• The Korean Journal of Malacology
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• v.31 no.1
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• pp.49-59
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• 2015

Eight species of the family Bithyniidae, Bithynia striatula, B. tentaculata, B. siamensis, B. leachi, B. kiusiuensis, B. misella, Bithynia sp. from Nepal, and Gabbia australis were studied for comparison of the radula structure by scanning electron microscope. Radular ribbons of B. siamensis and B. leachi had 60-70 rows, and the other species had 40-50 rows. Teeth of all species studied had symmetrical structure, i.e. a total of seven teeth (one central tooth, and one lateral and two pairs of marginal teeth on each side) in each row were observed. The basic tooth formula of eight bithyniids was 2:1:1:1:2. Numbers and shapes of cusps were slightly differ from individuals or species. The mesocone of the central tooth of B. striatula, B. tentaculata, B. siamensis and Bithynia sp. differed from those of the other species observed.

• The Plant Pathology Journal
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• v.34 no.6
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• pp.555-566
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• 2018

Two rhizobacteria Bacillus aryabhattai H26-2 and B. siamensis H30-3 were evaluated whether they are involved in stress tolerance against drought and high temperature as well as fungal infections in Chinese cabbage plants. Chinese cabbage seedlings cv. Ryeokgwang (spring cultivar) has shown better growth compared to cv. Buram-3-ho (autumn cultivar) under high temperature conditions in a greenhouse, whilst there was no difference in drought stress tolerance of the two cultivars. In vitro growth of B. aryabhattai H26-2 and B. siamensis H30-3 were differentially regulated under PEG 6000-induced drought stress at different growing temperatures (30, 40 and $50^{\circ}C$). Pretreatment with B. aryabhattai H26-2 and B. siamensis H30-3 enhanced the tolerance of Chinese cabbage seedlings to high temperature, but not to drought stress. It turns out that only B. siamensis H30-3 showed in vitro antifungal activities and in planta crop protection against two fungal pathogens Alternaria brassicicola and Colletotrichum higginsianum causing black spots and anthracnose on Chinese cabbage plants cv. Ryeokgwang, respectively. B. siamensis H30-3 brings several genes involved in production of cyclic lipopeptides in its genome and secreted hydrolytic enzymes like chitinase, protease and cellulase. B. siamensis H30-3 was found to produce siderophore, a high affinity iron-chelating compound. Expressions of BrChi1 and BrGST1 genes were up-regulated in Chinese cabbage leaves by B. siamensis H30-3. These findings suggest that integration of B. aryabhattai H26-2 and B. siamensis H30-3 in Chinese cabbage production system may increase productivity through improved plant growth under high temperature and crop protection against fungal pathogens.

• The Plant Pathology Journal
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• v.37 no.1
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• pp.79-85
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• 2021

Chemical and biological agents were evaluated to inhibit Colletotrichum fructicola, Phytophthora cactorum, and Lasiodiplodia theobromae causing strawberry diseases. Mycelial growths of C. fructicola were gradually arrested by increasing concentrations of fungicides pyraclostrobin and iminoctadine tris (albesilate). P. cactorum and L. theobromae were more sensitive to pyraclostrobin compared to C. fructicola, but iminoctadine tris (albesilate) was not or less effective to limit P. cactorum or L. theobromae, respectively. Bacillus siamensis H30-3 was antagonistic against the three pathogens by diffusible as well as volatile molecules, and evidently reduced aerial mycelial formation of P. cactorum. B. siamensis H30-3 growth was declined by at least 0.025 mg/ml of pyraclostrobin. The two fungicides additively inhibited mycelial growths of C. fructicola, but not of P. cactorum and L. theobromae. B. siamensis H30-3 volatiles led to less growth of C. fructicola than one reduced by the fungicides. Taken together, in vitro antimicrobial activities of the two fungicides together with or without B. siamensis H30-3 volatiles may be cautiously incorporated into integrated management of strawberry diseases dependent on causal pathogens.

