Leishmaniasis is a parasitic disease transmitted by the bite of infected sand flies. In Thailand, the species responsible belong to the subgenus Mundinia, including Leishmania martiniquensis and Leishmania orientalis, both of which have been implicated in human infections. Yet despite growing recognition of the disease as a local problem, the ecology of its vectors remains poorly understood, particularly in the cave-associated environments of the north where many species shelter and breed. Even less is known about the endosymbionts that live inside these insects and that, in other vector systems, have been shown to manipulate reproduction or interfere with pathogen development.

To close that gap, a team led by Puckavadee Somwang of Mae Fah Luang University and Kanok Preativatanyou of Chulalongkorn University collected female sand flies from two tourist caves and one livestock-associated site in Chiang Rai Province. The haul amounted to 298 specimens representing eight taxa across three genera: Phlebotomus, Sergentomyia, and Idiophlebotomus. Notably, the species composition differed markedly among the three collection sites, a pattern the authors interpret as habitat-associated structuring of sand fly communities. Caves, with their stable humidity and abundant vertebrate hosts, and livestock shelters, with their ready supply of blood meals, evidently support distinct assemblages of these insects.

The molecular screening was thorough. Each fly was tested for Leishmania DNA using quantitative PCR assays targeting the genus-level 18S rRNA gene together with species-specific markers, and positive results were complemented by ITS1-PCR coupled with nanopore sequencing, a portable sequencing technology that allows rapid reading of the parasite’s internal transcribed spacer region. The results were striking: Leishmania DNA was detected in 78 of the 298 flies, an infection rate of 26.2 percent. Both L. martiniquensis and L. orientalis were identified, and in four specimens the two species were detected simultaneously, a co-detection that underscores how multiple parasite species can circulate within the same vector populations.

The endosymbiont picture was even more dramatic. Wolbachia, the world’s most widespread intracellular bacterium in arthropods, was present in 228 flies, or 76.5 percent of the sample. Of these, 124 carried Wolbachia alone while 104 were co-infected with Cardinium, a second endosymbiont best known from mites, spiders, and various insects. Cardinium-only infections, by contrast, were rare, accounting for just 1.3 percent of specimens. This asymmetry suggests that Wolbachia dominates the endosymbiotic landscape of these sand flies, with Cardinium typically riding along as a co-infectant rather than establishing itself independently.

Whether these bacteria actually affect Leishmania presence was the study’s central question. Using Firth’s penalized logistic regression, a statistical method suited to sparse or imbalanced categorical data, the researchers tested the association between endosymbiont status and Leishmania DNA detection. Across all endosymbiont categories the overall association fell short of statistical significance, with a penalized likelihood ratio test yielding P = 0.083. But when the analysis zoomed in on specific categories, a telling pattern emerged: sand flies carrying Wolbachia alone had significantly lower odds of harboring Leishmania DNA than endosymbiont-free flies, with an odds ratio of 0.49 and a 95 percent confidence interval of 0.25 to 0.97, corresponding to P = 0.041. In other words, Wolbachia-positive flies were roughly half as likely to test positive for the parasite.

The authors are careful about interpretation. A lower odds of parasite DNA detection does not prove that Wolbachia blocks Leishmania; it could reflect differences in sand fly species composition, sampling variation, or the biology of particular host-endosymbiont combinations. Still, the finding echoes results from other vector systems, where Wolbachia has been deployed deliberately to reduce the transmission of dengue and other pathogens. If a similar interference operates in sand flies, the implications for leishmaniasis control in Thailand and beyond could be substantial, opening the door to endosymbiont-based strategies that reduce vector competence without relying on insecticides.

Beyond the association analysis, the study delivered a genetic inventory that is itself a first for Thailand. Haplotype-based analyses of the Wolbachia surface protein gene, wsp, revealed 16 distinct haplotypes, while sequencing of the Cardinium 16S rRNA gene uncovered 14 haplotypes. Phylogenetic reconstruction placed the Wolbachia strains within Supergroups A and B, the two lineages most commonly found in insects, and sorted the Cardinium sequences into Groups A and C. Neither the breadth of Wolbachia diversity nor the Cardinium lineages had been documented in Thai sand flies before, making this the first report of their genetic diversity in these vectors from the country.

Perhaps the most technically intriguing result came from structural analysis of the Wolbachia surface protein, or WSP, a protein embedded in the bacterium’s outer membrane and exposed to the host cell environment. One Wolbachia variant recovered from the sand fly species Sergentomyia barraudi carried a nine-amino-acid insertion, with the motif KDSTKQVTD, located within the HVR4 hypervariable region of the protein. Three-dimensional structural modeling predicted that this insertion produces localized conformational variation while leaving the conserved beta-barrel core of the protein intact. Crucially, the insertion sits within a surface-exposed loop region, precisely the kind of structural feature that can mediate interactions between the symbiont and its host. A closely related reference sequence, PQ606075, carries a nearly identical motif differing by a single substitution from arginine to lysine, suggesting this insertion is not a one-off anomaly but a recurring variant in the region’s Wolbachia populations.

Why does a surface protein insertion matter? WSP is a prime candidate for host-symbiont recognition, and variation in its exposed loops has been linked to differences in cytoplasmic incompatibility, the reproductive manipulation that allows Wolbachia to spread through insect populations. If certain WSP variants confer different interaction profiles with sand fly tissues, they might also differ in how they affect Leishmania development inside the insect. The study’s structural evidence therefore provides a concrete molecular handle for future work: researchers can now ask whether flies carrying the HVR4-insertion variant show different parasite loads than those with canonical WSP sequences.

