Mosquitoes (Diptera: Culicidae) are among the most medically significant insects, with several species acting as vectors for human pathogens. Although there are frequent reports of mosquito-borne ...diseases in the border island areas of Thailand, comprehensive data on the diversity and DNA barcoding of these mosquito species remain limited. This study investigated mosquito diversity in two main archipelagos in Thailand—the Trat archipelago (comprising Chang Island and Kood Island) and the Ranong archipelago (comprising Chang Island and Phayam Island)—and generated DNA barcode data from the mosquitoes found there. The survey across these islands discovered a total of 41 species, highlighting the presence of several species known to be vectors for human diseases. Thirty-seven mosquito species from the island areas were documented to provide reference DNA barcode sequences for mosquitoes in Thailand’s island regions. Two species,
Aedes fumidus
and
Finlaya flavipennis
, have been added as new
COI
sequence records in the database. DNA barcoding was highly effective in classifying almost all species by identifying barcoding gaps, except for
Anopheles baimaii
and
Anopheles dirus
, which could not be distinguished. Additionally, the study noted that geographical variations might influence certain mosquito species, such as
Anopheles barbirostris
A3 and
Mansonia dives
, causing them to be split into two distinct subgroups. The findings of this study are crucial, as they aid in classifying mosquito species using molecular techniques and expand our knowledge of disease vectors in these biodiverse regions.
Anopheles baimaii
(Diptera: Culicidae) significantly contributes to the transmission of parasites causing malaria in Southeast Asia and South Asia. This study examined the morphological (wing shape) ...and molecular (mitochondrial gene) variations of
An. baimaii
in four of Thailand’s border islands, and also investigated the presence of
Plasmodium
parasites in these mosquitoes. No
Plasmodium
infections were detected in the samples. Significant differences in wing shape were observed in most island populations (
p
< 0.05). A single-linkage tree, constructed using Mahalanobis distances, clustered the populations into two groups based on geographical locations. Genetic variation in
An. baimaii
was also analyzed through cytochrome
c
oxidase subunit I (
COI
) gene sequences. This analysis identified 22 segregating sites and a low nucleotide diversity of 0.004. Furthermore, 18 distinct haplotypes were identified, indicating a high haplotype diversity of 0.825. Neutrality tests for the overall population revealed a significantly negative Fu’s
Fs
value (-5.029), indicating a population expansion. In contrast, Tajima’s
D
yielded a negative value (-1.028) that did not reach statistical significance. The mismatch distribution analysis exhibited a bimodal pattern, and the raggedness index was 0.068, showing no significant discrepancy (
p
= 0.485) between observed and expected distributions. Pairwise genetic differentiation assessments demonstrated significant differences between all populations (
p
< 0.05). These findings provide valuable insights into the
COI
gene and wing morphometric variations in
An. baimaii
across Thailand's islands, offering critical information for understanding the adaptations of this malaria vector and guiding future comprehensive research.
Mansonia uniformis
(Diptera: Culicidae) is recognized as a vector of
Brugia malayi
and has been reported to transmit
Wuchereria bancrofti
, both causing lymphatic filariasis in humans. This study ...employed geometric morphometrics (GM) to investigate wing shape variation and analyzed genetic diversity through cytochrome
c
oxidase subunit 1 (
COI
) gene analyses in
Ma
.
uniformis
populations across Thailand. Wing GM analyses indicated significant differences in wing shape based on Mahalanobis distances among nearly all population pairs (
p
< 0.05), with no significant correlation between wing shape and geographic distance (
r
= 0.210,
p
> 0.05). Genetic analyses identified 63 haplotypes and 49 polymorphic sites, with the overall population exhibiting a nucleotide diversity of 0.006 (± 0.001) and a haplotype diversity of 0.912 (± 0.017). Deviations from neutrality, as indicated by Tajima’s
D
and Fu’s
FS
tests for the overall
Ma
.
uniformis
populations in Thailand, were statistically significant and negative, suggesting population expansion (both
p
< 0.05). Analysis of molecular variance revealed no significant genetic structure when all populations were categorized based on collection sites and geographic regions. However, significant differences in
F
ST
values were observed between some populations. These findings enhance our understanding of the geographical and genetic factors influencing
Ma
.
uniformis
populations, which are crucial for developing effective control strategies in Thailand.
