Objective:To predict the distribution of dengue vector Aedes(Ae.)albopictus and identify high-risk areas for dengue fever transmission.Methods:Data on Ae.albopictus occurrences were collected from electronic databases...Objective:To predict the distribution of dengue vector Aedes(Ae.)albopictus and identify high-risk areas for dengue fever transmission.Methods:Data on Ae.albopictus occurrences were collected from electronic databases.Ensemble models were developed to assess the impacts of climate,vegetation,and human activity on Ae.albopictus.The optimal ensemble model was then used to identify the distribution of suitable areas for Ae.albopictus.Results:After removing duplicate sites and retaining only one location per 100 m×100 m grid,189 Ae.albopictus breeding sites were identified.The optimal ensemble model revealed that Ae.albopictus exhibited higher breeding suitability in Shanghai under specific conditions:a normalized difference vegetation index of 0.1 to 0.6,maximum precipitation in the warmest month ranging from 400 mm to 470 mm,maximum temperature in the warmest month between 30.0℃and 31.0℃,and proximity to waterways within 0.5 km.The most suitable habitats for Ae.albopictus were primarily concentrated in Shanghai’s central urban areas and scattered across the inner suburban districts.Conclusions:The high-risk areas of Ae.albopictus are widely distributed throughout the central urban area and scattered across the inner suburban district of Shanghai,creating conditions conducive to the outbreak of dengue fever.It is essential to enhance targeted control measures for Ae.albopictus in the identified risk areas.展开更多
Objective: To investigate the efficacies of 12 essential oil(EO) formulations from three Zingiberaceae plants(Alpinia galanga, Curcuma zedoaria, and Zingiber cassumunar) individually and in combination with an augment...Objective: To investigate the efficacies of 12 essential oil(EO) formulations from three Zingiberaceae plants(Alpinia galanga, Curcuma zedoaria, and Zingiber cassumunar) individually and in combination with an augmenting Eucalyptus globulus(E. globulus) EO against females of Aedes albopictus(Ae. albopictus) and Anopheles minimus(An. minimus). Methods: These formulations were evaluated for their ovicidal, oviposition deterrent and adulticidal activities against Ae. albopictus and An. minimus by a topical method, a double-choice method and a WHO susceptibility test, respectively. Results: It was found that all formulations of Zingiberaceae plants EOs augmented with E. globulus EO were more effective in oviposition deterrent, ovicidal, and adulticidal activities against the two mosquito species than all of the formulations used without E. globulus EO. Their oviposition deterrent, ovicidal and adulticidal activities were equivalent to those of 10% w/v cypermethrin. In contrast, 70% v/v ethyl alcohol as a control alone was not effective at all. The highest synergistic effect in effective repellency against Ae. albopictus was achieved by 5% Alpinia galanga EO + 5% E. globulus EO and against An. minimus was 5% Zingiber cassumunar EO + 5% E. globulus EO. Moreover, the highest synergistic effects in ovicidal activities against Ae. albopictus and An. minimus were achieved by 10% Zingiber cassumunar EO + 10% E. globulus EO and 5% Curcuma zedoaria EO + 5% E. globulus EO, respectively. For the adulticidal activities, the highest synergistic effect against two mosquitoes was achieved by 5% Curcuma zedoaria EO + 5% E. globulus EO. Conclusions: These results suggest that Zingiberaceae plant EOs augmented with E. globulus EO have a high potential to be developed into oviposition deterrent, ovicidal, and adulticidal agents for controlling populations of Ae. albopictus and An. minimus.展开更多
Objective:To generate life table characteristics for the dengue vector Aedes albopictus(A. albopictus) under uncontrolled conditions,incorporating both the aquatic and the adult stages. Methods:Ten females derived fro...Objective:To generate life table characteristics for the dengue vector Aedes albopictus(A. albopictus) under uncontrolled conditions,incorporating both the aquatic and the adult stages. Methods:Ten females derived from wild pupae were allowed to fully blood-feed on restrained mice.774 eggs were hatched in seasoned water.F1 larvae were followed for development until their F2 counterparts emerged as adults.Some population parameters were monitored(Fl) or estimated(F2).Results:A.albopictus exhibited increased fecundity and egg hatch success. Immature development was quick.Immature survival was high,with lowest rate in the pupal stage.Adult emergence was about 81%and sex ratio was close to 1:1.Generational mortality(K) was about 28%.A high proportion of females completed a reproductive cycle and the obtained parity rate was predicted to lead to higher fecundity in the next generation.Conclusios:It can be concluded that natural A.albopictus populations in Penang seem largely determined by quick development in combination with low immature loss and increased oviposition.展开更多
Objective:To evaluate the larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri endocarp against Aedes aegypti,Aedes albopictus,Culex quinquefasciatus,and Anopheles minimus mosquitos.Methods:Larv...Objective:To evaluate the larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri endocarp against Aedes aegypti,Aedes albopictus,Culex quinquefasciatus,and Anopheles minimus mosquitos.Methods:Larvicidal activity was tested according to World Health Organization standard protocol.The third-stage larvae of each mosquito species were exposed to various concentrations of Dracaena loureiri crude extract and six groups of Dracaena loureiri fractionated extracts(RC-DT 009-014).Larval mortality rates were observed after 24 h and48 h of exposure.Then,a computerized probit analysis of the mortality data was performed to determine lethal concentration 50(LC_(50))and lethal concentration 90 values.Results:Anopheles minimus larvae(24-h LC_(50)77.88 mg/L)had the highest susceptibility to crude extract,whereas others(Aedes aegypti,24-h LC_(50)224.73 mg/L;Aedes albopictus,24-h LC_(50)261.75 mg/L;and Culex quinquefasciatus,24-h LC_(50)282.86 mg/L)were significantly less susceptible.The most effective groups of fractionated extracts were RC-DT 012 and RC-DT 013.The mosquito species most susceptible to fractionated extracts was Culex quinquefasciatus,with 24-h LC_(50)values of 0.66 and 0.94 mg/L for RC-DT 012 and RC-DT 013,respectively.Conclusions:The larvicidal activity of fractionated extracts is more effective than that of crude extract against all tested mosquito species.For the most effective alternative larvicide,purification and a phytochemical constituent analysis must be performed.展开更多
Objective: To record the human cases of dengue fever(DF) and investigate the Aedes mosquito species circulating during the Hanoi 2011 DF epidemics. Methods: 24 different outbreak points were recorded in 8 districts be...Objective: To record the human cases of dengue fever(DF) and investigate the Aedes mosquito species circulating during the Hanoi 2011 DF epidemics. Methods: 24 different outbreak points were recorded in 8 districts between August and December 2011. Results: 140 patients were hospitalized following dengue diagnostic with a predominance of males(59.3%) and the 15-34 age class. Only DENV-1(11.27%) and DENV-2(88.73%) serotypes were detected in human samples. Mosquito sampling performed in and around patients households revealed the predominance of Aedes aegypti(95.15%) versus Aedes albopictus(4.85%). There is a positive correlation between the population density of Aedes aegypti and the number of human cases and duration of outbreaks. Conclusions: This was not observed for Aedes albopictus. 3 pools of Aedes aegypti were positive with dengue virus, two with DENV-1 and one with DENV-2.展开更多
Objective: To investigate the larvicidal activity of Syzygium guineense(Myrtaceae)(S. guineense), Monodora myristica and Zanthoxylum heitzii(Rutaceae)(Z. heitzii) extracts against Aedes albopictus(Ae. albopictus).Meth...Objective: To investigate the larvicidal activity of Syzygium guineense(Myrtaceae)(S. guineense), Monodora myristica and Zanthoxylum heitzii(Rutaceae)(Z. heitzii) extracts against Aedes albopictus(Ae. albopictus).Methods: The larvicidal activity of the hydro-ethanolic extracts from these plant species was assessed at three different concentrations(50, 100 and 200 mg/L) on first-instar of Ae. albopictus larvae in comparison with untreated controls. Mortality rate was recorded daily for a period of 12 days. The values of LC_(50) and lethal time killing 50% of the tested individuals(LT_(50)) were calculated using the log-probit analysis.Results: The root extract of S. guineense exhibited the best activity with 100% mortality after 8 days of treatment at 200 mg/L, followed by the fruit extract of Z. heitzii with83.33% mortality at the same concentration. Nonetheless, larvae were most susceptible to the fruit extract of Z. heitzii both in terms of LC_(50)(39.89 mg/L) and LT_(50)(145.68 h). A statistically significant difference between the control and the group treated at 200 mg/L was noticed in all the extracts.Conclusions: The present study shows that the hydro-ethanolic extracts of S. guineense,Monodora myristica and Z. heitzii tested have significant larvicidal activity. These preliminary results are of great interest and some of these plant species can be proposed for the formulation of new bioinsecticides to control Ae. albopictus populations.展开更多