The research also carries practical value for disease surveillance. Because sand flies pick up Leishmania from infected hosts, screening them offers a form of xenomonitoring, a way to track parasite circulation in an area without directly sampling every human or animal resident. The high infection rate recorded in Chiang Rai, more than one in four flies, signals active parasite transmission in these environments and justifies closer surveillance in cave and livestock settings frequented by both local communities and tourists. The finding of two Mundinia species, including co-detections, further complicates the epidemiological picture, since different species can cause distinct clinical forms and may involve different reservoir hosts.

Funded by Thailand’s National Science, Research and Innovation Fund through Mae Fah Luang University and partially supported by the Asahi Glass Foundation, the study was approved by the animal research ethics committees of both Mae Fah Luang University and Chulalongkorn University. The authors, drawn from the School of Medicine at Mae Fah Luang University and the Center of Excellence in Vector Biology and Vector-Borne Disease at Chulalongkorn University, stress that their work is a starting point rather than a conclusion. The statistical signal linking Wolbachia to reduced parasite detection is suggestive but modest, and the cross-sectional design cannot establish causation.

What the study does establish is that the endosymbiotic world of Thai sand flies is far richer than previously appreciated, and that its diversity is structured, heritable, and potentially consequential for disease transmission. The next steps are clear from the data: experimental infections comparing Wolbachia-positive and Wolbachia-free sand fly lines, functional studies of the WSP insertion variant, and broader sampling across Thailand’s endemic regions to test whether the inverse association between Wolbachia and Leishmania holds at larger scales. If those experiments confirm a blocking effect, the humble bacteria living inside cave-dwelling sand flies could become unexpected allies in the fight against a neglected tropical disease.

Subject of Research: Endosymbiont–parasite associations between Leishmania (Mundinia), Wolbachia, and Cardinium in phlebotomine sand flies from Northern Thailand

Article Title: Molecular co-occurrence of Leishmania (Mundinia) spp., Wolbachia, and Cardinium in cave-associated phlebotomine sand flies from Northern Thailand: genetic diversity and endosymbiont–parasite associations

Article References: Somwang, P., Khositharattanakool, P., Sunantaraporn, S., Promrangsee, C., Yuanlae, S., Tepboonrueng, P., Siriyasatien, P., & Preativatanyou, K. (2026). Molecular co-occurrence of Leishmania (Mundinia) spp., Wolbachia, and Cardinium in cave-associated phlebotomine sand flies from Northern Thailand: genetic diversity and endosymbiont–parasite associations. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07727-0

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07727-0

Keywords: Leishmania, Mundinia, sand flies, Wolbachia, Cardinium, endosymbionts, genetic diversity, leishmaniasis, Thailand, vector biology, xenomonitoring, phlebotomine

The rationale for targeting mucins rests on their central role in tick biology. Mucins are heavily glycosylated proteins that, in ticks, contribute to the formation of the cement cone that anchors the mouthparts into the host skin during feeding, help modulate the host immune response at the bite site, and participate in assembling the peritrophic membrane that lines the tick gut and protects it from ingested blood and microbes. Because these functions are essential to feeding and survival, proteins involved in them are attractive vulnerabilities: antibodies circulating in the host’s blood would be ingested by the tick and could interfere with these processes from within the parasite.

Before committing to laboratory production, the team characterized Mucin-6 using bioinformatic tools. The predictions indicated a hydrophilic but intrinsically unstable protein with a molecular mass of 24.9 kilodaltons after removal of its signal peptide, the short N-terminal sequence that normally directs secretion. Importantly for vaccine design, the sequence was predicted to be rich in linear B-cell epitopes, the short stretches of amino acids that antibodies can recognize on a denatured or soluble protein. Abundant epitopes increase the likelihood that vaccination will elicit a robust and specific humoral response, which is the arm of immunity most relevant for an antigen that will be encountered by the tick through a blood meal.

To confirm that the gene is biologically relevant throughout the tick life cycle, the researchers used quantitative PCR to measure Mucin-6 expression across developmental stages and feeding states. The gene was transcribed at every stage examined, from larva to adult, with significantly higher expression in eggs. This broad and consistent expression profile matters for vaccine utility: an antigen expressed only in a narrow stage or feeding condition would leave windows in which the parasite is unprotected, whereas a constitutively expressed protein offers a target throughout the tick’s interaction with the vaccinated host.

With the sequence validated, the team moved to recombinant production. The Mucin-6 coding sequence was cloned into the pET28a expression vector and transformed into BL21(DE3) Escherichia coli, a standard laboratory strain engineered for high-level protein expression under T7 promoter control. On induction, the recombinant protein accumulated in inclusion bodies, the dense aggregates of misfolded protein that bacteria often form when expressing foreign or disulfide-rich proteins. The researchers recovered the protein from these bodies, renatured it to restore a soluble conformation, and purified it using nickel-nitrilotriacetic acid affinity chromatography, which exploits the histidine tag encoded by the pET28a vector. On SDS-PAGE, the purified recombinant Mucin-6 migrated at approximately 41 kilodaltons, larger than the predicted 24.9 kilodaltons of the mature protein, a discrepancy consistent with the tag and the anomalous electrophoretic behavior typical of mucin-like, compositionally biased proteins.

