| Aedes albopictus is an important vector of mosquitoes and blood-sucking harassment mosquitoes that transmits a variety of viruses,including dengue virus,Zika virus,chikungunya virus,yellow fever virus and other mosquito-borne viruses.At present,dengue fever has become a global public health concern,and it is also an arboviral infectious disease with rapid transmission rate and high incidence rate.The best strategy to prevent and control the spread of mosquito-borne infectious diseases,such as dengue fever,is the monitoring and control of vector mosquitoes.In China,Ae.albopictus is an important vector of dengue fever,and systematic work has been carried out for the monitoring and control of Ae.albopictus,but it still faces great challenges in practice.Compared with other vector organisms,Ae.albopictus has a stronger ecological niche plasticity and a wider range of temperature adaptation.In the early stage,it mainly breeds in the natural containers at the forest edge,and has now adapted to the urban environment.As the distribution range of Ae.albopictus is getting bigger and bigger,the increase of traffic and trade,climate warming and many other reasons have put forward new requirements for Ae.albopictus prevention and control.Especially in large cities with high population density and extensive Ae.albopictus breeding sites,Ae.albopictus remains a priority for the prevention and control of dengue fever and other mosquito-borne infectious diseases.Therefore,the study of population density,distribution and genetic population characteristics of Ae.albopictus vectors in population cluster areas has important public health significance for the development of mosquito control measures and disease warning.In this study,we took the mega-city of Shanghai as the study site,and studied the Ae.albopictus population in terms of population density,distribution characteristics and genetic population differentiation of the mosquito.Based on the existing mosquito routine monitoring data,the spatial distribution of Ae.albopictus was further spatially analysed at the street and town scales with the global spatial correlation,local spatial autocorrelation and spatial-temporal displacement model(The Space-time permutation model.A Poisson regression model with geographically weighted Poisson regression(GWPR)was used to study the spatial relationship between the abundance of Aedes populations and meteorological and environmental factors,and to analyze the effects of meteorological and environmental factors on the number of A.albopictus in streets and towns.For A.albopictus larvae,the pathway index,Brechart index and container index are commonly used for correlation studies.Based on simulated manual walking by Python code,a new method of monitor mosquito density using Monte Carlo simulated path sampling was established.And the absolute error and sampling efficiency of the spatial sampling results are calculated to explore the applicable scope of the index.To assess the genetic differentiation of Ae.albopictus populations in different years from the perspectives of population genetic structure,diversity and dispersal by using a combination of mitochondrial COI and ND5 genes and microsatellite loci.The main results of this study are as follows:1.Spatial distribution of Ae.albopictus : Based on the data of Ae.albopictus monitored by the carbon dioxide(CO2)mosquito trapping lamp method in Shanghai from 2018 to 2020,we explore the degree of spatial aggregation of Ae.albopictus distribution at the level of Shanghai city and towns.and make a visual display.We analyzed the regional and spatial structure of the aggregation of Ae.albopictus,and reveal the characteristics of the spatio-temporal distribution of Ae.albopictus.By matching the density data of Ae.Albopictus with the electronic maps of Shanghai towns and cities,we constructed a Geographic Information System(GIS)database for the study,and used global autocorrelation in spatial aggregation analysis,local autocorrelation analysis and Satscan spatio-temporal scanning statistical methods to study the spatial aggregation of Ae.albopictus,and the results were displayed through the visualization of Arc GIS.The results of global autocorrelation of Aedes distribution from 2018 to 2020 were statistically significant(Moran’s I> 0,P <0.05),suggesting that the spatial distribution of Ae.albopictus was spatially clustered.The results of local autocorrelation analysis and Satscan spatio-temporal scanning showed that the areas of aggregation of Ae.albopictus density occurred in different years were slightly different,and the 2018 In 2018,there were 9 "high-high" aggregations,4 "high-low"aggregations,3 "low-high" aggregations,and 17 "low-low" aggregations." clusters had 17;in 2019 there were six "high-high" clusters,four "high-low" clusters,seven"low-high" clusters,and seven In 2020,there are 18 "high-high" clusters,3 "high-low"clusters,7 "low-high" clusters,and 21 "low-low" clusters;in 2020,there are 18"high-high" clusters,3 "high-low" clusters,6 "low-high" clusters,and 6 "low-high"clusters.In 2020,there are 18 "high-high" clusters,3 "high-low" clusters,6 "low-high"clusters,and 20 "low-low" clusters.However,in terms of the regional environment,they are mainly concentrated in the suburban areas of Shanghai,as shown in the areas adjacent to the Outer Ring Road.In terms of time scale,the high-density aggregation of Ae.albopictus in peri-urban areas mainly occurred around August.2.Research on the