The Pearl River Delta,where Aedes albopictus(Ae.albopictus)is the only vector for dengue transmission,has exhibited one of the highest dengue burdens in southern China in recent decades.However,whether dengue virus(DE...The Pearl River Delta,where Aedes albopictus(Ae.albopictus)is the only vector for dengue transmission,has exhibited one of the highest dengue burdens in southern China in recent decades.However,whether dengue virus(DENV)can overwinter in Ae.albopictus in the Pearl River Delta has not been determined to date.In this study,300 field-derived Ae.albopictus mosquitoes from Guangzhou that were infected with the predominant endemic DENV-1 strain were investigated under simulated urban balcony environment from October 16,2016,to June 16,2017.The vertical transmission of DENV in the infected overwintering Ae.albopictus was analyzed.The DENV infected overwintering mosquitoes were evaluated for viral load at nine-time points using reverse transcription-quantitative PCR.The vector competence of the infected overwintering Ae.albopictus was also investigated by using suckling mice.Adult mosquitoes and larvae were found during the observation period.The vertical transmission of DENV-1 was documented.The DENV-1-positive rates between overwintering males and females had no difference.The proportion of DENV-1-positive overwintering mosquitoes decreased over time and had no difference beyond three months after the experiment.Overwintering mosquitoes can spread DENV-1 to hosts.No engorged mosquitoes at an ambient temperature below 15℃were observed.The ratio of engorged mosquitoes was positively correlated with the ambient temperature ranging from 15 to 30℃.Our results demonstrated that DENV can overwinter in Ae.albopictus in the Pearl River Delta,Ae.albopictus is the competent vector for DENV,and maintain autochthonous dengue outbreaks in the Pearl River Delta through vertical transmission.展开更多
Objective:To monitor the current duration of the application rates in vector programme and the level of Aedes albopictus larvae susceptibility from three selected areas in northeast district of Penang on two selected ...Objective:To monitor the current duration of the application rates in vector programme and the level of Aedes albopictus larvae susceptibility from three selected areas in northeast district of Penang on two selected larvicides,temephos and Bacillus thuringiensis subsp.israelensis(Bti) which are commonly used by Penang Health Department for vector control.Methods:The mosquito larvae were tested against two types of larvicides:(1) temephos(Abate®) with diagnostic dosage(0.012 mg/L) and operational dosage(1 mg/L) and(2)Bacillus thuringiensis subsp.israelensis(Vecto Bac®WG) with operational dosage ranging from 6 000 international toxic units per L to 24 000 international toxic unit per L.A total of 20 late third and early forth instar larvae were selected and transferred into paper cup sized 300 m L using wide-mouthed pipette.The larvae were distributed into each 300 m L paper cup containing 50 m L of aged tap water.The experiment was replicated five times for each concentration tested.Each test was repeated three times.The mortality was recorded after 24 h of exposure and recorded lethal time was based on 2 h for temephos and 6 h for Bti.The control consisted of ethanol for temephos and only seasoned water for Bti.Results:The result showed that Aedes albopictus from Flat Hamna,Kampung Sungai Gelugor and Kampung Tanjung Tokong were still susceptible to Bti and temephos.However,higher lethal time and resistance ratio were detected in strain from Flat Hamna which was a known dengue hot spot area in northeast of Penang.Conclusions:The application of temephos and Bti in vector control activity in these selected localities is still relevant in the control of Aedes larvae populations.展开更多
Objective： To obtain the complete β-actin gene from Aedes albopictus. Methods： Total RNA was extracted from C6/36 cells. Degenerate primers were designed based on the β-actin sequences of An. gambiae, Ae. aegypti,...Objective： To obtain the complete β-actin gene from Aedes albopictus. Methods： Total RNA was extracted from C6/36 cells. Degenerate primers were designed based on the β-actin sequences of An. gambiae, Ae. aegypti, Cx. pipiens pallens and D. melanogaster. By RT-PCR, the product was amplified, purified, cloned into the pGT vector and sequenced. The β-actin sequence was aligned and phylogenetically analyzed by the BLAST program and the CLUSTAL W program. Results： A sequence of 1132 bp including an open reading frame of 1131 bp was obtained （GenBank DQ657949）. The deduced protein had 376 amino acids. Aligned to SWISS-PROT, it exhibited a high level of identity with β-actins from Anopheles, Drosophila and Culex at the amino acid sequence level. Phylogenetic analysis indicated that Ae. albopictus β-acfin was much more homologous with invertebrate β- actin than with vertebrate β-actin. Conclusion： The gene may be used as the internal control in the experiments of Ae. albopictus.展开更多
Objective:To evaluate the growth inhibition activity of the crude extract of Cyperus aromaticus(C.aromaticus)cultured cells against the 3rd instar larvae of Aedes aegypti(Linn.)and Aedes albopictus Skuse(Ae.albopictus...Objective:To evaluate the growth inhibition activity of the crude extract of Cyperus aromaticus(C.aromaticus)cultured cells against the 3rd instar larvae of Aedes aegypti(Linn.)and Aedes albopictus Skuse(Ae.albopictus)under laboratory conditions,and determine the sublethal effects(EI_(50))of the crude extract of C.aromaticus cultured cells on some biological and morphological parameters of both Aedes mosquito species during two generations as well.Methods:The cell suspension cultures of C.aromaticus were activated from five callus lines(P4,Pa,Z1,Z6 and Ml)derived from the root explants of in vitro plantlets.The cultured cells were extracted in chloroform and used as plant material for the present study.For detection of juvenile hormone III.the crude extracts were analyzed by HPLC.Then the crude extracts of the three C.aromaticus cultured cell lines which contained varied amounts of juvenile hormone III[high level(P4 cell line),medium level(Z1 cell line)and low level(Ml cell line)]were tested against Aedes mosquito species.Laboratory evaluation was performed against late third instar larvae of the Vector Control Research Unit strains of Ae.aegypti and Ae.albopictus using the standard WHO method.The effects of EI_(50)of the C.aromaticus cultured P4 cells on fecundity,fertility,growth period,sex ratio,adult size and longevity of Aedes mosquitoes were assessed.Results:Bioassay tests presented the remarkable growth inhibition activity of the crude extracts of C.aromaticus cultured cells against the two Aedes mosquitoes.Between the two mosquito species,Ae.albopictus was more susceptible to the crude extracts with lower EI_(50)values.EI_(50)of the crude extract of C.aromaticus cultured cells(P4)increased the sterility indices in the parental generation females in both Aedes mosquito species.A significant delay in the pupal formation and adult emergence were observed in the parental generation of the both mosquito species.The sex ratio of the adult population either parental or F1 generation of the Aedes mosquito species was not significantly affected by the EI_(50)dosage of the crude extract of C.aromaticus cultured P4 cells.A significant decrease in the wing length of the treated adult(female and male)of Aedes aegypti as well as the treated female of Ae.albopictus were observed.Longevity of the adult female of the parental generation of both Aedes mosquitoes as well as females of F1 generation of Ae.albopictus were significantly decreased.Conclusions:The present study revealed the potential of the crude extract of C.aromaticus cultured cells in controlling vector mosquito populations in the effort to reduce the transmission of vector borne diseases.展开更多
