The effect of artificial light at night (ALAN) on the characteristics of diapause of Aedes albopictus

BACKGROUND

Recently, the effect of artificial light at night (ALAN) on the physiology and behavior of insects has gradually attracted the attention of researchers and has become a new research topic. Aedes albopictus is an important vector that poses a great public health risk. Further studies on the diapause of Ae. albopictus can provide a basis for new vector control, and it is also worth exploring whether the effect of ALAN on the diapause of Ae. albopictus will provide a reference for the prevention and control of infectious diseases mediated by Ae. albopictus.

METHODS

In this study, we experimentally studied the diapause characteristics of different geographical strains of Ae. albopictus under the interference of ALAN, explored the effect of ALAN on the diapause of Ae. albopictus and explored the molecular mechanism of ALAN on the diapause process through RNA-seq.

RESULTS

As seen from the diapause incidence, Ae. albopictus of the same geographic strain showed a lower diapause incidence when exposed to ALAN. The differentially expressed genes (DEGs) were mainly enriched in signaling and metabolism-related pathways in the parental females and diapause eggs of the ALAN group.

CONCLUSIONS

ALAN inhibits Ae. albopictus diapause. In the short photoperiod induced diapause of Ae. albopictus in temperate strain Beijing and subtropical strain Guangzhou, the disturbance of ALAN reduced the egg diapause rate and increased the egg hatching rate of Ae. albopictus, and the disturbance of ALAN also shortened the life cycle of Ae. albopictus eggs after hatching.

Possible potential spread of Anopheles stephensi, the Asian malaria vector

BACKGROUND

Anopheles stephensi is native to Southeast Asia and the Arabian Peninsula and has emerged as an effective and invasive malaria vector. Since invasion was reported in Djibouti in 2012, the global invasion range of An. stephensi has been expanding, and its high adaptability to the environment and the ongoing development of drug resistance have created new challenges for malaria control. Climate change is an important factor affecting the distribution and transfer of species, and understanding the distribution of An. stephensi is an important part of malaria control measures, including vector control.

METHODS

In this study, we collected existing distribution data for An. stephensi, and based on the SSP1-2.6 future climate data, we used the Biomod2 package in R Studio through the use of multiple different model methods such as maximum entropy models (MAXENT) and random forest (RF) in this study to map the predicted global An. stephensi climatically suitable areas.

RESULTS

According to the predictions of this study, some areas where there are no current records of An. stephensi, showed significant areas of climatically suitable for An. stephensi. In addition, the global climatically suitability areas for An. stephensi are expanding with global climate change, with some areas changing from unsuitable to suitable, suggesting a greater risk of invasion of An. stephensi in these areas, with the attendant possibility of a resurgence of malaria, as has been the case in Djibouti.

CONCLUSIONS

This study provides evidence for the possible invasion and expansion of An. stephensi and serves as a reference for the optimization of targeted monitoring and control strategies for this malaria vector in potential invasion risk areas.

Insecticide resistance status of Aedes aegypti in border areas of Yunnan Province

BACKGROUND

Aedes aegypti is a main vector of arboviral diseases, principally dengue, chikungunya, and Zika. Insecticides remain the most effective vector control method. Pyrethroid is the main insecticide currently used, and the long-term use of insecticides can cause mosquitoes to develop knockdown resistance. Studying the mutation sites and genotypes of Ae. aegypti can reveal the mutation characteristics and regional distribution of the kdr gene in an Ae. aegypti population. Testing for a correlation between the mutation rate in various populations and pyrethrin resistance can clarify the resistance mechanism.

RESULTS

The bioassay results showed that all 15 populations are resistant. In the study of the kdr gene, three non-synonymous mutations were identified in the DNA of first generation females from the wild Ae. aegypti population: S989P (TCC-CCC), V1016G (GTA-GGA), and F1534C (TTC-TGC). The mortality rate of the various populations was correlated with the mutation rate at the V1016G + F1534C locus, but not the S989P + V1016G locus.

CONCLUSION

Aedes aegypti populations in border regions of Yunnan Province are resistant to permethrin and beta-cyfluthrin. The insecticidal effect of beta-cyfluthrin is stronger than that of permethrin. The mutation rate at sites V1016G + F1534C is negatively correlated with the mortality of Ae. aegypti based on bioassays. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The predicted potential distribution of Aedes albopictus in China under the shared socioeconomic pathway (SSP)1-2.6

Aedes albopictus (Skuse) (Diptera: Culicidae) is one of the 100 most invasive species in the world and represents a significant threat to public health. The distribution of Ae. albopictus has been expanding rapidly due to increased international trade, population movement, global warming and accelerated urbanization. Consequently, it is very important to know the potential distribution area of Ae. albopictus in advance for early warning and control of its spread and invasion. We randomly selected 282 distribution sites from 27 provincial-level administrative regions in China, and used the GARP and MaxEnt models to analyze and predict the current and future distribution areas of Ae. albopictus in China. The results showed that the current range of Ae. albopictus in China covers most provinces such as Yunnan and Guizhou Provinces, and the distribution of Ae. albopictus in border provinces such as Tibet, Gansu and Jilin Provinces tend to expand westwards. In addition, the potential distribution area of Ae. albopictus in China will continue to expand westwards due to future climate change under the SSP126 climate scenario. Furthermore, the results of environmental factor filtering showed that temperature and precipitation had a large effect on the distribution probability of Ae. albopictus.

Potential Global Distribution of the Invasive Mosquito Aedes koreicus under a Changing Climate

Invasive alien species are a growing threat to natural systems, the economy, and human health. Active surveillance and responses that readily suppress newly established colonies are effective actions to mitigate the noxious consequences of biological invasions. Aedes (Hulecoeteomyia) koreicus (Edwards), a mosquito species native to East Asia, has spread to parts of Europe and Central Asia since 2008. In the last decade, Ae. koreicus has been shown to be a competent vector for chikungunya virus and Dirofilaria immitis. However, information about the current and potential distribution of Ae. koreicus is limited. Therefore, to understand the changes in their global distribution and to contribute to the monitoring and control of Ae. koreicus, in this study, the MaxEnt model was used to predict and analyze the current suitable distribution area of Ae. koreicus in the world to provide effective information.

Wolbachia infection in field-collected Aedes aegypti in Yunnan Province, southwestern China

Background

Wolbachia is gram-negative and common intracellular bacteria, which is maternally inherited endosymbionts and could expand their propagation in host populations by means of various manipulations. Recent reports reveal the natural infection of Wolbachia in Aedes Aegypti in Malaysia, India, Philippines, Thailand and the United States. At present, none of Wolbachia natural infection in Ae. aegypti has been reported in China.

Methods

A total of 480 Ae. aegypti adult mosquitoes were collected from October and November 2018 based on the results of previous investigations and the distribution of Ae. aegypti in Yunnan. Each individual sample was processed and screened for the presence of Wolbachia by PCR with wsp primers. Phylogenetic trees for the wsp gene was constructed using the neighbour-joining method with 1,000 bootstrap replicates, and the p-distance distribution model of molecular evolution was applied.

