Elucidating Scarab Divergence in an Evolutionary-Ecological Context through the Comprehensive Analysis of the Complete Mitogenome of Anomala.

Anomala Samouelle, 1819 is one of the specious genera of Coleoptera, with over 1000 known species, and includes some of the most destructive pests of crops or forests. Morphological convergence is a common phenomenon within this genus, making the identification of closely related species very difficult. To explore the phylogenetic placement of Anomalini and provide a basis for the classification and identification of Anomala, we comparatively analyzed the complete mitogenome of three Anomala species (A. exoleta, A. perplexa diana, and A. praecoxalis). Based on all accessible mitogenome data, we performed comparative mitochondrial genomics analysis of this genus and reconstructed the phylogenetic relationships of Scarabaeidae based on two datasets (protein-coding genes and amino acids) and two methods (Bayesian approach and maximum likelihood). The phylogenetic relationships found in this study highly support that the groups of Aphodiinae, Cetoniinae, Dynastinae, Rutelinae and Scarabaeinae are monophyletic. Interestingly, the phylogenetic clustering relationship was highly consistent with the Scarabaeidae diet, indicating that the herbivorous species and dung-eating species are clustered separately. The phylogenetic tree showed that the subfamily Melolonthinae and the genus Anomala are not monophyletic, suggesting that these two groups should be further revised with more data.

Evidence of Cross-Kingdom Gene Regulation by Plant MicroRNAs and Possible Reasons for Inconsistencies.

The debate on whether cross-kingdom gene regulation by orally acquired plant miRNAs is possible has been ongoing for nearly 10 years without a conclusive answer. In this study, we categorized plant miRNAs into different groups, namely, extracellular vesicle (EV)-borne plant miRNAs, extracted plant miRNAs, herbal decoction-borne plant miRNAs, synthetic plant miRNA mimics, and plant tissue/juice-borne plant miRNAs. This categorization aimed to simplify the analysis and address the question more specifically. Our evidence suggests that EV-borne plant miRNAs, extracted plant miRNAs, herbal decoction-borne plant miRNAs, and synthetic plant miRNA mimics consistently facilitate cross-kingdom gene regulation. However, the results regarding the cross-kingdom gene regulation by plant tissue- and juice-borne plant miRNAs are inconclusive. This inconsistency may be due to variations in study methods, a low absorption rate of miRNAs and the selective absorption of plant miRNAs in the gastrointestinal tract. Overall, it is deduced that cross-kingdom gene regulation by orally acquired plant miRNAs can occur under certain circumstances, depending on factors such as the types of plant miRNAs, the delivery mechanism, and their concentrations in the plant.

Action mechanisms and characteristics of miRNAs to regulate virus replication.

MicroRNAs (miRNAs) have the potential to be explored as antiviral products. It is known that miRNAs have different kinds of target mRNAs and different target sites in mRNAs, and that the action-modes of miRNAs at different target sites may be different. But there is no evidence demonstrating the significance of the differences for the regulation of viruses by miRNAs, which might be crucial for the exploration of miRNA-based antiviral products. Here the experimental studies about the antiviral effects of miRNAs, with validated target mRNAs and target sites in the mRNAs, were systematically collected, based on which the mechanisms whereby miRNAs regulated virus replication were systematically reviewed. And miRNAs' down-regulation rates on target mRNAs and antiviral rates were compared among the miRNAs with different target sites, to analyze the characteristics of action-modes of miRNAs at different target sites during virus replication.

Surveillance, epidemiology, and impact of the coronavirus disease 2019 interventions on the incidence of enterovirus infections in Nanchang, China, 2010-2022.

