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"Seok, Sangwoo"
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Resolving confusion in the native distribution of Aedes (Hulecoeteomyia) koreicus (Diptera: Culicidae)
2024
Recent studies on invasive Aedes koreicus (Edwards 1917) have been conducted to elucidate the source population introduced to Europe. However, current information about the native range of Ae. koreicus is not consistent. The purpose of this study is to resolve confusion in the native distribution of Ae. koreicus by reviewing available literature from the first description of the species in its native range in 1917 to the first invasion in Europe in 2008. Aedes koreicus have been recorded in China, Japan, Korea, and eastern Russia. The 2 existing records of Ae. koreicus from Hokkaido, Japan, however, is likely due to the misidentification of 2 different morphologically similar species, Ae. koreicoides (Sasa, Kano & Hayashi 1950) and Aedes japonicus (Theobald 1901). Upon re-examination of published records, we conclude that the native distribution of Ae. koreicus is confined to continental eastern Asian regions, specifically China, Korea, and eastern Russia.
Journal Article
Pyrethroid insecticide resistance of Aedes albopictus and Aedes aegypti (Diptera: Culicidae) across the Hawaiian Islands
by
Akbari, Omar S.
,
Mathias, Derrick K.
,
Seok, Sangwoo
in
Aedes
,
Aedes - drug effects
,
Aedes - genetics
2025
Background
Aedes albopictus
(Skuse, 1894) and
Aedes aegypti
(Linnaeus, 1762) (Diptera: Culicidae) are invasive species in the Hawaiian Islands as well as other islands of the Pacific and serve as the primary vectors of arboviruses such as dengue virus. Despite its significance to public health, data on their insecticide resistance remains limited. Knowledge of the level of insecticide resistance is critical in developing effective mosquito control strategies, especially when an arboviral disease outbreak occurs.
Methods
This study investigated the phenotypic and genotypic resistance of Hawaiian
Ae. albopictus
and
Ae. aegypti
to permethrin, one of the commonly used pyrethroids. Genomic sequences of 93
Ae. albopictus
samples from four Hawaiian Islands (Kaua‘i, O‘ahu, Maui, and the Island of Hawai‘i) were screened for non-synonymous mutations in the voltage-gated sodium channel (VGSC) gene (chromosome 3: 345,142,499–345,663,668). Phenotypic resistance to permethrin was assessed using a modified Centers for Disease Control and Prevention (CDC) bottle bioassay on
Ae. albopictus
and
Ae. aegypti
collected from two socio-environmentally distinct sites on the Island of Hawai‘i.
Results
Among 4101 single-nucleotide polymorphisms (SNPs) identified in the VGSC region of
Ae. albopictus
genomes from four Hawaiian Islands, 44 were classified as synonymous in the coding DNA sequence (CDS) region. No non-synonymous mutations were found in the CDS region, suggesting an absence of genotypic resistance to pyrethroids in these populations. In phenotypic assays, all individuals from the two
Ae. aegypti
populations and the
Ae. albopictus
population from Miloli‘i were completely knocked down within 10 min of permethrin exposure, indicating that both species remain phenotypically susceptible to permethrin. However, knockdown rates of less than 97% observed in the
Ae. albopictus
population from Kawaihae suggest early signs of the development of phenotypic resistance.
Conclusions
This study is the first to report the phenotypic insecticide resistance profile of Hawaiian
Aedes
mosquitoes. Hawaiian populations of
Ae. albopictus
and
Ae. aegypti
remain susceptible or are in the stage of developing resistance to pyrethroids, as demonstrated by the absence of VGSC mutations and high knockdown rates in permethrin bioassays. While no genotypic and phenotypic resistance was detected in these two
Aedes
species, monitoring for resistance in other mosquito species and through alternative mechanisms is needed.
Graphical Abstract
Journal Article
Population genomics of Aedes albopictus across remote Pacific islands for genetic biocontrol considerations
by
Akbari, Omar S.
,
Jacobsen, Christopher M.
,
Leong, Mark K. H.
in
Aedes - classification
,
Aedes - genetics
,
Aedes - virology
2025
Remote Pacific islands (RPI) are characterized by ecological isolation, diverse endemic species, and vulnerability to invasive organisms due to globalization-driven connectivity. Among these species, Aedes albopictus , a highly invasive vector of flaviviruses, has spread extensively across the RPI via human-mediated dispersal, posing significant health and economic burdens. While the population structure and the degree of gene flow between mosquito populations can inform the dispersal pathways critical for disease vector management, the population genetics of Ae. albopictus in Northern RPI remains understudied. The present work investigated the population structure and connectivity of Ae. albopictus populations from Guam, Hawaiian Islands, and the Republic of the Marshall Islands (RMI) to inform disease and vector-based biosecurity risks and develop targeted management strategies. This is the first assessment to develop and analyze whole genome sequences of Ae. albopictus for RPI, enabling more accurate estimates of differentiation, admixture, and ancestry. We found distinct genetic clustering between regions, distinct ancestry of populations across RPI, and potential invasions that originated from Hawaii and spread into the RMI, and invasions from North America that spread to Guam. These findings can inform biosecurity protocols to limit the invasion of Ae. albopictus and their associated diseases within Hawaii and around the Pacific. Given the significant degree of genetic differentiation, we found between islets, islands, and regions, the genome data from this study can be used to enable the development of locally confined geographically isolated gene drives. These drives may be used to prevent and control outbreaks of dengue, chikungunya, and Zika, diseases that have had devastating consequences in these remote island communities.
