Microplastics affect mosquito from aquatic to terrestrial lifestyles and are transferred to mammals through mosquito bites.

Microplastics (MPs) transfer from the environment to living organisms is a nonignorable global problem. As a complete metamorphosis insect, the larvae and adult Culex quinquefasciatus mosquito live in aquatic and terrestrial environments, respectively, where they easily access MPs. However, little is known about mosquitoes' potential role in MPs accumulation throughout ecosystems. Therefore, we conducted a study with different MPs particle sizes (0.1/1/10 µm) and concentrations (0.5/5/50 µg/mL) on Cx. quinquefasciatus to address this issue. Once exposed at the young larval stage, MPs could accompany the mosquitoes their entire life. The fluorescence signals of MPs in the larvae were mainly located in the intestines. Its intensity increased (from 3.72 × 106 AU to 5.45 × 107 AU) as the concentrations of MPs increases. The fluorescence signals of MPs were also detected in the blood and skin tissues of mice bitten by adult mosquitoes with MPs containing in their bodies. Mosquitos exposed to MPs showed longer larval pupation and eclosion time as well as lower adult body weight. In addition, MPs significantly reduced the lethal effect of pyrethroid insecticides (97.77 % vs. 48.88 %, p < 0.05) with 15.1 % removal of the deltamethrin concentration. After MPs exposure, the relative abundance of the Cx. quinquefasciatus gut microbiome, such as Wolbachia spp., Elizabethkingia spp., and Asaia spp., changed as the MPs size and concentration changes. Mosquitoes provide a new pathway for MPs accumulation and transfer to higher-level living organisms. Moreover, MPs significantly reduce the control effect of deltamethrin, providing new guidelines for mosquito insecticide application in MPs contamination circumstances.

Microbe community composition differences of hand skin on similar lifestyle volunteers: a small-scale study.

AIMS: Human skin is the first barrier against pathogens and environmental hazards and the highest contact frequency occurs with the hands. Environmental and personal metabolic factors may affect skin microbes. This study was conducted to clarify the diversity in the skin microbial community that was mainly due to individual skin metabolites rather than lifestyle and environmental factors. METHODS AND RESULTS: Skin microbiota samples were collected from 11 volunteers who met similar lifestyle inclusion criteria. The V3-V4 region of the 16S rRNA gene was amplified. After library construction and sequencing, we compared the composition and diversity of the hand skin microbiota in different sexes and BMI groups with bioinformation analysis. The whole sequence data were annotated as 42 phyla, 538 families, and 1215 genera. Four dominant phyla accounted for 97% of the total including Actinobacteriota (50.18%), Firmicutes (23.85%), Proteobacteria (21.64%) and Bacteroidota (2.05%). The genera that were detected in all subjects with high relative abundance were Cutibacterium, Staphylococcus, Corynebacterium, Streptococcus, Lawsonella, Enhydrobacter, Escherichia-Shigella, Asaia and Micrococcus. CONCLUSIONS: The diversity and richness of the microbiota of male hand skin in our study was higher than that of females. Interestingly, Cutibacterium, Staphylococcus, and Corynebacterium might serve as important skin microbiota to distinguish sexes.

A Swin Transformer-based model for mosquito species identification.

Mosquito transmit numbers of parasites and pathogens resulting in fatal diseases. Species identification is a prerequisite for effective mosquito control. Existing morphological and molecular classification methods have evitable disadvantages. Here we introduced Deep learning techniques for mosquito species identification. A balanced, high-definition mosquito dataset with 9900 original images covering 17 species was constructed. After three rounds of screening and adjustment-testing (first round among 3 convolutional neural networks and 3 Transformer models, second round among 3 Swin Transformer variants, and third round between 2 images sizes), we proposed the first Swin Transformer-based mosquito species identification model (Swin MSI) with 99.04% accuracy and 99.16% F1-score. By visualizing the identification process, the morphological keys used in Swin MSI were similar but not the same as those used by humans. Swin MSI realized 100% subspecies-level identification in Culex pipiens Complex and 96.26% accuracy for novel species categorization. It presents a promising approach for mosquito identification and mosquito borne diseases control.

Metagenome Sequencing Reveals the Microbiome of Aedes albopictus and Its Possible Relationship With Dengue Virus Susceptibility.

