Integrative approach by biologists increases accuracy of mosquito vector surveillance

Date:
August 20, 2021
Source:
National University of Singapore
Summary:
A team of researchers has developed an integrative approach that
increases the accuracy of mosquito surveillance and management. The
two- pronged strategy boosts accuracy in sampling by including
mosquito larvae, and species identification using short DNA
sequences.



FULL STORY ==========================================================================
A team of researchers from the National University of Singapore (NUS),
led by Assistant Professor Nalini Puniamoorthy from the Department of Biological Sciences, has developed an integrative approach that increases
the accuracy of mosquito surveillance and management.


==========================================================================
Many vector-borne diseases are transmitted by blood-sucking flies, such
as mosquitoes. Understanding the transmission risks of such diseases
requires knowledge of potential vectors in the area, including information
on vector diversity and abundance. In their study, the researchers
demonstrated the limitations of standard mosquito community surveillance methods and identification techniques which lead to inaccurate reflections
of mosquito community structures across different habitats.

To address this, the researchers took an integrative approach
comprising a two- pronged strategy to boost accuracy in sampling by
including mosquito larvae, and species identification using short DNA sequences, known as mini-barcodes, generated from a high technology
Next Generation Sequencing (NGS) platform. The enhanced data accuracy
can reduce error cascades in downstream analyses for both ecological
studies and vector surveillance. The approach can potentially be applied
to other blood-sucking flies of medical interest such as biting midges
and sandflies as well.

The findings were published in the Journal of Applied Ecology on 5
August 2021.

Reducing error cascades by enhancing data accuracy Traditional estimates
of mosquito diversity are typically based on adult female trapping
methods targeting host-seeking species. However, these may represent
a biased snapshot of an area's mosquito community structure as larval
stages are overlooked.

Including mosquito larvae sampling in various field sites in Singapore
improved overall diversity estimates by 38 per cent compared to a
sample comprising adult-only data. The enhanced estimate contributes to baseline knowledge on potential vectors in Singapore as some of these
mosquito species have been found to harbour various pathogens in other countries. Sampling larvae also facilitates targeted management of
mosquito species at the larval stage.

Identification of mosquitoes using traditional surveillance methods
based on external characteristics also poses a challenge due to physical similarities between different species, as well as variations within
individual species. The team employed a variety of sampling methods to
target both adult and larval mosquitoes, and demonstrated that the use
of mini-barcodes can differentiate species such as Aedes(Downsiomyia), Anopheles barbirostris complex and Culex (Lophoceraomyia) that are
challenging to identify based on adult appearances alone. The NUS
researchers were the first to successfully use the mini-barcodes on
mosquitoes, and show its utility to reduce misidentification in species estimation. Their results led to more accurate reports on species
diversity and the facilitation of vector control efforts, especially
for medically-relevant insect groups. In addition, damaged specimens
can be processed and identified using mini-barcodes, unlike standard surveillance methods.

Navigating a fragmented landscape "Rapid urbanisation and land use
changes in Singapore have resulted in a highly fragmented landscape
which increases contact zones between forests and densely populated urban spaces. Our approach plays a crucial role to enhance understanding of the diversity and composition of different species, and can help facilitate early-warning detection and design of suitable management strategies,"
said Asst Prof Nalini.

She and her team plan to study how diseases are transmitted
through mosquitoes, by looking at the reproductive traits of these
species. Specifically, they are using population genomics tools to study
the migration of species that occur in environments such as urban spaces
as well as those that occur primarily in forests but may have invaded semi-urban environments due to habitat loss.

The researchers also plan to conduct further studies on scaling up
species identification capabilities using DNA barcoding and industry applications for the integrated approach.

========================================================================== Story Source: Materials provided by
National_University_of_Singapore. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Huiqing Yeo, Tze Xuan Yeoh, Huicong Ding, Theodore Tze Ming Lee,
Nalini
Puniamoorthy. Morphology and mini‐barcodes: The inclusion of
larval sampling and NGS‐based barcoding improves robustness
of ecological analyses of mosquito communities. Journal of Applied
Ecology, 2021; DOI: 10.1111/1365-2664.13966 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210820111039.htm

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