Journal Article
The first genome sequence of Anopheles squamous from Macha, Zambia version 1; peer review: 2 approved
by
Collier, Travis C.
,
Simubali, Limonty
,
Norris, Douglas E.
in
Africa
,
Animals
,
Anopheles - genetics
2023
Despite efforts to minimize the impacts of malaria and reduce the number of primary vectors, malaria has yet to be eliminated in Zambia. Understudied vector species may perpetuate malaria transmission in pre-elimination settings.
Anopheles squamosus is one of the most abundantly caught mosquito species in southern Zambia and has previously been found with
Plasmodium falciparum sporozoites, a causal agent of human malaria. This species may be a critical vector of malaria transmission, however, there is a lack of genetic information available for
An. squamosus. We report the first genome data and the first complete mitogenome (Mt) sequence of
An. squamosus. The sequence was extracted from one individual mosquito from the Chidakwa area in Macha, Zambia. The raw reads were obtained using Illumina Novaseq 6000 and assembled through NOVOplasty alignment with related species. The length of the
An. squamosus Mt was 15,351 bp, with 77.9 % AT content. The closest match to the whole mitochondrial genome in the phylogenetic tree is the African malaria mosquito,
Anopheles gambiae. Its genome data is available through National Center for Biotechnology Information (NCBI) Sequencing Reads Archive (SRA) with accession number
SRR22114392. The mitochondrial genome was deposited in NCBI GenBank with the accession number
OP776919. The ITS2 containing contig sequence was deposited in GenBank with the accession number
OQ241725. Mitogenome annotation and a phylogenetic tree with related
Anopheles mosquito species are provided.
Journal Article
Complete mitogenome sequence of Aedes (Hulecoeteomyia) japonicus japonicus from Hawai'i Island
by
Collier, Travis C.
,
Akbari, Omar S.
,
Seok, Sangwoo
in
adults
,
Aedes
,
Aedes japonicus japonicus
2023
We report the first complete mitogenome (Mt) sequence of Aedes japonicus japonicus (Diptera: Culicidae). The sequence was extracted from one adult from the Big Island of Hawai'i Island. The length of the Ae. japonicus japonicus Mt was 16,528bp with 78.1% AT content. Its sequence is most similar to the Mt sequence of Aedes koreicus with 90.81% sequence identity. This is the first full Mt sequence available for this species and provides important genetic resource for studying population genetics and dynamics of this important invasive mosquito species.
Journal Article
Resolving confusion in the native distribution of Aedes
2024
Recent studies on invasive Aedes koreicus (Edwards 1917) have been conducted to elucidate the source population introduced to Europe. However, current information about the native range of Ae. koreicus is not consistent. The purpose of this study is to resolve confusion in the native distribution of Ae. koreicus by reviewing available literature from the first description of the species in its native range in 1917 to the first invasion in Europe in 2008. Aedes koreicus have been recorded in China, Japan, Korea, and eastern Russia. The 2 existing records of Ae. koreicus from Hokkaido, Japan, however, is likely due to the misidentification of 2 different morphologically similar species, Ae. koreicoides (Sasa, Kano & Hayashi 1950) and Aedes japonicus (Theobald 1901). Upon re-examination of published records, we conclude that the native distribution of Ae. koreicus is confined to continental eastern Asian regions, specifically China, Korea, and eastern Russia.
Journal Article
The potential invasion into North America and Europe by non-native mosquito, (Diptera: Culicidae)
2023
Aedes koreicus (Edward, 1917) (Diptera: Culicidae), a mosquito species native to East Asia, has spread to parts of Europe and Central Asia since 2008. The species shares ecological characteristics with Aedes japonicus (Theobald, 1901) (Diptera: Culicidae), which has already successfully invaded and established in North America and Europe. Given these similarities, it is plausible that Ae. koreicus may also invade North America in the future. However, the invasion of Ae. koreicus may be masked or have delayed detection due to their similar morphologies with Ae. japonicus. This study highlights the potential risks of invasion of Ae. koreicus into North America, especially in the northeastern United States, and for further expansion in Europe. We used the maximum entropy model to identify areas with a high likelihood of presence in North America and Europe using comprehensive occurrence records from East Asia, Central Asia, and Europe. We have identified 15 additional countries in Europe and 7 states in the United States that will likely have suitable environments for Ae. koreicus. Additionally, we reviewed the morphological characteristics of Ae. koreicus and Ae. japonicus and provided morphological keys to distinguish the 2 species. Morphological results contradicting previous studies suggested that finding the origin by morphological comparison between Ae. koreicus populations may need re-evaluation. The information presented here will be useful for researchers and public health professionals in high-risk areas to be informed about morphological characteristics to distinguish Ae. koreicus from similar-looking Ae. japonicus. These tools will allow more careful monitoring of the potential introduction of this highly invasive species.
