Forestry and Fisheries Promotion Center

Ishigaki, Japan

Forestry and Fisheries Promotion Center

Ishigaki, Japan

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China M.,Forestry and Fisheries Promotion Center | Nakamura H.,Okinawa Prefectural Sea Farming Center | Hamakawa K.,Okinawa Prefectural Fisheries Research and Extension Center | Tamaki E.,Okinawa Prefectural Sea Farming Center | And 4 more authors.
Fish Pathology | Year: 2013

In 2008, the myxosporean emaciation disease was found in cultured Malabar grouper Epinephelus malabaricus in a fish farm in Okinawa Prefecture, Japan. The disease occurred in winter when water temperature ranged from 21 to 26°C, and the cumulative mortality reached 20-50% among culture tanks. In affected fish, cranial bones were externally apparent due to severe emaciation. The intestinal wall was very thin and the liver exhibited conspicuous green color. Morphological and molecular analyses demonstrated that the causative myxosporean was Enteromyxum leei. Histopathological examinations revealed that the epithelia of the intestine and bile duct of diseased fish were heavily infected with E. leei. The common bile duct was often obstructed by severe inflammation with degenerated tissues and bacteria, suggesting that the abnormal color of the liver was caused by cholestasis. Some diseased fish recovered in a laboratory when water temperature increased naturally to 27-30°C in summer months, and the parasite was not detected in those fish. Experimental transmission of E. leei to naive Malabar grouper was successfully achieved by cohabitation with infected grouper or by feeding with the feces of infected fish. This is a new host and locality record for E. leei.


China M.,Forestry and Fisheries Promotion Center | Nakamura H.,Okinawa Prefectural Sea Farming Center | Hamakawa K.,Okinawa Prefectural Fisheries Research and Extension Center | Tamaki E.,Okinawa Prefectural Sea Farming Center | And 3 more authors.
Fish Pathology | Year: 2014

The effect of elevated water temperature on the myxosporean emaciation disease caused by Enteromyxum leei was tested in experimentally infected anemonefish Amphiprion ocellaris and naturally infected Malabar grouper Epinephelus malabaricus. Anemonefish reared at 30°C following infection had significantly lower parasite prevalence compared to fish reared at 23°C. After infection in anemonefish held at 23°C for 20 days, elevation of water temperature to 30°C reduced the prevalence. Holding infected Malabar grouper at 30°C resulted in a clearing of E. leei within 6 days. Histopathological observations showed that E. leei was eliminated following exfoliation of the intestinal epithelial cells. Although further replication of the study would be required, these results suggested that high water temperature treatment had a preventive and therapeutic effect on myxosporean emaciation disease. © 2014 The Japanese Society of Fish Pathology.


Shimizu Y.,Miyako Branch of the Okinawa Prefectural Plant Protection Center | Nishide Y.,Japan National Institute of Agrobiological Science | Tanaka S.,Japan National Institute of Agrobiological Science | Murata M.,Irabu Branch of Miyakojima City | And 4 more authors.
International Journal of Tropical Insect Science | Year: 2012

Upsurges in the populations of the migratory locust Locusta migratoria (L.) occurred in July 2011 at the airport and in sugarcane fields on Shimoji Island, Okinawa, Japan. In sugarcane fields and pathways, dark-coloured nymphs at early instars marched and infested sugarcane leaves. The number of locusts was estimated as approximately 1.4 million. After prompt control by spraying insecticides, the locust populations decreased remarkably in size at the airport and in sugarcane fields. The locust populations at the airport restored gradually and dark-coloured nymphs similar in appearance to typical gregarious forms were found marching on paved roads at the end of August. Insecticides were sprayed again in early September over those areas at the airport where nymphs were abundant. The locust populations rapidly declined and only a few locusts were observed thereafter on the island before winter. These observations indicate the importance of constant monitoring and prompt action for the control of locusts. The seasonal life cycle of this locust species on this island was studied by regularly sampling the locusts in the field, which revealed that this locust species produces three generations per year with different overwintering stages. © Copyright ICIPE 2012.