The immunization trial used six New Zealand White rabbits randomly assigned to a vaccinated group of three and a phosphate-buffered saline control group of three. Each vaccinated rabbit received 500 micrograms of recombinant Mucin-6 formulated with Freund’s adjuvant in three subcutaneous injections spaced 14 days apart. Enzyme-linked immunosorbent assays tracked the antibody response, revealing titers that reached 1:512,000 by day 35, an exceptionally high level indicating strong recognition of the recombinant antigen. Fourteen days after the final booster, the researchers challenged each rabbit with 30 adult ticks, 15 males and 15 females, and measured the parameters that define tick vaccine efficacy: engorgement weight, egg mass, blood-feeding duration and egg-hatching rate.

The results showed a consistent, statistically significant burden on the parasites. Ticks that fed on immunized rabbits had engorged body weights reduced by 13.6 percent and egg masses reduced by 14.7 percent compared with ticks fed on control rabbits, both differences significant at P less than 0.05. Blood-feeding duration was prolonged by 8.3 percent, suggesting that antibodies disrupted the efficiency of feeding, forcing ticks to remain attached longer to obtain a full blood meal. Combining the effects on tick weight and fecundity, the authors calculated an overall vaccine efficacy of 26.3 percent. While modest compared with the best commercial anti-tick formulations, this figure represents a meaningful proof of concept for a single antigen tested in its first host species.

A critical question for any recombinant antigen is whether antibodies raised against the laboratory-produced protein also recognize the native version in the parasite. The team addressed this by western blot, incubating tick lysates with serum from the immunized rabbits. The anti-rMucin-6 serum bound native Mucin-6 in tick extracts, confirming that the recombinant protein preserved epitopes present in the authentic tick protein and that the antibodies generated in the vaccinated animals could, in principle, engage their target during a natural blood meal. This cross-recognition underpins the observed phenotypic effects and strengthens the case that Mucin-6, rather than an artifact of immunization, is the operative antigen.

The study sits within a broader effort to develop anti-tick vaccines that reduce both parasite loads and pathogen transmission without the drawbacks of chemical acaricides. The only commercially available tick vaccine, based on the gut antigen Bm86 against Rhipicephalus microplus, demonstrated decades ago that vaccinating the host can starve and sterilize ticks from within, but its efficacy varies across tick species and regions, driving the search for new antigens. Secreted proteins such as mucins, which are exposed to host antibodies in the ingested blood and are functionally indispensable, form a promising class of candidates. The Hainan team’s work adds Mucin-6 to this pipeline and demonstrates a complete workflow, from epitope prediction and expression profiling through prokaryotic production and a controlled animal challenge.

Limitations remain before Mucin-6 could approach practical deployment. The trial involved a small number of animals, a single antigen and a single host species, and Freund’s adjuvant is unsuitable for veterinary or human use, so future work would need to test the antigen with licensed adjuvants, in larger cohorts, and ideally in combination with other antigens to push efficacy higher. The authors, led by corresponding author Qingfeng Guan with co-first authors Jie Chen and Yongchuan Zhu, conclude that Mucin-6 merits further evaluation as a candidate vaccine antigen against R. linnaei. Given that tick-borne diseases continue to expand their geographic range with changing climates and livestock movements, even incremental gains from antigen discovery of this kind carry substantial implications for animal health and the economics of tick control.

Subject of Research: Evaluation of the tick protein Mucin-6 from Rhipicephalus linnaei as a recombinant anti-tick vaccine antigen

Article Title: Prokaryotic expression and vaccine potential of Mucin-6 from Rhipicephalus linnaei

Article References: Chen, J., Zhu, Y., Zhao, J., Wang, J., Han, Q., & Guan, Q. (2026). Prokaryotic expression and vaccine potential of Mucin-6 from Rhipicephalus linnaei. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07675-9

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07675-9

Keywords: Rhipicephalus linnaei, Mucin-6, anti-tick vaccine, recombinant protein, prokaryotic expression, vaccine efficacy, tick control, humoral immunity, B-cell epitopes, Parasites & Vectors, livestock health, vector biology

Wolbachia is an intracellular bacterium that manipulates the reproduction of its insect hosts, most famously through a phenomenon known as cytoplasmic incompatibility. When males carrying a particular Wolbachia strain mate with females that either lack that strain or carry a different one, their fertilized eggs fail to hatch. This quirk of reproductive biology has become the foundation of several mosquito control approaches, including the incompatible insect technique, in which large numbers of Wolbachia-carrying male mosquitoes are released to mate with wild females and crash the population. Wolbachia also has pathogen-blocking properties, meaning it can interfere with the ability of mosquitoes to transmit viruses such as dengue, which underlies replacement strategies that spread virus-resistant Wolbachia strains through wild populations.

Unlike Aedes aegypti, the yellow fever mosquito, which does not naturally harbor Wolbachia, Aedes albopictus carries two native strains of the bacterium, designated wAlbA and wAlbB. In most populations studied elsewhere, individuals are superinfected, meaning they carry both strains simultaneously. This natural dual infection matters enormously for control programs because the outcome of any cytoplasmic incompatibility-based intervention depends on which strains are already circulating in the target population. If wild mosquitoes carry unexpected combinations of strains, or if the density of the bacteria in their tissues varies in unanticipated ways, releases of incompatible males may fail to suppress reproduction as intended.