Introduction: Pathogen spectrum of Hand, foot and mouth disease (HFMD) has substantially changed in the past decade in China. Growing evidence has indicated that anti-COVID-19 nonpharmaceutical interventions (NPIs) can support control of various infectious diseases, including intestinal diseases. Methods: In this study, HFMD cases were enrolled from sentinel hospitals of Nanchang, Jiangxi province, and enteroviruses were genotyped using specific real time RT-PCR. We systematically characterized the epidemiology of HFMD based on the continuous molecular surveillance and estimated the impact of COVID-19 intervention on HFMD incidence using seasonal autoregressive integrated moving average (ARIMA) models. Results: A total of 10247 HFMD cases were included during 2010-2022, of which 6121 enterovirus (EV)-positive cases (59.7%) were identified by real-time RT-PCR. Over 80% cases were associated with EV-A71 and coxsackievirus A16 (CVA16) during 2010-2012, while the type distribution significantly changed as CVA6 emerged to be dominant, accounting for 22.6%-59.6% during 2013-2022. It was observed that the prevalence patterns of EV-A71 and CVA16 were similar and both of them peaked in the second quarter and then leveled off. However, CVA6 was generally prevalent around the fourth quarter, demonstrating a staggered prevalence during 2010-2019. During the COVID-19 epidemic, the seasonal HFMD epidemic peak was restrained, and the ARIMA analysis indicated that the COVID-19 intervention had mitigated EV transmission during the first COVID-19 outbreak in early 2020. In addition, bivariate Spearman's cross-correlation coefficients were estimated for the major types CVA6, CVA16 and EV-A71. Our analyses indicated the possible existence of correlations among CVA6, CVA16 and EV-A71 prevalence in the epidemiological level. Discussion: Taken together, the type distribution of HFMD has substantially changed over the last decade and CVA6 and CVA16 are currently the most predominant types co-circulating in Nanchang. The anti-COVID-19 NPIs significantly reduced the incidence of EV infections.

Effect of Lactobacillus plantarum P9 on defecation, quality of life and gut microbiome in individuals with chronic diarrhoea: Protocol for a randomized, double-blind, placebo-controlled clinical trial.

Background: Probiotics may be an ideal choice for these patients, given it can improve the defecation and quality of life of individuals with chronic diarrhoea. However, evidence-based medical research is still limited to support its use as a diarrhoea agent. Method: A randomized, double-blind, placebo-controlled clinical trial is designed to pinpoint the efficiency and possible action modes of probiotics for chronic diarrhoea. 200 eligible volunteers with chronic diarrhoea are randomly assigned to a probiotic group (orally taking Lactobacillus plantarum p9 probiotics powder) or a placebo group. Except an independent project administrator who will be responsible for unblinding, the other researchers are blinded. Primary outcome is diarrhoea severity score, and secondary outcomes include weekly mean frequency of defecation, weekly mean stool appearance score, weekly mean stool urgency score, emotional state score, gut microbiome, and faecal metabolome. Each outcome measure will be assessed at the timepoints of pre-administration (day 0), administration (day 14 and/or 28), and post-administration (day 42) to identity inter- and intra-groups differences. Adverse events will be recorded to evaluate the safety of L. plantarum p9. Discussion: The study protocol will provide high-quality evidence for the use of probiotics as a diarrhoea agent when it is strictly conducted out, providing evidence regarding whether and to what extent L. plantarum p9 can improve the defecation and well-being of individuals with chronic diarrhoea. Trial registration: Chinese Clinical Trial Registry (ChiCTR) (NO. ChiCTR2000038410). Registered on November 22, 2020, https://www.chictr.org.cn/showproj.aspx?proj=56542.

Advances in studies of circulating microRNAs: origination, transportation, and distal target regulation.

In the past few years, numerous advances emerged in terms of circulating microRNA(miRNA) regulating gene expression by circulating blood to the distal tissues and cells. This article reviewed and summarized the process of circulating miRNAs entering the circulating system to exert gene regulation, especially exogenous miRNAs (such as plant miRNAs), from the perspective of the circulating miRNAs source (cell secretion or gastrointestinal absorption), the transport form and pharmacokinetics in circulating blood, and the evidence of distal regulation to gene expression, thereby providing a basis for their in-depth research and even application prospects.

One microRNA has the potential to target whole viral mRNAs in a given human coronavirus.