Tamaki M.,Okinawa Prefectural Agricultural Research Center | Hirata M.,Okinawa Prefectural Agricultural Research Center | Taniai N.,Okinawa Prefectural Agricultural Research Center | Akachi T.,Okinawa Prefectural Agricultural Research Center | And 5 more authors.
ICIIBMS 2015 - International Conference on Intelligent Informatics and Biomedical Sciences | Year: 2015

A non-aspirated air temperature and wind velocity sensor (NATVS) developed by Okushima et al. (2014) can measure wind velocity and temperature. The air temperature is calculated by measuring the temperature drop after heating a 30-μm-diameter tungsten wire for a short time. The wind velocity is calculated using the electrical resistance of this wire. Heat transfer to the air from the wire is calculated using the King equation. We extended the NATVS for use with incorporation with sensors of solar radiation, temperature, CO2 concentration, long wave radiation, and humidity (Extended NATVS). High-precision sensors of many kinds are necessary to increase the yield of horticulture products necessary to control the greenhouse environment appropriately and to analyze a greenhouse environment accurately. However, these are generally expensive. The extended NATVS is inexpensive. Using extended NATVS, a case study was conducted in a greenhouse with Bitter gourd cultivation. Generally, Bitter gourd farmers in Okinawa have continued ventilation during nighttime to control crop diseases by producing a low-humidity environment in the greenhouse. In contrast, to increase yields and to maintain disease control, it is desirable to store CO2 occurring from respiration of the crop by having no ventilation during nighttime. The amount of CO2 occurring by respiration of Bitter gourd can be stored in a greenhouse at night. Moreover, it is effective that crops be illuminated during that time so that the stored CO2 can be used for photosynthesis. We used the Extended NATVS to measure environmental factors in a greenhouse. Results show that farmers must improve the timing of film opening. Although farmers must consider the effects of solar radiation, the film probably must be opened by 10:00 a.m. One benefit of this method is that CO2 storage increases approximately 10% per day compared to opening of the side film at night. © 2015 IEEE.


Ukuda-Hosokawa R.,Okinawa Prefectural Plant Protection Center | Ukuda-Hosokawa R.,Okinawa Prefectural Agricultural Research Center | Sadoyama Y.,Okinawa Prefectural Plant Protection Center | Kishaba M.,Forestry and Fisheries Promotion Center | And 5 more authors.
Applied and Environmental Microbiology | Year: 2015

Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, "Candidatus Liberibacter asiaticus," and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of "Ca. Liberibacter asiaticus" in field populations of D. citri with experiments using field-collected insects to address how "Ca. Liberibacter asiaticus" infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from "Ca. Liberibacter asiaticus"-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were "Ca. Liberibacter asiaticus" positive. The infections were systemic across head-thorax and abdomen, ranging from 103 to 107 bacteria per insect. In spring, the infection densities were low in March, at~103 bacteria per insect, increasing up to 106 to 107 bacteria per insect in April and May, and decreasing to 105 to 106 bacteria per insect in late May, whereas the infection densities were constantly ~106 to 107 bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with "Ca. Liberibacter asiaticus" infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected "Ca. Liberibacter asiaticus"-infected insects suggested that (i) "Ca. Liberibacter asiaticus"-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level (~106 bacteria per insect) of "Ca. Liberibacter asiaticus" density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits "Ca. Liberibacter asiaticus" to citrus plants in a stochastic manner. These findings provide valuable insights into understanding, predicting, and controlling this notorious citrus pathogen. © 2015, American Society for Microbiology.


Miyagi A.,Okinawa Prefectural Agricultural Research Center | Ooishi T.,Okinawa Prefectural Agricultural Research Center | Ohno S.,Okinawa Prefectural Agricultural Research Center | Yoza K.,Okinawa Prefectural Agricultural Research Center | And 6 more authors.
Japanese Journal of Applied Entomology and Zoology | Year: 2011

Although Tetranychus urticae Koch (green form) has rarely been found on the southwestern region of Okinawa (the Sakishima Islands), we found an unexpected simultaneous occurrence of this species in 2009 in wax gourd greenhouses on one of the islands (Miyako Island). In that year, T. urticae occurred in 43% of wax gourd fields among the surveyed fields. In 2010, however, the frequency of occurrence naturally decreased; the species was found in only 3% of the fields from January to May and later become not found. These results have important implications for controlling spider mites on vegetable greenhouses in that area. Specifically, T. urticae can temporarily increase, but it cannot colonize the Sakishima Islands permanently due to some unknown biotic or abiotic factor(s). Neither the infestation frequency nor the species composition of other Tetanychus spider mites in the wax gourd greenhouses varied significantly between 2009 and 2010, suggesting that the occurrence of T. urticae did not affect the occurrence of other congeners.