Results

24 individual adult mosquito samples and 10 sample sites were positive for Wolbachia infection. The Wolbachia infection rate (IR) of each population ranged from 0 - 41.7%. The infection rate of group A alone was 0%-10%, the infection rate of group B alone was 0%-7.7%, and the infection rate of co-infection with A and B was 0-33.3%.

Conclusions

Wolbachia infection in wild Ae. aegypti in China is the first report based on PCR amplification of the Wolbachia wsp gene. The Wolbachia infection is 5%, and the wAlbA and wAlbB strains were found to be prevalent in the natural population of Ae. aegypti in Yunnan Province.

Genetic Diversity and Population Genetic Structure of Aedes albopictus in the Yangtze River Basin, China

Aedes albopictus is an indigenous primary vector of dengue and Zika viruses in China. Understanding the population spatial genetic structure, migration, and gene flow of vector species is critical to effectively preventing and controlling vector-borne diseases. The genetic variation and population structure of Ae. albopictus populations collected from 22 cities along the Yangtze River Basin were investigated with nine microsatellite loci and the mitochondrial CoxI gene. The polymorphic information content (PIC) values ranged from 0.534 to 0.871. The observed number of alleles (Na) values ranged from 5.455 to 11.455, and the effective number of alleles (Ne) values ranged from 3.106 to 4.041. The Shannon Index (I) ranged from 1.209 to 1.639. The observed heterozygosity (Ho) values ranged from 0.487 to 0.545. The FIS value ranged from 0.047 to 0.212. All Ae. albopictus populations were adequately allocated to three clades with significant genetic differences. Haplotype 2 is the most primitive molecular type and forms 26 other haplotypes after one or more site mutations. The rapid expansion of high-speed rail, aircraft routes and highways along the Yangtze River Basin have accelerated the dispersal and communication of mosquitoes, which appears to have contributed to inhibited population differentiation and promoted genetic diversity among Ae. albopictus populations.

Fine-scale genetic structure and wolbachia infection of aedes albopictus (Diptera: Culicidae) in Nanjing city, China

Background:Aedes albopictus is an indigenous primary vector of dengue and Zika viruses in China. Wolbachia is a gram-negative and common intracellular bacteria, which is maternally inherited endosymbionts and could expand their propagation in host populations by means of various manipulations. Compared with research on the dispersion of Ae. albopictus at the macrospatial level (mainly at the country or continent level), little is known about its variation and Wolbachia infection at the microspatial level, which is essential for its management. Meanwhile, no local cases of dengue fever have been recorded in the history of Nanjing, which implies that few adulticides have been applied in the city. Thus, the present study examines how the Ae. albopictus population varies and the Wolbachia infection status of each population among microspatial regions of Nanjing City.

Methods: The genetic structure of 17 Aedes albopictus populations collected from urban, urban fringe, and rural regions of Nanjing City was investigated based on 9 microsatellite loci and the mitochondrial coxI gene. The Wolbachia infection status of each population was also assessed with Wolbachia A- and Wolbachia B-specific primers.

Results: Nine out of 58 tested pairs of microsatellite markers were highly polymorphic, with a mean PIC value of 0.560, and these markers were therefore chosen for microsatellite genotyping analysis. The Na value of each Ae. albopictus population was very high, and the urban area populations (7.353 ± 4.975) showed a lower mean value than the urban fringe region populations (7.866 ± 5.010). A total of 19 coxI haplotypes were observed among 329 Ae. albopictus individuals via haplotype genotyping, with the highest diversity observed among the urban fringe Ae. albopictus populations (Hd = 0.456) and the lowest among the urban populations (Hd = 0.277). Each Ae. albopictus population showed significant departure from HWE, and significant population expansion was observed in only three populations from the urban (ZSL), urban fringe (HAJY), and rural areas (HSZY) (p < 0.05). Combined with DAPC analysis, all the Ae. albopictus populations were adequately allocated to two clades with significant genetic differences according to population structure analysis, and the best K value was equal to two. AMOVA results showed that most (96.18%) of the genetic variation detected in Ae. albopictus occurred within individuals (F_IT = 0.22238, p < 0.0001), while no significant positive correlation was observed via isolation by distance (IBD) analysis (R² = 0.03262, p = 0.584). The TCS network of all haplotypes showed that haplotype 1 (H1) and haplotype 4 (H4) were the most frequent haplotypes among all populations, and the haplotype frequency significantly increased from urban regions (36.84%) to rural regions (68.42%). Frequent migration was observed among Ae. albopictus populations from rural to urban regions via the urban fringe region, with four direct migration routes between rural and urban regions. Furthermore, Wolbachia genotyping results showed that most of the individuals of each population were coinfected with Wolbachia A and Wolbachia B. The independent infection rate of Wolbachia A was slightly higher than that of Wolbachia B, and no significant differences were observed among different regions.

Conclusion: In the microspatial environment of Nanjing City, the urban fringe region is an important region for the dispersion of Ae. albopictus populations between rural and urban areas, and Wolbachia A and Wolbachia B coinfection is the most common Wolbachia infection status in all Ae. albopictus populations among different regions.

The Potential Vector Competence and Overwintering of West Nile Virus in Vector Aedes Albopictus in China

West Nile virus (WNV) is an arbovirus, which causes widespread zoonotic disease globally. In China, it was first isolated in Jiashi County, Kashgar Region, Xinjiang in 2011. Determining the vector competence of WNV infection has important implications for the control of disease outbreaks. Four geographical strains of Aedes Albopictus (Ae. Albopictus) in China were allowed to feed on artificial infectious blood meal with WNV to determine the infection and transmission rate. The results indicated that four strains of Ae. Albopictus mosquitoes could infect and transmit WNV to 1- to 3-day-old Leghorn chickens. The infection rates of different strains were ranged from 16.7 to 60.0% and were statistically different (χ² = 12.81, p < 0.05). The highest infection rate was obtained from the Shanghai strain (60.0%). The transmission rates of Ae. Albopictus Shanghai, Guangzhou, Beijing, and Chengdu strains were 28.6, 15.2, 13.3, and 6.7%, respectively. Furtherly, the results reveal that Ae. Albopictus Beijing strain infected orally can transmit WNV transovarially even the eggs are induced diapausing. The study confirmed that WNV could survive in the diapause eggs of Ae. Albopictus and could be transmitted to progeny after diapause termination. This is of great significance for clarifying that the WNV maintains its natural circulation in harsh environments through inter-epidemic seasons.

Spatial statistical and environmental correlation analyses on vector density, vector infection index and Japanese encephalitis cases at the village and pigsty levels in Liyi County, Shanxi Province, China

Background

In the eco-epidemiological context of Japanese encephalitis (JE), geo-environmental features influence the spatial spread of the vector (Culex tritaeniorhynchus, Giles 1901) density, vector infection, and JE cases.

Methods

In Liyi County, Shanxi Province, China, the spatial autocorrelation of mosquito vector density, vector infection indices, and JE cases were investigated at the pigsty and village scales. The map and Enhanced Thematic Mapper (ETM) remote sensing databases on township JE cases and geo-environmental features were combined in a Geographic Information System (GIS), and the connections among these variables were analyzed with regression and spatial analyses.

