ABSTRACT
BACKGROUND: Shanghai has numerous high-rise apartment and office buildings, but the effects of these high-rise spaces on the vertical dispersal, oviposition and blood feeding behavior of Aedes albopictus are unknown. METHODS: In six multi-story building blocks in downtown Shanghai, 174 mosq-ovitraps (MOT) were placed both indoors and outdoors for Ae. albopictus collection at different vertical heights from the 1st to 6th floors and a terrace on the 8th floor. Collections were made for 4 months. The human landing catch (HLC) method for Ae. albopictus monitoring was also conducted on 6 consecutive days on six floors of two of the six buildings to study the feeding behavior of Ae. albopictus at different heights. RESULTS: Both MOTs and HLCs collected Ae. albopictus at all monitored heights. The vertical distribution, oviposition pattern and biting behavior varied significantly among the seven heights (1st-6th floors and 8th floor) (mosq-ovitrap index (MOI): X2 = 140.616, df = 6, P < 0.001; HLC: F (5, 138) = 15.111, P < 0.001). The MOI at low heights (1st + 2nd floors) was significantly higher than that at medium (3rd + 4th floor, P < 0.001) and high heights (5th + 6th floors, P < 0.001), and there was no significant difference in the MOI for the 3rd-6th floors. The outdoor MOIs were significantly higher than indoor MOIs at all heights (outdoor 23.09% vs. indoor 9.58%, X2 = 74.121, df = 1, P < 0.001). Aedes albopictus HLC density on the ground floor was significantly higher than that on all other heights (5.04 vs. 0.13, 0.29, 0.58, 0.79 and 1.50 per half hour, P < 0.05), while no difference was detected among the heights above the ground floor (P > 0.05). CONCLUSIONS: Aedes albopictus is more common near the ground level, but it can easily disperse to higher floors in the multi-story buildings of urban Shanghai. No significant differences in Ae. albopictus density were detected within the 3rd-6th floors using MOT or HLC. This suggests that Ae. albopictus might also disperse to areas above the 6th floor and seek hosts there. Aedes albopictus prefers to oviposit outdoors; however, Ae. albopictus was also able to inhabit, oviposit and engage in blood-feeding behavior indoors on different floors. The three-dimensional dispersal pattern of Ae. albopictus in urban areas could facilitate arbovirus transmission and increase the difficulty of dengue control.
Subject(s)
Aedes , Dengue , Animals , Female , Humans , China , Feeding Behavior , OvipositionABSTRACT
Objective To determine the seasonal fluctuation and population distribution of Aedes albopictus in Jiading District， and provide scientific evidence for the prevention and control of dengue fever and other Aedes-borne diseases. Methods In 2020， the mosq-ovitrap method and mosq-ovitrap index （MOI） were used to monitor and evaluate the density of Aedes albopictus in Jiading District. Spatial and temporal distribution of Aedes albopictus was determined. Chi-square test was used for statistical analysis. Results In 2020， the annual average MOI was determined to be 4.10， which was under safety threshold. The seasonal fluctuations showed a unimodal distribution， which peaked in July. The fluctuation trend in urban area was similar to the overall trend， while that in the non-urban area showed a bimodal distribution with peaks in June and August. The density of Aedes albopictus at different monitoring sites varied widely，with the highest MOI （6.64） at Anting town and the lowest MOI （2.09） at Huating town. The distribution of Aedes albopictus in different habitats also varied widely； the highest density was observed in environments as waste collection stations and construction sites， with the highest MOI 33.33 in waste collection stations in peak season. The MOI value of Aedes albopictus in residential areas was significantly higher than that in non-residential areas （χ2 = 6.082， P = 0.014）. Conclusion Aedes albopictus is quite common in Jiading District. In certain areas， Aedes density may exceed the safety threshold from May to September. More targeted mosquito control measures should be implemented in waste collection stations， construction sites and residential areas.
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Objective Based on mosq-ovitrap monitoring method of Aedes albopictus， to determine the spatial and temporal distribution of Aedes albopictus in Songjiang District and provide scientific evidence for prevention and control of mosquito-borne diseases. Methods From May to October， 2018‒2020， density of Aedes albopictus was monitored by using the mosq-ovitrap method. Sub-districts and towns were used as the monitoring units and the difference in mosquito ovitrap index （MOI） was compared by seasons， years and habitats. Results The total number of positive mosquito ovitraps was 1049 in 2018‒2020， and the average MOI was 8.10. Four sub-districts/towns in the urban area and the northern area had the relatively high MOIs. Moreover， MOIs in residential and external environments were higher than other habitats. In addition， MOI of Aedes albopictus decreased over years from 2018 to 2020. Conclusion Aedes albopictus is widely distributed in Songjiang District. Although the number of mosquito decreased over years after the implementation of mosquito control measures， reproduction of mosquito remains excessive in some areas and seasons. It is necessary to perform targeted control measures based on comprehensive monitoring methods.