• The Plant Pathology Journal
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• v.40 no.1
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• pp.1-15
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• 2024

The aim of this study was to isolate biocontrol bacteria that could antagonize brown rot of Dendrocalamus latiflorus, optimize the culture conditions, and develop an effective biocontrol preparation for brown rot of D. latiflorus. This study isolated a bacterium with an antagonistic effect on bamboo brown rot from healthy D. latiflorus rhizosphere soil. Morphology, molecular biology, and physiological biochemistry methods identified it as Bacillus siamensis. The following culturing media and conditions improved the inhibition effect of B. siamensis: the best culturing media were 2% sucrose, 1.5% yeast extract, and 0.7% potassium chloride; the optimal culturing time, temperature, pH, and inoculation amount were 48 h, 30℃, 6, and 20%. The optimum formula of the applying bacterial suspension was 14% sodium dodecyl benzene sulfonate emulsifier, 4% Na₂HPO₄·2H₂O, 0.3% hydroxypropyl methylcellulose thickener, and 20% B. siamensis. The pot experiment results showed the control effect of applying bacterial suspension, diluted 1,000 times is still better than that of 24% fenbuconazole suspension. The applying bacterial suspension enables reliable control of brown rot in D. latiflorus.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.133-145
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• 2005

Eight species of bithyniids, Bithynia leachi, B. tentaculata, B. siamensis, B. misella, B. kiusiuensis, B. striatula, Bithynia sp. from Nepal and Gabbia australis were collected from 1957 to 1988. The samples were relaxed with pentobarbital and fixed with 70% ethyl alcohol. There was no significant difference in internal structure of soft body, except the male reproductive system. The alimentary canal of the bithyniids consisted of mouth, buccal mass, esophagus, stomach, intestine, rectum and anus. The heart consisted of an auricle and a ventricle, located at left side of the stomach in the visceral hump. The ctenidium comprised 40-70 subtriangular lamellae. Eight ganglia were located around upper esophagus. The female reproductive system comprised ovary, oviduct, spermaaheca, and albumin gland. The male reproductive system was composed of testis, seminal vesicle, prostate gland, vas deferens, penial duct, and penis in order. Male was distinguished externally from the female by a bifid penis.

• Parasites, Hosts and Diseases
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• v.51 no.2
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• pp.183-189
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• 2013

The occurrence of 37-collar spined echinostome metacercariae in freshwater snails was investigated in 6 districts of Chiang Mai Province, Thailand, from October 2011 to April 2012. A total of 2,914 snails that belong to 12 species were examined, and 7 snail species (Clea helena, Eyriesia eyriesi, Bithynia funiculata, Bithynia siamensis siamensis, Filopaludina doliaris, Filopaludina sumatrensis polygramma, and Filopaludina martensi martensi) were found infected with echinostome metacercariae. The prevalence of metacercariae was the highest in Filopaludina spp. (38.5-58.7%) followed by B. funiculata (44.0%), E. eyriesi (12.5%), B. siamensis siamensis (8.2%), and C. helena (5.1%). Metacercariae were experimentally fed to hamsters and domestic chicks, and adult flukes were recovered from both hosts at days 15 and 20 post-infection. The adult flukes were identified based on morphological features, morphometrics, host-parasite relationships, and geographical distribution. They were compatible to Echinostoma revolutum or Echinostoma jurini, with only minor differences. As the adults were recovered from both hamsters and chicks, our specimens were more compatible to E. revolutum rather than E. jurini (reported only from mammals). This is the first report for metacercariae of E. revolutum in the snail host, C. helena, and also confirmed that Filopaludina spp., E. eryresi, and Bithynia spp. act as the second intermediate hosts of E. revolutum under natural conditions, which are indigenously distributed in Chiang Mai province.

• Parasites, Hosts and Diseases
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• v.56 no.3
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• pp.247-257
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• 2018

