Kozo Watanabe

Ehime University · Center for Marine Environmental Studies (CMES)

Protist species are distributed worldwide. The processes that enabled this global distribution are unclear. One possible means is through the oceanic dispersal of freshwater protists, although this has not been investigated in detail to date. Here, the ability of resting cysts to tolerate saline conditions is examined as a possible mechanism that e...

Microbial community inhabiting the intestine of the shrimp (Penaeus monodon) and their surrounding environments (e.g., water and sediment) is considered as a key contributing factor for the sustainable farming of shrimp. Indiscriminate application of antibiotics in aquaculture is a growing concern due to the emergence of antibiotic resistant bacter...

Metabarcoding is a molecular-based tool capable of large quantity high-throughput species identification from bulk samples that is a faster and more cost-effective alternative to conventional DNA-sequencing approaches. Still, further exploration and assessment of the laboratory and bioinformatics strategies are required to unlock the potential of m...

Freshwater biomonitoring is essential for aquatic biodiversity conservation. Advances in high-throughput sequencing allowed parallel sequencing of community samples containing DNA from environmental samples, i.e., metabarcoding. Two approaches of DNA-based method are widely used, bulk-sample metabarcoding the use of bulk tissues such as insects and...

Background: Wastewater surveillance has expanded globally to monitor the spread of infectious diseases. An inherent challenge is substantial noise and bias in wastewater data due to their sampling and quantification process, leading to the limited applicability of wastewater surveillance as a monitoring tool and the difficulty. Aim: In this study,...

The adaptive divergence of Aedes aegypti populations to heterogeneous environments may be a driving force behind the recent expansion of their habitat distribution and outbreaks of dengue disease in urbanized areas. In this study, we investigated the population genomics of Ae. aegypti at a regional scale in Metropolitan Manila, Philippines using do...

The cranefly (Tipuloidea) fauna of the Western Balkans is still poorly known. In this study, occurrence data of 77 species is reported, of which two species are newly recorded for Albania, eight species for Bosnia and Herzegovina, twelve for Croatia, and seven for Slovenia, respectively. A new species, Baeoura neretvaensis Kolcsár & d’Oliveira, sp....

The superfamily Tipuloidea contains the following cranefly families: Cylindrotomidae, Limoniidae, Pediciidae and Tipulidae, with 1267 species known in Europe. Recent studies have increased our knowledge regarding these families substantially, but craneflies still represent an understudied group, even in Europe. A previous paper focused on European...

Ixodid ticks, such as Ixodes ovatus and Haemaphysalis flava , are important vectors of tick-borne diseases in Japan, such as Japanese spotted fever caused by Rickettsia japonica (i.e., the pathogen). This study describes the population genetic structure and gene flow of I. ovatus and H. flava and their Rickettsia infection rates along an altitudina...

Freshwater biodiversity undergoes degradation due to climate change. Researchers have inferred the effects of climate change on neutral genetic diversity, assuming the fixed spatial distributions of alleles. However, the adaptive genetic evolution of populations that may change the spatial distribution of allele frequencies along environmental grad...

Stream ecosystems are spatially heterogeneous, with many different habitat patches distributed within a small area. The influence of this heterogeneity on the biodiversity of benthic insect communities is well documented; however, studies of the role of habitat heterogeneity in species coexistence and assembly remain limited. Here, we investigated...

Chaoborus phantom midges have a cosmopolitan distribution and are often abundant inhabitants of lentic water bodies during their immature stages. Chaoborus punctipennis, a native species of lakes in the USA and Canada, is reported for the first time in the Palaearctic region in Ehime Prefecture, Japan, as invasive taxon. The species is easy to iden...

Wolbachia are maternally transmitted bacteria that are utilized for arboviral disease prevention. Cytoplasmic incompatibility (CI) and viral blocking, two characteristics that make Wolbachia suitable for vector control, both depend on bacterial infection prevalence and density. Although numerous mosquito species naturally harbor Wolbachia, the prev...

Aim Both gene flow and genetic drift can affect the genetic diversity of interacting populations. However, the influence of the complex evolutionary histories of species may be obscured by simplified assumptions about how these roles operate in nature. To examine this issue, we mechanistically explored the relative importance of environment-mediate...

Japanese species of the subgenera Oreophila Lackschewitz and Parormosia Alexander of the genus Ormosia Rondani (Limoniidae) are revised. Two new species Ormosia (Oreophila) komazawai Kato & Kolcsár, sp. nov. and Ormosia (Parormosia) phalara Kato & Kolcsár, sp. nov. are described. The identities of all Japanese species of the two subgenera are clari...