Results

At the pigsty level, the vector density but not the infection index of the vector was spatially autocorrelated. For the pigsty vector density, the cotton field area was positively related, whereas the road length and the distance between pigsties and gullies were negatively related. In addition, the vector infection index was correlated with the pigsty vector density (PVD) and the number of pigs. At the village level, the vector density, vector infection index, and number of JE cases were not spatially autocorrelated. In the study area, the geo-environmental features, vector density, vector infection index, and JE case number comprised the Geo-Environment-Vector-JE (GEVJ) intercorrelation net system. In this system, pig abundance and cotton area were positive factors influencing the vector density first. Second, the infection index was primarily influenced by the vector density. Lastly, the JE case number was determined by the vector infection index and the wheat area.

Conclusions

This study provided quantitative associations among geo-environmental features, vectors, and the incidence of JE in study sties, one typical northern Chinese JE epidemiological area without rice cultivation. The results highlighted the importance of using a diverse range of environmental management methods to control mosquito disease vectors and provided useful information for improving the control of vector mosquitoes and reducing the incidence of JE in the northern Chinese agricultural context.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05305-8.

Screening for odorant receptor genes expressed in Aedes aegypti involved in host-seeking, blood-feeding and oviposition behaviors

Background

Aedes aegypti is one of the most important vectors of zoonotic diseases worldwide, and its survival and reproductive processes depend heavily on its olfactory system. In this study, the expression levels of all odorant receptor (OR) genes of Ae. aegypti were explored during different physiological periods to identify olfactory genes that may be associated with mosquito blood-feeding and the search for oviposition sites.

Methods

Four experimental groups, consisting of Ae. aegypti males, pre-blood-feeding females, post-blood-feeding females and post-oviposition females, were established. A total of 114 pairs of primers targeting all messenger RNA encoded by OR genes were designed based on the whole genome of Ae. aegypti. The expression of OR genes was evaluated by real-time fluorescence quantitative PCR for relative quantification and the comparison of differences between groups.

Results

A total of 53 differentially expressed OR genes were identified between males and females in Ae. aegypti antennae. Also, eight, eight and 13 differentially expressed OR genes were identified in pre- versus post-blood-feeding females, in pre- versus post-oviposition females and in post-blood-feeding versus post-oviposition females, respectively. In addition, 16 OR genes were significantly differentially expressed in multiple physiological periods of the mosquitoes.

Conclusions

A large number of ORs with significant intergroup differences and high expression levels were screened in this study. Some of these genes are reported for the first time, providing possible targets for the development of mosquito control pathways based on the olfactory system.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05196-9.

Deltamethrin interacts with Culex quinquefasciatus odorant-binding protein: a novel potential resistance mechanism

BACKGROUND

Odorant-binding proteins (OBPs) play important roles in many physiological processes of mosquitoes. Previous high-throughput sequencing studies have revealed that some OBPs of Culex quinquefasciatus might be involved in the development of resistance to insecticides.

METHODS

Based on the results of sequencing analyses, the OBP28 gene was selected for evaluation in this study. Three laboratory strains of Cx. quinquefasciatus [susceptible strain (SS), deltamethrin-resistant strain 1 (HN) and deltamethrin-resistant strain 2 (RR)] were first examined by using the Centers for Disease Control and Prevention bottle bioassay, after which the expression level of the OBP28 gene in the susceptible and deltamethrin-resistant strains was determined by real-time quantitative polymerase chain reaction. The OBP28 gene in deltamethrin-resistant strain RR was silenced using RNA interference technology. The expression level of OBP28 and the resistance level were tested in the silenced strain and control strain after microinjection of double-stranded RNA for a 48-h interference period. Four field-collected strains (henceforth 'field strains') of Cx. quinquefasciatus were also examined for their resistance to deltamethrin and levels of OBP28 expression. Finally, a correlation analysis between deltamethrin resistance and gene expression was carried out for all seven strains, i.e. the four field strains and the three laboratory strains.

RESULTS

In the bioassay, the mortality of SS, HN and RR was 100%, 21.33% and 1.67%, respectively. The relative expression levels of OBP28 in strains HN and RR were 6.30- and 6.86-fold higher, respectively, than that of strain SS. After silencing of the OBP28 gene, the mortality of strain RR was 72.20% and that of the control strain 26.32%. The mortality of strain RR increased significantly after interference compared to that of the control strain. There was a negative correlation between OBP28 gene expression and mortality in adult mosquitoes after exposure to deltamethrin.

CONCLUSIONS

To our knowledge, this study shows for the first time a correlation between the expression of a gene coding for OBP and insecticide resistance in mosquitoes. The potential resistance mechanism that was elucidated provides a new target gene for the surveillance of resistance in mosquitoes.

[Survey on present status of noise exposure of workers in metal processing industry]

Objective: To investigate the distribution of noise exposure between non-steady state noise and steady-state noise for metal processing workers, which will provide scientific basis for the prevention and treatment of noise hazards in metal processing industry. Methods: The cross-section method was used to investigate the noise exposure of 737 workers from three metal processing industries in Zhejiang Province from October to December 2017. The general demographic information and occupational history were collected by questionnaire. The noise was recorded by individual noise meters, and the noise exposure intensity (equivalent continuous A-weighted noise exposure level normalized to an 8 h-working-day, L(Aeq, 8 h)) and kurtosis were calculated. Results: Workers exposed to noise in the metal processing industry were mainly 18-40 years old (527 workers, 71.51%) , men (570 workers, 77.34%) , and junior high school education background (416 workers, 56.45%) . There were 572 workers (77.61%) with noise exposure intensity (L(Aeq, 8 h)) greater than 85 dB (A) , 558 workers (75.71%) exposed to non-steady state noise (kurtosis ≥4) , and 634 workers (86.02%) with exposure duration less than 8 years. Among the 30 work types investigated, the work types with noise intensity reaching 100% were the stamping, welding and others from a children's car manufacturing factory in Ningbo, operating, chamfering, tapping, and thread rolling from an automobile parts manufacturing factory in Ningbo; The work types with a rate of 100% exposed to non-steady state noise were the grinding from a children's car manufacturing factory in Ningbo, assembling, assembly operating and others from an automobile brake manufacturing factory in Wenzhou, and polishing from an automobile parts manufacturing factory in Ningbo. Conclusion: Metal processing workers have a high rate of over-standard exposed to high noise intensity and a high proportion exposed to non-steady state noise. It is necessary to take sound insulation and noise reduction engineering control, and strengthen personal protection and occupational health management measures to prevent and control the noise hazards.

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.

Dispersal patterns and population genetic structure of Aedes albopictus (Diptera: Culicidae) in three different climatic regions of China

Background

Aedes albopictus is an indigenous primary vector for dengue and Zika viruses in China. Compared with its insecticide resistance, biology and vector competence, little is known about its genetic variation, which corresponds to environmental variations. Thus, the present study examines how Ae. albopictus varies among different climatic regions in China and deciphers its potential dispersal patterns.