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BACKGROUND: The Mosq-ovitrap (MOT) is currently used for routine surveillance of container-breeding Aedes in China. However, the effectiveness of monitoring Aedes albopictus using the MOT and other mosquito monitoring methods, such as the Ovitrap (OT) and the CO2-light trap (CLT), have not been extensively compared. Moreover, little is known about the spatial-temporal correlations of eggs with adult Ae. albopictus abundance among these three types of traps. METHODS: Comparative field evaluation of MOT, OT and CLT for Ae. albopictus monitoring was conducted simultaneously at two city parks and three residential neighborhoods in downtown Shanghai for 8 months from April 21 to December 21, 2017. RESULTS: Significantly more Ae. albopictus eggs were collected from both MOTs and OTs when traps remained in the field for 10 d or 7 d compared with 3 d (MOT: 50.16, 34.15 vs. 12.38 per trap, P < 0.001; OT: 3.98, 2.92 vs. 0.63 per trap, P < 0.001). Egg collections of MOTs were significantly greater than OTs for all three exposure durations (Percent positive: X 2 = 72.251, 52.420 and 51.429, P value all < 0.001; egg collections: t = 8.068, 8.517 and 10.021, P value all <0.001). Significant temporal correlations were observed between yields of MOT and CLT in all sampling locations and 3 different MOT exposure durations (correlation coefficient r ranged from 0.439 to 0.850, P values all < 0.05). However, great variation was found in the spatial distributions of Ae. albopictus density between MOT and CLT. MOT considerably underestimated Ae. albopictus abundances in areas with high Ae. albopictus density (>25.56 per day â trap by CLT). CONCLUSION: The MOT was more efficient than the OT in percent positive scores and egg collections of Ae. albopictus. The minimum length of time that MOTs are deployed in the field should not be less than 7 d, as Ae. albopictus collections during this period were much greater than for 3 d of monitoring. MOT considerably underestimated Ae. albopictus abundance in areas with high Aedes albopictus density compared to CLT. In areas with moderate Aedes albopictus densities, MOT results were significantly correlated with CLT catches.
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Objective @#To estimate the risk threshold of route index（RI）and mosq-ovitrap index（MOI）based on Breteau index（BI）,as supplements for dengue fever risk monitoring in specific habitats. @*Methods @#Two towns and two streets were selected from nine towns（streets）in Jiashan County,and then one village（community）was selected from each of them as a Aedes albopictus monitoring site. The BI,RI and MOI were employed at the same time and area from April to October in the year 2018. Linear regression models were built with RI,MOI and BI to calculate the dengue risk threshold of RI and MOI according to BI. @*Results @#The linear regression model of BI（X）and RI（Y）was Y=0.145+0.662X（P<0.05）,of BI（X）and MOI（Y）was Y=3.423+0.524X（P<0.05）. If BI=5（having risk of transmission of dengue fever）,then RI=3.455（95%CI：1.717-5.198）,MOI=6.043（95%CI：-0.327-12.417）. If BI=10（having risk of outbreak）,then RI=6.765（95%CI：5.018-8.518）,MOI=8.663（95%CI：2.260-15.071）. If BI=20（having risk of epidemic）,then RI=13.385（95%CI：11.326-15.453）,MOI=13.903（95%CI：6.352-21.461）.@*Conclusion @#The dengue fever risk threshold of RI estimated by BI had a narrow 95%CI and could be applied for dengue fever risk assessment,while the risk threshold of MOI had a wide 95%CI and the application value needed further study.
ABSTRACT
BACKGROUND: The surveillance of vector mosquitoes is important for the control of mosquito-borne diseases. To identify a suitable surveillance tool for the adult dengue vector Aedes albopictus, the efficacy of the BG-Sentinel trap, CDC light trap and Mosquito-oviposition trap (MOT) on the capture of vector mosquitoes were comparatively evaluated in this study. METHODS: The capture efficiencies of the BG-Sentinel trap, CDC light trap and Mosquito-oviposition trap for common vector mosquitoes were tested in a laboratory setting, through the release-recapture method, and at two field sites of Guangzhou, China from June 2013 to May 2014. The captured mosquitoes were counted, species identified and compared among the three traps on the basis of species. RESULTS: In the release-recapture experiments in a laboratory setting, the BG-Sentinel trap caught significantly more Aedes albopictus and Culex quinquefasciatus than the CDC light trap and Mosquito-ovitrap, except for Anopheles sinensis. The BG-Sentinel trap had a higher efficacy in capturing female rather than male Ae. albopictus and Cx. quinquefasciatus, but the capture in CDC light traps displayed no significant differences. In the field trial, BG-Sentinel traps collected more Aedes albopictus than CDC light traps and MOTs collected in both urban and suburban areas. The BG-Sentinel trap was more sensitive for monitoring the population density of Aedes albopictus than the CDC light trap and MOT during the peak months of the year 2013. However, on an average, CDC light traps captured significantly more Cx. quinquefasciatus than BG-Sentinel traps. The population dynamics of Cx. quinquefasciatus displayed a significant seasonal variation, with the lowest numbers in the middle of the year. CONCLUSIONS: This study indicates that the BG-Sentinel trap is more effective than the commonly used CDC light trap and MOT in sampling adult Aedes albopictus and Culex quinquefasciatus. We recommend its use in the surveillance of dengue vector mosquitoes in China.