Microbial communities in the hyporheic zone (HZ) are important in self-purification as the riverbed is metabolically active and responsible for the retention, storage and mineralisation of organic matter transported to the surface water. However, studies exploring HZ microbial community responses to disturbances (e.g. floods) remain scarce. Here, w...

Riverine metabarcoding data were obtained from the Takamigawa River, a tributary of the Kinokawa River, in Nara Prefecture (Central Honshu, Japan). We extracted DNA from bulk community samples of aquatic organisms, most of which could not be morphologically identified at species level due to their small body size (0.12 - 2 mm length). A partial cod...

(1) Background: This paper will present an elaboration of the risk assessment methodology by Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH (GIZ), Eurac Research and United Nations University Institute for Environment and Human Security (UNU-EHS) for the assessment of dengue. (2) Methods: We validate the risk assessment model by best-...

Ixodid ticks, such as Ixodes ovatus and Haemaphysalis flava, are important vectors of tick-borne diseases in Japan, such as Japanese spotted fever caused by Rickettsia sp (i.e., the pathogen). This study describes the population genetic structure and gene flow of I. ovatus and H. flava and their Rickettsia infection rates along an altitudinal gradi...

Objective This study examined the knowledge, attitudes, and practices (KAP) of an at-risk population living in Niigata prefecture regarding tick-borne diseases (TBDs) and preventive strategies. Methods A cross-sectional questionnaire-based study was conducted to assess the KAP of the community. Results In total, 186 responses were received. Among...

Using a stable isotope two- and three-source mixing model, we evaluated trophic contributions of reservoir-derived plankton, epilithon, and terrestrial leaves to stream macroinvertebrates at two dam upstream and four dam outlet reaches. We compared four different habitat types co-occurring within the reaches: lotic habitat, bar-head lentic habitat,...

Dengue Hemorrhagic Fever (DHF) is a major mosquito-borne viral disease. Studies have reported a strong correlation between weather, the abundance of Aedes aegypti, the vector of DHF virus, and dengue incidence. However, this conclusion has been based on the general climate pattern of wide regions. In general, however, the human population, level of...

Helopeltis bakeri Poppius is a major insect pest of cacao, Theobroma cacao L. in the Philippines. It is one of the four Helopeltis species endemic to the Philippines, easily recognizable for its sexual dimorphism. Up to date, no developmental biology and host plant list have been recorded for H. bakeri. Here, we report its life history, conduct sur...

It is essential to explore and define the level of taxonomic identification and quantification approaches for diversity and biomonitoring studies, given their potential influence on assessing and interpreting ecological outcomes. This study assessed the response of benthic macroinvertebrate communities to restore and construct gravel bars in a dam-...

A morphological and molecular study of 17 Cylindrotomidae species revealed that the two subspecies of Cylindrotoma distinctissima , the Nearctic C. americana Osten Sacken, 1865, stat. reval. and the Palearctic C. distinctissima (Meigen, 1818), represent separated lineages and consequently are raised to species level. Cylindrotoma japonica Alexander...

Background: Sequential membrane filtration as a pre-processing step for capturing sediment-associated microorganisms could provide good quality and integrity DNA that can be preserved and kept at ambient temperatures before community profiling through culture-independent molecular techniques. However, the effects of sample pre-processing via filtra...

We investigated the effect of habitat heterogeneity within river reaches on macroinvertebrate commu-nity structure at upstream and downstream reaches of dams in Miyagi Prefecture, Japan. We compared environmental conditions and macroinvertebrate community structures among four habitat types, i.e., lotic habitat, bar-head lentic habitat, bar-tail le...

The larva of the Balkan microendemic Isoperla vevcianensis Ikonomov, 1980 (Plecoptera: Perlodidae: Isoperlinae) is described on the basis of larvae associated with adults by means of cox1 sequences similarities. Eggs and everted penis of the male are described for the first time. The larva possessed blunt paraprocts which were previously sharp amon...

Background Bandung, the fourth largest city in Indonesia and capital of West Java province, has been considered a major endemic area of dengue, and studies show that the incidence in this city could increase and spread rapidly. At the same time, estimation of incidence could be inaccurate due to a lack of reliable surveillance systems. To provide s...

The development and evaluation of DNA metabarcoding protocols for haplotype-level resolution require attention, specifically for population genetic analysis, i.e., parallel estimation of genetic diversity and dispersal patterns among multiple species present in a bulk sample. Further exploration and assessment of the laboratory and bioinformatics s...