MicroRNAs (miRNAs) can repress viral replication by targeting viral messenger RNA (mRNA), which makes them potential antiviral agents. The antiviral effects of miRNAs on infectious viruses have been explored extensively; however, recent studies mainly considered the action modes of miRNAs, neglecting another key factor, the molecular biology of viruses, which may be particularly important in the study of miRNA actions against a given virus. In this paper, the action modes of miRNAs and the molecular biology of viruses are jointly considered for the first time and based on the reported roles of miRNAs on viruses and human coronaviruses (HCoVs) molecular biology, the general and specific interaction modes of miRNAs-HCoVs are systematically reviewed. It was found that HCoVs transcriptome is a nested set of subgenomic mRNAs, sharing the same 5' leader, 3' untranslated region (UTR) and open reading frame (ORF). For a given HCoV, one certain miRNA with a target site in the 5' leader or 3' UTR has the potential to target all viral mRNAs, indicating tremendous antiviral effects against HCoVs. However, for the shared ORFs, some parts are untranslatable attributed to the translation pattern of HCoVs mRNA, and it is unknown whether the base pairing between the untranslated ORFs and miRNAs plays a regulatory effect on the local mRNAs where the untranslated ORFs are located; therefore, the regulatory effects of miRNAs with targets within the shared ORFs are complicated and need to be confirmed. Collectively, miRNAs may bepromising antiviral agents against HCoVs due to their intrinsically nested set of mRNAs, and some gaps are waiting to be filled. In this review, insight is provided into the exploration of miRNAs that can interrupt HCoVs infection.

Effects of Lactobacillus plantarum P9 Probiotics on Defecation and Quality of Life of Individuals with Chronic Constipation: Protocol for a Randomized, Double-Blind, Placebo-Controlled Clinical Trial.

Background: Although probiotics have been shown to improve constipation-related symptoms, a clear consensus on the use of probiotics as a constipation-relieving agent has not been reached, which is attributed to the limited available evidence and inconsistent protocols used in existing studies. Method: A randomized, double-blind, placebo-controlled clinical trial is designed to study the efficiency and possible mechanism of action of probiotics for chronic constipation, in which 200 eligible volunteers with chronic constipation will be randomly assigned to a probiotic group (oral Lactobacillus plantarum P9 probiotic powder, 100 billion colony-forming units (CFUs)/day) or a placebo group. Volunteers, treatment distributors, data collectors, and data analysts will be blinded. The primary outcome is the weekly mean frequency of complete spontaneous bowel movements (CSBMs), and secondary outcomes include weekly mean frequency of CSBMs ≥3, weekly mean frequency of spontaneous bowel movements (SBMs), weekly mean stool appearance score, weekly mean difficulty of passing stool score, weekly percentage of volunteers who use auxiliary measures to assist with defecation (WPUAMA), quality-of-life (QOL) score, emotional status score, gut microbiome, and faecal metabolome. Each outcome measure will be assessed at the time points of preadministration (day 0), administration (day 14 and/or 28), and postadministration (day 42) to identify inter- and intragroup differences. Adverse events will be recorded to evaluate the safety of L. plantarum P9. Discussion. The protocol will provide methodological guidance for other similar studies, avoiding methodological bias and ultimately facilitating the formulation of consensus on the use of probiotics as a constipation-relieving agent. In addition, the results are more comprehensive than those of existing studies and may objectively and scientifically reflect the effectiveness of L. plantarum P9 on constipation. If the expected study findings are obtained, L. plantarum P9, taken as a probiotic, may become a complementary choice for chronically constipated patients. This trial is registered with Chinese Clinical Trial Registry (ChiCTR) (no. ChiCTR2000038396) registered on November 22, 2020, https://www.chictr.org.cn/showproj.aspx?proj=54024.

Protocol of a randomized, double-blind, placebo-controlled study of the effect of probiotics on the gut microbiome of patients with gastro-oesophageal reflux disease treated with rabeprazole.