Objective: To evaluate the efficacy of symbiotic bacteria, Xenorhabdus indica, Xenorhabdus stockiae, Photorhabdus luminescens subsp. akhurstii and Photorhabdus luminescens subsp. hainanensis as a larvicide against Aed...Objective: To evaluate the efficacy of symbiotic bacteria, Xenorhabdus indica, Xenorhabdus stockiae, Photorhabdus luminescens subsp. akhurstii and Photorhabdus luminescens subsp. hainanensis as a larvicide against Aedes aegypti and Aedes albopictus. Methods: Larvae(L3-L4) of Aedes aegypti and Aedes albopictus were given 2 m L of a suspension 107-108 CFU/m L of each symbiotic bacterium. Distilled water and Escherichia coli ATCC襅25922 were used as the control. The mortality rate of the larval mosquitoes was observed at 24, 48, 72 and 96 h. The experiment was performed in triplicates. Results: The larvae of both Aedes species started to die at 24 h exposure. Aedes aegypti showed the highest mortality rate(87%-99%), 96 h after exposure to Xenorhabdus stockiae(b NBP22.2_TH). The mortality rate of Aedes albopictus was between 82% and 96% at 96 h after exposure to Xenorhabdus indica(b KK26.2_TH). Low effectiveness of distilled water and Escherichia coli ATCC襅25922 were observed in both Aedes larvae, with a mortality rate of 2% to 12%. Conclusions: The study confirms the oral toxicity of Xenorhabdus and Photorhabdus bacteria against Aedes spp. Xenorhabdus stockiae and Xenorhabdus indica may be an alternative agent for control Aedes spp. This is basic information for further study on the mechanism of action on Aedes larvae or application to control mosquito larvae in the community.展开更多
Objective:To determine the suitable ecological habitats of Aedes(Ae.)aegypti and Ae.albopictus in Iran due to climate change by the 2070s.Methods:All data relating to the spatial distribution of Ae.aegypti and Ae.albo...Objective:To determine the suitable ecological habitats of Aedes(Ae.)aegypti and Ae.albopictus in Iran due to climate change by the 2070s.Methods:All data relating to the spatial distribution of Ae.aegypti and Ae.albopictus worldwide,which indicated the geographical coordinates of the collection sites of these mosquitoes,were extracted from online scientific websites and entered into an Excel file.The effect of climatic and environmental variables on these mosquitoes was evaluated using the MaxEnt model in the current and future climatic conditions in the 2030s,2050s,and 2070s.Results:The most suitable areas for the establishment of Ae.aegypti are located in the southern and northern coastal areas of Iran,based on the model outputs.The modelling result for suitable ecological niches of Ae.albopictus shows that in the current climatic conditions,the southern half of Iran from east to west,and parts of the northern coasts are prone to the presence of this species.In the future,some regions,such as Gilan and Golestan provinces,will have more potential to exist/establish Ae.albopictus.Also,according to the different climate change scenarios,suitable habitats for this species will gradually change to the northwest and west of the country.The temperature of the wettest season of the year(Bio8)and average annual temperature(Bio1)were the most effective factors in predicting the model for Ae.aegypti and Ae.albopictus,respectively.Conclusions:It is required to focus on entomological studies using different collection methods in the vulnerable areas of Iran.The future modelling results can also be used for long-term planning to prevent the entry and establishment of these invasive Aedes vectors in the country.展开更多
Objective:To develop an artificial and modified Wolbaehia removal technique using tetracycline from naturally Wolbachia infected Aedes albopictus(Ae.albopictus)so as to be able to produce generations of Wolbaehia free...Objective:To develop an artificial and modified Wolbaehia removal technique using tetracycline from naturally Wolbachia infected Aedes albopictus(Ae.albopictus)so as to be able to produce generations of Wolbaehia free offsprings.Methods:In this study,seven different tetracycline treatment methods were conducted to obtain the best removal method.Four methods focused on larvae tetracycline treatment,one method on both larvae and adult tetracycline treatment and the last two methods on adult mosquito sucrose treatment.Results:All larval tetracycline treatments resulted in either high larvae mortality,sterile F_o adult mosquitoes or unsuccessful Wolbaehia removal.Treatment of both larvae and adults resulted in reduced larvae mortality,successful Wolbachia removal but slow mosquito fecundity.As for the adult treatment,1.0 mg/mL as previously published was not aisle to completely remove Wolbaehia in F,generation whereas 1.25 mg/mL successfully removed Wolbachia from F,and F,mosquitoes in 2 weeks.Conclusions:This method is different from the previously published methods as it provides an improved Watbachia removal technique from Ae.albopictus with high egg hatchability.low larvae mortality,increased fecundity and better Wolbaehia removal rate.展开更多
The frequent cases of dengue incidences are leading cause of illness and death in urban areas and Aedes albopictus (Skuse) is a primary vector for Dengue transmission in India. Synthesis of leaf mediated silver nanopa...The frequent cases of dengue incidences are leading cause of illness and death in urban areas and Aedes albopictus (Skuse) is a primary vector for Dengue transmission in India. Synthesis of leaf mediated silver nanoparticles especially with Pongamia pinnata is a potential substitute for the existing organophosphorus insecticides like Tenophos, malathion and fenthion etc., for mosquito control programme. The nanoparticles were characterized by UV-visible absorption spectrum, X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) and Transmission Electron Microscopy (TEM). Analysis of TEM showed that the synthesized silver nanoparticles are in spherical shape with average size of 20 nm. Further the XRD analysis confirms the nano-crystalline phase of silver with face centred cubic (FCC) crystal structure. GC-MS analysis elucidated the presence of two active ingredients, such as 9-Octadecenoic acid (Z) and n-hexadecanoic acid, which are the prominent substances considered as larvicide. Larvae were exposed to varying concentrations of plant extracts and synthesized silver nanoparticles for 24 hours. From the results, it is found that plant extracts showed moderate larvicidal effects but, the synthesized silver nanoparticles had found to be toxic to larvae at LC50 (0.25 ppm) and LC90 (1 ppm).展开更多
The vast majority of all global species have circadian rhythm cycles that allow them to adapt to natural environments.These regular rhythms are regulated by core clock genes and recent studies have also implicated rol...The vast majority of all global species have circadian rhythm cycles that allow them to adapt to natural environments.These regular rhythms are regulated by core clock genes and recent studies have also implicated roles for microRNAs in this regulation.Oviposition is an important circadian behavior in the reproductive cycle of insect vectors of diseases,and little is known about the rhythm or its regulation in mosquitoes.Aedes albopictus is a diurnal mosquito that transmits arboviruses and is the major cause of outbreaks of dengue fever in China.We analyzed the oviposition rhythm patterns of A.albopictus under different light/dark conditions and show that the mosquitoes have an oviposition peak between zeitgeber time 9(ZT 9)and ZT 12.Furthermore,the antagomir-mediated knockdown of expression of the microRNA miR-2940-1 affected the oviposition rhythm of A.albopictus.These data support the conclusion that miR-2940-1 is involved in the regulation of oviposition rhythm in A.albopictus and provide a foundation for using oviposition rhythms as a new target for vector mosquito control.展开更多