Despite the global importance of these questions, the infection status of Hawaiian Aedes albopictus had remained poorly characterized. A research team led by Sangwoo Seok and senior authors Eric P. Caragata and Yoosook Lee of the Florida Medical Entomology Laboratory at the University of Florida, working with collaborators from state and federal agencies in Hawaiʻi and the University of California, set out to fill this gap. Using quantitative PCR, a laboratory technique that can detect and precisely quantify the amount of bacterial DNA in an individual mosquito, the team characterized Wolbachia infections in 399 specimens collected from two islands: Oʻahu and the Island of Hawaiʻi.

The headline finding was that Wolbachia is nearly universal in these populations: 98.5 percent of the mosquitoes tested were infected. However, the composition of those infections was strikingly lopsided. Every infected specimen carried wAlbB, but only 28.6 percent were superinfected with wAlbA. In other words, the vast majority of Hawaiian Aedes albopictus carry only a single Wolbachia strain, a pattern that departs from the double infection typically assumed for this species. This lower-than-expected prevalence of wAlbA establishes an important baseline for any future biocontrol effort in the region, because it means the resident bacterial landscape is not uniform across individuals.

The study also revealed that infection dynamics are strongly shaped by the sex of the mosquito. Females were significantly more likely than males to harbor wAlbA, and bacterial density, the quantity of Wolbachia per individual, was significantly higher in females for both strains. This sex bias has practical implications because only female mosquitoes bite and transmit viruses, and because cytoplasmic incompatibility manifests through the interaction between infected males and uninfected or differently infected females. A sex-skewed distribution of native strains therefore changes the arithmetic of any release program designed around mating incompatibility.

Environmental factors also left their mark on the bacterial communities. The prevalence of wAlbA was associated with the island of collection and with precipitation at the collection site, suggesting that local climate and geography influence which mosquitoes carry the second strain. By contrast, the prevalence of wAlbB did not vary significantly with sex, island, temperature, or precipitation, indicating that the two native strains respond to different ecological pressures. Temperature is known from laboratory studies to affect Wolbachia density, and rainfall shapes breeding habitat availability, so these field associations provide a real-world counterpart to experimental work on how environmental conditions modulate symbiont infections.

Perhaps the most technically intriguing results concern the interactions between the two strains when they coexist in the same mosquito. In superinfected individuals, wAlbB consistently exhibited higher density than wAlbA, and wAlbB density was higher in superinfected mosquitoes than in those carrying wAlbB alone. Both strains reached higher densities in females than in males. In females, the densities of the two strains were positively correlated, meaning mosquitoes with more wAlbA also tended to have more wAlbB, whereas no such correlation existed in males. These sex-specific microbe-microbe dynamics suggest that the two symbionts do not simply compete for host resources; their relationship differs fundamentally between the sexes, possibly reflecting differences in tissue tropism, vertical transmission requirements, or host physiology.

For the design of Wolbachia-based control in Hawaiʻi, these findings carry a clear warning. Population suppression projects that rely on cytoplasmic incompatibility depend on predictable mating outcomes between released and wild mosquitoes. If a substantial fraction of wild females carry only wAlbB while released males carry both strains or a different combination, the strength of incompatibility may vary across the population, diluting the effectiveness of releases. Similarly, the sex and site-specific variation in bacterial density could influence how faithfully the released strains are transmitted to the next generation. The authors emphasize that future projects in the region must account for these varying patterns of infection before strategies are developed and implemented, rather than assuming a uniform superinfection across the archipelago.

The study, funded in part by the U.S. Environmental Protection Agency’s Science to Achieve Results program, the USDA National Institute of Food and Agriculture, and the National Institutes of Health, and conducted with permits from Hawaiʻi’s national parks, demonstrates the value of baseline surveillance before intervention. As Hawaiʻi confronts recurring outbreaks of dengue and the expanding range of mosquito vectors in a warming climate, understanding the invisible bacterial passengers of its mosquitoes has become a practical necessity. The nearly universal presence of wAlbB, the patchy distribution of wAlbA, and the complex density relationships between the strains together form a map of the biological terrain on which any future Wolbachia campaign will be fought, and this research provides the first careful survey of that terrain across the Hawaiian Islands.

Subject of Research: Native Wolbachia infection prevalence and density in Hawaiian Aedes albopictus mosquito populations

Article Title: Native Wolbachia infection dynamics across Aedes albopictus (Diptera: Culicidae) populations in Hawaiʻi

Article References: Seok, S., Salama, L., Vorsino, A. E., Leong, M. K. H., Haines, W. P., Jacobsen, C. M., Akbari, O. S., Caragata, E. P., & Lee, Y. (2026). Native Wolbachia infection dynamics across Aedes albopictus (Diptera: Culicidae) populations in Hawaiʻi. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07695-5

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07695-5

Keywords: Wolbachia, Aedes albopictus, Hawaiʻi, cytoplasmic incompatibility, mosquito control, dengue, Zika, chikungunya, endosymbiont, quantitative PCR, invasive species, vector biology

Single-cell RNA sequencing, or scRNA-seq, does something deceptively simple: instead of measuring the collective gene activity of an entire tissue, it profiles the transcriptome of individual cells. The transcriptome, the complete set of RNA molecules in a cell, acts as the bridge between the static genome and dynamic biological function. Bulk transcriptomics blurs this picture, masking the heterogeneity of the many cell types that make up even a small organ such as a mosquito midgut. By deconstructing tissues into their constituent cells, scRNA-seq allows researchers to discover rare cell populations, reconstruct developmental trajectories and map communication networks between cells. The technology has already driven breakthroughs in oncology, neuroscience and virology, and the review’s authors, led by Li-Bo Liu and Jia-Hong Wu of Guizhou Medical University, contend that mosquitoes are its next great frontier.

