Molecular docking; anangiotensinconverting enzyme (ACE); larvicidal; Chromatography

Comparative population genetics of the invasive mosquito Aedes albopictus and the native mosquito Aedes flavopictus in the Korean peninsula

BackgroundAedes mosquitoes are important invasive species contributing to the spread of chikungunya, dengue fever, yellow fever, zika virus, and other dangerous vector-borne diseases. Aedes albopictus is native to southeast Asia, with rapid expansion due to human activity, showing a wide distribution in the Korean peninsula. Aedes flavopictus is considered to be native to East Asia, with a broad distribution in the region, including the Korean peninsula. A better understanding of the genetic diversity of these species is critical for establishing strategies for disease prevention and vector control.MethodsWe obtained DNA from 148 specimens of Ae. albopictus and 166 specimens of Ae. flavopictus in Korea, and amplified two mitochondrial genes (COI and ND5) to compare the genetic diversity and structure of the two species.ResultsWe obtained a 658-bp sequence of COI and a 423-bp sequence of ND5 from both mosquito species. We found low diversity and a nonsignificant population genetic structure in Ae. albopictus, and high diversity and a nonsignificant structure in Ae. flavopictus for these two mitochondrial genes. Aedes albopictus had fewer haplotypes with respect to the number of individuals, and a slight mismatch distribution was confirmed. By contrast, Ae. flavopictus had a large number of haplotypes compared with the number of individuals, and a large unimodal-type mismatch distribution was confirmed. Although the genetic structure of both species was nonsignificant, Ae. flavopictus exhibited higher genetic diversity than Ae. albopictus.ConclusionsAedes albopictus appears to be an introduced species, whereas Ae. flavopictus is endemic to the Korean peninsula, and the difference in genetic diversity between the two species is related to their adaptability and introduction history. Further studies on the genetic structure and diversity of these mosquitos will provide useful data for vector control.

Neem oil as natural pesticide: Pseudo ternary diagram and computational study

Bitter principles of neem oil have proven activity against agricultural pests. The neem oil is also reported for its potential insecticidal and mosquito repellency properties. As active principles of a non-edible neem oil cannot be separated from oil itself, formulating microemulsions of neem oil have a promising future. Microemulsions are preferred over conventionally used pesticide systems like for their long-term thermodynamic stability, safety, low viscosity, cost economy and aesthetic appeal. A pseudo ternary diagram is a convenient way of determining the compositions of the stable microemulsions and macroemulsions. By identifying specific regions in such plots, possible economical compositions can be determined. Such compositions use optimum quantities of surfactants. Moreover, our molecular docking analysis of an active principles of neem oil against odorant binding proteins, viz. 3N7H and 3Q8I suggested that compound, nimbin had higher binding affinities towards OBPs with docking scores of −87.4861 and −105.696 ​kcal/mol than their corresponding reference ligands. Thus, for a safer, an effective and an economical designing and developments of natural mosquito repellents, this study can be considered useful.

Diet-Microbiota Interactions Alter Mosquito Development.

Gut microbes and diet can both strongly affect the biology of multicellular animals, but it is often difficult to disentangle microbiota–diet interactions due to the complex microbial communities many animals harbor and the nutritionally variable diets they consume. While theoretical and empirical studies indicate that greater microbiota diversity is beneficial for many animal hosts, there have been few tests performed in aquatic invertebrates. Most mosquito species are aquatic detritivores during their juvenile stages that harbor variable microbiotas and consume diets that range from nutrient rich to nutrient poor. In this study, we produced a gnotobiotic model that allowed us to examine how interactions between specific gut microbes and diets affect the fitness of Aedes aegypti, the yellow fever mosquito. Using a simplified seven-member community of bacteria (ALL7) and various laboratory and natural mosquito diets, we allowed larval mosquitoes to develop under different microbial and dietary conditions and measured the resulting time to adulthood and adult size. Larvae inoculated with the ALL7 or a more complex community developed similarly when fed nutrient-rich rat chow or fish food laboratory diets, whereas larvae inoculated with individual bacterial members of the ALL7 community exhibited few differences in development when fed a rat chow diet but exhibited large differences in performance when fed a fish food diet. In contrast, the ALL7 community largely failed to support the growth of larvae fed field-collected detritus diets unless supplemented with additional protein or yeast. Collectively, our results indicate that mosquito development and fitness are strongly contingent on both diet and microbial community composition.

Chemical Composition and In Vitro Evaluation of the Mosquito (Anopheles) Repellent Property of Neem (Azadirachta indica) Seed Oil

As one of the killer diseases in the world, malaria contributes to child mortality and global death annually. As a result, many reactive mechanisms have evolved to control and repel mosquitoes. The use of synthetic mosquito repellents with N,N-Diethyl-meta-toluamide (DEET) is one of the popular interventions despite its dermatological limitations such as skin irritations. Ethnobotanical reviews have identified that the adoption of natural repellents promises high repellence on mosquitoes with minimal side effects compared with synthetic ones. However, this has received little attention in modern pharmaceutical literature. This research is focused on the formulation of a natural mosquito repellent from the oil extracted from Azadirachta indica (A. Juss). The oil cream was formulated in concentrations of 10% v/w, 12.5% v/w, 15% v/w, 17.5% v/w, and 20% v/w using an in vitro evaluation approach. Pharmacopoeia characteristics of the cream such as pH, viscosity, spreadability, and organoleptic properties were carried out to verify acidity, permeation, and flow properties of the formulated cream. The spreadability rate was inversely proportional to the concentration of the cream in terms of oil content falling from 1.24 gm/s to 0.84 gm/s from concentrations 10% v/w to 20% v/w correspondingly. Skin irritation tests, however, indicated traces of irritation at 20% v/w. Repellency properties of the cream revealed a lasting effect on the mosquitoes, although this was dependent on concentration levels. Formulations of 17.5% v/w and 20% v/w neem seed oil cream had an equal repellency effect of 87.5%, whereas the synthetic repellent had a repellency of 75% within a justifiable time frame for all the formulations. This work shows that plant-based mosquito repellents promise a healthier approach in controlling mosquito bites, protecting the skin, and preventing malaria.