Abstract
Anopheles
(
Cellia
)
dirus
Peyton & Harrison and
Anopheles baimaii
Sallum & Peyton are sibling species within the Dirus complex belonging to the Leucosphyrus group, and have been ...incriminated as primary vectors of malaria in Thailand. In the present study, DNA barcoding and geometric morphometrics were used to distinguish between
An. dirus
and
An. baimaii
in the international border areas, Trat Province, eastern Thailand. Our results revealed that DNA barcoding based on the cytochrome
c
oxidase subunit I gene could not be used to distinguish
An. dirus
from
An. baimaii
. The overlapping values between intra- and interspecific genetic divergence indicated no barcoding gap present for
An. dirus
and
An. baimaii
(ranging from 0 to 0.99%). However, the results of the geometric morphometric analysis based on the wing shape clearly distinguished
An. dirus
and
An. baimaii
, with 92.42% of specimens assigned to the correct species. We concluded that geometric morphometrics is an effective tool for the correct species identification of these two malaria vectors. Our findings could be used to make entomological surveillance information more accurate, leading to further effective mosquito control planning in Thailand and other countries in Southeast Asia.
Laojun S, Chaiphongpachara T. 2020. Comparative study of larvicidal activity of commercial essential oils from aromatic rosemary, vanilla, and spearmint against the mosquito Aedes aegypti. ...Biodiversitas 21: 2383-2389. Dengue fever is a dangerous mosquito-borne viral disease of humans. This disease is caused by dengue virus, a member of the genus Flavivirus of the family Flaviviridae. The Aedes aegypti mosquito is a principal vector for this virus. To control Ae. aegypti populations, there is extensive focus on larval eradication, because breeding sites are often close to human populations, especially man-made containers. The objective of this research was to evaluate the efficacy of commercial essential oils from rosemary (Rosmarinus officinalis), vanilla (Vanilla planifolia), and spearmint (Mentha spicata) with regard to larvicidal activity against Ae. aegypti larvae after 24 and 48-hours of exposure in the laboratory. The results showed highly efficacious larvicidal activity, with median lethal doses (LC50) of 0.23, 0.10, and 0.12 ppm after 24-hour exposure to commercial rosemary, vanilla, and spearmint oil, respectively. The results of this study will be useful for the control of a common dengue vector and may replace the use of pesticides that may have broad environmental impacts.
There are four species of
mosquitoes in Thailand, including
,
,
, and
The accurate species identification of adult
mosquitoes based on morphological features requires many body parts, including the ...abdominal terga and wing. However, species identification is difficult in the case of damaged specimens when some of their morphological character is missing due to transit or gathering in the field. Thus, we evaluated the efficacy of the landmark-based geometric morphometric (GM) approach for the discrimination of
species in Thailand. In addition, DNA barcoding was also used in parallel with the GM approach to identify the species. Larvae of
were collected, raised into adults, and identified based on their morphological characteristics. The validated reclassification test results clearly demonstrated that wing shape resulted in a high level of success in identification (correct identifications ranged from 92.50% to 100%); however, based on the DNA barcoding analyses, our results showed that it was poorly effective in identifying
and
based on an overlap between the intraspecific and interspecific divergence. Moreover, our survey results provide updates on the distribution of
and
in Thailand. This research will help medical entomologists more efficiently identify mosquitoes in the genus
, resulting in more effective mosquito control and surveillance.
Japanese encephalitis (JE) is a viral infection of the brain caused by the Japanese encephalitis virus, which spreads globally, particularly in 24 countries of Southeast Asia and the Western Pacific ...region. In Thailand, the primary vectors of JE are
,
, and
of the
subgroup. The morphologies of three mosquito species are extremely similar, making identification challenging. Thus, geometric morphometrics (GM) and DNA barcoding were applied for species identification. The results of cross-validation reclassification revealed that the GM technique based on wing shape analysis had relatively high potential for distinguishing
,
, and
(total performance = 88.34% of correctly assigned individuals). While the DNA barcoding yielded excellent results in identifying these
species based on the DNA barcode gap (average intraspecific genetic distance = 0.78% ± 0.39% and average interspecific genetic distance = 6.14% ± 0.79%). However, in the absence of the required facilities for DNA barcoding, GM techniques can be employed in conjunction with morphological methods to enhance the reliability of species identification. Based on the results of this study, our approach can help guide efforts to identify members of the
subgroup, which will be useful for the effective vector control of JE in Thailand.
