Chagyo Kenkyu Hokoku (Tea Research Journal)
Online ISSN : 1883-941X
Print ISSN : 0366-6190
ISSN-L : 0366-6190
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Volume 2021, Issue 131
Displaying 1-5 of 5 articles from this issue
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Original Articles
  • Development of Resistance in the Tea Leaf Roller, Caloptilia theivora (Lepidoptera: Gracillariidae), to Diamide Insecticides in Kagoshima Prefecture, Japan.
    Takeshi Fukuda, Kunihiko Matsuhira, Shoko Higashitarumizu, Takeshi Kam ...
    2021 Volume 2021 Issue 131 Pages 1-7
    Published: June 30, 2021
    Released on J-STAGE: July 01, 2023
    DOIhttps://doi.org/10.5979/cha.2021.131_1
    JOURNAL FREE ACCESS
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    Reduction of control effects by diamide insecticides against eggs and young larvae of the tea leaf roller, Caloptilia theivora (Lepidoptera: Gracillariidae), one of the major pests of tea, was confirmed by field and laboratory tests throughout the tea fields in Minamikyushu, Kagoshima Prefecture, Japan. In the field, chlorantraniliprole, cyantraniliprole and ginotefran were less effective than spinetram and methoxyphenozide, while the latter two showed 95 % or more control effect. In the laboratory, larval mortality by flubendiamide was between 6.9 % and 23.3 % to the Minamikyushu population while 100 % in the other population. Chlorantraniliprole and cyantraniliprole showed similar tendency but the mortality was 26.7 %-70.0 % and 60.4 %-100 %, respectively, depending on the larval stage of treatment. LC50-value of chlorantraniliprole determined in 2018 was drastically increased from the values determined in 2013. The reasons for development of resistance are discussed.

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  • Influence of Continuous Ingestion of Matcha Latte on Stress: A Preliminary Study
    Manami Monobe, Sachiko Nomura, Kaori Ema
    2021 Volume 2021 Issue 131 Pages 9-14
    Published: June 30, 2021
    Released on J-STAGE: July 01, 2023
    DOIhttps://doi.org/10.5979/cha.2021.131_9
    JOURNAL FREE ACCESS
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    Matcha has high contents of theanine, caffeine, and epigallocatechin gallate (EGCG). Among these, theanine reduces psychological and physiological stress responses, although this effect is disturbed by caffeine and EGCG. It was reported that the continuous ingestion of high-quality matcha, whose molar ratio of caffeine + EGCG combined to theanine + arginine combined was maintained at less than two, reduces stress responses1). However, most matcha on the market has an unfavorable ratio. In a previous study, we investigated the influence of the continuous ingestion of matcha with a ratio of over two, on emotional behaviors after stress in mice. Continuous ingestion of the matcha may prevent loss of motivation after stress2). Therefore, we investigated the influence of the continuous ingestion of matcha products, matcha latte, on the change of motivation after stress in humans. Because activation of the sympathetic nervous system is associated with motivation change, the salivary α-amylase activity was monitored as an index of sympathetic nervous activity. Continuous ingestion of the matcha latte prevented impairment of the response of α-amylase activity to stress, and this may be due to the synergistic effects of caffeine and other matcha components. Taken together, continuous ingestion of matcha may contribute to the maintenance of motivation.

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