Ingestion of radioactively contaminated diets for two generations in the pale grass blue butterfly

Abstract

BackgroundThe release of radioactive materials due to the Fukushima nuclear accident has raised concern regarding the biological impacts of ingesting radioactively contaminated diets on organisms. We previously performed an internal exposure experiment in which contaminated leaves collected from polluted areas were fed to larvae of the pale grass blue butterfly, Zizeeria maha, from Okinawa, which is one of the least polluted localities in Japan. Using the same experimental system, in the present study, we further examined the effects of low-level-contaminated diets on this butterfly. Leaves were collected from two localities in Tohoku (Motomiya (161 Bq/kg) and Koriyama (117 Bq/kg)); two in Kanto (Kashiwa (47.6 Bq/kg) and Musashino (6.4 Bq/kg)); one in Tokai (Atami (2.5 Bq/kg)); and from Okinawa (0.2 Bq/kg). In addition to the effects on the first generation, we examined the possible transgenerational effects of the diets on the next generation.ResultsIn the first generation, the Tohoku groups showed higher rates of mortality and abnormalities and a smaller forewing size than the Okinawa group. The mortality rates were largely dependent on the ingested dose of caesium. The survival rates of the Kanto-Tokai groups were greater than 80%, but the rates in the Tohoku groups were much lower. In the next generation, the survival rates in the Tohoku groups were below 20%, whereas those of the Okinawa groups were above 70%. The survival rates in the second generation were independent of the locality of the leaves ingested by the first generation, indicating that the diet in the second generation was the determinant of their survival. Moreover, a smaller forewing size was observed in the Tohoku groups in the second generation. However, the forewing size was inversely correlated with the cumulative caesium dose ingested throughout the first and second generations, indicating that the diet in the first generation also influenced the forewing size of the second generation.ConclusionsBiological effects are detectable under a low ingested dose of radioactivity from a contaminated diet. The effects are transgenerational but can be overcome by ingesting a non-contaminated diet, suggesting that at least some of the observed effects are attributable to non-genetic physiological changes.

Geographical distribution of morphological abnormalities and wing color pattern modifications of the pale grass blue butterfly in northeastern Japan

“…, ; Nohara et al . ,b) so that the present results can be compared directly with previous results. Wing color pattern modifications were examined visually with the naked eye.…”

“…, , ; Nohara et al . ,b; Taira et al . , ), gall‐forming aphids (morphological abnormalities in field samples) (Akimoto ), the Japanese monkey (possible hematological aberrations) (Hayama et al .…”

Variation in chronic radiation exposure does not drive life history divergence among Daphnia populations across the Chernobyl Exclusion Zone

“…We tested whether selection played a primary role in shaping populations by examining whether the variation associated with population fitness (instantaneous growth rate, r) declines with dose rate. We also examined whether radiation reduced mean population fitness by testing whether Daphnia fitness declines with dose rate, as would be consistent with previous studies that have demonstrated laboratory exposure to radiation reduces invertebrate fitness (Nohara et al, 2014;Parisot, Bourdineaud, Plaire, Adam-Guillermin, & Alonzo, 2015;Sarapultseva & Gorski, 2013).…”

Fukushima's lessons from the blue butterfly: A risk assessment of the human living environment in the post-Fukushima era

“…Previously, my research team carried out a feeding experiment in which the host plant leaves from Fukushima were fed to the larvae of the pale grass blue butterfly from Okinawa, one of the least‐contaminated localities in Japan (Hiyama et al 2012; Nohara, Hiyama et al ; Nohara, Taira et al ; Taira, Hiyama et al ). This simple but important experiment tested if the Fukushima leaves are safe enough for butterfly larvae to eat.…”

“…Faced with an accident that shook the entire nation, our laboratory team decided to use this butterfly as a model to assess the biological impacts of the Fukushima accident (Otaki , , ). Our team has published a series of articles that help to understand how the butterflies in Fukushima have coped with the aftermath of the FDNPP accident (Hiyama, Nohara et al ; Hiyama et al , ; Nohara, Hiyama et al ; Nohara, Taira et al ; Taira et al ; Taira, Hiyama et al ; Taira, Iwasaki et al ). Comments from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) on our research can be found in the UNSCEAR Report (UNSCEAR ).…”