Dengue fever virus (DENV) is a mosquito-borne flavivirus that poses a serious risk to human health. Aedes albopictus is a widely distributed vector of dengue fever in China. Based on the impact of physiological activity, the microbiome in A. albopictus will provide a novel environment-friendly approach to control DENV transmission. We performed metagenomic sequencing on A. albopictus before and after exposure to DENV blood meal to detect microbiome variation of A. albopictus with different susceptibilities to DENV. The dominant phyla in A. albopictus microbiome were Proteobacteria and Ascomycota, and the dominant genera were Aspergillus and Metarhizium. Gammaproteobacteria bacterium, Lactobacillus harbinensis, and Neurospora crassa differed significantly after DENV infection. There were 15 different microorganisms found to be involved in mosquito immunity and metabolism, such as Alphaproteobacteria bacterium, Methyloglobulus morosus, and Shigella sonnei, which might have an impact on the DENV susceptibility of A. albopictus. It was hypothesized that the lack of specific bacteria may lead to increased susceptibility of A. albopictus to DENV. Interventions in the microbiome composition or specific bacteria of A. albopictus may affect the susceptibility to DENV and control the mosquito-borne diseases efficiently.

Screening of olfactory genes related to blood-feeding behaviors in Culex pipiens quinquefasciatus and Culex pipiens molestus by transcriptome analysis.

BACKGROUND: Culex pipiens quinquefasciatus Say (Cx. quinquefasciatus) and Culex pipiens form molestus Forskal (Cx. molestus) in the Culex pipiens complex group show considerable differences in host seeking, blood feeding, mating behavior and in vector competence. Blood-feeding mosquito behaviors are closely related to their olfactory gene expression and olfactory gene repertoire composition. Comparing olfactory genes between these two subspecies with significantly different blood-feeding behaviors can support further research on the molecular mechanism of the Culex pipiens complex olfactory sensory system, providing a new approach for determining candidate attractant or repellent compounds. METHODS: Non-blood-feeding (NBF) and post-blood-feeding (PBF) olfactory system transcriptomes of the two subspecies were sequenced, and the biological functions of their differentially expressed genes were described by bioinformatics analysis. A quantitative polymerase chain reaction (qPCR) was applied to validate the RNA-seq data. The roles of particular olfactory receptors in Cx. quinquefasciatus blood-feeding behaviors were evaluated by RNAi. RESULTS: Five, 7, 24, and 3 Cx. quinquefasciatus-specific OBPs, Cx. molestus-specific OBPs, Cx. quinquefasciatus-specific ORs and Cx. molestus-specific ORs were identified, respectively. The majority of selected ORs were consistent with the predicted transcriptome sequencing results after qRT-PCR validation. OR5 was expressed only in Cx. quinquefasciatus, and OR65 was the only gene upregulated after blood feeding in Cx. molestus. The blood-feeding rates of the OR5 and OR78 dsRNA groups were significantly lower (4.3%±3.1% and 13.3%±11.5%) than those of the enhanced green fluorescence protein (EGFP) group (64.5%±8.7%). CONCLUSION: Most OBPs and ORs were expressed in both subspecies but showed divergence in expression level. OR5 and OR65 might be species-specific expressed genes that regulate the olfactory behaviors of Cx. quinquefasciatus and Cx. molestus, respectively. The RNA interference of OR5 and OR78 could inhibit the blood-feeding behavior of Cx. quinquefasciatus, providing new targets for screening effective repellent compounds to control mosquito-borne diseases effectively and efficiently.

Metagenome Sequencing Reveals the Midgut Microbiota Makeup of Culex pipiens quinquefasciatus and Its Possible Relationship With Insecticide Resistance.

Midgut microbiota can participate in the detoxification and metabolism processes in insects, but there are few reports on the relationship between midgut microbiota and insecticide resistance in mosquitoes. In this study, we performed metagenomic sequencing on a susceptible strain (SS), a field-collected Hainan strain (HN), and a deltamethrin-resistant strain (RR) of Culex pipiens quinquefasciatus to understand the diversity and functions of their midgut microbiota. The results revealed differences in midgut microbiota among the three strains of Cx. pipiens quinquefasciatus. At the phylum level, Proteobacteria was the most prominent, accounting for nearly 70% of their midgut microbes. At the genus level, Aeromonas made up the highest proportion. In addition, Aeromonas, Morganella, Elizabethkingia, Enterobacter, Cedecea, and Thorsellia showed significant differences between strains. At the species level, Bacillus cereus, Enterobacter cloacae complex sp. 4DZ3-17B2, Streptomyces sp. CNQ329, and some species of Pseudomonas and Wolbachia were more abundant in the two resistant strains. Principal component analysis (PCA) showed that the SS strain had significantly different metagenomic functions than the two deltamethrin-resistant strains (HN and RR strain). The HN and RR strains differed from the SS strain in more than 10 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The analysis of species abundance and functional diversity can provide directions for future studies.