Background Production, marketability and consumer preference of red tilapia often depends upon the intensity of coloration. Hence, new approaches to develop coloration are now geared to improve market acceptability and profit. This study evaluated the effects of carotenoid-rich diets on the phenotypic coloration, carotenoid level, weight gain and e...

• Comprehensive restoration programs are expected to influence sediment-associated microbial community structure and functional diversity following changes attributed to the restoration of habitat characteristics in the dam-impacted channel. • To address if the construction or recreation of in-channel structures, i.e., gravel bars, by implementing...

The development and evaluation of DNA metabarcoding protocols for haplotype-level resolution require attention, specifically for population genetic analysis, i.e., parallel estimation of genetic diversity and dispersal patterns among multiple species present in a bulk sample. Further exploration and assessment of the laboratory and bioinformatics s...

Exploring and clearly defining the level of taxonomic identification and quantification approaches for diversity and biomonitoring studies are essential, given its potential influence on the assessment and interpretation of ecological outcomes. In this study, we evaluated the response of benthic macroinvertebrate communities to the restoration or c...

Antimicrobial resistance (AMR) is one of the top 10 global public health threats facing humanity, especially in low-resource settings, and requires an interdisciplinary response across academia, government, countries, and societies. If unchecked, AMR will hamper progress towards reaching the United Nations Sustainable Development Goals (SDGs), incl...

Background Wolbachia is the most common bacterial endosymbiont of arthropods, such as the medically important Aedes albopictus and recent reports also detected in Aedes aegypti . Our study showed additional support for the presence of wolbachia in Ae. albopictus and Ae. aegypti using Wolbachia specific markers, wsp , and 16S. Main text This study...

Limoniidae is one of the most species-rich Dipteran families, with 661 reported species in Europe. Despite the fact that the European limoniid crane fly fauna has been studied ever since Carolus Linnaeus, it is still poorly known. In this study, we summarise the taxonomic and faunistic studies of European Limoniidae, which described new species and...

Wolbachia is the most common bacterial endosymbiont of arthropods, such as the medically important Aedes albopictus and Aedes aegypti. Both Wolbachia and mitochondrial DNA are maternally inherited. This study collected 12 adult Aedes albopictus and 359 Aedes aegypti from 183 households in a dengue-prone area, Manila, Philippines, between June and S...

Ixodid ticks (Acari:Ixodidae) are essential vectors of tick-borne diseases in Japan. In this study, we characterized the population genetic structure and inferred genetic divergence in two widespread and abundant ixodid species, Ixodes ovatus and Haemaphysalis flava. Our hypothesis was that genetic divergence would be high in I. ovatus because of t...

Background Dengue is an endemic vector-borne disease influenced by environmental factors such as landscape and climate. Previous studies separately assessed the effects of landscape and climate factors on mosquito occurrence and dengue incidence. However, both factors concurrently coexist in time and space and can interact, affecting mosquito devel...

The aim of the study is to assess the acute oral toxicity of ethanolic extracts of Antidesma bunius (L.) Spreng [Bignay] in ICR mice in accordance to OECD guideline 423. Single doses of Bignay fruit extracts ranging from 500 mg/kg to 2000 mg/kg, as well as a vehicle control, were given orally and monitored for 14 days. We observed that there is no...

Aedes aegypti is inherently susceptible to arboviruses. The geographical expansion of this vector host species has led to the persistence of Dengue, Zika, and Chikungunya human infections. These viruses take advantage of the mosquito’s cell to create an environment conducive for their growth. Arboviral infection triggers transcriptomic and protein...

The virulence and drug resistance of globally prevalent Candida albicans has presented complications toward its control while advances in effective antivirulence drugs remain critical. Emerging methods are now being evaluated to facilitate development of novel therapeutic approaches against this pathogen. This study focuses on the biofilm formation...

Background: Holorusia Loew, 1863 (Diptera: Tipulidae) is a relatively large crane fly genus with a wide distribution in the Afrotropic, Australasian-Oceanian, Eastern Palearctic, Oriental and Nearctic Regions. Although the genus is well known to include the largest crane fly species, the immature stages are, thus far, only described for the larva...

The hallmark of Acute Lung Injury/Acute Respiratory Distress Syndrome (ALI/ARDS) is inflammation-induced alveolar-vascular barrier destruction and neutrophilic infiltration that leads to the formation of cytokines and oxygen radicals. The objective of the study is to investigate the protective and toxicological effects of Antidesma bunius (L.) Spre...