Matsumoto K.,Saga University | Yasaka R.,Saga University | Yasaka R.,Kagoshima University | Setoyama T.,Yakult Honsha CO. | And 3 more authors.
Journal of General Plant Pathology | Year: 2016

Pepper veinal mottle virus (PVMV) has been detected in chilli pepper (Capsicum annuum) for the first time on Ishigaki Island of Okinawa Prefecture, Japan. In the early 2010s, leaves of chilli plants (cv. Kahat-ace) developed virus-like symptoms such as rugosity, mosaic, vein banding, mottling, distortion with puckering and malformation. The biologically cloned isolate OKP2 was able to infect solanaceous plants such as bell pepper, chilli pepper, petunia, tomato, Nicotiana benthamiana and N. clevelandii. The coat-protein-encoding region shared 99 % nucleotide identity with that of PVMV-ns1 isolate collected in Taiwan. The implications of this record are discussed. © 2015, The Phytopathological Society of Japan and Springer Japan.


PubMed | Forestry and Fisheries Promotion Center, Japan National Institute of Advanced Industrial Science and Technology, Kagoshima University and Okinawa Prefectural Plant Protection Center
Type: Journal Article | Journal: Applied and environmental microbiology | Year: 2015

Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, Candidatus Liberibacter asiaticus, and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of Ca. Liberibacter asiaticus in field populations of D. citri with experiments using field-collected insects to address how Ca. Liberibacter asiaticus infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from Ca. Liberibacter asiaticus-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were Ca. Liberibacter asiaticus positive. The infections were systemic across head-thorax and abdomen, ranging from 10(3) to 10(7) bacteria per insect. In spring, the infection densities were low in March, at 10(3) bacteria per insect, increasing up to 10(6) to 10(7) bacteria per insect in April and May, and decreasing to 10(5) to 10(6) bacteria per insect in late May, whereas the infection densities were constantly 10(6) to 10(7) bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with Ca. Liberibacter asiaticus infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected Ca. Liberibacter asiaticus-infected insects suggested that (i) Ca. Liberibacter asiaticus-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level ( 10(6) bacteria per insect) of Ca. Liberibacter asiaticus density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits Ca. Liberibacter asiaticus to citrus plants in a stochastic manner. These findings provide valuable insights into understanding, predicting, and controlling this notorious citrus pathogen.


Wakamura S.,Okinawa Prefectural Plant Protection Center | Wakamura S.,Kyoto Gakuen University | Yasui H.,Japan National Institute of Agrobiological Science | Shimatani M.,Okinawa Prefectural Plant Protection Center | And 7 more authors.
Applied Entomology and Zoology | Year: 2011

In 2010, abrupt outbreaks of the African armyworm, Spodoptera exempta (Walker), occured on the Tarama, Iriomote and Kikai Islands in southwestern Japan. Analysis by gas chromatography-electroantennographic detection (GC-EAD) revealed two EAG-active compounds on male antenna in crude extract of virgin females. These compounds were identified as (9Z)-9-tetradecenyl acetate (Z9-14:Ac) and (9Z,12E)-9,12-tetradecadienyl acetate (Z9E12-14:Ac) in ca. 90:10 ratio by subsequent GC-MS analyses. (11Z)-11-Hexadecenyl acetate (Z11-16:Ac), which had previously been identified as a third component in the Kenyan population, was not detected. Binary blends of Z9-14:Ac and Z9E12-14:Ac at ratios between 99:1 and 90:10 showed a potent attractiveness in the field, superior to that of virgin females and comparable to that of the three-component formulation determined in Kenya. For the population survey, a 98:2 blend was used. In Tarama, only a few moths of S. exempta were captured with a light trap during the night when more than 600 males were captured with synthetic sex pheromone; more S. exempta captures with a light trap had been reported than with sex-pheromone traps in Kenya. This indicates that the Okinawan population has different properties from the Kenyan population in pheromone composition and behavioral response to light. © 2011 The Japanese Society of Applied Entomology and Zoology.

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