Methods

The genetic variation and population structure of 17 Ae. albopictus populations collected from three climatic regions of China were investigated with 11 microsatellite loci and the mitochondrial coxI gene.

Results

Of 44 isolated microsatellite markers, 11 pairs were chosen for genotyping analysis and had an average PIC value of 0.713, representing high polymorphism. The number of alleles was high in each population, with the n_e value increasing from the temperate region (3.876) to the tropical region (4.144). Twenty-five coxI haplotypes were detected, and the highest diversity was observed in the tropical region. The mean Ho value (ca. 0.557) of all the regions was significantly lower than the mean He value (ca. 0.684), with nearly all populations significantly departing from HWE and displaying significant population expansion (p value < 0.05). Two genetically isolated groups and three haplotype clades were evaluated via STRUCTURE and haplotype phylogenetic analyses, and the tropical populations were significantly isolated from those in the other regions. Most genetic variation in Ae. albopictus was detected within populations and individuals at 31.40 and 63.04%, respectively, via the AMOVA test, and a relatively significant positive correlation was observed among only the temperate populations via IBD analysis (R² = 0.6614, p = 0.048). Recent dispersions were observed among different Ae. albopictus populations, and four major migration trends with high gene flow (Nm > 0.4) were reconstructed between the tropical region and the other two regions. Environmental factors, especially temperature and rainfall, may be the leading causes of genetic diversity in different climatic regions.

Conclusions

Continuous dispersion contributes to the genetic communication of Ae. albopictus populations across different climatic regions, and environmental factors, especially temperature and rainfall, may be the leading causes of genetic variation.

Graphical abstract

A Mouse Model of SARS-CoV-2 Infection and Pathogenesis

Since December 2019, a novel coronavirus SARS-CoV-2 has emerged and rapidly spread throughout the world, resulting in a global public health emergency. The lack of vaccine and antivirals has brought an urgent need for an animal model. Human angiotensin-converting enzyme II (ACE2) has been identified as a functional receptor for SARS-CoV-2. In this study, we generated a mouse model expressing human ACE2 (hACE2) by using CRISPR/Cas9 knockin technology. In comparison with wild-type C57BL/6 mice, both young and aged hACE2 mice sustained high viral loads in lung, trachea, and brain upon intranasal infection. Although fatalities were not observed, interstitial pneumonia and elevated cytokines were seen in SARS-CoV-2 infected-aged hACE2 mice. Interestingly, intragastric inoculation of SARS-CoV-2 was seen to cause productive infection and lead to pulmonary pathological changes in hACE2 mice. Overall, this animal model described here provides a useful tool for studying SARS-CoV-2 transmission and pathogenesis and evaluating COVID-19 vaccines and therapeutics.

•

Human ACE2 knockin mice were generated by using CRISPR/Cas9 technology

•

SARS-CoV-2 leads to robust replication in lung, trachea, and brain

•

SARS-CoV-2 causes interstitial pneumonia and elevated cytokine in aged hACE2 mice

•

High dose of SARS-CoV-2 can establish infection via intragastric route in hACE2 mice

RNA interference of odorant receptor CquiOR114/117 affects blood-feeding behavior in Culex quinquefasciatus

The odorant receptors (ORs) play a critical role for mosquitoes in the identification of blood-feeding hosts and other physiological processes. The OR8 subfamily in mosquitoes has been shown to be strongly involved in the detection the mammalian host associated odor, 1-octen-3-ol. CquiOR114/117 has been shown to be an orthologous OR8 in Culex quinquefasciatus Say. In this study, the expression of CquiOR114/117 in the different developmental stages of Cx. quinquefasciatus was detected by the amplification of CquiOR114/117 with real-time fluorescence quantitative polymerase chain reaction (PCR). RNA interference (RNAi) technology was used to interfere with the expression of CquiOR114/117 in females to observe the blood-feeding behavior change. The results showed that the expression level of CquiOR114/117 in the egg-to-pupa stage was significantly lower than that in the adult stage and that the expression level of the female mosquitoes peaked on the third day after emergence. The expression of CquiOR114/117 was significantly decreased in the 2-6 days after the injection of dsRNA compared with the control groups. The analysis of the blood-feeding behavior showed a significant positive correlation between CquiOR114/117 expression and the engorgement rate of the mosquitoes. CquiOR114/117 is speculated to have an effect on the blood-feeding behavior of Cx. quinquefasciatus.

The polymorphism and geographical distribution of knockdown resistance of adult Anopheles sinensis populations in eastern China

Background

Anopheles sinensis is one of the major malaria vectors in China and other southeast Asian countries, including Vietnam, Cambodia, Thailand. Vector control is considered to be the critical measure for malaria control, while the increasing prevalence of insecticide resistance caused by long-term use of insecticides, especially pyrethroids, is threatening the successful control of An. sinensis. In order to understand the underlying resistance mechanisms involved and molecular basis, the principal malaria vector, An. sinensis from Jiangsu and Anhui provinces, Southeast China, was investigated.

Methods

The adult Anopheles mosquitoes were sampled from multiple sites across Jiangsu and Anhui provinces, and sufficient mosquitoes collected from eleven sites for insecticide susceptibility bioassays. The DIIS4–DIIS6 region of the para-type sodium channel gene was amplified and sequenced, then multiple PCR and Taqman assays were used to assess the frequencies of kdr mutations at the target gene.

Results

In the present study, most of the adult An. sinensis populations were pyrethroids resistant, which indicated the presence of kdr resistance mutations in the para-type sodium channel gene. Sequence analyses demonstrated the kdr mutation existed at codon 1014 in Jiangsu and Anhui provinces. In adult An. sinensis, three mutant types (TTT L1014F, TTC L1014F, and TGT L1014C) of kdr alleles were detected, while no wild type (TTG L1014) was observed. The TTC L1014F mutation was first reported in Anhui province.

Conclusions

The highly polymorphic kdr alleles were observed in all the adult An. sinensis populations, which suggested that in-depth studies are required for carrying on insecticide resistance monitoring and specific resistance mechanisms studying into establish effective long-term malaria vector control program in eastern China.

Spatial Distribution of Culex tritaeniorhynchus Giles, 1901 (Diptera: Culicidae) in Relation to Pigsties and Other Geo-environmental Features in Dao County, Hunan Province, China

In this study, we investigated the spatial distribution of Culex tritaeniorhynchus Giles, 1901 (Diptera: Culicidae) (the vector of Japanese B Encephalitis) and geo-environmental features (rice fields, forests, watercourses, and highways) correlated with their abundance in pigsties of Dao County, Hunan Province, China. First, light trapping in pigsties was carried out to determine vector density. Second, based on Advanced Land Observing Satellite remote-sensing datasets, spatial datasets of mosquito density and various geo-environmental features were constructed using Geography Information System. Finally, spatial statistical analysis and general linear regression were used to analyze the spatial distribution of vectors in relation to the geo-environmental features correlating with the abundance of mosquitoes in pigsties. As the results show, the distribution of mosquitoes in pigsties was not spatially autocorrelated, and several geo-environmental features that were either positively or negatively correlated with mosquito abundance in pigsties were identified. The application of these results to improve the control of vectors of Japanese B Encephalitis is also discussed.