Abstract Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne virus with a mortality rate of up to 30%. First identified in China in 2009, it was later reported in ...other Asian countries, including Thailand in 2020. SFTSV has been detected in several tick species, including Rhipicephalus sanguineus , known for infesting dogs. We conducted a seroprevalence study of SFTSV in Bangkok and Nong Khai, Thailand, by analyzing 1162 human samples collected between 2019 and 2023. The testing method relied on IgG detection using ELISA and confirmed though a virus seroneutralization test. The results indicated that out of the participants, 12 (1.1%) tested positive for anti-SFTSV IgG antibodies; however, none exhibited positive results in the seroneutralization assay. Additionally, molecular detection of SFTSV, Crimean-Congo hemorrhagic fever (CCHF), Coxiella spp., Bartonella spp., and Rickettsia spp. was performed on 433 Rh. sanguineus ticks collected from 49 dogs in 2023 in Chachoengsao Province, Thailand. No evidence of these pathogens was found in ticks. These findings highlight the importance of exploring viral cross-reactivity. Furthermore, it is important to conduct additional studies to isolate SFTSV from animals and ticks in order to identify the potential transmission routes contributing to human and animal infections in Thailand.
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•Seasonal fluctuations observed in the larval densities of coastal mosquito species Anopheles epiroticus and Culex sitiens in Central Thailand.•Certain water quality factors and ...meteorological parameters in coastal areas influence mosquito vector populations.•Geometric morphometric analysis reveals significant seasonal wing shape variations in both species, highlighting their adaptation to coastal environmental conditions.
Mosquitoes (Diptera: Culicidae) are small hematophagous insects that serve as disease vectors by transmitting pathogens to humans and animals. This study was conducted on the coastline of Samut Songkhram Province in Thailand's central region to evaluate the impact of environmental factors on coastal mosquitoes, namely Anopheles epiroticus and Culex sitiens. A zero-inflated negative binomial (ZINB) regression was employed to assess the relationship between the density of larval mosquitoes and water quality factors. Spearman's rank correlation was used to examine the relationship between the number of adult mosquitoes and meteorological factors, and the geometric morphometric (GM) technique was used to study the wing size and shape of adult mosquitoes throughout different seasons. The ZINB analysis revealed a significant negative relationship (p < 0.05) between dissolved oxygen, high-range phosphate, and the number of An. epiroticus larvae. Conversely, in the case of Cx. sitiens, there was a significant positive relationship between nitrate-nitrogen and larval density (p < 0.01), while dissolved oxygen exhibited a significant negative relationship (p < 0.05). Regarding adult mosquitoes, relative humidity was positively correlated with the abundance of adult Cx. sitiens (r = 0.85, p < 0.01), whereas each meteorological parameter—temperature, relative humidity, rainfall, wind speed, and atmospheric pressure—was negatively correlated with adult An. epiroticus abundance (p < 0.05 for each). The GM analysis revealed statistically significant seasonal variations in wing shapes for both species (p < 0.05 for all seasonal comparisons), underscoring their adaptation to seasonal environmental conditions in coastal habitats.
(
)
Linton & Harbach, a coastal mosquito (also called a brackish mosquito), is a secondary vector species of malaria distributed throughout eastern and southern regions of Thailand. This research ...aimed to investigate the differences of wing size and shape of this female
species in Samut Songkhram Province, Thailand occurring over time between 2015 and 2017.
Coordinates of 13 landmarks were selected and digitized. Centroid size (CS) was used to estimate wing size. Shape variables were used to estimate wing shape and were calculated from the Generalized Procrustes Analysis following principal components of the partial warp. The statistically significant differences of the average wing size based on CS and wing shape based on Mahalanobis distances in each year were estimated using the non-parametric permutation testing with 1,000 cycles after Bonferroni correction with a significance level of 0.05 (
< 0.05).
The
population in year 2016 had the highest average (3.61 mm), and the population in year 2017 had the lowest (3.47 mm). In this study, there was no difference in the size of wing between
population in the years 2015 and 2016 (
> 0.05). The
population in year 2017 was significantly smaller than the population in the years 2015 and 2016 (
< 0.05). All pairwise comparisons of wing shape Mahalanobis distances were significantly different in year 2017 compared with 2015 and 2016 (
< 0.01).
These results indicate differences of wings occur over time that affect the morphological variability of
. The differences in weather conditions in each year affect the adaptive and morphological changes of mosquitoes in coastal areas.
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