Maoqing Gong

Objective: This study aimed to monitor the resistance status of adult Aedes albopictus ( Ae. albopictus ) to commonly used insecticides in Jining (Shandong Province), Guangzhou (Guangdong Province), and Haikou (Hainan Province), and to provide evidence for improving vector control strategies. Methods: Between May and July 2024–2025, field-collected Ae. albopictus larvae from the three regions were reared under laboratory conditions. Adult insecticide susceptibility was assessed using the WHO tube test. Species identity was confirmed morphologically under a dissecting microscope. Genomic DNA was extracted from individual female mosquitoes, and fragments of the voltage-gated sodium channel ( VGSC ) gene were amplified by PCR and sequenced. kdr mutations were analyzed using BioEdit software. Results: Across the three regions, 24-hour mortality rates of Ae. albopictus exposed to 0.03% deltamethrin, 0.4% permethrin, and 0.08% lambda-cyhalothrin were all below 80%, indicating resistance. For 0.05% propoxur, mortality rates were 100%, 79.21%, and 98.17% in Jining, Guangzhou, and Haikou, respectively. For 0.5% malathion, mortality rates were 88.12%, 98.06%, and 88.12%, respectively. In Guangzhou, mortality rates for 0.08% beta-cyfluthrin and cis-cypermethrin were both below 80%, while in Jining and Haikou, they ranged from 86.17% to 93.88%. Mutations were detected at VGSC codons 1016, 1532, and 1534 in all three populations. The GGA/G allele at codon 1016 was found only in Guangzhou (4.17%). At codon 1532, a single mutant allele (ACC/T) was detected (2.43%), with three genotypes observed: I/I (96.12%), I/T (2.91%), and T/T (0.97%). At codon 1534, five alleles were identified: TTC (F) (35.44%), TCC (S) (24.27%), TGC (C) (38.35%), TTG (L) (1.46%), and CTC (L) (0.49%), forming seven genotypes, including F/F (18.44%), F/C (6.80%), F/S (23.30%), F/L (3.88%), S/S (7.77%), C/C (30.10%), and S/C (9.71%). Conclusion: The studied Ae. albopictus populations showed high resistance to three commonly used pyrethroid insecticides, while relatively lower resistance was observed for propoxur and malathion. kdr mutation frequencies varied across regions, with generally low mutation rates at codon 1016. The mutation frequency at codon 1534 was lower in Jining than in Guangzhou and Haikou, whereas codon 1532 showed a relatively higher mutation frequency in Jining. These findings highlight the importance of rational insecticide use, continuous resistance monitoring, and rotation of insecticides to delay resistance development and spread.

Background: Culex pipiens pallens is a significant vector of mosquito-borne diseases, and its autogenous trait exerts a critical impact on population expansion and disease transmission risks. Understanding the regulatory effect of gut-specific symbiotic bacteria on the autogeny of Cx. pipiens pallens will provide a microbial perspective to elucidate the mechanisms underlying the formation of autogenous reproductive strategies and provide a theoretical basis for the development of novel mosquito-borne disease control. Methods: Autogenous Cx. pipiens pallens were utilized to isolate and culture gut-specific symbiotic bacteria. Green fluorescent protein (GFP) labeling technology and absolute quantitative real-time polymerase chain reaction (qRT-PCR) were used to confirm the colonization ability of the symbiotic bacteria in the guts of anautogenous Cx. pipiens pallens . The alterations in the expression levels of reproductive-related genes were verified by relative qRT-PCR. 20-Hydroxyecdysone (20E), juvenile hormone (JH), and the concentrations of vitellogenin were measured to assess the vitellogenesis. Continuous multi-generational treatment with bacteria was applied to anautogenous Cx. pipiens pallens to evaluate transgenerational effects. Larval stage, pupation rate, pupal stage, emergence rate, male:female ratio, blood-feeding rate, oviposition rate, and hatching rate were recorded to assess the effects of the symbiotic bacteria on the reproductive and developmental phenotypes in the anautogenous Cx. pipiens pallens . Results: The gut-specific symbiotic bacterium isolated from autogenous Cx. pipiens pallens was identified as Brevundimonas aurantiaca , a Gram-negative rod-shaped bacterium that forms orange-yellow circular colonies on Caulobacter medium. B. aurantiaca successfully colonized in the midgut of anautogenous Cx. pipiens pallens and achieved vertical transmission. The reproductive phenotype of anautogenous Cx. pipiens pallens is complex and significant alterations were observed in two aspects investigated. By the fifth generation, the bacteria-treated group compared with the untreated anautogenous group showed decreased blood-feeding rate (87.7% vs 96.3%) and prolonged larval development (8.3 d vs 7.4 d). Conclusions: The symbiotic bacterium B. aurantiaca may be associated with changes in the reproductive strategy of anautogenous Cx. pipiens pallens , although direct mechanistic evidence is not provided in this study. These findings not only provide an important microbial regulatory perspective for understanding the molecular mechanisms underlying autogeny in mosquitoes, but also offer potential targets for the development of novel symbiont-based biocontrol strategies against mosquito-borne diseases.

