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• Spatiotemporal Dynamics of Genetic Diversity in the Pale Grass Blue Butterfly After the Fukushima Nuclear Accident

  Toki, M; Taira, W; Sakauchi, K; Otaki, JM

  DIVERSITY-BASEL ( Diversity )  17 ( 10 )   2025.09 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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• Mitochondrial Genetic Mutations in the Pale Grass Blue Butterfly: Possible DNA Damage via the Fukushima Nuclear Accident and Real-Time Molecular Evolution

  Toki, M; Taira, W; Sakauchi, K; Otaki, JM

  DIVERSITY-BASEL ( Diversity )  17 ( 4 ) 275 - 275   2025.04 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  The pale grass blue butterfly Zizeeria maha has been used to evaluate the biological effects of the Fukushima nuclear accident in 2011. Here, we examined the DNA sequences of the mitochondrial gene cytochrome oxidase subunit I (COI) of Z. maha using the field samples collected in 2011–2014 and 2021. Among 641 individuals from 44 localities in Northeastern Japan, we detected a heteroplasmic nonsynonymous nucleotide substitution in one out of three 2012 individuals from Hirono, Fukushima Prefecture, where the biological impact of radioactive pollution was the highest among the localities surveyed in 2012, suggesting DNA damage via initial exposure to short-lived radionuclides. An additional 80 individuals from Hirono in 2021 did not show any substitution, suggesting the extinction of the Hirono mutant by 2021. We also detected another heteroplasmic and homoplasmic nonsynonymous substitution in four out of five 2014 individuals from Shibata, Niigata Prefecture, where radioactive pollution was low. These substitutions were not present in the GenBank records of Z. maha and its sister species Z. karsandra, indicating that intraspecific variation may exceed interspecific variation in Z. maha. These results highlight not only the possible impact of the initial exposure in Fukushima but also real-time molecular evolution of butterflies in the field.

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• The second decade of the blue butterfly in Fukushima: Untangling the ecological field effects after the Fukushima nuclear accident.

  Otaki JM, Sakauchi K, Taira W

  Integrated environmental assessment and management ( Integrated Environmental Assessment and Management )  18 ( 6 ) 1539 - 1550   2022.11 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Many field observations of the biological effects of the Fukushima nuclear accident have been reported in the first decade after the accident. A series of observational and experimental studies have demonstrated causal adverse effects on the pale grass blue butterfly even at the low-level radiation exposure in the "field," contrary to the dosimetric view that insects are generally tolerant of radiation exposure. However, it has been demonstrated that the pale grass blue butterfly is tolerant of high oral doses of anthropogenic radioactive cesium (137 Cs) under "laboratory" conditions. This field-laboratory paradox can be explained by ecological field effects; for example, radiation stress in the field causes physiological and biochemical changes in the host plant, which then trophically affects butterfly larvae. The second decade of butterfly-based Fukushima research will be devoted to demonstrating how such adverse field effects occur. Changes in the host plant's nutritional contents likely affect butterfly physiology. The host plant may also upregulate secondary metabolites that affect herbivorous insects. The plant may be affected by changes in endophytic soil microbes in radioactively contaminated areas. If demonstrated, these results will reveal that the delicate ecological balances among the butterfly, its host plant, and soil microbes have been affected by radioactive pollution in Fukushima, which has important implications for environmental policies and human health. Integr Environ Assess Manag 2022;18:1539-1550. © SETAC.

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• Ingestional Toxicity of Radiation-Dependent Metabolites of the Host Plant for the Pale Grass Blue Butterfly: A Mechanism of Field Effects of Radioactive Pollution in Fukushima.

  Morita A, Sakauchi K, Taira W, Otaki JM

  Life (Basel, Switzerland) ( Life )  12 ( 5 )   2022.04 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Biological effects of the Fukushima nuclear accident have been reported in various organisms, including the pale grass blue butterfly Zizeeria maha and its host plant Oxalis corniculata. This plant upregulates various secondary metabolites in response to low-dose radiation exposure, which may contribute to the high mortality and abnormality rates of the butterfly in Fukushima. However, this field effect hypothesis has not been experimentally tested. Here, using an artificial diet for larvae, we examined the ingestional toxicity of three radiation-dependent plant metabolites annotated in a previous metabolomic study: lauric acid (a saturated fatty acid), alfuzosin (an adrenergic receptor antagonist), and ikarugamycin (an antibiotic likely from endophytic bacteria). Ingestion of lauric acid or alfuzosin caused a significant decrease in the pupation, eclosion (survival), and normality rates, indicating toxicity of these compounds. Lauric acid made the egg-larval days significantly longer, indicating larval growth retardation. In contrast, ikarugamycin caused a significant increase in the pupation and eclosion rates, probably due to the protection of the diet from fungi and bacteria. These results suggest that at least some of the radiation-dependent plant metabolites, such as lauric acid, contribute to the deleterious effects of radioactive pollution on the butterfly in Fukushima, providing experimental evidence for the field effect hypothesis.