BACKGROUND: For patients with gastro-oesophageal reflux symptoms, the preferred treatment is proton pump inhibitor (PPI) administration for approximately 8 weeks. However, long-term use of PPIs can cause gut microbiome (GM) disturbances. This study is designed to evaluate the effect of probiotics combined with a PPI on the GM and gastrointestinal symptoms of patients with gastro-oesophageal reflux disease (GERD). METHOD: This is a randomized, double-blind, placebo-controlled trial. A total of 120 eligible patients with GERD will be randomized into the experimental group or the control group. The treatment includes two phases: the initial treatment period lasts 8 weeks (weeks 1-8), and the maintenance treatment period lasts 4 weeks (weeks 9-12). During the initial treatment period, the experimental group will take rabeprazole and LiHuo probiotics, and the control group will take rabeprazole and a probiotic placebo; during the maintenance treatment period, the experimental group will take LiHuo probiotics, and the control group will take a probiotic placebo. The primary measure is the change in the GM. The secondary measures are the Reflux Disease Questionnaire (RDQ) score, Gastrointestinal Symptom Rating Scale (GSRS) score, faecal metabolome (FM), body mass index, Los Angeles grade of oesophagitis, adverse event (AE) rate and treatment compliance. Each outcome indicator will be assessed at day 0 (before administration), day 28 and/or 56 (during administration), and day 84 (end of administration) to reveal intragroup differences. AEs will be monitored to assess the safety of LiHuo probiotics. DISCUSSION: This will be the first trial to use the intestinal flora metagene method to analyse the effects of probiotics on patients with GERD receiving long-term PPI treatment. The goal is to provide evidence for the use of probiotics to reduce intestinal flora disorders and other symptoms of gastrointestinal discomfort in patients with GERD who have used PPIs for a long period. TRIAL REGISTRATION: Chinese Clinical Trial Registry (ChiCTR) (NO. ChiCTR2000038409). Registered on November 22, 2020, http://www.chictr.org.cn/showproj.aspx?proj=56358 .

Moxibustion for alleviating chemotherapy-induced gastrointestinal adverse effects: A systematic review of randomized controlled trials.

OBJECTIVE: This systematic review aims to assess whether moxibustion is effective and safe for gastrointestinal adverse effects, a common and thorny issue arising from chemotherapy. METHODS: Seven electronic databases were searched up to August 28, 2021, to identify randomized controlled trials (RCTs) comparing moxibustion versus non-moxibustion treatments for various gastrointestinal adverse effects after chemotherapy. The Karnofsky performance status (KPS) and quality of life scores and the incidence of moxibustion-related adverse events were also investigated. Effects in meta-analyses were measured by risk ratios (RRs) or mean differences (MDs). RESULTS: Thirty-two RCTs (n = 2990) were included. Compared to the controls, moxibustion significantly reduced the incidences of nausea/vomiting (RR 0.70, 95% CI 0.61-0.79), severe nausea/vomiting (RR 0.39, 95% CI 0.29-0.51), diarrhoea (RR 0.56, 95% CI 0.38-0.82), constipation (RR 0.59, 95% CI 0.44-0.78), and abdominal distension (RR 0.60, 95% CI 0.46-0.78). The KPS (MD 7.53, 95% CI 3.42-11.64) and quality of life (MD 8.88, 95% CI 0.96-16.80) scores were also significantly improved after moxibustion. The results did not support a benefit of moxibustion on inappetence (RR 0.69, 95% CI 0.40-1.22) or abdominal pain (RR 0.60, 95% CI 0.28-1.30). All adverse events related to moxibustion were mild. CONCLUSIONS: Moderate-to very-low-quality evidence suggests that moxibustion may be safely used as an adjuvant treatment after chemotherapy to reduce the incidences of nausea and vomiting, diarrhoea, constipation, and abdominal distension and improve the performance status and quality of life in patients with malignant tumours. Its effects on abdominal pain and inappetence are uncertain.

Systematic Evaluation of Toxicity of Aconite Based on Bibliometric Method.

AIM: Based on the bibliometric method, the toxicity of aconite is analyzed and evaluated. METHODS: Studies on the toxicity of aconite were retrieved from CNKI, CQVIP, Chinese Biomedical Literature Service System, and PubMed, ranging from January 1985 to November 2020. All those studies were formed into the Database of Literature of Toxicity of Aconite (DLTA). Studies on the toxicity of aconite were retrieved from CNKI, CQVIP, SinoMed, and PubMed, respectively. Collecting relevant information in DLTA, we analyzed the hotspots, factors and mechanism of aconite toxicity, and attenuation methods. RESULTS: A total of 445 studies on the toxicity of aconite have been collected. "Compatibility attenuation" and "Processing attenuation" have been the hotspots of aconite toxicity in recent years. Many studies support that the main toxic reactions of aconite are heart damage, liver toxicity, nephrotoxicity, and neurotoxicity. The toxic effect of aconite is related to the effect on the central nervous system. Exciting the vagus nerve reduces the autonomy of the sinus node and damages myocardial cells. The decoction time, dosage, and administration of aconite are the main factors of the toxicity of aconite. There are few studies about the effect of the origin of aconite and the specifications of the medicinal materials on toxicity. Therefore, it is impossible to analyze its relevance. At present, the commonly used methods to reduce the toxicity of aconite mainly include three methods: drug compatibility, processing, and decoction. The most common compatibility with aconite medicines includes licorice, dried ginger, ginseng, and ephedra. Black sliced aconite, steamed slices, and fried slices are less toxic than other processed products. Aconite decoction for more than 60 minutes can basically reach the safe range, and more than 2 hours of decoction may cause the loss of active ingredients. CONCLUSIONS: The research on the mechanisms of aconite dosage-efficacy-toxicity, compatibility, processing, liver toxicity, and nephrotoxicity is still not comprehensive and in-depth. Researchers should perfect toxicity studies of aconite, remove the constraints that affect its clinical application, and promote the clinical use of aconite safely and reasonably.

