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Kuriwada T.,Japan National Agriculture and Food Research Organization | Kumano N.,Okinawa Prefectural Plant Protection Center | Shiromoto K.,Okinawa Prefectural Plant Protection Center | Haraguchi D.,Okinawa Prefectural Agricultural Research Center
Journal of Applied Entomology | Year: 2014

For ensuring the effectiveness of sterile insect technique (SIT) programmes, maintaining the reproductive competitiveness and dispersal ability of mass-reared sterile males is essential. Inadvertent selection is an important genetic process that frequently occurs during mass rearing to produce sterile males. We investigated the effect of mass-rearing conditions on the responsiveness to sex pheromones and spontaneous flight activity of males of the sweetpotato weevil Cylas formicarius (Coleoptera: Brentidae). There were no significant differences in the responsiveness to sex pheromones and spontaneous flight activity between wild and mass-reared strains. These results indicate that mass-reared strains of C. formicarius might not cause serious problems for implementing SIT programmes. © 2013 Blackwell Verlag GmbH.


Horita M.,Japan National Institute for Agro - Environmental Sciences | Suga Y.,Nagasaki Agricultural and Forestry Technical Development Center | Ooshiro A.,Okinawa Prefectural Agricultural Research Center | Tsuchiya K.,Kyushu University
Journal of General Plant Pathology | Year: 2010

We assessed the geographic distribution, biovar, phylotype, DNA fingerprints (rep-PCR), and/or endoglucanase sequence of potato bacterial wilt pathogen, Ralstonia solanacearum (Rs), in Japan. Rs has been isolated from potato fields in southwestern, warm, temperate regions. Of the 188 isolates, 74 belonged to biovar N2 (39%), 44 to biovar 3 (24%), and 70 to biovar 4 (37%). Biovars N2 and 4 strains were widely distributed, from northern (Hokkaido) to southern (Okinawa) Japan. Based on the results of multiplex-PCR analysis, every potato strains belonged to either phylotype I or IV. Phylotype I comprised both biovars 3 and 4 strains. On the other hand, phylotype IV included biovar N2 strains. None of the strains belonged to phylotype II or III or biovar 1 or 2. Phylogenetic analysis based on DNA fingerprints and endoglucanase gene sequences clarified the genetic diversity of the Japanese potato strains and the close genetic relationship between the Japanese strains and the Asian strains in phylotypes I and IV. © 2010 The Phytopathological Society of Japan and Springer.


Onaga S.,Kagoshima University | Chinen K.,University of Ryukyus | Chinen K.,Okinawa Prefectural Agricultural Research Center | Ito S.,University of Ryukyus | Taira T.,University of Ryukyus
Process Biochemistry | Year: 2011

A complementary DNA encoding the thermostable chitinase of pineapple (Ananas comosus), designated PLChiA, was cloned, sequenced, and expressed in Escherichia coli cells. The determined nucleotide sequence of the gene revealed an 882-bp open reading frame that encoded a putative signal sequence (25 amino acids) and a mature protein (268 amino acids, 27,757 Da). Based on the amino acid sequence homology, PLChiA belongs to the class III chitinases in glycoside hydrolase family 18. The recombinant enzyme was purified to homogeneity by a single-step column chromatography. The purified enzyme displayed optimal catalytic activity at ρH 3.0 and 70 °C and had a molecular mass of 27.8 kDa on SDS gel. Strikingly, the half-life was more than 5.2 days when heated at ρH 7.0 and 75 °C. The half-lives at ρH 7.0 were 4.5 h at 80 °C and 27 min at 85 °C. Even at 80 °C, the half-life was 65 min at ρH 4.0. Hence, PLChiA is the most thermostable chitinase reported to date from land plants. © 2010 Elsevier Ltd.