Introduction: Whipworm (Trichuris trichiura) coexists with symbiotic microbiota in the gastrointestinal ecosystem. There is a paucity of data on the association between whipworm infection and the gut microbiota composition in elderly individuals. This study was designed to investigate changes in gut microbiota and function and its metabolite profile in patients with whipworm infection.Methods: We used 16S rRNA gene sequencing to identify microbial signatures associated with whipworm infection. Subsequently, shotgun metagenomic sequencing revealed functional changes that highlighted disruptions in microbial gene expression and metabolic pathways influencing host health. Ultraperformance liquid chromatography-mass spectrometry metabolomics was used to characterize whipworm infectioninduced metabolic perturbations and elucidate metabolite dynamics linked to microbial activity. Collectively, this multi-omics approach deciphered structural, functional, and metabolic remodeling of the gut ecosystem that distinguished whipworm-infected patients from healthy controls.Results: Analyses of the gut microbiome in patients with whipworm infection revealed significantly increased observed species richness and ACE indices, along with an enrichment of Prevotella 9-driven enterotypes. Additionally, metagenomic and metabolomic analyses indicated enrichment in metabolic pathways related to amino acid, energy and carbohydrate metabolism. Metabolic network analysis further suggested that the upregulated Prevotella copri and Siphoviridae sp. were positively correlated with elevated levels of myristic acid and DL-dipalmitoylphosphatidylcholine.Conclusion: These findings suggest that whipworm infection significantly remodels the gut microbiome ecosystem and compromises intestinal homeostasis.

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

Background: Future distribution of dengue risk is usually predicted based on predicted climate changes using general circulation models (GCMs). However, it is difficult to validate the GCM results and assess the uncertainty of the predictions. The observed changes in climate may be very different from the GCM results. We aim to utilize trends in observed climate dynamics to predict future risks of Aedes albopictus in China. Methods: We collected Ae. albopictus surveillance data and observed climate records from 80 meteorological stations from 1970 to 2021. We analyzed the trends in climate change in China and made predictions on future climate for the years 2050 and 2080 based on trend analyses. We analyzed the relationship between climatic variables and the prevalence of Ae. albopictus in different months/seasons. We built a classification tree model (based on the average of 999 runs of classification and regression tree analyses) to predict the monthly/seasonal Ae. albopictus distribution based on the average climate from 1970 to 2000 and assessed the contributions of different climatic variables to the Ae. albopictus distribution. Using these models, we projected the future distributions of Ae. albopictus for 2050 and 2080. Results: The study included Ae. albopictus surveillance from 259 sites in China found that winter to early spring (November–February) temperatures were strongly correlated with Ae. albopictus prevalence (prediction accuracy ranges 93.0–98.8%)—the higher the temperature the higher the prevalence, while precipitation in summer (June–September) was important predictor for Ae. albopictus prevalence. The machine learning tree models predicted the current prevalence of Ae. albopictus with high levels of agreement (accuracy > 90% and Kappa agreement > 80% for all 12 months). Overall, winter temperature contributed the most to Ae. albopictus distribution, followed by summer precipitation. An increase in temperature was observed from 1970 to 2021 in most places in China, and annual change rates varied substantially from -0.22 ºC/year to 0.58 ºC/year among sites, with the largest increase in temperature occurring from February to April (an annual increase of 1.4–4.7 ºC in monthly mean, 0.6–4.0 ºC in monthly minimum, and 1.3–4.3 ºC in monthly maximum temperature) and the smallest in November and December. Temperature increases were lower in the tropics/subtropics (1.5–2.3 ºC from February–April) compared to the high-latitude areas (2.6–4.6 ºC from February–April). The projected temperatures in 2050 and 2080 by this study were approximately 1–1.5 °C higher than those projected by GCMs. The estimated current Ae. albopictus risk distribution had a northern boundary of north-central China and the southern edge of northeastern China, with a risk period of June–September. The projected future Ae. albopictus risks in 2050 and 2080 cover nearly all of China, with an expanded risk period of April–October. The current at-risk population was estimated to be 960 million and the future at-risk population was projected to be 1.2 billion. Conclusions: The magnitude of climate change in China is likely to surpass GCM predictions. Future dengue risks will expand to cover nearly all of China if current climate trends continue.