Development of miRNA-Based Approaches to Explore the Interruption of Mosquito-Borne Disease Transmission.

MicroRNA (miRNA or miR)-based approaches to interrupt the transmission of mosquito-borne diseases have been explored since 2005. A review of these studies and areas in which to proceed is needed. In this review, significant progress is reviewed at the level of individual miRNAs, and miRNA diversification and relevant confounders are described in detail. Current miRNA studies in mosquitoes include four steps, namely, identifying miRNAs, validating miRNA-pathogen interactions, exploring action mechanisms, and performing preapplication investigations. Notably, regarding the Plasmodium parasite, mosquito miRNAs generally bind to mosquito immunity- or development-related mRNAs, indirectly regulating Plasmodium infection; However, regarding arboviruses, mosquito miRNAs can bind to the viral genome, directly modifying viral replication. Thus, during explorations of miRNA-based approaches, researchers need select an ideal miRNA for investigation based on the mosquito species, tissue, and mosquito-borne pathogen of interest. Additionally, strategies for miRNA-based approaches differ for arboviruses and protozoan parasites.

Complete mitochondrial genome of Penthimia melanocephala Motschulsky, 1863 (Hemiptera: Cicadellidae: Deltocephalinae).

Penthimia is the largest genus in the tribe Penthimiini of the subfamily Deltocephalinae. To date, there are no available mitogenome sequences from Penthimia. In this study, we have sequenced and annotated the complete mitogenome of Penthimia melanocephala (Motschulsky 1863), the mitogenome is 15,308 bp in length, which including 13 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNAs), 22 transfer RNAs (tRNAs) and a long non-coding region (control Region), base composition of whole sequences are A (50.4%), C (15.3%), G (10.0%), and T (24.3%). All PCGs started with the typical ATN codon and stopped with the typical TAN codon except for COII and COIII stopped with single T. Within phylogenetic tree, Deltocephalinae members were clustered into a clade. The complete mitogenome of P. melanocephala can provide essential DNA molecular data for further evolutionary and phylogenetic analysis.

Description of a new species of the leafhopper genus Reticuluma Cheng amp; Li, 2005 (Hemiptera: Cicadellidae: Penthimiini) from China with a key to species.

A new species Reticuluma bipennata sp. nov. from China is described and illustrated, and can be distinguished from other Reticuluma by the aedeagal shaft with a pair of wing-shaped processes on the lateral margin. A key to all species of the genus based on the features of males and a map showing the geographic distribution of the genus are given.

China's practice to prevent and control COVID-19 in the context of large population movement.

BACKGROUND: The emerging infectious disease, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses a serious threat in China and worldwide. Challenged by this serious situation, China has taken many measures to contain its transmission. This study aims to systematically review and record these special and effective practices, in hope of benefiting for fighting against the ongoing worldwide pandemic. METHODS: The measures taken by the governments was tracked and sorted on a daily basis from the websites of governmental authorities (e.g. National Health Commission of the People's Republic of China). And the measures were reviewed and summarized by categorizations, figures and tables, showing an ever-changing process of combating with an emerging infectious disease. The population shift levels, daily local new diagnosed cases, daily mortality and daily local new cured cases were used for measuring the effect of the measures. RESULTS: The practices could be categorized into active case surveillance, rapid case diagnosis and management, strict follow-up and quarantine of persons with close contacts, and issuance of guidance to help the public understand and adhere to control measures, plus prompt and effective high-level policy decision, complete activation of the public health system, and full involvement of the society. Along with the measures, the population shift levels, daily local new diagnosed cases, and mortality were decreased, and the daily local new cured cases were increased in China. CONCLUSIONS: China's practices are effective in controlling transmission of SARS-CoV-2. Considering newly occurred situations (e.g. imported cases, work resumption), the control measures may be adjusted.