Kijima K.,Okinawa Prefectural Agricultural Research Center | Ganaha-Kikumura T.,Okinawa Prefectural Agricultural Research Center | Ohno S.,Okinawa Prefectural Agricultural Research Center
Japanese Journal of Applied Entomology and Zoology | Year: 2011

When flower thrips Frankliniella intonsa (Trybom) increased in February and April 2009 in a bell pepper greenhouse on Okinawa Island, southwestern Japan, we found a marked injury to the fruit skin that has not been reported to date. The characteristics of the fruit damage are described and illustrated. A large number of larvae of F. intonsa were observed in the damaged portions. The same damage was induced when larvae or adults were inoculated into the surface of bell pepper fruit under laboratory conditions. These results indicate that F. intonsa caused the injury. We must remain alert to possible expansion of this injury.


Arakaki N.,Okinawa Prefectural Agricultural Research Center | Yamazawa H.,Japan National Institute of Agrobiological Science | Yamazawa H.,Tokai Gakuin University | Wakamura S.,Japan National Institute of Agrobiological Science | Wakamura S.,Kyoto Gakuen University
Applied Entomology and Zoology | Year: 2011

Egg parasitoids Telenomus euproctidis Wilcox (Hymenoptera: Scelionidae) were attracted to egg masses laid by wingless immobile female Orgyia postica (Lepidoptera: Lymantriidae). Virgin females, a solvent extract of pheromone glands, and a synthetic sex pheromone, (6Z,9Z,11S,12S)-11,12-epoxyhenicosa-6,9-diene (posticlure), also attracted this parasitoid in the field, demonstrating that T. euproctidis uses the sex pheromone of female Org. postica as a kairomone to locate host eggs. © 2011 The Japanese Society of Applied Entomology and Zoology.


Hirose N.,Okinawa Prefectural Agricultural Research Center
Nippon Shokuhin Kagaku Kogaku Kaishi | Year: 2012

Shiikuwasha (Citrus depressa Hayata) is a well-known traditional citrus fruit from Okinawa, with over 200 cultivars and varieties reported. The harvest season of Shiikuwasha is extensive, from August to February, and Shiikuwasha has a unique usage pattern. Unripe fruit, harvested in August and September, is used for cooking, while partially ripe fruit, available from October to December, is used for machining (mainly for juice). Ripe fruit with reduced acidity is available in January and February and is used unmodified. Polymethoxylated flavones (PMFs) are characteristic components of Shiikuwasha. Depending on harvest time and variety, alterations in juice quantities, citric acid concentrations, and PMFs were observed. Most applications of Shiikuwasha involve juice processing. Notably, the efficiency of Shiikuwasha juice production is only about 50%. Many useful components are contained in the peel, and remain in the residue. A comparison of extraction methods revealed that a multi-stage extraction recovered more useful components. According to marketing research, consumer demand exists for products of Shiikuwasha as a seasoning. Therefore, we are developing applications (especially as seasonings) for juice residue containing essential oils and PMFs.


Tabata J.,Japan National Institute for Agro - Environmental Sciences | Ohno S.,Okinawa Prefectural Agricultural Research Center
Applied Entomology and Zoology | Year: 2015

The grey pineapple mealybug, Dysmicoccus neobrevipes Beardsley, originally found on Hawaii and on Australasian islands, was recently discovered on a southwestern island (Ishigaki Island) of Japan. Because D. neobrevipes is known to attack many fruits and other crops, it is essential to establish a strategy to prevent the spread of this potential pest. Detection and monitoring by use of pheromone traps would provide important information about its distribution. The sex pheromone of D. neobrevipes has been isolated and identified as (E)-2-isopropyl-5-methylhexa-3,5-dien-1-yl acetate, although its absolute configuration was unknown. In this study, we achieved enantioselective synthesis of this compound by use of porcine pancreas lipase (PPL)-catalyzed acylation. Acetyl transfer from vinyl acetate to prochiral 2-isopropyl-1,3-propanediol in the presence of PPL in an organic solvent predominantly produced the (R) enantiomer of the monohydroxy acetate (86 % ee). In contrast, PPL-catalyzed hydrolysis of 2-isopropyl-1,3-diacetoxypropane in phosphate buffer yielded the (S) enantiomer of the monohydroxy acetate (75 % ee). Each enantiomer of the monohydroxy acetate was oxidized to a formyl acetate then coupled with a Wittig reagent, to produce the (R)-(−) and (S)-(+) pheromones. Analysis by gas chromatography with a chiral column and by polarimetry revealed the natural pheromone to be the (S)-(+) enantiomer. In a field trap experiment, the attractiveness of the pheromone produced by this route was equivalent to that of the pure (+) enantiomer (>99 % ee). © 2015, The Japanese Society of Applied Entomology and Zoology.


