Dataset Information

Aedes aegypti container preference for oviposition and its possible implications for dengue vector surveillance in Delhi, India.

ABSTRACT:

Objectives

Dengue is a mosquito-borne viral disease globally transmitted by Aedes aegypti. The most effective method to prevent the transmission of the disease is proficient vector control. Understanding the breeding behaviour of the responsible vectors is very pertinent in this regard; therefore, the present study was conducted to understand Ae. aegypti behaviour regarding the selection of containers for oviposition in the megacity of Delhi.

Methods

A household survey in different localities within Delhi was carried out during 2018-2019. All available containers were inspected for the presence of immature Ae. aegypti. In entomological surveillance, the ovipositional preference of Aedes was computed using the breeding preference ratio, container index in the field, and laboratory settings, and associations of dengue cases with monthly variation in environmental factors and container type were also calculated.

Results

The household larval survey in 40 localities showed that 40% of 27,776 water-holding containers in 3,400 houses were plastic, followed by overhead tanks (26.2%), and coolers (12.1%). The most preferred breeding habitat was clay pots (9.3%), followed by metallic containers (8.5%) and solid waste (7.1%). A laboratory-based study showed that Aedes preferred clay containers (81.8%) over 4 other types of containers (plastic, paper, metal, and glass).

Conclusions

The present study provides a rationale for using clay containers as a possible surveillance tool (ovitraps) or as a vector control tool. This information might aid researchers in developing novel traps and targeting preferred containers for larval control activities during transmission and non-transmission seasons.

SUBMITTER: Prasad P

PROVIDER: S-EPMC10728616 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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Publications

Aedes aegypti container preference for oviposition and its possible implications for dengue vector surveillance in Delhi, India.

Prasad Pooja P Lata Suman S Gupta Sanjeev Kumar SK Kumar Pawan P Saxena Rekha R Arya Deepak Kumar DK Singh Himmat H

Epidemiology and health 20230823

<h4>Objectives</h4>Dengue is a mosquito-borne viral disease globally transmitted by Aedes aegypti. The most effective method to prevent the transmission of the disease is proficient vector control. Understanding the breeding behaviour of the responsible vectors is very pertinent in this regard; therefore, the present study was conducted to understand Ae. aegypti behaviour regarding the selection of containers for oviposition in the megacity of Delhi.<h4>Methods</h4>A household survey in differen ...[more]

PMID: 37641822

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Project description:BackgroundBecause no dengue vaccine or antiviral therapy is commercially available, controlling the primary mosquito vector, Aedes aegypti, is currently the only means to prevent dengue outbreaks. Traditional models of Ae. aegypti assume that population dynamics are regulated by density-dependent larval competition for food and little affected by oviposition behavior. Due to direct impacts on offspring survival and development, however, mosquito choice in oviposition site can have important consequences for population regulation that should be taken into account when designing vector control programs.Methodology/principal findingsWe examined oviposition patterns by Ae. aegypti among 591 naturally occurring containers and a set of experimental containers in Iquitos, Peru. Using larval starvation bioassays as an indirect measure of container food content, we assessed whether females select containers with the most food for their offspring. Our data indicate that choice of egg-laying site is influenced by conspecific larvae and pupae, container fill method, container size, lid, and sun exposure. Although larval food positively influenced oviposition, our results did not support the hypothesis that females act primarily to maximize food for larvae. Females were most strongly attracted to sites containing immature conspecifics, even when potential competitors for their progeny were present in abundance.Conclusion/significanceDue to strong conspecific attraction, egg-laying behavior may contribute more to regulating Ae. aegypti populations than previously thought. If highly infested containers are targeted for removal or larvicide application, females that would have preferentially oviposited in those sites may instead distribute their eggs among other suitable, previously unoccupied containers. Strategies that kill mosquitoes late in their development (i.e., insect growth regulators that kill pupae rather than larvae) will enhance vector control by creating "egg sinks," treated sites that exploit conspecific attraction of ovipositing females, but reduce emergence of adult mosquitoes via density-dependent larval competition and late acting insecticide.