The technical pipeline is demanding at every step. Researchers must dissect tissues or collect hemolymph, isolate single cells or nuclei, capture them, prepare sequencing libraries and run high-throughput sequencing before any computational analysis begins. Each choice carries biological consequences. Enzymatic dissociation can stress cells and induce artificial transcriptional responses, and fragile or large cell types may be selectively lost. For tissues that resist dissociation, such as the brain or fat body, single-nucleus RNA sequencing offers an alternative that preserves cell-type proportions, though at the cost of losing cytoplasmic transcripts. The incorporation of unique molecular identifiers allows digital counting of original transcripts and mitigates amplification bias, while the choice between plate-based methods such as Smart-seq2, which deliver near-complete transcript coverage of relatively few cells, and droplet-based systems such as 10x Genomics Chromium, which profile tens of thousands of cells at shallower depth, fundamentally shapes what can be observed.

These trade-offs are not abstract. In studies of the malaria mosquito Anopheles gambiae, the high throughput of 10x Chromium succeeded in capturing megacytes, a rare hemocyte subpopulation making up only about 0.5 percent of immune cells, whereas Smart-seq2’s superior sensitivity identified phagocytic granulocytes that the droplet platform missed. Both findings were validated by in situ hybridization, confirming that the discrepancies stemmed from technical characteristics rather than false positives. The review’s authors emphasize that such variation demands rigorous reporting standards, including adherence to emerging minimum-information guidelines for single-cell experiments, explicit documentation of platforms and computational parameters, and independent validation of novel cell types before they are accepted as biological reality rather than computational artifacts.

What has the technology actually revealed? Perhaps the most striking lesson is that classical cell classifications were far too coarse. Mosquito hemocytes, the insect immune cells, were traditionally divided into granulocytes, oenocytoids and prohemocytes. Single-cell profiling has exploded this scheme into a multilevel system, showing that granulocytes comprise conventional, proliferative, antimicrobial and phagocytic subtypes, alongside megacytes that appear to coordinate immune responses mediated by hemocyte differentiation factor. Intriguingly, megacytes were not detected in Aedes aegypti, suggesting genuinely distinct immune lineages among vector species rather than a technical artifact, and challenging the assumption of a universal insect immune cell blueprint. The midgut epithelium has undergone a similar refinement: enterocytes once treated as a uniform class now resolve into five subtypes enriched for distinct digestive enzymes or immune factors, while enteroendocrine cells split into three subtypes specializing in different neuropeptide signals.

ScRNA-seq has also uncovered cell populations that fit no existing category. In the fat body of blood-fed Aedes aegypti, researchers identified fat-body-yolk cells, which coexpress markers of metabolic fat body tissue, ovarian reproductive tissue, stem cell genes and even eggshell formation genes. Their persistence after a blood meal, even when no oviposition sites are available, hints at a poised state dedicated to maintaining reproductive readiness, a possible adaptation to unpredictable breeding opportunities. The authors caution, however, that transcriptional identity does not equal validated function; the hypothesized roles of these cells in lipid transport, resource reallocation and defense remain compelling but untested. Cell atlases have now been extended to salivary glands, testes and the nervous system, laying groundwork for a comprehensive reference that could inform next-generation insecticides, gene-drive strategies and transmission-blocking interventions.

The technology’s power to dissect dynamic physiology is vividly illustrated by the response to a blood meal, the event that makes mosquitoes dangerous. Within one day of feeding, three nascent enterocyte clusters surged from 0.4 percent to 52.2 percent of midgut cells, an expansion too rapid for new cell generation and one that points to transdifferentiation of existing cells, though the origin remains unresolved. In the fat body, trophocyte proportions shifted between two and seven days post-feeding, with upregulation of trehalose synthesis genes and immune regulators coupling metabolic reprogramming to immune activation. Hemocyte numbers doubled by day seven, and even the brain participated: single-nucleus sequencing revealed dramatic transcriptional changes in glial cells within three hours of feeding, including upregulation of steroid hormone receptors and circadian clock genes, implicating glia as regulators of the post-blood-meal behavioral switch.

Sexual dimorphism, too, has acquired a cellular basis. Female Aedes aegypti brains are enriched for specific Kenyon cells, dopaminergic neurons and projection neurons, while male brains contain higher proportions of particular glial cells and other neuronal classes. Sex-biased gene expression follows, with males showing higher expression of the sex determination factor Nix and females expressing dipeptidyl peptidases at elevated levels. Notably, the sex determination gene doublesex is more highly expressed in glial cells than in neurons, suggesting an underappreciated role for glia in establishing sexual identity. In sensory organs, male-specific epithelial-like cells in antennae and female-specific neurons in the proboscis provide cellular correlates for sex-specific behaviors such as host-seeking. Single-nucleus data have likewise challenged the one neuron–one receptor dogma of sensory coding, revealing frequent coexpression of odorant and ionotropic receptors, and coexpression of taste and temperature sensors in gustatory neurons, expanding the theoretical coding capacity of the mosquito nervous system.