Direct observation of the topological spin configurations mediated by the substitution of rare-earth element Y in MnNiGa alloy

The evolution of topological magnetic domains microscopically correlates the dynamic behavior of memory units in spintronic application. Nanometric bubbles with variation of spin configurations have been directly observed in a centrosymmetric hexagonal magnet (Mn_0.5Ni_0.5)₆₅(Ga_1-yY_y)₃₅ (y = 0.01) using Lorentz transmission electron microscopy. Magnetic bubbles instead of biskyrmions are generated due to the enhancement of quality factor Q caused by the substitution of rare-earth element Y. Furthermore, the bubble density and diversified spin configurations are systematically manipulated via combining the electric current with perpendicular magnetic fields. The magnetic bubble lattice at zero field is achieved after the optimized manipulation.

Identification of Differentially Expressed Genes In Deltamethrin-Resistant Culex pipiens quinquefasciatus

Culex quinquefasciatus is one of China's major house-dwelling mosquito species and an important vector of filariasis and encephalitis. Chemical treatments represent one of the most successful approaches for comprehensive mosquito prevention and control. However, the widespread use of chemical pesticides has led to the occurrence and development of insecticide resistance. Therefore, in-depth studies of resistance to insecticides are of vital importance. In this study, we performed a gene expression analysis to investigate genes from Cx. quinquefasciatus that may confer pyrethroid resistance. We aimed to understand the mechanisms of Cx. quinquefasciatus resistance to pyrethroid insecticides and provide insights into insect resistance management. Using a resistance bioassay, we determined the deltamethrin LC₅₀ values (lethal concentration required to kill 50% of the population) for Cx. quinquefasciatus larvae in the F₂₁, F₂₃, F₂₄, F₂₆, F₂₇, and F₃₀ generations. The 7 tested strains exhibited pesticide resistance that was 25.25 to 87.83 times higher than that of the SanYa strain. Moreover, the expression of the OBPjj7a (odorant-binding protein OBPjj7a), OBP28 (odorant-binding protein OBP28), and E2 (ubiquitin-conjugating enzyme) genes was positively correlated with deltamethrin resistance ( R² = 0.836, P = 0.011; R² = 0.788, P = 0.018; and R² = 0.850, P = 0.009, respectively) in Cx. quinquefasciatus. The expression of 4 additional genes, H/ACA, S19, SAR2, and PGRP, was not correlated with deltamethrin resistance. In summary, this study identified 3 Cx. quinquefasciatus genes with potential involvement in deltamethrin resistance, and these results may provide a theoretical basis for the control of mosquito resistance and insights into resistance detection.

The genetic diversity and population structure of domestic Aedes aegypti (Diptera: Culicidae) in Yunnan Province, southwestern China

BACKGROUND

There was no record of Aedes aegypti in Yunnan Province, China, until 2002, but this species is now continuously found in nine cities (or counties). Until now, little was known about the genetic diversity and population structure of this invasive species. Thus, a detailed understanding of the invasion strategies, colonisation and dispersal of this mosquito from a population genetics perspective is urgently needed for controlling and eliminating this disease vector.

METHODS

The genetic diversity and population structure of Ae. aegypti communities were analysed by screening nine microsatellite loci from 833 Ae. aegypti mosquitoes sampled from 28 locations in Yunnan Province.

RESULTS

In total, 114 alleles were obtained, and the average polymorphic information content (PIC) value was 0.672. The value of the alleles per locus ranged from 2.90 to 5.18, with an average of 4.04. The value of He ranged from 0.353 to 0.681, and the value of Ho within populations ranged from 0.401 to 0.689. Of the 28 locations, two showed significant departures from the Hardy-Weinberg equilibrium (HWE) with P-values less than 0.05, and a bottleneck effect was detected among locations from Ruili and the border areas with the degree of 60% and 50%, respectively. Combined with the F-statistics (FIT = 0.222; FCT = 0.145), the analysis of molecular variance (AMOVA) revealed that there was substantial molecular variation among individuals, accounting for 77.76% of the sample, with a significant P-value (<0.0001). The results suggest that genetic differences in Ae. aegypti originated primarily among individuals rather than among populations. Furthermore, the STRUCTURE and UPGMA cluster analyses showed that Ae. aegypti from the border areas were genetically isolated compared to those from the cities Ruili and Jinghong, consistent with the results of the Mantel test (R 2 = 0.245, P < 0.0001).

CONCLUSIONS

Continuous invasion contributes to the maintenance of Ae. aegypti populations' genetic diversity and different invasion accidents result in the genetic difference among Ae. aegypti populations of Yunnan Province.

Efficacy of Omega-3 Polyunsaturated Fatty Acids Supplementation in Managing Overweight and Obesity: A Meta-Analysis of Randomized Clinical Trials

OBJECTIVE

Studies in rodents and humans have indicated that omega-3 polyunsaturated fatty acids (n-3 PUFA) may reduce weight. The aim of this meta-analysis was to evaluate evidence for the efficacy of n-3 PUFA in managing overweight and obesity.

METHODS

We performed a systematic search of PubMed, Embase, and Cochrane Central Register of Controlled Trials until May 2015. Two reviewers independently determined the eligibility of studies and assessed the reporting quality of included randomized controlled trials (RCTs).

RESULTS

A total of 11 RCTs involving 617 participants were included in this meta-analysis. Based on the meta-analysis of nine studies, a statistically nonsignificant difference was revealed in weight loss between n-3 PUFA and placebo (p=0.99; weighted mean difference [WMD]: 0.00; 95% confidence interval [CI] -0.42 to 0.43), whereas n-3 PUFA was superior to placebo in reducing serum triglyceride levels (p=0.0007; standard median difference [Std MD]: -0.59; 95% CI -0.93 to -0.25). Based on meta-analysis of seven studies, the analysis of aggregated data showed a significant reduction in waist circumference (p=0.005; WMD: -0.53; 95% CI -0.90 to -0.16). There were no significant differences in body mass index, total serum levels of cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol, and fasting glucose levels.

CONCLUSIONS

The evidence from RCTs showed that n-3 PUFA might effectively reduce waist circumference and triglyceride levels in overweight and obese adults, but n-3 PUFA may not effectively reduce body weight. Given the small number and poor quality of RCTs included in the meta-analysis, these results are inconclusive. A large-scale, well-designed RCT is needed to further address this issue.