Antivirus effectiveness of ivermectin on dengue virus type 2 in Aedes albopictus.

BACKGROUND: Dengue fever is the most rapidly spreading mosquito-borne viral disease over the past 50 years, with a 30-fold increase in global incidence. Dengue vector control is a key component for the dengue control strategy, since no absolutely effective vaccine or drug is available yet. However, the rapid rise and spread of mosquito insecticide resistance have become major threats to the efficiency of insecticide-based vector control activities. Thus, innovative vector control tools are badly needed. This study aims to confirm the antivirus effectiveness of ivermectin on dengue virus type 2 (DENV-2) in Aedes albopictus (Skuse, 1894), then to explore its potential use in the combating to the dengue epidemics. METHODS: Aedes albopictus were first infected with DENV-2 in human whole blood, and at the fourth day after infectious blood feeding, they were divided into eight groups. Seven of them were held for six days with access to 0, 2, 4, 8, 16, 32 and 64 ng/ml ivermectin, respectively, and the last one was set as a historical control group, which was stored at -80°C until being detected at the same time with the other groups. Each mosquito was detected using real-time fluorescent RT-PCR kit. DENV-2 RNA concentration (copies/ml) and infection rate in each group were compared. RESULTS: Both of quantitatively and qualitatively inhibiting effects of ivermectin have been detected in this study. Generally, DENV-2 replicated well in Aedes albopictus without ivermectin intervention, whose virus loads exhibited significantly higher when the mosquitoes were holding from 4 days to 10 days after infectious blood feeding. In contrast, with the treatment of ivermectin, the infection rate was reduced by as much as 49.63%. The regression equation between infection rates (Y2) and ivermectin concentration log2 values (X2) was obtained as Y2 = 91.41-7.21*X2 with R2 = 0.89. CONCLUSION: Ivermectin can directly or indirectly inhibit DENV-2 multiplication in Aedes albopictus. Moreover, the actual concentration for application in zooprophylaxis needs to be confirmed in the further field trials.

Effects of Microclimate Condition Changes Due to Land Use and Land Cover Changes on the Survivorship of Malaria Vectors in China-Myanmar Border Region.

In the past decade, developing countries have been experiencing rapid land use and land cover changes, including deforestation and cultivation of previously forested land. However, little is known about the impact of deforestation and land-use changes on the life history of malaria vectors and their effects on malaria transmission. This study examined the effects of deforestation and crop cultivation on the adult survivorship of major malaria mosquitoes, Anopheles sinensis and An. minimus in the China-Myanmar border region. We examined three conditions: indoor, forested, and banana plantation. Mean survival time of An. sinensis in banana plantation environment was significantly longer than those in forested environment, and mosquitoes exhibited the longest longevity in the indoor environment. This pattern held for both males and females, and also for An. minimus. To further test the effect of temperature on mosquito survival, we used two study sites with different elevation and ambient temperatures. Significantly higher survivorship of both species was found in sites with lower elevation and higher ambient temperature. Increased vector survival in the deforested area could have an important impact on malaria transmission in Southeast Asia. Understanding how deforestation impacts vector survivorship can help combat malaria transmission.

Anopheles sinensis mosquito insecticide resistance: comparison of three mosquito sample collection and preparation methods and mosquito age in resistance measurements.