The most consequential applications may lie in host–pathogen interactions. Conventional scRNA-seq pipelines discard non-host reads as contamination, but adapted protocols, notably 5′ capture methods compatible with microfluidic platforms, can capture viral RNAs that lack polyadenylated tails. Using such approaches, researchers found that Zika virus preferentially targets enteroendocrine cells and enterocytes in the Aedes aegypti midgut, while West Nile virus reaches its highest loads in enteroendocrine cells of Culex tarsalis, hinting at a conserved flaviviral susceptibility tied to these cells’ signaling and secretory functions. In Anopheles gambiae, dual host–parasite sequencing showed that Plasmodium ookinetes preferentially interact with midgut progenitor cells during epithelial traversal, an interaction conserved across Anopheles species and parasite isolates. Immune responses are equally illuminating: enterocytes infected with Zika express antimicrobial peptides, whereas West Nile virus infection in Culex tarsalis produced no broad tissue-level immune activation, a finding that challenges the midgut’s reputation as a key site of innate immune defense and may partly explain that species’ vector competence.

These discoveries are already generating testable intervention targets. The enrichment of apolipophorin III in Zika-infected enteroendocrine cells led to RNA interference experiments confirming that this lipid transport protein supports viral replication, marking it as a candidate target. Similarly, single-cell analysis identified the LL3 gene as highly expressed in megacytes and essential for the hemocyte differentiation factor-mediated anti-Plasmodium response, establishing a rare cell type as a critical regulatory node in malaria vector immunity. The review’s authors are candid about remaining obstacles: cell annotation still leans heavily on Drosophila orthology, atlases remain incomplete for organs such as ovaries and compound eyes, and most findings await functional validation. The path forward, they argue, lies in integrating spatial transcriptomics, single-cell multiomics and perturbation-based experiments to build predictive models of mosquito–pathogen interactions. If that integration succeeds, single-cell insights accumulated over the past several years could mature from a discovery engine into the foundation of a new generation of targeted vector control strategies.

Subject of Research: Application of single-cell RNA sequencing to mosquito biology and mosquito–pathogen interactions

Article Title: Single-cell RNA sequencing unravels mosquito biology and host–pathogen interactions

Article References: Liu, L.-B., Ye, H.-B., Tian, Z.-H., Zeng, X.-H., & Wu, J.-H. (2026). Single-cell RNA sequencing unravels mosquito biology and host–pathogen interactions. Parasites & Vectors, 19(1), Article 426. https://doi.org/10.1186/s13071-026-07460-8

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07460-8

Keywords: single-cell RNA sequencing, mosquito, vector biology, host–pathogen interactions, cell atlas, Zika virus, West Nile virus, Plasmodium, malaria, dengue, vector control, transcriptomics

The research team, led by Yu-hao Li, Zhi-zhao Zhang, Tong Fu, Xiao-bo Liu, Jian-xin Cui, Peng Cheng and Yu-hong Guo, drew on expertise from the National Institute for Communicable Disease Control and Prevention at the Chinese Center for Disease Control and Prevention, the Breeding Research Center of Insect Pests’ Natural Enemies at the Henan Institute of Science and Technology, and the Shandong Institute of Parasitic Diseases. Their goal was explicitly practical: to provide a scientific basis and theoretical support for the formulation of integrated control strategies against a mosquito whose expanding range continues to put hundreds of millions of people at risk of arboviral disease. Understanding how far and how long these insects can travel is a cornerstone of any attempt to predict outbreaks and target interventions.

To capture flight capacity in a controlled and comparable way, the researchers worked with a laboratory strain of Aedes albopictus under strictly standardized environmental conditions, holding temperature, humidity and photoperiod constant throughout the experiments. This was essential because ambient conditions are known to influence insect metabolism and muscle performance, and any uncontrolled variation could have confounded the comparisons between sexes and age classes. Male and female adults were tested at a finely resolved series of ages: every day from one to ten days after emergence, and then again at fifteen, twenty and twenty-five days of age, giving a total of thirteen age points that trace the full arc of adult physiological development.

The central instrument of the study was the flight mill, a classic tethered-flight technique that has been used for decades to quantify the flight potential of insects ranging from moths to beetles to mosquitoes. In a flight mill apparatus, an insect is attached to a lightweight rotating arm and flies in circles; sensors record the number of rotations, which can be converted into cumulative distance, total flight duration and average speed. Because the insect flies against minimal resistance in still air, flight mill measurements do not reproduce the exact aerodynamics of free flight in the field, but they are widely regarded as a robust proxy for an individual’s intrinsic flight capacity, allowing large numbers of insects to be compared under identical conditions.

For each mosquito, the team measured three parameters: cumulative flight distance, cumulative flight duration and average flight speed. These three metrics capture complementary dimensions of flight performance. Distance reflects overall dispersal potential, the quantity most directly relevant to how far a mosquito could carry a virus from one habitat patch to another. Duration reflects endurance, the ability to sustain flight over time, which matters for insects that must traverse hostile or resource-poor landscapes. Average speed reflects the intensity of flight effort and the mechanical power output of the flight muscles. Analyzing all three together gives a far richer picture of flight biology than any single metric alone.