Background:Dengue(DENV),chikungunya(CHIKV)and Zika virus(ZIKV),are mosquito-borne viruses of medical importance in most tropical and subtropical regions.Vector control,primarily through insecticides,remains the primar...Background:Dengue(DENV),chikungunya(CHIKV)and Zika virus(ZIKV),are mosquito-borne viruses of medical importance in most tropical and subtropical regions.Vector control,primarily through insecticides,remains the primary method to prevent their transmission.Here,we evaluated insecticide resistance profles and identifed important underlying resistance mechanisms in populations of Aedes aegypti and Ae.albopictus from six different regions in Cameroon to pesticides commonly used during military and civilian public health vector control operations.Methods:Aedes mosquitoes were sampled as larvae or pupae between August 2020 and July 2021 in six locations across Cameroon and reared until the next generation,G1.Ae.aegypti and Ae.albopictus adults from G1 were tested following World Health Organization(WHO)recommendations and Ae.aegypti GO adults screened with real time melting curve qPCR analyses to genotype the F1534C,V1016l and V410L Aedes kdr mutations.Piperonyl butoxide(PBO)assays and real time qPCR were carried out from some cytochrome p450 genes known to be involved in metabolic resistance.Statistical analyses were performed using Chi-square test and generalized linear models.Results:Loss of susceptibility was observed to all insecticides tested.Mortality rates from tests with 0.25%permethrin varied from 24.27%to 85.89%in Ae.aegypti and from 17.35%to 68.08%in Ae.albopictus.Mortality rates for 0.03%deltamethrin were between 23.30%and 88.20%in Ae.aegypti and between 69.47%and 84.11%in Ae.albopictus.We found a moderate level of resistance against bendiocarb,with mortality rates ranging from 69.31%to 90.26%in Ae.aegypti and from 86.75%to 98.95%in Ae.albopictus.With PBO pre-exposure,we found partial or fully restored suscepti bility to pyrethroids and bendiocarb.The genes Cyp9M6F88/87 and Cyp9J10 were overexpressed in Ae.aegypti populations from Douala sites resistant to permethrin and deltamethrin.Cyp6P12 was highly expressed in alphacypermethrin and permethrin resistant Ae.albopictus samples.F1534C and V1016l mutations were detected in A.aegypti mosquitoes and for the first time V410L was reported in Cameroon.Conclusions:This study revealed that Ae.aegypti and Ae albopictus are resistant to multiple insecticide classes with multiple resistance mechanisms implicated.These findings could guide insecticide use to control arbovirus vectors in Cameroon.展开更多
Background Understanding of mosquito spatiotemporal dynamics is central to characterize candidate field sites for the sterile insect technique(SIT)testing,and is critical to the effective implementation and evaluation...Background Understanding of mosquito spatiotemporal dynamics is central to characterize candidate field sites for the sterile insect technique(SIT)testing,and is critical to the effective implementation and evaluation of pilot sterile male release programs.Here,we present a detailed description of Aedes albopictus(Skuse)egg-laying activity over a 6-year period in urban areas identified as potential SIT testing sites on Reunion Island.Method Weekly entomological collections using ovitraps were carried out in residential and adjacent uninhabited habitats in two urban areas,Duparc and Bois Rouge,in the municipality of Sainte Marie,Reunion Island.Time-series data incorporating the frequency of positive ovitraps and the total number of eggs/ovitrap recorded each time at each locality during the study period from May 2013 to December 2018 were analyzed with multifaceted statistical approaches including descriptive statistics and spatiotemporal analyses incorporating the role of climatic factors on overall ovitrap productivity.Results During the ovitrap survey,the proportion of egg-positive ovitraps differed among study sites(χ2=50.21,df=2,P<0.001),being relatively lower in Duparc(89.5%)than in Bois-Rouges(95.3%)and the adjacent buffer zone(91.2%).Within each neighborhood,Ae.albopictus egg abundance varied by month in a roughly seasonal pattern marked by a single peak occurring more regularly February each year,a decline at the onset of the austral winter in July,followed by a period of lower ovitrap productivity in August and September.Fluctuation in both positivity rate and eggs densities per ovitraps were related to annual and seasonal variations in local temperature and rainfall(P<0.001 in all cases).The spatial analysis also captured substantial between-and within-habitats heterogeneity,whereby the overall ovitrap productivity was higher in residential areas than in the buffer zone.Conclusions Collectively,these results reveal that the distribution of Ae.albopictus oviposition activity is shaped by local habitat heterogeneity and seasonal climatic factors.Overall,this study provides baseline insights into the reproductive dynamics of Ae.albopictus,which would assist in planning locally tailored SIT interventions,while addressing concerns related to focal areas of high egg-laying intensity and potential immigration of females from natural areas.展开更多
Background:Aedes albopictus is distributed widely in China,as a primary vector of Dengue fever and Chikungunya fever in south of China.Chemical insecticide control is one of the integrated programmes to prevent mosqui...Background:Aedes albopictus is distributed widely in China,as a primary vector of Dengue fever and Chikungunya fever in south of China.Chemical insecticide control is one of the integrated programmes to prevent mosquito-borne diseases.Long-term applications of pyrethroids have resulted in the development of resistance in Ae.albopictus populations in China.However,the susceptibility of Ae.albopictus to pyrethroids in Hainan Island was unclear.Knockdown resistance(kdr),caused by point mutations in the VGSC gene,is one of the mechanisms that confer resistance to DDT and pyrethroids.This study was to investigate the resistance level of Ae.albopictus populations in Haikou City to three pyrethroid insecticides,and elucidate the relationship between the resistant phenotype and kdr mutations.Methods:The Aedes albopictus samples were collected in Xinbu Island(XI),Longtang Town(LT),Shishan Town(ST),Baishamen Park(BP),and Flower Market(FM)from Haikou City,Hainan Island,China.The larval susceptibility to deltamethrin,permethrin and beta-cypermethrin was tested by larval bioassays,and adult susceptibility to deltamethrin and DDT was determined by adult bioassays.The degree of resistance was determined by resistance ratio value(RR50>3)for larvae and by mortality for adult.The kdr alleles at codon 1534 of the VGSC gene were genotyped.The relationship between kdr genotypes and resistant phenotypes was analyzed by Chi-square test.Results:Out of five populations,assessed by larval bioassays,XI was susceptible to deltamethrin and permethrin;LT was susceptible to permethrin and beta-cypermethrin;and ST was susceptible to permithrin.FM and BP both were resistant to all of the three pyrethroids,and FM showed the highest degree of resistance,with RR50 values from 65.17 to 436.36.A total of 493 individuals from the larval bioassays were genotyped for kdr alleles.Five alleles were detected,including two wildtype alleles,TTC(F)(67.04%)and TTT(F)(0.41%),and three mutant alleles,TGC(C)(0.30%),TCC(S)(31.54%)and TTG(L)(0.71%).There was a clear correlation between mutant alleles(or F1534S)and resistant phenotypes(P<0.01).Conclusion:Two novel kdr mutant alleles F1534S and F1534L were detected in the pyrethroid resistant populations of Ae.albopictus in Haikou Hainan,China.For the first time,the mutant F1534S was associated with pyrethroid resistance in Ae.albopictus.展开更多
Background:Arboviral disease transmitted by Aedes albopictus such as dengue fever is an important threat to human health.Pyrethroid resistance raises a great challenge for mosquito control.A systematic assessment of A...Background:Arboviral disease transmitted by Aedes albopictus such as dengue fever is an important threat to human health.Pyrethroid resistance raises a great challenge for mosquito control.A systematic assessment of Ae.albopictus resistance status in China is urgently needed,and the study of correlation between pyrethroid resistance and knockdown resistance(kdr)mutations would provide information to guide the control of the Ae.albopictus vector.Methods:Five field populations of Ae.albopictus were collected from Jinan(JN),Hangzhou(HZ),Baoshan(BS),Yangpu(YP)and Haikou(HK),China in 2017.Insecticide-impregnated papers were prepared with four pyrethroid chemicals,deltamethrin,permethrin,beta-cypermethrin and lambda-cyhalothrin.The susceptibility of Ae.albopictus to pyrethroids was tested by the WHO tube assay.Kdr mutations were identified by PCR and sequencing.Moreover,the correlation analysis between kdr alleles and pyrethroid resistance was performed.Results:All five populations of Ae.albopictus showed resistance to four pyrethroid insecticides.One kdr mutant allele at codon 1532 and three at 1534 were detected with frequency of 5.33%(I1532T),44.20%(F1534S),1.83%(F1534 L)and 0.87%(F1534C),respectively.Both 1532 and 1534 mutation mosquitoes were found in the BS and YP populations.Allele I1532T was negatively correlated with deltamethrin resistance phenotype(OR<1),while F1534S mutation was positively correlated with deltamethrin and permethrin resistance(OR>1).Conclusions:The five field populations of Ae.albopictus adults were all resistant to deltamethrin,permethrin,betacypermethrin and lambda-cyhalothrin.Mutant F1534S was clearly associated with pyrethroid resistance phenotype in Ae.albopictus and this could be developed as a molecular marker to monitor the pyrethroid resistance problem in China.展开更多
基金supported by Three-Year Initiative Plan for Strengthening Public Health System Construction in Shanghai(2023-2025)Key Discipline Project(No.GWVI-11.1-12).