The aim of this study was to conduct a freshwater snail survey in Mae Lao agricultural basin to assess the diversity with a focus on habitat types and their larval trematode infections. Snails were collected and examined in 14 sites of Mae Lao agricultural basin from August 2016 to October 2017. A total of 1,688 snail individuals were collected and classified into 7 families, 8 genera, and 12 species. Snail diversity and habitat types were higher in rice paddies than irrigation canals and streams. The most abundant species was Bithynia siamensis siamensis, representing 54.6% of the sample. Three species of snails act as first intermediate host were found with cercarial infections. They were Filopaludina sumatrensis polygramma, B. s. siamensis, and Melanoides tuberculata. The cercariae were categorized into 7 types; echinostome, monostome, gymnocephalous, virgulate, parapleurolophocercous, pleurolophocercous and megalurous cercariae. Parapleurolophocercous cercariae constituted the most common type of cercariae recovered, contributing 41.2% of all infections in snails. Echinostome metacercariae infections were found in 6 snail species with 7.6% prevalence. In addition, the metacercaria of avian trematode, Thapariella sp. were found in Filopaludina spp. snails and B. funiculata with a prevalence of 0.5%. This is the first report for Thapariella metacercariae in the snail host, B. funiculata, and also confirmed that viviparid and bithyniid snails act as the second intermediate hosts of this trematode. This work will provide new information on the distribution and intermediate host of trematode in this area.

• The Korean Journal of Malacology
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• v.10 no.1
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• pp.19-26
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• 1994

Eight species of the family Bithyniidae, Bithynia tentaculata, B. leachi, B. siaminsis, B manchourica, B misella, B. kiusiuensis, Gabbia australis and a Bithynia wp. collected from Nepal, were studied for their relationship between species. Total 20 characters were employed for the principal component analysis(PCA) and taxonomic distance. G. misella and B. kiusiuensis were closely related and similar to G. australis. B. manchourica, B. tentaculata and B. siamensis relatively closed group, and taxonomic distance of B. leachi was far from the other species.

• Parasites, Hosts and Diseases
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• v.51 no.5
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• pp.537-544
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• 2013

The present study was performed to observe histopathological changes in tissues of Bithynia siamensis goniomphalos (Gastropoda, Bithyniidae) incubated in crude extract solutions of camellia (Camellia oleifera) seed and mangosteen (Garcinia mangostana) pericarp, and furthermore to estimate the molluscicidal effects of 2 plant substances. Substantial numbers of bithyniid snails were incubated in various concentrations of 2 plant solution for 24 hr. As the positive control, snails incubated in various concentrations of niclosamide, a chemical molluscicide, were used. The histopathological findings were observed in sectioned snail specimens of each experimental and control groups. The results showed that both camellia and mangosteen extracts had molluscicidal effects at 24 hr with 50% lethal concentration ($LC_{50}$) at concentrations of 0.003 and 0.002 g/ml, respectively, while niclosamide had $LC_{50}$ at concentrations 0.599 ppm. B. siamensis goniomphalos snail tissues (foot, gill, and digestive system) showed disruption of columnar muscle fibers of the foot, reduction of the length and number of gill cilia, numerous mucous vacuoles, and irregularly shaped of epithelial cells. Irregular apical and calciferous cells, dilatation of the digestive gland tubule, and large hemolymphatic spaces, and irregular apical surfaces, detachment of cilia, and enlargement of lysosomal vacuoles of epidermis were also shown in all groups. By the present study, it is confirmed that 2 plants, camellia and mangosteen, are keeping some substance having molluscicidal effects, and histopathological findings obtained in this study will provide some clues in further studies on their action mechanisms to use them as natural molluscicides.

• Research in Plant Disease
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• v.30 no.2
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• pp.114-123
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• 2024

In July 2022, stem rot symptom was found in a peony plant grown in a pot under a greenhouse at Jinju, Gyeongnam Province, South Korea. Two fungal species were isolated from the infected peony stems and cultured on 1/2-strength potato dextrose agar for identification. The morphological characteristics of the fungal isolates were examined, and nucleotide sequences of the internal transcribed spacer region, β-tubulin and translation elongation factor 1-α were analysed. The pathogenicity of the two isolates was confirmed in detached peony leaves, according to Koch's postulates. To our knowledge, this is the report of Neopestalotiopsis clavispora and Sclerotinia sclerotiorum as the causal agents of peony stem rots. Antifungal activity of chemical fungicide propineb and rhizobacterium Bacillus siamensis H30-3 was shown against the two plant pathogenic fungi N. clavispora and S. sclerotiorum.Unidentified diffusible and volatile compounds from B. siamensis H30-3 could suppress in vitro mycelial growths of N. clavispora JJ 8-2-1 and S. sclerotiorum JJ 8-2-2.