| Objective1.In order to provide scientific reference for the sustainable control of Aedes albopictus and to assess the risk of occurrence,transmission and epidemic of dengue fever by establishing the background database and investigating the population density,distribution,habitat type and the seasonal fluctuation of the Aedes albopictus in Dapeng new area of Shenzhen City.2.To investigate the resistance status of adult Aedes albopictus against three types(pyrethroid,organophosphorus and carbamate)of commonly used chemical insecticides and provide a scientific basis to use insecticides reasonably and improve the control effect in Dapeng new district of Shenzhen City.3.To master the dengue virus carrying status of the wild Aedes albopictus and to provide predictive and early warning information for the prevention and control of dengue epidemic in the Dapeng new district.Methods1.The special monitoring of the Aedes albopictus was carried out by using mosquito ovipositor trap and the larval density was monitored by using breteau index methods from 2017 to 2018.Meanwhile,the larval samples were collected during the monitoring process for subsequent experimental research.2.The contact tube method,recommended by WHO,was used to identify the resistance level of Aedes albopictusto three types(pyrethroid,organophosphorus and carbamate)of commonly used chemical insecticides.3.Adult Aedes albopictus nucleic acid was extracted by Roche High Pure Viral RNA Kit,and real-time reverse transcriptase polymerase chain reaction technology was used to detect the dengue virus.Result1.Two-year surveille average MOI,MI and OI were 8.45,4.24 and 5.96,respectively.The 2017 average MOI,MI and OI were 7.30,3.53 and 5.18,respectively.The 2018 average MOI,MI and OI were 9.07,4.62 and 6.37,respectively.In 2017,MOI,MI and OI were the highest in parks,the MOI and OI were lowest in hospitals(P < 0.05),the OI was lowest in tourist attractions(P > 0.05)in different habitats.In 2018,the MOI,MI and OI were the highest in parks,the MOI and MI were lowest in tourist attractions and the OI was lowest in hospitals in different habitats(P< 0.05).Aedes albopictus could be detected throughout 2017 and2018 all year round.The seasonal fluctuation trend were single-peak distribution,and the peak occurs in August.The fluctuation ranges of aedes albopictus density,MOI、MI and OI were 0.68-14.44,0.52-7.71 and 0.17-11.88 respectively(2017);MOI、MI and OI are 0.76-23.76,0.34-11.60 and 0.10-17.59 respectively(2018).2.The results of the Aedes albopictus larvae surveilled: a total of 41,390 households and 17,181 dropsy were investigated,1951 the positive were 1951and2514 in two years.The average BI,CI and HI were 6.07,14.63 and 4.71,respectively;7.53,21.77 and 5.61,respectively(2017);5.27,11.63 and 4.22,respectively(2018).Two year surveillance,BI and HI were highest in residential areas and lowest in tourist attractions in different habitats(P<0.05);Temporary containers were the main water containers in different habitats,and the positive rate between the two types of containers was statistically significant(P<0.05),different habitats positive rate between the two types of containers in were statistically significant(P<0.05).In 2017,idle containers were the main breeding containers of the Aedes albopictus.The positive rate of waste tires was the highest in residential areas and tourist attractions,moreover,the positive rate of idle containers was the highest in the external environment(P< 0.01).In 2018,idle containers were the main breeding containers in residential areas and external environment,but the positive rate of waste tires was the highest in residential areas and that the idle containers was the highest in external environment;However,bonsai/aquatic plants containers was the main breeding containers in tourist attractions,the positive rate was the highest whit bamboo head/tree hole/clefts(P<0.01).Larvae could be detected throughout 2017 and2018 all year round,the seasonal fluctuation indexes BI and HI show single peak distribution and the peak appears in August(2017),while the peak appears in July(2018),however,CI shows multi-peak distribution.The BI fluctuation range of the density of larvae in different months was 1.17-15.08(2017)、0.95-11.97(2018).3.Resistance level of adult aedes albopictus in dapeng new area: the mortality rate within 24 h in Kuichong street ranged from 74.11%-98.25%,in which 0.1%deltamethrin,1.4% cis-permethrin and 0.4% cypermethrin were resistant,and the remaining were suspicious or sensitive.The 24 h mortality of Dapeng street ranged from 51.40%-98.25%,in which 0.1% deltamethrin,3% permethrin,1.4%cis-permethrin,0.4% cypermethrin and 0.05% propofol were resistant,and the remaining were suspicious or sensitive.The 24 h mortality rate of the Nanao streets ranged from 69.17%-100%,in which 0.1% deltamethrin,1.4% cis-permethrin and0.4% cypermethrin were resistant,and the remaining were suspicious or sensitive.4.Dengue virus carryiage of Aedes albopictus in dapeng new area: During a high incidence of Dengue fever(4-10 months)on 2018,a total of 8,950 adult Aedes albopictus samples were collected and tested in 305 batches,with an average of 29 samples per batch.One batch of suspected positive results was detected,with a positive batch rate of 0.99% and the lowest infection rate(MIR)of 0.33.Conclusion1.Aedes albopictus is widely distributed in Dapeng new district.Although the population density of has decreased in 2018,but it still at a high level,especially in May to October.Therefore,the job about surveillance,prevention and control of the key areas such as residential areas,parks should be strengthened.2.Aedes albopictus were developed resistance to deltamethrin,cis-cypermethrin and high-efficiency cypermethrin in three streets in Dapeng new area,and the another insecticides were suspicious or sensitive.The chemical suggested that sued the high-efficiency cyhalothrin to replace the pyrethroids above all.3.Dengue virus has tested a batch of suspected positive,suggest that there are existence the risk of dengue fever outbreak in Dapeng areas,should step up the screening of Aedes albopictus for dengue virus carryage,at the same time,according to the surveillance results of mosquito-borne and Dengue infection situation to assess and prevent the risk of dengue fever. |
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