influence of meteorological and environmental factors on the characteristics of Ae.albopictus populations: This part of the study intends to further study the meteorological and environmental factors affecting Ae.albopictus populations,to explore the relationship between Ae.albopictus populations and meteorological and environmental indicators,and to analyse the influence of meteorological and environmental factors on spatial and temporal variations in the abundance of Ae.Albopictus populations.The study mainly collected monitoring data from mosquito ovitraps(MOTs)during the peak season of Ae.albopictus in July-September in Shanghai,and used Poisson regression model and GWPR model to investigate the relationship between the abundance of Ae.albopictus populations and the meteorological and environmental indicators at the street and town levels.The influence of meteorological factors on Ae.albopictus at the urban scale was complex,with a core-periphery pattern of temperature effects,which positively influenced mosquito abundance in some towns located in the urban core.The effect of relative humidity was not significant.Precipitation was not significantly associated with Ae.albopictus numbers in August and September,but there was a trend towards a positive effect in July.Although the effect of precipitation on MOI was not significant in most of the towns in July and September,the variable had a significant positive effect on mosquito density in a large number of towns with high precipitation.This implies that at relatively low levels of precipitation,an increase in precipitation does not necessarily increase mosquito density.In the factor of environmental variables,the dominant environmental variables were more stable in urban areas than in suburban areas.In urban areas,Normalised Vegetation Index(NDVI)was the most important environmental variable affecting mosquito populations,while in suburban areas,mosquito populations were most significantly affected.NDVI,road length,housing price and number of inhabitants positively affected mosquito density over a three-month period at the 99% significance level.The coefficients for road length and housing price were negative.House price was the main variable in some towns located in peri-urban areas where sanitation conditions are relatively poor,and this may increase the chances of mosquito breeding.Therefore,more resources should be allocated to the relatively economically backward streets and towns for mosquito vector control in actual mosquito control efforts.3.Ae.albopictus route index spatial sampling method study: In an area of the suburban junction of Shanghai,a new method to monitor mosquito density using Monte Carlo simulated path sampling,based on Python code,was established to obtain more sample size and preliminarily analyze the influence of different path sampling methods on the monitoring results.Using Monte Carlo simulation of 1000 route index surveys.Similarly,taking the sampling density as the absolute error of <2.50 as an example the simple random sampling method needs to walk through at least 150 buildings,while the left and right spatial sampling method only needs to walk through 100 buildings,which significantly reduces the sample size required for monitoring and improves the monitoring efficiency.4.Microsatellite-based detection of Ae.Albopictus genetic population characteristics: In 2020,the number of alleles(na)of Ae.albopictus populations in nine districts of Shanghai ranged from 2.889 ± 0.928(MH)～ 12.111 ± 4.961(CM),and the effective alleles(ne)ranged from 2.393 ± 0.811(MH)～ 4.834 ± 1.808(SJ),and the diversity index ranged from 0.889 ± 0.396(MH)～ 1.780 ± 0.383(SJ).Except for Minhang District(MH)where the observed heterozygosity(Ho = 0.611 ±0.373)was greater than the expected heterozygosity(He = 0.523 ± 0.217),the observed heterozygosity of Ae.albopictus populations in the other eight districts(0.465 ± 0.187 ～ 0.567 ± 0.211)was significantly lower than the expected heterozygosity(0.704 ± 0.167 ～ 0.765 ± 0.096).0.096).Meanwhile,except for Ae.albopictus in Minhang District(CM),the degree of self-hybridization of Ae.albopictus in all other eight districts reached a significant level and all populations significantly deviated from the Harwin equilibrium.The populations of Ae.albopictus in Chongming(CM),Jinshan(JS),Hongkou(HK),Fengxian(FX)and Qingpu(QP)districts spread to each other and the Nm values were higher than 0.6,while the populations of Baoshan(BS)and Qingpu(QP)districts,Hongkou(HK)and Songjiang(SJ)districts.Huangpu(HP)and Songjiang(SJ)districts spread to each other in a unidirectional way with the Nm values 0.49,0.71 and 0.67,respectively.Ae.albopictus populations evolved into four molecular clusters,which also coincided with the DAPC analyses.Ae.albopictus populations in Minhang(MH)were significantly discrete from those of other districts in Cluster I,and those of the other eight districts were discrete in Cluster II(JS,CM and FX)in Quadrant 4,Cluster III(HP,SJ,HK and QP)in Quadrants I and II,and Cluster IV(BS)in Quadrant III,respectively.Meanwhile,the results of UGPMA analysis also indicated that the Ae.albopictus populations in these nine zones evolved into four clustered branches.The results of the stepwise mutation model(S.M.M.)showed that among these nine Ae.albopictus populations,all eight districts,except for the Ae.albopictus population in Minhang district(MH),showed significant bottleneck effects.The allele number(na)of Ae.albopictus