Aedes aegypti is inherently susceptible to arboviruses. The geographical expansion of this vector host species has led to the persistence of Dengue, Zika and Chikungunya human infections. These viruses take advantage of the mosquito’s cell to create an environment conducive for their growth. Arboviral infection triggers transcriptomic and protein d...

DNA metabarcoding is a robust method for environmental impact assessments of freshwater ecosystems that enables the simultaneous multi-species identification of complex mixed community samples from different origins using extracellular and total genomic DNA. The development and evaluation of DNA metabarcoding protocols for haplotype level resolutio...

Background: While early detection and effective control of epidemics depend on appropriate surveillance methods, the Philippines bases its dengue fever surveillance system on a passive surveillance method (notifications from barangay/village health centers, municipal or city health offices, hospitals, and clinics). There is no available mHealth (mo...

Dengue is endemic in tropical and subtropical countries and is transmitted mainly by Aedes aegypti. Mosquito movement can be affected by human-made structures such as roads that can act as a barrier. Roads can influence the population genetic structure of Ae. aegypti. We investigated the genetic structure and gene flow of Ae. aegypti as influenced...

We performed tick surveys in all regions (Kaetsu, Chuetsu, Joetsu, and Sado) of the Niigata prefecture, Japan. A total of 105 field surveys were done from 2016 to 2018 in 41 sites, from north to south, in the prefecture. All 4806 ticks collected were identified and classified by species, sex, and developmental stage. Twelve species were recorded: D...

Background: High water demand accompanied with an unreliable piped water supply has forced urban residents to store water in containers. This situation potentially increases the number of breeding sites for mosquito vectors, such as Aedes. Method: This study aimed to test the hypothesis if piped water connection availability, tap water use, and hig...

Japanese spotted fever, a tick-borne disease caused by Rickettsia japonica, was firstly described in southwestern Japan. There was a suspicion of Rickettsia japonica infected ticks reaching the non-endemic Niigata Prefecture after a confirmed case of Japanese spotted fever in July 2014. Therefore, from 2015 to 2017, 38 sites were surveyed and ricke...

Comperiella calauanica is a host-specific endoparasitoid and effective biological control agent of the diaspidid Aspidiotus rigidus, whose outbreak from 2010 to 2015 severely threatened the coconut industry in the Philippines. Using the maximum entropy (Maxent) algorithm, we developed a species distribution model (SDM) for C. calauanica based on 19...

The population genetic structure of Aedes aegypti (Linnaeus, 1762) has been studied in order to understand its role as an efficient vector. Several studies utilized an integrative approach; to combine genetic and phenotypic data to determine its population structure but these studies have only focused on female populations. To address this particul...

Introduction: Epidemics caused by outbreaks of the dengue virus (DENV) have been prevalent in Indonesia since it was first reported in 1968. Bandung, the capital city of West Java, Indonesia, is one of the regions where dengue is the most prevalent in Indonesia. Since late 2019; however, the coronavirus disease 2019 (COVID-19), caused by severe acu...

Japanese species of the genus Nipponomyia Alexander, 1924 are revised. Two new species, Nipponomyia okinawensis Kolcsár & Kato, sp. nov. and N. yakushimensis Kolcsár & Kato, sp. nov. are described from the Ryukyu Islands. Images of habitus and wings, illustrations of male and female terminalia, and distribution maps are provided for the Japanese sp...

Ixodid tick species such as Ixodes ovatus and Haemaphysalis flava are essential vectors of tick-borne diseases in Japan. In this study, we used the genetic structure at two mitochondrial loci (cox1, 16S rRNA gene) to infer gene flow patterns of I. ovatus and H. flava from Niigata Prefecture, Japan. The ticks were collected in 29 (307 adult I. ovatu...

Japanese species of the genus Ulomorpha Osten Sacken, 1869 are revised and U. amamiana Kato & Kolcsár, sp. nov. and U. longipenis Kato & Kolcsár, sp. nov. are described. A key to the four Japanese species of the genus is provided, with images of habitus and wings, and drawings of their male terminalia. Ulomorpha amamiana Kato & Kolcsár, sp. nov. is...

Background Vector control measures are critical for the prevention and reduction of dengue virus (DENV) transmission. Effective vector control is reliant not only on knowledge of mosquito abundance, but also on the timely and accurate detection of mosquito-borne infection. Mosquito-based virus surveillance programs typically rely on pool-based mosq...

Dengue, caused by the bite of female Aedes mosquitoes is a public health concern in tropical and subtropical countries such as Philippines. Human made structures such as roads can influence the population genetic structure of Ae. aegypti. For this study, we investigated the genetic structure and gene flow of Ae. aegypti as influenced by road in a v...