Multiple-Insecticide Resistance and Classic Gene Mutations to Japanese Encephalitis Vector Culex tritaeniorhynchus from China

Widespread resistance of insect pests to insecticides has been widely reported in China and there is consequently an urgent need to adjust pest management strategies appropriately. This requires detailed information on the extent and causes of resistance. The aim of the present study was to investigate levels of resistance to 5 insecticides among 12 strains of Culex tritaeniorhynchus, a major vector of Japanese encephalitis in China. Resistance to deltamethrin, beta-cypermethrin, permethrin, dichlorvos, and propoxur were measured using larval bioassays. The allelic frequency of knockdown resistance (kdr) and acetylcholinesterase (AChE) mutations were determined in all strains. Larval bioassay results indicated that the field strains collected from different sites were resistant to deltamethrin, beta-cypermethrin, permethrin, dichlorvos, and propoxur, with resistance ratio values ranging from 1.70- to 71.98-fold, 7.83- to 43.07-fold, 3.54- to 40.03-fold, 291.85- to 530.89-fold, and 51.32- to 108.83-fold, respectively. A polymerase chain reaction amplification of specific alleles method for individual was developed to detect genotypes of the AChE gene mutation F455W in Cx. tritaeniorhynchus. The frequency of the AChE gene mutation F455W was 100.00% in all strains, making this mutation of no value as a marker of resistance to organophosphorous and carbamate pesticides in Cx. tritaeniorhynchus in China. The kdr allele was present in all strains at frequencies of 10.00-29.55%. Regression analysis indicated a significant correlation between kdr allele frequencies and levels of resistance to deltamethrin, beta-cypermethrin, and permethrin. These results highlight the need to monitor and map insecticide resistance in Cx. tritaeniorhynchus and to adjust pesticide use to minimize the development of resistance in these mosquitoes.

An Unmanned Aerial Vehicle-Mounted Cold Mist Spray of Permethrin and Tetramethylfluthrin Targeting Aedes albopictus in China

Aedes albopictus is the primary vector of dengue fever and dengue hemorrhagic fever in China. Although there are previous studies on the application of adulticides to control this species, the application methods have either been back-pack or vehicle-mounted systems. However, many sites are too large to be effectively treated with back-pack sprayers, and the lack of roads restricts the use of vehicle-mounted sprayers. This paper provides the first study of using unmanned aerial vehicles to conduct cold mist sprays on Ae. albopictus habitats. A spray containing 4% permethrin and 1% tetramethylfluthrin was applied at an effective application rate of 9.0 mg/m(2). This method reduced Ae. albopictus populations by more than 90%. The results indicate this novel spray system is a powerful method to achieve a rapid decline of mosquito population in Ae. albopictus habitats in China.

Host-Seeking Behavior and Arbovirus Detection in Mosquitoes of Habahe County, Xinjiang Uigur Autonomous Region, China

Mosquitoes in Habahe County of Xinjiang Uigur Autonomous Region in China are considered a serious nuisance problem to local residents, but little is known of their role in enzootic disease. Therefore, host-seeking behavior and virus detection in mosquitoes were investigated in this study. Adult host-seeking mosquitoes were sampled using the Centers for Disease Control and Prevention (CDC) light traps operated at three locations in June through August 2008. Nine traps were used at each location at 3 different heights (1 m, 3 m, and 5 m). Seven mosquito species from 4 genera were collected by CDC light traps in different habitats. In total, 90,055 mosquitoes were captured, of which Aedes vexans was the most abundant species, comprising 88.02% of all mosquitoes collected. The second most abundant species was Anopheles messese, which comprised about 5.86%. Other species caught were Culex modestus (2.89%), Aedes caspius (1.11%), Coquillettidia richiardii (0.61%), Ae. dorsalis (1.36%), and An. hyrcanus (0.14%). About 93.5% of Ae. vexans individuals were caught in CO2-baited CDC light traps at 1 m above the ground. The highest numbers of Cx. modestus were caught at the highest trap level, 5 m above ground. Overall, significantly more mosquitoes of all species were collected at dusk than at dawn. Based on blood-meal analyses, Ae. vexans and An. messese fed on various vertebrate hosts, whereas Cx. modestus fed on ducks only. From a total of 335 mosquito pools tested, 10 pools of Ae. vexans were found positive for alphavirus. Comparison with the gene database revealed that the alphavirus deoxyribonucleic acid fragment obtained (GenBank accession no. HM160530) was 100% homologous at the nucleotide level to chikungunya virus isolate LK (PB) chik3408, chikungunya virus isolate SGEHICHD122508, and chikungunya virus strain FD080231. The results of this study suggest that ongoing, integrated mosquito and arbovirus surveillance is necessary in this river wetland.

Artificial Selection for Different Host Preferences in Culex pipiens pallens (Diptera: Culicidae) Mosquitoes

Most mosquito species display host preferences that are a crucial determinant of the transmission rate of mosquito-borne pathogens. Although a transgenic approach, based on driving genes for zoophily into vector populations, has been advocated as a malaria control strategy by the World Health Organization since 1982, the genes involved in mosquito host choice remain poorly understood. Culex pipiens pallens Coquillet mosquitoes were artificially selected for two different host preferences in a specially designed experimental enclosure. Of 3,035 mosquitoes obtained from larvae and pupae collected from the wild (the F0 generation), 27% preferentially fed on pigeons and 16% fed on mice. Following artificial selection for these host preferences over successive generations, the percentage of mosquitoes that preferred to feed on pigeons or mice gradually increased, eventually stabilizing at ∼55 and 34%, respectively, after the sixth generation. Intergenerational differences in host preferences were significant (P < 0.001). Furthermore, differences in host preferences between mosquitoes selected to prefer pigeons and those selected to prefer mice were both significant and consistent over almost six generations.

Relationship between insecticide resistance and kdr mutations in the dengue vector Aedes aegypti in Southern China

Background

Aedes aegypti is an important vector for dengue virus and thus has been targeted with pyrethroid insecticides in many areas of the world. As such, resistance has been detected to several of these insecticides, including in China, but the mechanisms of the resistance are not well understood in this country.

Methods

Using the World Health Organization larval mosquito bioassay, five field populations of Aedes aegypti from Southern China were characterized for their resistance to cypermethrin and cyhalothrin. RNA extraction with PCR amplification, cloning and sequencing of the sodium channel gene was followed by comparisons of susceptible and wild mosquito strains Additionally, genomic DNA was used for Allele-specific PCR (AS-PCR) genotyping of the sodium channel genes to detect S989P, V1016G and F1534C mutations and allow for correlation analysis of resistance expression for the different mutations.

Results

All wild strains expressed resistance to cypermethrin and cyhalothrin and the resistance expression between the two insecticides was highly correlated suggesting cross-resistance between these two pyrethroids. The AS-PCR technique effectively distinguished individual genotypes for all three mutations. Among the five wild strains tested, two strains carried all three mutations. Although the S989P and V1016G mutations were positively correlated to resistance expression of both pyrethroids, the F1534C mutation was negatively correlated.

Conclusions

Our methodology proved highly reliable and will aid future detection of kdr mutations. The three sodium channel mutations were common in the Ae. aegypti strains sampled from Southern China. The V1016G mutation appears to be the most important kdr mutation in Ae. aegypti strains in Southern China.