populations in seven districts of Shanghai in 2022 was between 9.125 ± 2.357(CM)～ 10.500 ±4.629(QP),effective alleles(ne)ranged from 3.929 ± 1.069(BS)～ 4.513 ± 2.159(HK),and diversity indices ranged from 1.598 ± 0.326(CM)～ 1.693 ± 0.313(HP).The expected heterozygosity of Ae.albopictus populations of 7 districts(The expected heterozygosity(He)of Ae.albopictus populations in the seven zones ranged from 0.742 ± 0.083 to 0.753 ± 0.076 was significantly higher than the observed heterozygosity(Ho)which ranged from 0.530 ± 0.200 to 0.664 ± 0.244.Albopictus had a significant selfing level in all areas and all groups significantly deviated from Harwarm equilibrium(P <0.0001).Bayesian-based population structure analysis showed that Ae.albopictus populations evolved into two molecular groups,which was also consistent with the DAPC analysis,in which Ae.albopictus populations in Baoshan District(BS)were mainly distributed in the second quadrant and Ae.albopictus populations in the other districts were significantly discrete into separate evolutionary branches.Meanwhile,the results of UGPMA analysis also showed that Ae.albopictus populations in these seven districts evolved into two clustered branches,in which Ae.albopictus populations in Baoshan District clustered into a single Cluster I,while Ae.albopictus populations in Chongming District(CM),Hongkou District(HK),Fengxian District(FX),Huangpu District(HP),Songjiang District(SJ)and Qingpu District(QP)clustered into one branch.As a result of Ae.albopictus dispersal,the Ae.albopictus populations in each region mainly came from the unidirectional dispersal of Ae.albopictus in Chongming District(CM),and the Nm values were all higher than0.44;meanwhile,there was mutual dispersal among the Ae.albopictus populations in Qingpu District(QP),Hongkou District(HK),Baoshan District(BS),and Songjiang District(SJ),and the Nm values were all higher than 0.38.Among the seven Ae.albopictus populations,,except for Ae.albopictus populations in Chongming District(CM),the other six districts showed significant bottleneck effects.5.Population characteristics of Ae.albopictus based on mitochondrial detection:The results of population diversity analysis based on the mitochondrial COI gene showed that 35 haplotypes were detected in the Ae.albopictus population in Shanghai in2020,and the haplotype diversity(Hd)ranged from 0.0510 to 0.6079.Among them,except for Baoshan District(BS)and Minhang District(MH),all the other areas had haplotypes greater than five.In 2022,a total of 60 haplotypes were detected in Ae.albopictus in Shanghai,and the haplotype diversity(Hd)ranged from 0.3377 to0.5836.Among them,except for Baoshan District(BS),Chongming District(CM)and Hongkou District(HK),the haplotypes of Ae.albopictus population in other regions were greater than 10.Based on the population diversity analysis of mitochondrial ND 5gene,we showed that 12 haplotypes were detected in the population of Ae.albopictus in Shanghai in 2020,and the haplotype diversity(Hd)ranged from 0.0000 to 0.2160.While 7 haplotypes were detected in the 2022 Shanghai with the Hd ranging from0.0000 to 0.1071.The results of the mitochondrial COI gene-based Ae.albopictus population structure dispersal indicated that Ae.albopictus populations in Baoshan District(BS),Chongming District(CM),Qingpu District(QP),Fengxian District(FX),Jinshan District(JS),Huangpu District(HP),and Hongkou District(HK)of Shanghai in2020 showed significant population expansion(P < 0.05),with population dispersal reaching the differential level in Chongming District(CM),Qingpu District(QP),Fengxian District(FX),and Hongkou District(HK).The Tajima’ D index of Ae.albopictus populations in seven districts of Shanghai in 2022 was in the range of-2.6061 ～-1.8487,and the P-values of Ae.albopictus populations in all the districts reached the significant level(P < 0.05);meanwhile,the Fu’s Fs indices of Ae.albopictus populations were in the range of-6.8905 ～-2.0028,except for Chongming District(CM)and Songjiang District(SJ),the P-values of Ae.albopictus populations in other areas reached significant levels(P < 0.05).Conclusion: In this study,the spatial distribution of Ae.Albopictus population was analysed using spatial statistics in Shanghai,and it was found that the density of Ae.albopictus showed spatial aggregation on the spatial scale in the towns,and that the high density of Ae.albopictus mainly occurred around August on the temporal scale;the influence factors of Ae.albopictuswere investigated using the global Poisson regression model and the geographically-weighted Poisson regression model,and the influence of the meteorological factors on the population density was complex.It was found that meteorological factors had a complex impact on Ae.albopictus population density,while environmental variables had a relatively uniform impact on Ae.Albopictus population density,NDVI and Ae.albopictus distribution were correlated,and roads and house prices were negatively correlated with Ae.albopictus population distribution.The path index method based on spatial sampling can obtain more reliable Ae.albopictus monitoring results.Route index and Brett index were positively correlated in single-family residential environments.Using microsatellite DNA and mitochondrial DNA as research tools,it was found that the dispersal mode of Ae.albopictus was correlated with the mode of human flow and logistics in the dispersal area under anthropogenic disturbance. |
PDF Full Text Request