Statistical analysis was carried out with generalized linear models, or GLMs, fitted with a Gamma distribution and a log link function, an approach well suited to strictly positive, right-skewed response variables such as distances and durations. Sex and age were entered as fixed factors, and their interaction, sex multiplied by age, was tested using likelihood ratio tests. This modeling framework allowed the researchers to ask not only whether males and females differ and whether flight changes with age, but also whether the trajectory of age-related change itself differs between the sexes, a subtler question that turns out to be central to the biology of this species.

The results were clear and, in places, striking. For cumulative flight distance, all three effects were significant: age mattered, sex mattered, and the interaction between sex and age mattered as well. Across the sampled ages, females displayed a significantly longer mean cumulative flight distance than males, confirming that the sex responsible for blood feeding and pathogen transmission is also the sex with the greater dispersal engine. For cumulative flight duration, age and the sex-by-age interaction were significant, although sex alone was not, meaning that the endurance gap between males and females emerges and shifts across the adult lifespan rather than being a constant difference. For average flight speed, both sex and age had significant main effects, but there was no significant sex-by-age interaction, indicating that the speed difference between the sexes remains comparatively stable as the insects grow older.

Taken together, these patterns demonstrate distinct age-related changes and sexual dimorphism in the flight capacity of Aedes albopictus, with the dimorphism itself varying dynamically across ages. The authors interpret this as highly consistent with mosquito physiological development and ecological functional differentiation. In biological terms, the story makes sense: newly emerged adults must complete sclerotization and reproductive maturation, flight muscles and energy reserves change over the first days of adult life, and females in particular undergo cycles of host seeking, blood digestion and egg development that reshape their energetic priorities. Males, whose ecological role centers on locating mates rather than seeking blood hosts, face different selective pressures on sustained flight, and the data suggest these pressures translate into measurably different flight trajectories.

The public health implications of the study are considerable. Aedes albopictus has spread from its native range in Southeast Asia across every inhabited continent over the past several decades, aided by the global trade in used tires and other water-holding containers that harbor its eggs and larvae. Because female mosquitoes can transmit dengue, chikungunya, Zika and yellow fever viruses, quantitative estimates of how far females of a given age can fly feed directly into models of epidemic spread, surveillance design and the placement of traps and control barriers. The authors emphasize that their findings offer a quantitative basis for predicting the dispersal potential of the species and for optimizing the timing and targets of control measures, information they describe as being of great reference value for the precise prevention and control of mosquito-borne infectious diseases such as dengue fever.

The study also illustrates a broader principle in vector biology: control programs that ignore the age structure and sex structure of vector populations may misallocate resources. If flight capacity peaks and declines at specific ages, then interventions aimed at interrupting dispersal, such as source reduction around breeding sites, spatial repellents or the release of sterile or Wolbachia-infected males, can be timed and targeted more effectively when the flight behavior of each sex and age class is known. Conversely, assuming that all adults pose an equal dispersal risk could lead to surveillance gaps precisely where and when the strongest fliers are active. By anchoring those assumptions in systematic flight mill data and rigorous statistical modeling, this research turns a basic entomological question into actionable epidemiological knowledge, and it underscores how much practical value can still be extracted from carefully executed laboratory studies of a familiar backyard pest.

Subject of Research: Age- and sex-dependent flight capacity of the mosquito Aedes albopictus measured by tethered flight

Article Title: The potential flight capacity of Aedes albopictus

Article References: Li, Y.-H., Zhang, Z.-Z., Fu, T., Liu, X.-B., Cui, J.-X., Cheng, P., & Guo, Y.-H. (2026). The potential flight capacity of Aedes albopictus. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07721-6

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07721-6

Keywords: Aedes albopictus, Asian tiger mosquito, flight capacity, flight mill, tethered flight, sexual dimorphism, mosquito age, vector biology, dengue, mosquito-borne disease, dispersal, Parasites & Vectors

The investigation began with a deceptively simple behavioral question: given a choice, do mosquitoes prefer well-fed or undernourished hosts? Using controlled dietary restriction in laboratory mice, the researchers ran paired preference assays with multiple medically important mosquito species and found a consistent and striking result. Female mosquitoes preferentially oriented toward and fed on the undernourished animals. Because host-seeking in mosquitoes is governed by a layered integration of sensory cues, including carbon dioxide, heat, humidity, vision, and above all odor, the team reasoned that nutritional status might be altering the volatile chemical signature that hosts emit into the air. Behavioral experiments in which cues were selectively masked or manipulated confirmed that the differential attraction was olfactory in nature, pointing the investigators toward the skin surface as the source of the signal.

Gas chromatography-mass spectrometry analysis of volatile emissions from the skin of undernourished mice revealed a specific chemical culprit: elevated levels of volatile aldehydes. When these aldehydes were presented to mosquitoes in isolation or applied to otherwise unattractive hosts, they acted as potent attractants, reproducing the preference pattern observed with live undernourished animals. The aldehydes were not produced by the hosts themselves. Instead, they emerged from an unexpected intermediate player, the community of commensal bacteria that colonizes the skin. Sequencing and culture-based analyses showed that undernutrition was associated with a marked dysbiosis of the skin microbiota, with certain bacterial taxa proliferating to excessive densities and shifting their metabolic output toward aldehyde production. In effect, the mosquito-attractive odor was a microbial byproduct, released in greater quantities whenever the host’s nutritional state deteriorated.