Host feeding patterns of mosquitoes in a rural malaria-endemic region in hainan island, china

Malaria is endemic in Wangxia Village of Hainan Island. In this area little is known about the host seeking behavior and feeding habit of mosquitoes. Three sites representing the most common habitat types in the village were selected to study the host seeking behavior and feeding habit of mosquitoes. Of the total 9 species belonging to 4 genera (Armigeres, Culex, Aedes, and Anopheles) collected in Wangxia Village, Culex tritaeniorhynchus and Cx. pipiens quinquefasciatus were the most commonly collected species. Armigeres subalbatus and Anopheles sinensis were moderately common species. Blood meal analysis confirmed that Cx. tritaeniorhynchus and Cx. p. quinquefasciatus fed on multiple hosts, mainly poultry but occasionally other animals. Anopheles sinensis, a vector of malaria, fed predominately on cattle hosts, followed by humans. Anopheles maculatus and An. barbirostris fed on both humans and domestic animals. Our results indicate that most mosquitoes in this area preferred domestic animals over humans and showed a tendency to feed on multiple hosts within the same gonotrophic cycle. Therefore, the potential role of domestic animals in arbovirus transmission should be evaluated as part of a strategy for controlling mosquito-borne diseases in this region.

Evaluation of Vegetation Treatment With Lambda-Cyhalothrin to Control Aedes vexans and Simulium maculatum in Northern China

The mosquito Aedes vexans and black fly Simulium maculatum are important blood-sucking pests in northern China. Control of these pests using current methods is difficult because of complex larval developmental sites. In the present study, lambda-cyhalothrin was applied as a barrier spray to vegetation and various structures surrounding human dwellings for control against the adults of each species. The barrier spray resulted in an 88.2-99.4% reduction in Ae. vexans abundance and a 67.8-89.6% reduction in S. maculatum abundance for 2 wk postapplication. Our results indicated that lambda-cyhalothrin applied as a barrier spray to vegetation and other structures that serve as harborage for adults of both species could be adopted as part of an integrated pest management approach against these pests.

Vector competence of Aedes albopictus and Aedes aegypti (Diptera: Culicidae) for DEN2-43 and New Guinea C virus strains of dengue 2 virus

The vector competence of Aedes albopictus and Aedes aegypti with regard to DEN2-43 and New Guinea C (NGC) virus strains of Dengue 2 viruses was assessed and compared. The infection and dissemination rate and distribution of DEN2-43 antigens in orally infected Ae. albopictus was investigated using the reverse transcription polymerase chain reaction and an indirect immunofluorescence assay. To better understand the initial infection, dissemination and transmission of these viral strains in vector mosquitoes, Ae. albopoictus and Ae. aegypti were fed an artificial blood meal containing either the DEN2-43 or NGC strain. There was no significant difference in the infection and dissemination rates of DEN2-43 and NGC virus strains in Ae. albopictus, however, Ae. aegypti was more susceptible to infection by NGC than DEN2-43 vrius strain. Ae. albopictus mosquitoes infected with the NGC strain developed a higher percentage of midgut infections than those infected with the DEN2-43 strain (t=2.893, df=7, P=0.024). Approximately 26.7% of midgut samples were positive for the NGC antigen 5 days after infection, and 80% of mosquitoes had infected midgets after 15 days. The NGC antigen first became evident in mosquito salivary glands on Day 5, and 40% of mosquitoes had infected salivary by Day 9. In contrast, the DEN2-43 antigen first became evident in salivary glands on Day 7. The infection rate of NGC and DEN2-43 virus strains in salivary glands were similar. These results indicate that Ae. albopictus and Ae. aegypti are moderately competent vectors for the DEN2-43 virus, which could provide basic data for the epidemiology study of dengue fever in China.

Evaluation of Pioneer eco-backpack sprayer and Twister XL backpack sprayer using Aqualuer against caged adult Aedes albopictus and Culex quinquefasciatus

A Pioneer Eco-Backpack electric cold ultra-low volume (ULV) sprayer and a gas-powered Twister XL 3950 series 2 motorized knapsack ULV sprayer with Aqualuer (20.6% permethrin AI) were evaluated against caged adult Aedes albopictus and Culex quinquefasciatus in St. Augustine, FL. The Pioneer Eco-Backpack sprayer provided 100% knockdown of both species of mosquitoes at 15 min; the Twister XL backpack sprayer resulted in 17-23% knockdown at 15 min. Both backpack sprayers with Aqualuer resulted in 100% mortality of both species at 24 h. The new Pioneer Eco-Backpack sprayer powered by electricity could be a potential tool for mosquito control.

Biting activity and host attractancy of mosquitoes (Diptera: Culicidae) in Manzhouli, China

The biting activity and host attractancy of vector mosquitoes are important in assessing the risk of arbovirus transmission, especially where migratory and nonmigrating bird species congregate, such as in Hulun Lake, Manzhouli. In 2009, the population distribution, species diversity, biting activity, and host attractancy of mosquitoes were investigated in Hulan Lake and its associated prairie area. The adult mosquitoes were captured either by human volunteers using aspirators in mosquito nets, by CO2-baited light traps, or by animal-baited traps. In total, 27,004 mosquitoes, representing three genera and 10 species, were collected from Manzhouli, China, in July 2009, of which Aedes dorsalis (Meigen) were most predominant species, followed by Ae. vexans (Meigen). Biting activity peaks by Ae.flavescens (Muller), Ae. dorsalis, and Culex modestus (Facalbi) on human subjects were investigated. Four mosquito species were captured from different animal sheds (sheep, cattle, and goose). Ae. flavescens was more abundant in the cattle shed than in the other two sheds. The Ae. dorsalis in the sheep shed was much higher than in the other animal sheds. The Ae.flavescens collected via chicken-baited traps were significantly higher than those collected via rabbit-baited and pigeon-baited traps. There were no significant differences in the number of Ae. dorsalis and Ae. vexans collected using the three different animal traps.

A preliminary investigation of the mechanisms underlying the effect of berberine in preventing high-fat diet-induced insulin resistance in rats

Berberine exerts insulin resistance-improving effects, the underlying mechanism of which is not well understood. We herein aimed to examine the effects of berberine on mediators of insulin signaling in pancreatic β- and α- islet cells and hepatocytes using a rat obesity model. Rats were fed the following diets for 22 weeks: normal control (NC); normal+berberine (NC+BBR 200 mg/kg/day); high-fat (HF); HF+BBR(1) (BBR 100 mg/kg/day); HF+BBR(2) (BBR 200 mg/kg/day). Metabolic parameters were assessed and mediators of insulin signaling were quantified by immunohistochemistry. The HF diet significantly increased body weight (BW), visceral fat (VF), the visceral fat to BW ratio (VF/BW), and insulin resistance index in the HF group compared with the NC group. Both doses of BBR significantly reduced HF diet-induced increases in BW, VF, and VF/BW. IR and IRS-1 expression in β-cells was significantly lower in the HF group, but not the HF+BBR groups, compared with the NC and NC+BBR groups. Glucagon expression in α-cells was significantly higher in the HF group compared with all other groups. IR expression in α-cells was significantly lower in the HF group compared with the NC, NC+BBR, and HF+BBR(2) groups. IR expression in hepatocytes was significantly lower in the HF group compared with all groups. Our preliminary findings suggest that berberine may ameliorate the development of insulin resistance by differentially preventing alterations in expression of IR, IRS-1, and glucagon in β-cells, α-cells, and hepatocytes.