BACKGROUND: Insecticide resistance monitoring in malaria mosquitoes is essential for guiding the rational use of insecticides in vector control programs. Resistance bioassay is the first step for insecticide monitoring and it lays an important foundation for molecular examination of resistance mechanisms. In the literature, various mosquito sample collection and preparation methods have been used, but how mosquito sample collection and preparation methods affect insecticide susceptibility bioassay results is largely unknown. The objectives of this study were to determine whether mosquito sample collection and preparation methods affected bioassay results, which may cause incorrect classification of mosquito resistance status. METHODS: The study was conducted in Anopheles sinensis mosquitoes in two study sites in central China. Three mosquito sample collection and preparation methods were compared for insecticide susceptibility, kdr frequencies and metabolic enzyme activities: 1) adult mosquitoes collected from the field; 2) F1 adults from field collected, blood-fed mosquitoes; and 3) adult mosquitoes reared from field collected larvae. RESULTS: Mosquito sample collection and preparation methods significantly affected mortality rates in the standard WHO tube resistance bioassay. Mortality rate of field-collected female adults was 10-15% higher than in mosquitoes reared from field-collected larvae and F1 adults from field collected blood-fed females. This pattern was consistent in mosquitoes from the two study sites. High kdr mutation frequency (85-95%) with L1014F allele as the predominant mutation was found in our study populations. Field-collected female adults consistently exhibited the highest monooxygenase and GST activities. The higher mortality rate observed in the field-collected female mosquitoes may have been caused by a mixture of mosquitoes of different ages, as older mosquitoes were more susceptible to deltamethrin than younger mosquitoes. CONCLUSIONS: Female adults reared from field-collected larvae in resistance bioassays are recommended to minimize the effect of confounding factors such as mosquito age and blood feeding status so that more reliable and reproducible mortality may be obtained.

[Changes of pyrethroid resistance and P450 monooxygenase activity with age in Anopheles sinensis in Huainan City, Anhui Province, China].

OBJECTIVE: To study the effect of mosquito age on the pyrethroid resistance and P450 monooxygenase activity in Anopheles sinensis in Huainan City, Anhui Province, China, as well as the molecular mechanism of pyrethroid resistance. METHODS: Anopheles mosquito larvae were collected in fields, and were emerged to adults. Then the pyrethroid resistance and P450 monooxygenase activity of female mosquitoes were detected 1, 3, 6, 9, 12, 15 d and 20 d after emergence. Meanwhile, the resistance level and P450 monooxygenase activity of the sensitive mosquitoes in lab were detected as the control group. RESULTS: curves of pyrethroid resistance and P450 monooxygenase activity changes with the mosquito age presented unsymmetrically reversed "U" type. At 1 d after emergence, the resistance level and P450 monooxygenase activity were lower, and then they increased quickly. When 3-9 d after emergence, the resistance level and P450 monooxygenase activity rose to the highest level, and entered into plateau, then declined gradually. Compared to the sensitive mosquitoes in lab, the P450 monooxygenase activity of those in the field was higher at 3-12 d after emergence, but lower at 1 d after emergence, and at 15 and 20 d after emergence, they were almost equal to each other. CONCLUSION: The mosquito age is a confounding factor in the detection of resistance level and enzyme activity. The promotion of activity of P450 monooxygenase may be one of the reasons of the resistance. Using female adults with different ages in the field as study subjects may underestimate the real resistance level of mosquitoes, and mislead the use of insecticides.

Relationship between knockdown resistance, metabolic detoxification and organismal resistance to pyrethroids in Anopheles sinensis.

Anopheles sinensis is the most important vector of malaria in Southeast Asia, including China. Currently, the most effective measure to prevent malaria transmission relies on vector control through the use of insecticides, primarily pyrethroids. Extensive use of insecticides poses strong selection pressure on mosquito populations for resistance. Resistance to insecticides can arise due to mutations in the insecticide target site (target site resistance), which in the case of pyrethroids is the para-type sodium channel gene, and/or the catabolism of the insecticide by detoxification enzymes before it reaches its target (metabolic detoxification resistance). In this study, we examined deltamethrin resistance in An. sinensis from China and investigated the relative importance of target site versus metabolic detoxification mechanisms in resistance. A high frequency (>85%) of nonsynonymous mutations in the para gene was found in populations from central China, but not in populations from southern China. Metabolic detoxification as measured by the activity of monooxygenases and glutathione S-transferases (GSTs) was detected in populations from both central and southern China. Monooxygenase activity levels were significantly higher in the resistant than the susceptible mosquitoes, independently of their geographic origin. Stepwise multiple regression analyses in mosquito populations from central China found that both knockdown resistance (kdr) mutations and monooxygenase activity were significantly associated with deltamethrin resistance, with monooxygenase activity playing a stronger role. These results demonstrate the importance of metabolic detoxification in pyrethroid resistance in An. sinensis, and suggest that different mechanisms of resistance could evolve in geographically different populations.