The next question was mechanistic: why would a poor diet destabilize the skin microbiome in the first place? The answer lay in the dermal sebaceous glands, the microscopic structures that secrete sebum, a lipid-rich film coating the outer skin. The researchers found that undernutrition impaired the secretion of free fatty acids from these glands. Free fatty acids are not merely structural components of the skin barrier; they possess well-documented antimicrobial activity, suppressing the overgrowth of bacteria on the surface. With fatty acid output diminished, this chemical shield weakened, and commensal skin bacteria expanded unchecked. The team demonstrated this causal chain experimentally: restoring antimicrobial fatty acids, or reducing bacterial loads with antibiotics, both reversed the microbiota expansion and abolished the excess aldehyde emissions, thereby eliminating the heightened attractiveness of undernourished mice to mosquitoes.

To rule out confounding factors such as fur and general husbandry, the researchers extended their experiments to SKH1 hairless mice, in which skin surface chemistry can be sampled directly. The same pattern held. Undernutrition drove sebaceous dysfunction, skin bacterial overgrowth, dysbiosis, elevated aldehyde production, and increased mosquito attraction, providing a clean replication of the mechanism in a model system where the skin itself is fully accessible to analysis. The authors also showed that the effect operates in both directions of the transmission cycle. Undernourished mice were not only more likely to be bitten; they were also more susceptible to infection with dengue virus (DENV), developing higher viral loads. When mosquitoes fed on these viremic, undernourished hosts, the insects acquired virus more efficiently, and when infected mosquitoes subsequently fed, transmission onward was enhanced.

This dual effect, increasing both the probability that a host infects a mosquito and the probability that an infected mosquito infects a host, is what gives the finding its epidemiological weight. Vector-borne pathogens depend on a chain of events, each of which carries a probability, and interventions that raise or lower any single link can have outsized effects on the reproduction of an epidemic. By strengthening two links at once, host attractiveness and host infectivity, undernutrition may function as a critical modulator of transmission efficacy at the population level. The researchers present a model in which the prevalence of undernourished individuals within a community critically shapes the intensity of arbovirus circulation, a proposition with obvious implications for the geography of disease burden.

The human relevance of the mechanism was tested directly. In a cohort of undernourished human subjects, the team documented skin microbiota alterations mirroring those seen in mice, alongside elevated emission of volatile aldehydes from the skin. In behavioral assays, undernourished participants were more attractive to mosquitoes than their well-nourished counterparts. These converging lines of evidence, spanning rodent models, chemical analytics, microbiology, and human physiology, elevate the study beyond a correlation and support a coherent biological narrative: caloric and nutritional insufficiency suppresses sebaceous antimicrobial output, permits bacterial overgrowth, changes the skin’s volatile signature, and rewires the chemical conversation between humans and mosquitoes.

The broader context is sobering. Undernutrition and mosquito-borne disease overlap extensively across the tropics and subtropics, where food insecurity, poverty, and endemic dengue, malaria, Zika, and other arboviruses co-occur. Earlier work from the same field had established that host nutritional status can influence arbovirus virulence and evolution, and that host serum iron modulates dengue virus acquisition by mosquitoes, indicating that diet intersects with vector-borne transmission at multiple physiological levels. The new study adds skin chemistry and microbiota to this list and identifies a targetable axis. If aldehyde emissions and bacterial overgrowth mediate the effect, then interventions that restore sebaceous antimicrobial lipids, modulate the skin microbiome, or neutralize aldehyde cues could, in principle, reduce the excess bite risk borne by malnourished individuals, complementing bed nets, repellents, and vaccines.

For public health planners, the message is that nutritional support programs may double as disease control programs. Addressing undernutrition in regions where mosquito-borne pathogens are endemic would not only alleviate the direct morbidity and mortality of deficiency itself, but could also dampen the transmission cycles that keep those pathogens circulating. The authors argue that undernutrition should be recognized as a key driver of mosquito-borne disease transmission in nature, a reframing that places nutrition squarely within the toolkit of vector-borne disease control. As climate change expands the range of Aedes and Anopheles vectors and as food insecurity persists or worsens in many endemic regions, understanding and disrupting the metabolic link between diet, skin microbiota, and mosquito behavior may prove essential to bending the curves of some of the world’s most persistent epidemics.

Subject of Research: How undernutrition increases host attractiveness to mosquitoes and promotes the transmission of mosquito-borne diseases through skin microbiota changes.

Article Title: Undernutrition enhances host attractiveness to mosquitoes and transmission of mosquito-borne diseases

Article References: Wang, M., Song, X., Zhu, Y., Niu, J., Wang, G., Wang, Y., Xiao, H., Lei, D., Wu, T., Liu, L., Wang, P., Wang, J., & Cheng, G. (2026). Undernutrition enhances host attractiveness to mosquitoes and transmission of mosquito-borne diseases. Cell Research. https://doi.org/10.1038/s41422-026-01291-z

Image Credits: AI Generated

DOI: 10.1038/s41422-026-01291-z

Keywords: undernutrition, mosquito-borne diseases, dengue virus, skin microbiota, volatile aldehydes, sebaceous glands, fatty acids, host-seeking behavior, arboviruses, vector biology, malnutrition, disease transmission