文摘Objective:To predict the distribution of dengue vector Aedes(Ae.)albopictus and identify high-risk areas for dengue fever transmission.Methods:Data on Ae.albopictus occurrences were collected from electronic databases.Ensemble models were developed to assess the impacts of climate,vegetation,and human activity on Ae.albopictus.The optimal ensemble model was then used to identify the distribution of suitable areas for Ae.albopictus.Results:After removing duplicate sites and retaining only one location per 100 m×100 m grid,189 Ae.albopictus breeding sites were identified.The optimal ensemble model revealed that Ae.albopictus exhibited higher breeding suitability in Shanghai under specific conditions:a normalized difference vegetation index of 0.1 to 0.6,maximum precipitation in the warmest month ranging from 400 mm to 470 mm,maximum temperature in the warmest month between 30.0℃and 31.0℃,and proximity to waterways within 0.5 km.The most suitable habitats for Ae.albopictus were primarily concentrated in Shanghai’s central urban areas and scattered across the inner suburban districts.Conclusions:The high-risk areas of Ae.albopictus are widely distributed throughout the central urban area and scattered across the inner suburban district of Shanghai,creating conditions conducive to the outbreak of dengue fever.It is essential to enhance targeted control measures for Ae.albopictus in the identified risk areas.
基金supported by Faculty of Agricultural Technology,KMITL,Bangkok,Thailand(Grant no 01-04-002)the National Research Council of Thailand(GRAD 6007KMITL)
文摘Objective: To investigate the efficacies of 12 essential oil(EO) formulations from three Zingiberaceae plants(Alpinia galanga, Curcuma zedoaria, and Zingiber cassumunar) individually and in combination with an augmenting Eucalyptus globulus(E. globulus) EO against females of Aedes albopictus(Ae. albopictus) and Anopheles minimus(An. minimus). Methods: These formulations were evaluated for their ovicidal, oviposition deterrent and adulticidal activities against Ae. albopictus and An. minimus by a topical method, a double-choice method and a WHO susceptibility test, respectively. Results: It was found that all formulations of Zingiberaceae plants EOs augmented with E. globulus EO were more effective in oviposition deterrent, ovicidal, and adulticidal activities against the two mosquito species than all of the formulations used without E. globulus EO. Their oviposition deterrent, ovicidal and adulticidal activities were equivalent to those of 10% w/v cypermethrin. In contrast, 70% v/v ethyl alcohol as a control alone was not effective at all. The highest synergistic effect in effective repellency against Ae. albopictus was achieved by 5% Alpinia galanga EO + 5% E. globulus EO and against An. minimus was 5% Zingiber cassumunar EO + 5% E. globulus EO. Moreover, the highest synergistic effects in ovicidal activities against Ae. albopictus and An. minimus were achieved by 10% Zingiber cassumunar EO + 10% E. globulus EO and 5% Curcuma zedoaria EO + 5% E. globulus EO, respectively. For the adulticidal activities, the highest synergistic effect against two mosquitoes was achieved by 5% Curcuma zedoaria EO + 5% E. globulus EO. Conclusions: These results suggest that Zingiberaceae plant EOs augmented with E. globulus EO have a high potential to be developed into oviposition deterrent, ovicidal, and adulticidal agents for controlling populations of Ae. albopictus and An. minimus.
基金Supported by grants from Universiti Sains Malaysi(No:#07-05-16-MG1-GM15,#1001/PBIOLOGI/842004)
文摘Objective:To generate life table characteristics for the dengue vector Aedes albopictus(A. albopictus) under uncontrolled conditions,incorporating both the aquatic and the adult stages. Methods:Ten females derived from wild pupae were allowed to fully blood-feed on restrained mice.774 eggs were hatched in seasoned water.F1 larvae were followed for development until their F2 counterparts emerged as adults.Some population parameters were monitored(Fl) or estimated(F2).Results:A.albopictus exhibited increased fecundity and egg hatch success. Immature development was quick.Immature survival was high,with lowest rate in the pupal stage.Adult emergence was about 81%and sex ratio was close to 1:1.Generational mortality(K) was about 28%.A high proportion of females completed a reproductive cycle and the obtained parity rate was predicted to lead to higher fecundity in the next generation.Conclusios:It can be concluded that natural A.albopictus populations in Penang seem largely determined by quick development in combination with low immature loss and increased oviposition.
基金supported by the Naresuan University Research Fund(Reference Number:R2560B057)
文摘Objective:To evaluate the larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri endocarp against Aedes aegypti,Aedes albopictus,Culex quinquefasciatus,and Anopheles minimus mosquitos.Methods:Larvicidal activity was tested according to World Health Organization standard protocol.The third-stage larvae of each mosquito species were exposed to various concentrations of Dracaena loureiri crude extract and six groups of Dracaena loureiri fractionated extracts(RC-DT 009-014).Larval mortality rates were observed after 24 h and48 h of exposure.Then,a computerized probit analysis of the mortality data was performed to determine lethal concentration 50(LC_(50))and lethal concentration 90 values.Results:Anopheles minimus larvae(24-h LC_(50)77.88 mg/L)had the highest susceptibility to crude extract,whereas others(Aedes aegypti,24-h LC_(50)224.73 mg/L;Aedes albopictus,24-h LC_(50)261.75 mg/L;and Culex quinquefasciatus,24-h LC_(50)282.86 mg/L)were significantly less susceptible.The most effective groups of fractionated extracts were RC-DT 012 and RC-DT 013.The mosquito species most susceptible to fractionated extracts was Culex quinquefasciatus,with 24-h LC_(50)values of 0.66 and 0.94 mg/L for RC-DT 012 and RC-DT 013,respectively.Conclusions:The larvicidal activity of fractionated extracts is more effective than that of crude extract against all tested mosquito species.For the most effective alternative larvicide,purification and a phytochemical constituent analysis must be performed.
基金supported in part by the Erasmus Mundus project MAHEVAthe CNRS-UM1-UM2 PEPS project MoD yCAsupported by the Entomology department, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
文摘Objective: To record the human cases of dengue fever(DF) and investigate the Aedes mosquito species circulating during the Hanoi 2011 DF epidemics. Methods: 24 different outbreak points were recorded in 8 districts between August and December 2011. Results: 140 patients were hospitalized following dengue diagnostic with a predominance of males(59.3%) and the 15-34 age class. Only DENV-1(11.27%) and DENV-2(88.73%) serotypes were detected in human samples. Mosquito sampling performed in and around patients households revealed the predominance of Aedes aegypti(95.15%) versus Aedes albopictus(4.85%). There is a positive correlation between the population density of Aedes aegypti and the number of human cases and duration of outbreaks. Conclusions: This was not observed for Aedes albopictus. 3 pools of Aedes aegypti were positive with dengue virus, two with DENV-1 and one with DENV-2.