Urasaki N.,Okinawa Prefectural Agricultural Research Center | Tarora K.,Okinawa Prefectural Agricultural Research Center | Shudo A.,Okinawa Prefectural Agricultural Research Center | Ueno H.,Shinshu University | And 4 more authors.
PLoS ONE | Year: 2012

Papaya (Carica papaya) is a trioecious plant species that has male, female and hermaphrodite flowers on different plants. The primitive sex chromosomes genetically determine the sex of the papaya. Although draft sequences of the papaya genome are already available, the genes for sex determination have not been identified, likely due to the complicated structure of its sex-chromosome sequences. To identify the candidate genes for sex determination, we conducted a transcriptome analysis of flower samples from male, female and hermaphrodite plants using high-throughput SuperSAGE for digital gene expression analysis. Among the short sequence tags obtained from the transcripts, 312 unique tags were specifically mapped to the primitive sex chromosome (X or Yh) sequences. An annotation analysis revealed that retroelements are the most abundant sequences observed in the genes corresponding to these tags. The majority of tags on the sex chromosomes were located on the X chromosome, and only 30 tags were commonly mapped to both the X and Yh chromosome, implying a loss of many genes on the Yh chromosome. Nevertheless, candidate Yh chromosome-specific female determination genes, including a MADS-box gene, were identified. Information on these sex chromosome-specific expressed genes will help elucidating sex determination in the papaya. © 2012 Urasaki et al.


Kijima K.,Okinawa Prefectural Agricultural Research Center | Kijima K.,Okinawa Prefectural Plant Protection Center | Tarora K.,Okinawa Prefectural Agricultural Research Center
Japanese Journal of Applied Entomology and Zoology | Year: 2010

White grub Dasylepida ishigakiensis (Coleoptera: Scarabaeidae) is an important pest that infests the roots and underground stems of sugarcane. Thus, the establishment of an effective control method for this pest is urgently required. Changes in the vertical distribution of third stadium larvae of D. ishigakiensis in the soil were surveyed in a post-harvest sugarcane field on Miyako Island, Okinawa, in 2005. Although 73.8% of third stadium larvae were captured within 30 cm soil depth on March 17, the rate decreased to 38.1% on April 5 and to 25.0% on April 17, suggesting that most larvae move to deeper soil from the end of March to mid-April. The possibility of physical control by rotary tillage while the larvae are in shallow soil (0 to 30 cm) was examined in another field on March 16, 2005, with three treatments: 1) control, 2) tilling once and 3) tilling twice. The number of living larvae per sugarcane stool with tilling once or twice was much lower than in the control. Furthermore, the difference between the control and tilling twice six days after treatment was significant. These results indicate that tilling sugarcane fields by mid-March after the harvest can effectively control D. ishigakiensis larvae.


Arakaki N.,Okinawa Prefectural Agricultural Research Center | Hokama Y.,Okinawa Prefectural Agricultural Research Center | Yamamura K.,Japan National Institute for Agro - Environmental Sciences
Applied Entomology and Zoology | Year: 2010

The dispersal distance of the larvae of the sugarcane click beetle Melanotus okinawensis Ôhira (Coleoptera: Elateridae) in soil was estimated using the mark-recapture method. Grid lines with 30-cm intervals were set 10×10 in a fallow field after sugarcane harvest. Sixty marked larvae were released twice at the center of the grid. The tip of the corneous process on the last abdominal segment was cut and used for marking. Germinating rice seed baits were placed at the 10×10 intersection points of grid lines at a depth of 10 cm in order to recapture larvae. All traps were examined at two-day intervals. The estimate of lifetime natural mean dispersal distance (±SE) was 105.6 (±20.1) cm. The estimate of the natural survival rate per day was 0.861. The diffusion coefficient was estimated to be 613.

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