Journal Article
The Potential Invasion Into North America and Europe by non-native mosquito, Aedes koreicus (Diptera: Culicidae)
2023
Aedes koreicus (Edward, 1917) (Diptera: Culicidae), a mosquito species native to East Asia, has spread to parts of Europe and Central Asia since 2008. The species shares ecological characteristics with Aedes japonicus (Theobald, 1901) (Diptera: Culicidae), which has already successfully invaded and established in North America and Europe. Given these similarities, it is plausible that Ae. koreicus may also invade North America in the future. However, the invasion of Ae. koreicus may be masked or have delayed detection due to their similar morphologies with Ae. japonicus. This study highlights the potential risks of invasion of Ae. koreicus into North America, especially in the northeastern United States, and for further expansion in Europe. We used the maximum entropy model to identify areas with a high likelihood of presence in North America and Europe using comprehensive occurrence records from East Asia, Central Asia, and Europe. We have identified 15 additional countries in Europe and 7 states in the United States that will likely have suitable environments for Ae. koreicus. Additionally, we reviewed the morphological characteristics of Ae. koreicus and Ae. japonicus and provided morphological keys to distinguish the 2 species. Morphological results contradicting previous studies suggested that finding the origin by morphological comparison between Ae. koreicus populations may need re-evaluation. The information presented here will be useful for researchers and public health professionals in high-risk areas to be informed about morphological characteristics to distinguish Ae. koreicus from similar-looking Ae. japonicus. These tools will allow more careful monitoring of the potential introduction of this highly invasive species.
Journal Article
Field Evaluation of ln2Care Mosquito Traps to Control Aedes aegypti and Aedes albopictus in Hawai'i Island
by
Seok, Sangwoo
,
Lee, Yoosook
,
Wang, Xiaodi
in
Aedes albopictus
,
Dengue viruses
,
Genetic vectors
2023
Aedes aegypti Linnaeus and Aedes albopictus Skuse are vectors of dengue virus and responsible for multiple autochthonous dengue outbreaks in Big Island, Hawai'i. Control of Ae. aegypti and Ae. albopictus has been achieved in ln2Care trap trials, which motivated us to investigate this potential control approach in the Big Island. Our ln2Care trial was performed in the coastal settlement of Miloli'i in the southwest of Big Island where both Ae. aegypti and Ae. albopictus are found. This trial starting in the second week of July and ending in the last week of October 2019 fell within the traditional wet season in Miloli'i. No significant reduction in egg or adult counts in our treatment areas following 12 wk of two ln2Care trap placements per participating household were observed. In fact, an increase in numbers of adults during the trial reached levels that required the local mosquito abatement program to stop the ln2Care trap trial and institute a thorough source reduction and treatment campaign. The source reduction campaign revealed a large variety and quantity of water sources competed with the oviposition cups we had placed, which likely lowered the chances of our oviposition cups being visited by pyriproxyfen-contaminated Aedes adults exiting the ln2Care traps. Key words: Hawai'i, Aedes aegypti, Aedes albopictus, control, ln2Care
Journal Article
Field Evaluation of ln2Care Mosquito Traps to Control Aedes aegypti and Aedes albopictus
by
Akbari, Omar S.
,
Seok, Sangwoo
,
Lee, Yoosook
in
Aedes albopictus
,
Dengue viruses
,
Genetic vectors
2023
Aedes aegypti Linnaeus and Aedes albopictus Skuse are vectors of dengue virus and responsible for multiple autochthonous dengue outbreaks in Big Island, Hawai'i. Control of Ae. aegypti and Ae. albopictus has been achieved in ln2Care trap trials, which motivated us to investigate this potential control approach in the Big Island. Our ln2Care trial was performed in the coastal settlement of Miloli'i in the southwest of Big Island where both Ae. aegypti and Ae. albopictus are found. This trial starting in the second week of July and ending in the last week of October 2019 fell within the traditional wet season in Miloli'i. No significant reduction in egg or adult counts in our treatment areas following 12 wk of two ln2Care trap placements per participating household were observed. In fact, an increase in numbers of adults during the trial reached levels that required the local mosquito abatement program to stop the ln2Care trap trial and institute a thorough source reduction and treatment campaign. The source reduction campaign revealed a large variety and quantity of water sources competed with the oviposition cups we had placed, which likely lowered the chances of our oviposition cups being visited by pyriproxyfen-contaminated Aedes adults exiting the ln2Care traps.
Journal Article