Project description:Dengue is the most prevalent arboviral disease world-wide and its primary vector is the mosquito Aedes aegypti. The current lack of commercially-available vaccines makes control of vector populations the only effective strategy to prevent dengue transmission. Aedes aegypti geographic populations exhibit great variability in insecticide resistance and susceptibility to dengue infection. The characterization of single nucleotide polymorphisms (SNPs) as molecular markers to study quantitatively this variation is needed greatly because this species has a low abundance of microsatellite markers and limited known restriction fragments length polymorphisms (RFLPs) and single-strand conformation polymorphism (SSCP) markers.We used RNA-seq to characterize SNPs in three Ae. aegypti strains, including the Liverpool (LVP) strain, from which the current genome annotation is derived. We identified 131,764 unique genome locations with at least one alternative nucleotide to what is reported in the reference annotation. These comprised changes in both open-reading frames (ORFs) and untranslated regions (UTRs) of transcripts. An in depth-look at sequence variation in immunity genes revealed that those associated with autophagy, MD2-like receptors and Peptidoglycan Recognition Proteins had more sequence variation in their 3'UTRs than mutations associated with non-synonymous changes. This supports the conclusion that these genes had maintained their functional specificity while being adapted to different regulatory domains. In contrast, a number of peroxidases, serpins and Clip-domain serine proteases exhibited conservation of putative UTR regulatory sequences while displaying diversification of the ORFs. Transcriptome evidence also was found for ~2500 novel transcriptional units (NTUs) not annotated in the reference genome.The transcriptome-wide assessment of within and inter-strain polymorphisms in Ae. aegypti adds considerably to the number of molecular markers available for genetic studies in this mosquito. Additionally, data supporting NTU discovery emphasizes the need for continuous amendments of the reference genome annotation.

Project description:BackgroundMosquitoes belonging to genus Aedes are the prime vectors of several arboviral diseases such as Dengue, Zika and Chikungunya worldwide. Every year numerous cases of dengue infections occur throughout the world, proper control of which depends on efficient vector control. However the onset of insecticide resistance has resulted in failure of vector control approaches.Principal findingsThis study was carried out to unveil the degree of prevailing insecticide resistance along with its underlying mechanisms among the primary dengue vector in dengue endemic districts of West Bengal, India through standard WHO protocol. It was observed that, the majority of the tested populations were found to possess resistance to more than one insecticide. In adult bioassay, the toxicity levels of the six tested insecticides was found to decrease in the following order: deltamethrin > lambdacyhalothrin > malathion > propoxur > permethrin > DDT. In larval bioassay, one of the tested populations was found to possess moderate resistance against temephos, mortality percentage 92.5% and 79.8% for WHO (0.0200 ppm) and National Vector Borne disease Programme, India recommended dose (0.0125 ppm) respectively. Carboxylesterases were found to be involved in conferring resistance as revealed in synergistic and quantitative assay against temephos in North Dinajpur (NDP) population and malathion in Alipurduar (APD) and Darjeeling (DAR) populations. Similar correlations were also observed in the majority of the tested populations between reduced susceptibilities against pyrethroid insecticides and Cytochrome P450s activity.ConclusionEfficient disease management in this region can only be achieved through proper integrated vector management along with tools to minimize insecticide resistance. This study may help the concerned authorities in the formulation of an effective vector control strategy throughout this region incorporating the knowledge gained through this study.

Project description:Background and objectiveThe study is based on hypothesis that whether continuous entomological surveillance of Ae. aegypti and simultaneous appropriate interventions in key containers during non-transmission (December-May) months would have any impact on breeding of Aedes and dengue cases during the following transmission months (June-November). The impact of the surveillance and intervention measures undertaken during non-transmission months were assessed by entomological indicators namely container index (CI), house index (HI), pupal index (PI) and breteau index (BI).MethodsA total of 28 localities of West Zone of Delhi with persistent dengue endemicity were selected for the study. Out of these localities, 20 were included in study group while other 8 localities were in control group. IEC and various Aedes breeding control activities were carried out in study group in both non-transmission and transmission season whereas control group did not have any such interventions during non-transmission months as per guidelines of MCD. These activities were undertaken by a team of investigators from NIMR and SDMC, Delhi. In control group, investigators from NIMR carried out surveillance activity to monitor the breeding of Aedes mosquito in localities.ResultsComparison of baseline data revealed that all indices in control and study group of localities were comparable and statistically non-significant (p>0.05). In both study and control groups, indices were calculated after pooling data on seasonal basis, i.e., transmission and non-transmission months for both years. The test of significance conducted on all the four indices, i.e., HI, PI, CI, and BI, revealed a significant difference (p<0.05) between the study group and control group during transmission and non-transmission months except in HI. Due to consistent intervention measures undertaken in non-transmission months in study group, reduction in CI, HI, BI and PI was observed 63%, 62%, 64% and 99% respectively during transmission months as compared to control group where increase of 59%, 102%, 73% and 71% respectively. As a result of reduction in larval indices, no dengue case (except one NS1) was observed in study group, whereas 38 dengue cases were observed in control group.ConclusionThrough this pilot study, it is concluded that proper intervention in non-transmission season reduces vector density and subsequently dengue cases in transmission season.

Dataset Information

Aedes aegypti container preference for oviposition and its possible implications for dengue vector surveillance in Delhi, India.

Objectives

Methods

Results

Conclusions

Publications

Aedes aegypti container preference for oviposition and its possible implications for dengue vector surveillance in Delhi, India.

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