Figure 1

(a) Collection localities. A red dot indicates the location of the Fukushima Dai-ichi NPP. Black dots and black half dots indicate the cities from which the first-voltine adults were collected. Brown dots and brown half dots indicate cities from which the host plant leaves were collected for the internal exposure experiment. All experiments were performed in Okinawa, marked by a blue dot. Inset shows the collection localities around the NPP. (b) Representative wings with normal (leftmost) and aberrant colour patterns. Numbers 1, 2, 3, and 4 indicate the first, second, third, and fourth spot arrays, respectively, and “D” indicates the discal spot. Red arrows indicate loss, dislocation, and weak expression of spots (left individual), weak expression and dislocation of spots (middle individual), and enlargement of spots (right individual). These samples were caught in Mito except for the leftmost aberrant specimen, which was caught in Iwaki. Scale bar, 1.0 cm. (c) Male forewing sizes from various localities. The first quartile and third quartile were indicated by horizontal bars at the bottom and top of the box, respectively. Median is indicated as the centre line inside the box. Outliers were indicated by dots. A red dot indicates the mean value and a red bar the standard deviation (SD). Holm-corrected p-values are shown, which were obtained for pairwise comparisons among 8 localities using t tests with pooled SD. Only male samples were used here because when the female samples were used to obtain eggs, broken wings resulted from the egg collection procedure. Samples from Shiroishi (n = 5) and Koriyama (n = 3) were excluded because of small sample sizes. (d) Scatter plot of the male forewing size and ground radiation dose at each collection locality. Pearson correlation coefficient r = −0.74 (Holm-corrected p = 0.029). (e) Representative morphological abnormalities. From left to right, dented eyes (Shiroishi), deformed left eye (Iwaki), deformed right palpus (Takahagi), and deformed wing shape (Fukushima). Arrowheads indicate deformation. Scale bars, 0.50 mm with the exception of the rightmost bar, which is 1.0 cm.