文摘Objective: To investigate the larvicidal activity of Syzygium guineense(Myrtaceae)(S. guineense), Monodora myristica and Zanthoxylum heitzii(Rutaceae)(Z. heitzii) extracts against Aedes albopictus(Ae. albopictus).Methods: The larvicidal activity of the hydro-ethanolic extracts from these plant species was assessed at three different concentrations(50, 100 and 200 mg/L) on first-instar of Ae. albopictus larvae in comparison with untreated controls. Mortality rate was recorded daily for a period of 12 days. The values of LC_(50) and lethal time killing 50% of the tested individuals(LT_(50)) were calculated using the log-probit analysis.Results: The root extract of S. guineense exhibited the best activity with 100% mortality after 8 days of treatment at 200 mg/L, followed by the fruit extract of Z. heitzii with83.33% mortality at the same concentration. Nonetheless, larvae were most susceptible to the fruit extract of Z. heitzii both in terms of LC_(50)(39.89 mg/L) and LT_(50)(145.68 h). A statistically significant difference between the control and the group treated at 200 mg/L was noticed in all the extracts.Conclusions: The present study shows that the hydro-ethanolic extracts of S. guineense,Monodora myristica and Z. heitzii tested have significant larvicidal activity. These preliminary results are of great interest and some of these plant species can be proposed for the formulation of new bioinsecticides to control Ae. albopictus populations.
基金This project was supported by the Provincial Science and Technology Projects of Guangdong Province,China(Grant numbers:2014A020219007,2015A020218003,2016A020219006 and 2017A020215101)the Medical Scientific Research Foundation of Guangdong Province,China(Grant numbers:A2018167).
文摘The Pearl River Delta,where Aedes albopictus(Ae.albopictus)is the only vector for dengue transmission,has exhibited one of the highest dengue burdens in southern China in recent decades.However,whether dengue virus(DENV)can overwinter in Ae.albopictus in the Pearl River Delta has not been determined to date.In this study,300 field-derived Ae.albopictus mosquitoes from Guangzhou that were infected with the predominant endemic DENV-1 strain were investigated under simulated urban balcony environment from October 16,2016,to June 16,2017.The vertical transmission of DENV in the infected overwintering Ae.albopictus was analyzed.The DENV infected overwintering mosquitoes were evaluated for viral load at nine-time points using reverse transcription-quantitative PCR.The vector competence of the infected overwintering Ae.albopictus was also investigated by using suckling mice.Adult mosquitoes and larvae were found during the observation period.The vertical transmission of DENV-1 was documented.The DENV-1-positive rates between overwintering males and females had no difference.The proportion of DENV-1-positive overwintering mosquitoes decreased over time and had no difference beyond three months after the experiment.Overwintering mosquitoes can spread DENV-1 to hosts.No engorged mosquitoes at an ambient temperature below 15℃were observed.The ratio of engorged mosquitoes was positively correlated with the ambient temperature ranging from 15 to 30℃.Our results demonstrated that DENV can overwinter in Ae.albopictus in the Pearl River Delta,Ae.albopictus is the competent vector for DENV,and maintain autochthonous dengue outbreaks in the Pearl River Delta through vertical transmission.
基金Funded by FGRS Grant by Ministry of Education and Universiti Sains Malaysia(203/PBIOLOGI/6711359)
文摘Objective:To monitor the current duration of the application rates in vector programme and the level of Aedes albopictus larvae susceptibility from three selected areas in northeast district of Penang on two selected larvicides,temephos and Bacillus thuringiensis subsp.israelensis(Bti) which are commonly used by Penang Health Department for vector control.Methods:The mosquito larvae were tested against two types of larvicides:(1) temephos(Abate®) with diagnostic dosage(0.012 mg/L) and operational dosage(1 mg/L) and(2)Bacillus thuringiensis subsp.israelensis(Vecto Bac®WG) with operational dosage ranging from 6 000 international toxic units per L to 24 000 international toxic unit per L.A total of 20 late third and early forth instar larvae were selected and transferred into paper cup sized 300 m L using wide-mouthed pipette.The larvae were distributed into each 300 m L paper cup containing 50 m L of aged tap water.The experiment was replicated five times for each concentration tested.Each test was repeated three times.The mortality was recorded after 24 h of exposure and recorded lethal time was based on 2 h for temephos and 6 h for Bti.The control consisted of ethanol for temephos and only seasoned water for Bti.Results:The result showed that Aedes albopictus from Flat Hamna,Kampung Sungai Gelugor and Kampung Tanjung Tokong were still susceptible to Bti and temephos.However,higher lethal time and resistance ratio were detected in strain from Flat Hamna which was a known dengue hot spot area in northeast of Penang.Conclusions:The application of temephos and Bti in vector control activity in these selected localities is still relevant in the control of Aedes larvae populations.
基金This work was supported by the National Natural Science Foundationof China(No.30628022 and No.30671827)
文摘Objective： To obtain the complete β-actin gene from Aedes albopictus. Methods： Total RNA was extracted from C6/36 cells. Degenerate primers were designed based on the β-actin sequences of An. gambiae, Ae. aegypti, Cx. pipiens pallens and D. melanogaster. By RT-PCR, the product was amplified, purified, cloned into the pGT vector and sequenced. The β-actin sequence was aligned and phylogenetically analyzed by the BLAST program and the CLUSTAL W program. Results： A sequence of 1132 bp including an open reading frame of 1131 bp was obtained （GenBank DQ657949）. The deduced protein had 376 amino acids. Aligned to SWISS-PROT, it exhibited a high level of identity with β-actins from Anopheles, Drosophila and Culex at the amino acid sequence level. Phylogenetic analysis indicated that Ae. albopictus β-acfin was much more homologous with invertebrate β- actin than with vertebrate β-actin. Conclusion： The gene may be used as the internal control in the experiments of Ae. albopictus.
基金supported by University Sains Malaysia(USM)with the grant No 304.PBIOLOGI.650272.C112
文摘Objective:To evaluate the growth inhibition activity of the crude extract of Cyperus aromaticus(C.aromaticus)cultured cells against the 3rd instar larvae of Aedes aegypti(Linn.)and Aedes albopictus Skuse(Ae.albopictus)under laboratory conditions,and determine the sublethal effects(EI_(50))of the crude extract of C.aromaticus cultured cells on some biological and morphological parameters of both Aedes mosquito species during two generations as well.Methods:The cell suspension cultures of C.aromaticus were activated from five callus lines(P4,Pa,Z1,Z6 and Ml)derived from the root explants of in vitro plantlets.The cultured cells were extracted in chloroform and used as plant material for the present study.For detection of juvenile hormone III.the crude extracts were analyzed by HPLC.Then the crude extracts of the three C.aromaticus cultured cell lines which contained varied amounts of juvenile hormone III[high level(P4 cell line),medium level(Z1 cell line)and low level(Ml cell line)]were tested against Aedes mosquito species.Laboratory evaluation was performed against late third instar larvae of the Vector Control Research Unit strains of Ae.aegypti and Ae.albopictus using the standard WHO method.The effects of EI_(50)of the C.aromaticus cultured P4 cells on fecundity,fertility,growth period,sex ratio,adult size and longevity of Aedes mosquitoes were assessed.Results:Bioassay tests presented the remarkable growth inhibition activity of the crude extracts of C.aromaticus cultured cells against the two Aedes mosquitoes.Between the two mosquito species,Ae.albopictus was more susceptible to the crude extracts with lower EI_(50)values.EI_(50)of the crude extract of C.aromaticus cultured cells(P4)increased the sterility indices in the parental generation females in both Aedes mosquito species.A significant delay in the pupal formation and adult emergence were observed in the parental generation of the both mosquito species.The sex ratio of the adult population either parental or F1 generation of the Aedes mosquito species was not significantly affected by the EI_(50)dosage of the crude extract of C.aromaticus cultured P4 cells.A significant decrease in the wing length of the treated adult(female and male)of Aedes aegypti as well as the treated female of Ae.albopictus were observed.Longevity of the adult female of the parental generation of both Aedes mosquitoes as well as females of F1 generation of Ae.albopictus were significantly decreased.Conclusions:The present study revealed the potential of the crude extract of C.aromaticus cultured cells in controlling vector mosquito populations in the effort to reduce the transmission of vector borne diseases.