Background: Mosquitoes are important vectors for a range of diseases, contributing to high rates of morbidity and mortality in the human population. Culex pipiens pallens is dominant species of Culex mosquito in northern China and a major vector for both West Nile virus and Bancroftian filariasis. Insecticide application were largely applied to control the mosquito-mediated spread of these diseases, contributing to increasing rates of resistance in the mosquito population. The voltage-gated sodium channel (Vgsc) gene is the target site of pyrethroids, and mutations in this gene cause knockdown resistance (kdr). While these kdr mutations are known to be critical to pyrethroid resistance, their evolutionary origins remain poorly understood. Clarifying the origins of these mutations is potential to guide further vector control and disease prevention efforts. Accordingly, the present study was designed to study the evolutionary genetics of kdr mutations and their association with the population structure of Cx. p. pallens in Shandong province, China. Methods: Adult Culex females were collected from Shandong province and subjected to morphological identification under a dissection microscope. Genomic DNA were extracted from the collected mosquitoes, the Vgsc gene were amplified via PCR and sequenced to assess kdr allele frequencies, intron polymorphisms, and kdr codon evolution. In addition, population genetic diversity and related population characteristics were assessed by amplifying and sequencing the mitochondrial cytochrome C oxidase I (COI) gene. Results: Totally, 263 Cx. p. pallens specimens were used for DNA barcoding and sequencing analyses to assess kdr allele frequencies in nine Culex populations. The kdr codon L1014 in the Vgsc gene identified two non-synonymous mutations (L1014F and L1014S) in the analyzed population. These mutations were present in the eastern hilly area and west plain region of Shandong Province. However, only L1014F mutation was detected in the southern mountainous area and Dongying city of Shandong Province, where the mutation frequency was low. Compared to other cities, population in Qingdao revealed significant genetic differentiation. Spatial kdr mutation patterns are likely attributable to some combination of prolonged insecticide-mediated selection coupled with the genetic isolation of these mosquito populations. Conclusions: These data suggest that multiple kdr alleles associated with insecticide resistance are present within the Cx. p. pallens populations of Shandong Province, China. The geographical distributions of kdr mutations in this province are likely that the result of prolonged and extensive insecticide application in agricultural contexts together with frequent mosquito population migrations. In contrast, the low-frequency kdr mutation detected in central Shandong Province populations may originate from the limited selection pressure in this area and the relative genetic isolation. Overall, the study compares the genetic patterns revealed by a functional gene with a neutral marker and demonstrates the combined impact of demographic and selection factors on population structure.

The extensive use of chemical insecticides for public health and agricultural purposes has increased the occurrence and development of insecticide resistance. This study used transcriptome sequencing to screen 10 upregulated metabolic detoxification enzyme genes from Aedes albopictus resistant strains. Of these, CYP6A14 and CYP6N6 were found to be substantially overexpressed in the deltamethrin-induced expression test, indicating their role in deltamethrin resistance in Ae. albopictus. Furthermore, the corresponding 60-kDa recombinant proteins, CYP6A14 and CYP6N6, were successfully expressed using the Escherichia coli expression system. Enzyme activity studies revealed that CYP6A14 (5.84 U/L) and CYP6N6 (6.3 U/L) have cytochrome P450 (CYP450) enzyme activity. In vitro, the metabolic analysis revealed that the recombinant proteins degraded deltamethrin into 1-oleoyl-sn-glycero-3-phosphoethanolamine and 2′,2′-dibromo-2′-deoxyguanosine. Subsequently, the CYP450 genes in larvae of Ae. albopictus were silenced by RNA interference technology to study deltamethrin resistance in vivo. The silencing of CYP6A14 and CYP6N6 increased the mortality rate of mosquitoes without affecting their survival time, spawning quantity, hatching rate, and other normal life activities. Altogether, CYP6A14 and CYP6N6 belong to the CYP6 family and mutually increase deltamethrin resistance in Ae. albopictus.

Background: Culex pipiens pallens (Diptera: Culicidae) can survive at low temperature for long periods. Understanding the effects of low-temperature stress on the gut microflora and gene expression levels in Cx. pipiens pallens, as well as their correlation, will contribute to the study of the overwintering mechanism of Cx. pipiens pallens. Methods: The gut bacteria were removed by antibiotic treatment, and the survival of Cx. pipiens pallens under low-temperature stress was observed and compared with the control group. Then, full-length 16S rRNA sequencing and the Illumina HiSeq X Ten sequencing platform were used to evaluate the gut microflora and gene expression levels in Cx. pipiens pallens under low-temperature stress. Results: Under the low-temperature stress of 7 °C, the median survival time of Cx. pipiens pallens in the antibiotic treatment group was significantly shortened by approximately 70% compared to that in the control group. The species diversity index (Shannon, Simpson, Ace, Chao1) of Cx. pipiens pallens decreased under low-temperature stress (7 °C). Non-metric multidimensional scaling (NMDS) analysis divided all the gut samples into two groups: control group and treatment group. Pseudomonas was the dominant taxon identified in the control group, followed by Elizabethkingia and Dyadobacter; in the treatment group, Pseudomonas was the dominant taxon, followed by Aeromonas and Comamonas. Of the 2417 differentially expressed genes (DEGs), 1316 were upregulated, and 1101 were downregulated. Functional GO terms were enriched in 23 biological processes, 20 cellular components and 21 molecular functions. KEGG annotation results showed that most of these genes were related to energy metabolism-related pathways. The results of Pearson’s correlation analysis showed a significant correlation between the gut microcommunity at the genus level and several DEGs. Conclusions: These results suggest that the mechanism of adaptation of Cx. pipiens pallens to low-temperature stress may be the result of interactions between the gut bacterial community and transcriptome. Graphical