Field evaluation of a large-scale barrier application of bifenthrin on a golf course to control floodwater mosquitoes

In order to better understand the role a barrier application plays in an integrated mosquito management program, we applied a bifenthrin barrier application to a large golf course community and evaluated the mosquito population, service requests, and money spent for control from our barrier site as well as a site that was only treated via ground ultra-low-volume (ULV) application or that was left as a control site. Both the barrier application (t = 2.63, df = 126, P = 0.0147) and the ground ULV application (t = 2.49, df = 126, P = 0.0054) significantly reduced mosquito populations compared to the control, but means within treatments did not differ from each other. Mosquito populations in Centers for Disease Control and Prevention traps were reduced by 84% by barrier application and by 52% by ground ULV application at 6 wk posttreatment compared with untreated control. The 2 major species collected during the evaluation period were Anopheles crucians (81%) and Aedes atlanticus (13%). Anopheles crucians was significantly reduced compared with controls for the barrier application (t = 1.55, df = 126, P = 0.003) and ground ULV application (t = 1.85, df = 126, P = 0.052). Aedes atlanticus was significantly reduced by the barrier application (t = 1.54, df = 128, P = 0.002) but not by ground ULV application (P = 0.083). Overall the barrier application resulted in a significant decrease (chi2 = 35.4, df = 1, P < 0.0001) in the number of service requests and ground ULV application (chi2 = 5.3, df = 1, P = 0.02) compared to the site that was only treated with ground ULV application. The barrier application saved an estimated $2,700. Thus, large-scale barrier applications are an appropriate tool for control of floodwater mosquito populations.

Insecticidal activity of five commercial mosquito coils against Anopheles albimanus, Aedes albopictus, and Culex quinquefasciatus

The insecticidal activity of 4 mosquito coils containing pyrethroid ester insecticides and 1 mosquito coil containing 15% citronella oil was evaluated against adult female Anopheles albimanus, Aedes albopictus, and Culex quinquefasciatus. Two of the pyrethroid mosquito coils containing 0.08% meperfluthrin showed the strongest insecticidal activity, and all 4 pyrethroid coils produced significantly higher mortality than the citronella coil across all 3 test species.

Efficacy evaluation of a fumigant containing permethrin and deltamethrin against vector mosquitoes

The efficacy of a new smoke-generating formulation (fumigant), containing the active ingredient permethrin (69 g/kg) and deltamethrin (3.9 g/kg) per cartridge, was evaluated against adult female Anopheles albimanus, Aedes aegypti, and Culex quinquefasciatus in a large vehicle storage building (22 x 13 x 4.5 m3), Florida, U.S.A., and against Cx. pipiens complex and Ae. albopictus in a furnished apartment (12 x 7 x 3.5 m3) in Israel. In the storage building, the use of 2 fumigant cartridges resulted in 100% mortality for all 3 species in 15 min. Using 1 cartridge resulted in 100% mortality in An. albimanus, 98% in Ae. aegypti, and 97% in Cx. quinquefasciatus in 15 min; and 100% mortality for both Ae. aegypti and Cx. quinquefasciatus at 30 min. In the apartment in Israel, both Ae. albopictus and Cx. pipiens showed 100% mortality when exposed to the fumigant cartridge for 15 min. Based on these preliminary data, the test formulation (fumigant) could be a valuable tool for controlling mosquitoes.

Evaluation of octenol and Lurex as baits in Mosquito Magnet Pro traps to collect vector mosquitoes in China

The effectiveness of the attractants 1-octen-3-ol (octenol) and L-lactic acid (Lurex) on the collection of Aedes albopictus, Culex tritaeniorhynchus, Cx. pipiens pallens, and Anopheles sinensis was first evaluated in Mosquito Magnet Pro traps in Yamenkou and Badachu residential areas, Beijing City, and Lishui area, Zhejiang Province, China. The Mosquito Magnet Pro traps baited with octenol collected significantly more Ae. albopictus, Cx. tritaeniorhynchus, and An. sinensis, but fewer Cx. pipiens pallens than collection by the traps alone. There were no significant differences in the numbers of Cx. pipiens pallens, Cx. tritaeniorhynchus, and An. sinensis collected by Mosquito Magnet Pro traps baited with Lurex compared to the traps alone, but the Mosquito Magnet Pro traps baited with Lurex collected significantly more Ae. albopictus than the number collected by the traps alone at 2 areas in Beijing.

Experimental studies on comparison of the potential vector competence of four species of Culex mosquitoes in China to transmit West Nile virus

To assess the risk that indigenous mosquitoes in China are capable of transmitting and sustaining West Nile virus (WNV), four important Culex mosquito species, Culex tritaeniorhynchus, Culex modestus, Culex pipiens pallens, and Culex pipiens quinquefasciatus, were allowed to feed on the artificial infectious blood meal with WNV dose of 10(6.8) plaque-forming unit/ml and tested approximately 2 wk later to determine infection and transmission rates. The results indicated that four Culex mosquitoes were competent laboratory vectors of WNV. The infection rates and transmission rates were statistical differences among different species of mosquito (chi2 = 20.620, P = 0.000; chi2 = 15.020, P = 0.005, respectively). The highest infection rate and transmission rate were obtained with Cx. tritaeniorhynchus (87.5 and 74.2%, respectively).

Evaluation of lambda-cyhalothrin barrier spray on vegetation for control of Aedes albopictus in China

Aedes albopictus is a primary nuisance pest and disease vector in China. Control of Ae. albopictus using current methods is difficult because of diverse larval breeding sites. In the present study, lambda-cyhalothrin was applied as a barrier spray to vegetation surrounding human dwellings for control of adult mosquito populations. Compared to the landing rate counts in the untreated control site, the barrier spray resulted in an 83-98% reduction of Ae. albopictus within 9 wk posttreatment. The study results indicate that lambda-cyhalothrin applied as a barrier spray to vegetation can reduce Ae. albopictus landing rates collections for more than 2 months.

Evaluation of lurex 3, octenol, and CO2 sachet as baits in Mosquito Magnet Pro traps against floodwater mosquitoes

Field evaluation of Lurex 3, 1-octen-3-ol (octenol), and CO2 sachet as baits in Mosquito Magnet Pro traps (MMP) for collecting adult mosquitoes was conducted at 2 different locations in northeast Florida. A total of 18 species of mosquitoes were collected by the MMP baited with the 3 attractant baits in St. Augustine, FL. The MMP baited with octenol collected significantly more mosquitoes than the traps baited with Lurex 3 and the CO2 sachet. A total of 6 floodwater mosquito species were collected by the MMP baited with the 3 attractant baits in Elkton, FL. The MMP baited with Lurex 3 or octenol collected more mosquitoes than the MMP baited with CO2 sachet or MMP alone.