基金supported by Higher Education Research Promotion,The Commission on Higher Education,Thailand(Grant No.R2558A008)Naresuan University(Grant No.R2557B013)
文摘Objective: To evaluate the efficacy of symbiotic bacteria, Xenorhabdus indica, Xenorhabdus stockiae, Photorhabdus luminescens subsp. akhurstii and Photorhabdus luminescens subsp. hainanensis as a larvicide against Aedes aegypti and Aedes albopictus. Methods: Larvae(L3-L4) of Aedes aegypti and Aedes albopictus were given 2 m L of a suspension 107-108 CFU/m L of each symbiotic bacterium. Distilled water and Escherichia coli ATCC襅25922 were used as the control. The mortality rate of the larval mosquitoes was observed at 24, 48, 72 and 96 h. The experiment was performed in triplicates. Results: The larvae of both Aedes species started to die at 24 h exposure. Aedes aegypti showed the highest mortality rate(87%-99%), 96 h after exposure to Xenorhabdus stockiae(b NBP22.2_TH). The mortality rate of Aedes albopictus was between 82% and 96% at 96 h after exposure to Xenorhabdus indica(b KK26.2_TH). Low effectiveness of distilled water and Escherichia coli ATCC襅25922 were observed in both Aedes larvae, with a mortality rate of 2% to 12%. Conclusions: The study confirms the oral toxicity of Xenorhabdus and Photorhabdus bacteria against Aedes spp. Xenorhabdus stockiae and Xenorhabdus indica may be an alternative agent for control Aedes spp. This is basic information for further study on the mechanism of action on Aedes larvae or application to control mosquito larvae in the community.
基金Research Deputy,Tehran University of Medical Sciences,grant No.46857。
文摘Objective:To determine the suitable ecological habitats of Aedes(Ae.)aegypti and Ae.albopictus in Iran due to climate change by the 2070s.Methods:All data relating to the spatial distribution of Ae.aegypti and Ae.albopictus worldwide,which indicated the geographical coordinates of the collection sites of these mosquitoes,were extracted from online scientific websites and entered into an Excel file.The effect of climatic and environmental variables on these mosquitoes was evaluated using the MaxEnt model in the current and future climatic conditions in the 2030s,2050s,and 2070s.Results:The most suitable areas for the establishment of Ae.aegypti are located in the southern and northern coastal areas of Iran,based on the model outputs.The modelling result for suitable ecological niches of Ae.albopictus shows that in the current climatic conditions,the southern half of Iran from east to west,and parts of the northern coasts are prone to the presence of this species.In the future,some regions,such as Gilan and Golestan provinces,will have more potential to exist/establish Ae.albopictus.Also,according to the different climate change scenarios,suitable habitats for this species will gradually change to the northwest and west of the country.The temperature of the wettest season of the year(Bio8)and average annual temperature(Bio1)were the most effective factors in predicting the model for Ae.aegypti and Ae.albopictus,respectively.Conclusions:It is required to focus on entomological studies using different collection methods in the vulnerable areas of Iran.The future modelling results can also be used for long-term planning to prevent the entry and establishment of these invasive Aedes vectors in the country.
基金Supported by University Malaya liesearch Grant of (MRG) with grant NO:RG372/11HTM
文摘Objective:To develop an artificial and modified Wolbaehia removal technique using tetracycline from naturally Wolbachia infected Aedes albopictus(Ae.albopictus)so as to be able to produce generations of Wolbaehia free offsprings.Methods:In this study,seven different tetracycline treatment methods were conducted to obtain the best removal method.Four methods focused on larvae tetracycline treatment,one method on both larvae and adult tetracycline treatment and the last two methods on adult mosquito sucrose treatment.Results:All larval tetracycline treatments resulted in either high larvae mortality,sterile F_o adult mosquitoes or unsuccessful Wolbaehia removal.Treatment of both larvae and adults resulted in reduced larvae mortality,successful Wolbachia removal but slow mosquito fecundity.As for the adult treatment,1.0 mg/mL as previously published was not aisle to completely remove Wolbaehia in F,generation whereas 1.25 mg/mL successfully removed Wolbachia from F,and F,mosquitoes in 2 weeks.Conclusions:This method is different from the previously published methods as it provides an improved Watbachia removal technique from Ae.albopictus with high egg hatchability.low larvae mortality,increased fecundity and better Wolbaehia removal rate.
文摘The frequent cases of dengue incidences are leading cause of illness and death in urban areas and Aedes albopictus (Skuse) is a primary vector for Dengue transmission in India. Synthesis of leaf mediated silver nanoparticles especially with Pongamia pinnata is a potential substitute for the existing organophosphorus insecticides like Tenophos, malathion and fenthion etc., for mosquito control programme. The nanoparticles were characterized by UV-visible absorption spectrum, X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) and Transmission Electron Microscopy (TEM). Analysis of TEM showed that the synthesized silver nanoparticles are in spherical shape with average size of 20 nm. Further the XRD analysis confirms the nano-crystalline phase of silver with face centred cubic (FCC) crystal structure. GC-MS analysis elucidated the presence of two active ingredients, such as 9-Octadecenoic acid (Z) and n-hexadecanoic acid, which are the prominent substances considered as larvicide. Larvae were exposed to varying concentrations of plant extracts and synthesized silver nanoparticles for 24 hours. From the results, it is found that plant extracts showed moderate larvicidal effects but, the synthesized silver nanoparticles had found to be toxic to larvae at LC50 (0.25 ppm) and LC90 (1 ppm).
基金supported by grants from the Key R&D Program of Guangdong Province(2022B1111030002)the National Natural Science Foundation of China(31830087 and 82261128003/2022YFML1001)the National Institutes of Health,USA(AI136850)to X.-G.C.A.A.J.is a Donald Bren Professor at the University of California,Irvine.
文摘The vast majority of all global species have circadian rhythm cycles that allow them to adapt to natural environments.These regular rhythms are regulated by core clock genes and recent studies have also implicated roles for microRNAs in this regulation.Oviposition is an important circadian behavior in the reproductive cycle of insect vectors of diseases,and little is known about the rhythm or its regulation in mosquitoes.Aedes albopictus is a diurnal mosquito that transmits arboviruses and is the major cause of outbreaks of dengue fever in China.We analyzed the oviposition rhythm patterns of A.albopictus under different light/dark conditions and show that the mosquitoes have an oviposition peak between zeitgeber time 9(ZT 9)and ZT 12.Furthermore,the antagomir-mediated knockdown of expression of the microRNA miR-2940-1 affected the oviposition rhythm of A.albopictus.These data support the conclusion that miR-2940-1 is involved in the regulation of oviposition rhythm in A.albopictus and provide a foundation for using oviposition rhythms as a new target for vector mosquito control.