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• Metabolomic Profiles of the Creeping Wood Sorrel Oxalis corniculata in Radioactively Contaminated Fields in Fukushima: Dose-Dependent Changes in Key Metabolites.

  Sakauchi K, Taira W, Otaki JM

  Life (Basel, Switzerland) ( Life )  12 ( 1 )   2022.01 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  The biological impacts of the Fukushima nuclear accident, in 2011, on wildlife have been studied in many organisms, including the pale grass blue butterfly and its host plant, the creeping wood sorrel Oxalis corniculata. Here, we performed an LC-MS-based metabolomic analysis on leaves of this plant collected in 2018 from radioactively contaminated and control localities in Fukushima, Miyagi, and Niigata prefectures, Japan. Using 7967 peaks detected by LC-MS analysis, clustering analyses showed that nine Fukushima samples and one Miyagi sample were clustered together, irrespective of radiation dose, while two Fukushima (Iitate) and two Niigata samples were not in this cluster. However, 93 peaks were significantly different (FDR < 0.05) among the three dose-dependent groups based on background, low, and high radiation dose rates. Among them, seven upregulated and 15 downregulated peaks had single annotations, and their peak intensity values were positively and negatively correlated with ground radiation dose rates, respectively. Upregulated peaks were annotated as kudinoside D (saponin), andrachcinidine (alkaloid), pyridoxal phosphate (stress-related activated vitamin B6), and four microbe-related bioactive compounds, including antibiotics. Additionally, two peaks were singularly annotated and significantly upregulated (K1R1H1; peptide) or downregulated (DHAP(10:0); decanoyl dihydroxyacetone phosphate) most at the low dose rates. Therefore, this plant likely responded to radioactive pollution in Fukushima by upregulating and downregulating key metabolites. Furthermore, plant-associated endophytic microbes may also have responded to pollution, suggesting their contributions to the stress response of the plant.

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Other Papers 【 display / non-display 】

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• Rdioactive contamination effects on the pale grass blue

  Wataru Taira

  THE JAPAN BUTTERFLY CONSERVATION SOCIETY NEWSLETTER   ( 26 ) 10 - 17   2018.07

   

Presentations 【 display / non-display 】

Presentations 【 display / non-display 】

• 放射能汚染地域におけるヤマトシジミのDNA 配列解析及び遺伝的多様性

  平良 渉，土岐 万理子, 阪内 香，大瀧 丈二

  第10回福島原発事故による周辺生物への影響に関する勉強会  2025.11  -  2025.11 

• 亜熱帯性マダラコオロギの内因性胚休眠を打破する環境要因の検証

  武方宏樹、平良渉、竹村明洋

  第32回日本時間生物学会学術大会  (京都府京都市)  2025.10  -  2025.10 

• マングローブスズ幼虫の概潮汐リズム

  吉村粛孝、左倉和喜、平良渉、武方宏樹、後藤慎介

  第32回日本時間生物学会学術大会  (京都府京都市)  2025.10  -  2025.10 

• 亜熱帯性マダラコオロギ胚休眠を打破する温度条件の検証

  武方 宏樹, 平良 渉, 竹村 明洋

  日本動物学会第96回名古屋大会  (愛知県名古屋市)  2025.09  -  2025.09 

• Both laboratory work and field work are required to understand the pale grass blue butterfly in Fukushima: a possibility of field effects to be considered.

  Taira W, Sakauchi K, Toki M, Yamashito Y, Grung R, Otaki J

  1900.01  -  1900.01 

Grant-in-Aid for Scientific Research 【 display / non-display 】

Grant-in-Aid for Scientific Research 【 display / non-display 】

• The biological impacts of radiocesium in considering its chemical properties and effects on potassium channels

  Grant-in-Aid for Early-Career Scientists

  Project Year: 2021.04  -  2025.03 

  Direct: 3,600,000 (YEN)  Overheads: 4,680,000 (YEN)  Total: 1,080,000 (YEN)

• The biological impacts of radiocesium in considering its chemical properties and effects on potassium channels

  Grant-in-Aid for Early-Career Scientists

  Project Year: 2021.04  -  2025.03 

  Direct: 3,600,000 (YEN)  Overheads: 4,680,000 (YEN)  Total: 1,080,000 (YEN)