Viral Metagenomics Analysis of Rodents From Two Border Provinces Located in Northeast and Southwest China.

Objective: Wild animal pathogen surveillance will help to understand the next possible pandemic in advance. Rodents, which have close contact with humans, are generally regarded as a key factor for zoonotic disease control. Given the variation in rodent virus composition in diverse ecologies, we conducted a study on the viral infection of rodents of diverse species in different typical environments of Heilongjiang and Yunnan Provinces, located in northeastern and southwestern China, respectively. Methods: Viral metagenomics sequencing and bioinformatic analysis were performed to determine the different distributions of rodent-borne viruses in typical environments of Heilongjiang and Yunnan Provinces, China. After viral culture and PCR confirmation, genomic and phylogenetic quantitative analysis was performed on the detected hantaviruses (HVs) and Beilong viruses (BeiVs). Results: Nineteen rodents from three species and 35 rodents from five species of rodents were collected from Heilongjiang and Yunnan Provinces, respectively. Although the number and number of species of rodents trapped in the northeast were fewer than those in the southwest, viruses annotated from rodents in Heilongjiang were more diverse than those in Yunnan. Rodents carried 22 virus families in Heilongjiang and 13 families in Yunnan. Sequences assembled from Rattus norvegicus were annotated to the M, L, and S segments of HV, and all were clustered within the Seoul-type hantavirus (SEOV). There were 2 (R81Q, S698T) and 4 (K153R, M168I, I279S, and R1790K) amino acid site substitutions in M and L compared with the versions in the most homologous strains. Two BeiV isolates from Rattus norvegicus were closely related to BeiV from brown rats in Hong Kong, with high bootstrap values of >90% in the N segment and > 95% in the L segment. They were further clustered with Tailam virus, forming a distinct group in Paramyxoviridae. Conclusion: The rodents from Heilongjiang and Yunnan located in northeast and southwest China, respectively, had different viral spectra, and only one-third (10/32) of virus families were detected in both areas. The predominant viruses were HV and BeiV in the Hantaviridae and Paramyxoviridae families, respectively. Rodent-borne viruses in the same species were similar in different geographic disparate areas owing to their similar close contact with human habitats and human activities. Additional attention should be given to the monitoring of neglected rodent-borne viruses, especially opportunistic viruses with currently low loads.

Transcriptome analysis of Aedes aegypti Aag2 cells in response to dengue virus-2 infection.

BACKGROUND: Dengue virus (DENV) is a flavivirus transmitted by mosquitoes that is prevalent in tropical and subtropical countries and has four serotypes (DENV1-4). Aedes aegypti, as the main transmission vector of DENV, exhibits strong infectivity and transmission. With the aim of obtaining a better understanding of the Ae. aegypti-DENV interaction, the transcriptome changes in DENV-2-infected Aag2 cells were studied to describe the immune responses of mosquitoes using the Ae. aegypti Aag2 cell line as a model. METHODS: RNAseq technology was used to sequence the transcripts of the Ae. aegypti Aag2 cell line before and after infection with DENV-2. A bioinformatics analysis was then performed to assess the biological functions of the differentially expressed genes, and the sequencing data were verified by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). RESULTS: The transcriptome analysis generated 8866 unigenes that were found in both groups, 225 unigenes that were only found in the infection group, and 683 unigenes that only existed in the control group. A total of 1199 differentially expressed genes, including 1014 upregulated and 185 downregulated genes, were identified. The bioinformatics analysis showed that the differentially expressed genes were mainly involved in the longevity regulating pathway, circadian rhythm, DNA replication, and peroxisome, purine, pyrimidine, and drug metabolism. The qRT-PCR verification results showed the same trend, which confirmed that the expression of the differentially expressed genes had changed, and that the transcriptome sequencing data were reliable. CONCLUSIONS: This study investigated the changes in the transcriptome levels in the DENV-2-infected Ae. aegypti Aag2 cell line, which provides a faster and effective method for discovering genes related to Ae. aegypti pathogen susceptibility. The findings provide basic data and directions for further research on the complex mechanism underlying host-pathogen interactions.