文摘Background:Dengue(DENV),chikungunya(CHIKV)and Zika virus(ZIKV),are mosquito-borne viruses of medical importance in most tropical and subtropical regions.Vector control,primarily through insecticides,remains the primary method to prevent their transmission.Here,we evaluated insecticide resistance profles and identifed important underlying resistance mechanisms in populations of Aedes aegypti and Ae.albopictus from six different regions in Cameroon to pesticides commonly used during military and civilian public health vector control operations.Methods:Aedes mosquitoes were sampled as larvae or pupae between August 2020 and July 2021 in six locations across Cameroon and reared until the next generation,G1.Ae.aegypti and Ae.albopictus adults from G1 were tested following World Health Organization(WHO)recommendations and Ae.aegypti GO adults screened with real time melting curve qPCR analyses to genotype the F1534C,V1016l and V410L Aedes kdr mutations.Piperonyl butoxide(PBO)assays and real time qPCR were carried out from some cytochrome p450 genes known to be involved in metabolic resistance.Statistical analyses were performed using Chi-square test and generalized linear models.Results:Loss of susceptibility was observed to all insecticides tested.Mortality rates from tests with 0.25%permethrin varied from 24.27%to 85.89%in Ae.aegypti and from 17.35%to 68.08%in Ae.albopictus.Mortality rates for 0.03%deltamethrin were between 23.30%and 88.20%in Ae.aegypti and between 69.47%and 84.11%in Ae.albopictus.We found a moderate level of resistance against bendiocarb,with mortality rates ranging from 69.31%to 90.26%in Ae.aegypti and from 86.75%to 98.95%in Ae.albopictus.With PBO pre-exposure,we found partial or fully restored suscepti bility to pyrethroids and bendiocarb.The genes Cyp9M6F88/87 and Cyp9J10 were overexpressed in Ae.aegypti populations from Douala sites resistant to permethrin and deltamethrin.Cyp6P12 was highly expressed in alphacypermethrin and permethrin resistant Ae.albopictus samples.F1534C and V1016l mutations were detected in A.aegypti mosquitoes and for the first time V410L was reported in Cameroon.Conclusions:This study revealed that Ae.aegypti and Ae albopictus are resistant to multiple insecticide classes with multiple resistance mechanisms implicated.These findings could guide insecticide use to control arbovirus vectors in Cameroon.
文摘Background Understanding of mosquito spatiotemporal dynamics is central to characterize candidate field sites for the sterile insect technique(SIT)testing,and is critical to the effective implementation and evaluation of pilot sterile male release programs.Here,we present a detailed description of Aedes albopictus(Skuse)egg-laying activity over a 6-year period in urban areas identified as potential SIT testing sites on Reunion Island.Method Weekly entomological collections using ovitraps were carried out in residential and adjacent uninhabited habitats in two urban areas,Duparc and Bois Rouge,in the municipality of Sainte Marie,Reunion Island.Time-series data incorporating the frequency of positive ovitraps and the total number of eggs/ovitrap recorded each time at each locality during the study period from May 2013 to December 2018 were analyzed with multifaceted statistical approaches including descriptive statistics and spatiotemporal analyses incorporating the role of climatic factors on overall ovitrap productivity.Results During the ovitrap survey,the proportion of egg-positive ovitraps differed among study sites(χ2=50.21,df=2,P<0.001),being relatively lower in Duparc(89.5%)than in Bois-Rouges(95.3%)and the adjacent buffer zone(91.2%).Within each neighborhood,Ae.albopictus egg abundance varied by month in a roughly seasonal pattern marked by a single peak occurring more regularly February each year,a decline at the onset of the austral winter in July,followed by a period of lower ovitrap productivity in August and September.Fluctuation in both positivity rate and eggs densities per ovitraps were related to annual and seasonal variations in local temperature and rainfall(P<0.001 in all cases).The spatial analysis also captured substantial between-and within-habitats heterogeneity,whereby the overall ovitrap productivity was higher in residential areas than in the buffer zone.Conclusions Collectively,these results reveal that the distribution of Ae.albopictus oviposition activity is shaped by local habitat heterogeneity and seasonal climatic factors.Overall,this study provides baseline insights into the reproductive dynamics of Ae.albopictus,which would assist in planning locally tailored SIT interventions,while addressing concerns related to focal areas of high egg-laying intensity and potential immigration of females from natural areas.
基金supported by the YM’s grant 81371848 from the National Natural Sciences Foundation of China.
文摘Background:Aedes albopictus is distributed widely in China,as a primary vector of Dengue fever and Chikungunya fever in south of China.Chemical insecticide control is one of the integrated programmes to prevent mosquito-borne diseases.Long-term applications of pyrethroids have resulted in the development of resistance in Ae.albopictus populations in China.However,the susceptibility of Ae.albopictus to pyrethroids in Hainan Island was unclear.Knockdown resistance(kdr),caused by point mutations in the VGSC gene,is one of the mechanisms that confer resistance to DDT and pyrethroids.This study was to investigate the resistance level of Ae.albopictus populations in Haikou City to three pyrethroid insecticides,and elucidate the relationship between the resistant phenotype and kdr mutations.Methods:The Aedes albopictus samples were collected in Xinbu Island(XI),Longtang Town(LT),Shishan Town(ST),Baishamen Park(BP),and Flower Market(FM)from Haikou City,Hainan Island,China.The larval susceptibility to deltamethrin,permethrin and beta-cypermethrin was tested by larval bioassays,and adult susceptibility to deltamethrin and DDT was determined by adult bioassays.The degree of resistance was determined by resistance ratio value(RR50>3)for larvae and by mortality for adult.The kdr alleles at codon 1534 of the VGSC gene were genotyped.The relationship between kdr genotypes and resistant phenotypes was analyzed by Chi-square test.Results:Out of five populations,assessed by larval bioassays,XI was susceptible to deltamethrin and permethrin;LT was susceptible to permethrin and beta-cypermethrin;and ST was susceptible to permithrin.FM and BP both were resistant to all of the three pyrethroids,and FM showed the highest degree of resistance,with RR50 values from 65.17 to 436.36.A total of 493 individuals from the larval bioassays were genotyped for kdr alleles.Five alleles were detected,including two wildtype alleles,TTC(F)(67.04%)and TTT(F)(0.41%),and three mutant alleles,TGC(C)(0.30%),TCC(S)(31.54%)and TTG(L)(0.71%).There was a clear correlation between mutant alleles(or F1534S)and resistant phenotypes(P<0.01).Conclusion:Two novel kdr mutant alleles F1534S and F1534L were detected in the pyrethroid resistant populations of Ae.albopictus in Haikou Hainan,China.For the first time,the mutant F1534S was associated with pyrethroid resistance in Ae.albopictus.
基金This work was supported by National Natural Sciences Foundation of China(No.81371848)the Infective Diseases Prevention and Cure Project of China(No.2017ZX10303404–002).
文摘Background:Arboviral disease transmitted by Aedes albopictus such as dengue fever is an important threat to human health.Pyrethroid resistance raises a great challenge for mosquito control.A systematic assessment of Ae.albopictus resistance status in China is urgently needed,and the study of correlation between pyrethroid resistance and knockdown resistance(kdr)mutations would provide information to guide the control of the Ae.albopictus vector.Methods:Five field populations of Ae.albopictus were collected from Jinan(JN),Hangzhou(HZ),Baoshan(BS),Yangpu(YP)and Haikou(HK),China in 2017.Insecticide-impregnated papers were prepared with four pyrethroid chemicals,deltamethrin,permethrin,beta-cypermethrin and lambda-cyhalothrin.The susceptibility of Ae.albopictus to pyrethroids was tested by the WHO tube assay.Kdr mutations were identified by PCR and sequencing.Moreover,the correlation analysis between kdr alleles and pyrethroid resistance was performed.Results:All five populations of Ae.albopictus showed resistance to four pyrethroid insecticides.One kdr mutant allele at codon 1532 and three at 1534 were detected with frequency of 5.33%(I1532T),44.20%(F1534S),1.83%(F1534 L)and 0.87%(F1534C),respectively.Both 1532 and 1534 mutation mosquitoes were found in the BS and YP populations.Allele I1532T was negatively correlated with deltamethrin resistance phenotype(OR<1),while F1534S mutation was positively correlated with deltamethrin and permethrin resistance(OR>1).Conclusions:The five field populations of Ae.albopictus adults were all resistant to deltamethrin,permethrin,betacypermethrin and lambda-cyhalothrin.Mutant F1534S was clearly associated with pyrethroid resistance phenotype in Ae.albopictus and this could be developed as a molecular marker to monitor the pyrethroid resistance problem in China.
