The collapse of the Fukushima Dai-ichi Nuclear Power Plant caused a massive release of radioactive materials to the environment. A prompt and reliable system for evaluating the biological impacts of this accident on animals has not been available. Here we show that the accident caused physiological and genetic damage to the pale grass blue Zizeeria maha, a common lycaenid butterfly in Japan. We collected the first-voltine adults in the Fukushima area in May 2011, some of which showed relatively mild abnormalities. The F₁ offspring from the first-voltine females showed more severe abnormalities, which were inherited by the F₂ generation. Adult butterflies collected in September 2011 showed more severe abnormalities than those collected in May. Similar abnormalities were experimentally reproduced in individuals from a non-contaminated area by external and internal low-dose exposures. We conclude that artificial radionuclides from the Fukushima Nuclear Power Plant caused physiological and genetic damage to this species.
On August 9th 2012, we published an original research article in Scientific Reports, concluding that artificial radionuclides released from the Fukushima Dai-ichi Nuclear Power Plant exerted genetically and physiologically adverse effects on the pale grass blue butterfly Zizeeria maha in the Fukushima area. Immediately following publication, many questions and comments were generated from all over the world. Here, we have clarified points made in the original paper and answered questions posed by the readers.
To evaluate the effects of the Fukushima nuclear accident on the surrounding area, we studied the pale grass blue butterfly Zizeeria maha, the most common butterfly in Japan. We here review our important findings and their implications. We found forewing size reduction, growth retardation, high mortality rates, and high abnormality rates in the field and reared samples. The abnormality rates observed in September 2011 were higher than those observed in May 2011 in almost all localities, implying transgenerational accumulation of genetic damage. Some of the abnormal traits in the F1 generation were inherited by the F2 generation. In a particular cross, the F2 abnormality rate scored 57%. The forewing size reduction and high mortality and abnormality rates were reproduced in external and internal exposure experiments conducted in our laboratory using Okinawa larvae. We observed the possible real-time evolution of radiation resistance in the Fukushima butterflies, which, in retrospect, indicates that field sampling attempts at the very early stages of such accidents are required to understand the ecodynamics of polluted regions. We propose, as the postulates of pollutant-induced biological impacts, that the collection of phenotypic data from the field and their relevant reproduction in the laboratory should be the basis of experimental design to demonstrate the biological effects of environmental pollutants and to investigate the molecular mechanisms responsible for these effects.
Animals often express behavioral preferences for different types of food or other resources, and these preferences can evolve or shift following association with novel food types. Shifts in preference can involve at least two phenomena: a change in rank preference or a change in specificity. The former corresponds to a change in the order in which hosts are preferred, while a shift in specificity can be an increase in the tendency to utilize multiple hosts. These possibilities have been examined in relatively few systems that include extensive population-level replication. The Melissa blue butterfly, Lycaeides melissa, has colonized exotic alfalfa, Medicago sativa, throughout western North America. We assayed the host preferences of 229 females from ten populations associated with novel and native hosts. In four out of five native-associated populations, a native host was preferred over the exotic host, while preference for a native host characterized only two out of five of the alfalfa-associated populations. Across all individuals from alfalfa-associated populations, there appears to have been a decrease in specificity: females from these populations lay fewer eggs on the native host and more eggs on the exotic relative to females from native-host populations. However, females from alfalfa-associated populations did not lay more eggs on a third plant species, which suggests that preferences for specific hosts in this system can potentially be gained and lost independently. Geographic variation in oviposition preference in L. melissa highlights the value of surveying a large number of populations when studying the evolution of a complex behavioral trait.
Male adult butterflies of many species have characteristic odors originating from the disseminating organs known as androconia. Despite the fact that androconia exist in several species, there have been few investigations on adult scents from the lycaenid species. Celastrina argiolus ladonides (Lycaenidae) is a common species in Eurasia. We have reported that male adults of this species emit a faint odor, and the major components causing this odor have been newly found in the Insecta. By using field-caught individuals, we determined the chemical nature and location of this odor in the butterfly. Gas chromatography-mass spectrometry (GC-MS) analyses revealed that two lactone compounds, lavender lactone and δ-decalactone, are present in the extracts of males but absent in those of the females. On an average, approximately 50 ng of each compound was found per male. Chiral GC analyses performed using enantiomerically pure standards revealed that the natural lavender lactone was a mixture of two enantiomers with an R/S ratio of 32:68, whereas the natural δ-decalactone contained only the R-enantiomer. When the analyses were conducted using different parts-forewings, hindwings, and body-of three males, the lactones were more abundantly found on the forewings and hindwings than on the body. Microscopic observation of the wings demonstrated that battledore scales known as androconia are scattered on the upper surface of both the wings of C. argiolus ladonides males. These results indicate that the specialized scales on the wings of males serve as scent-disseminating organs.
A field survey of Mount Cameroon, South-West Province, Cameroon, revealed two butterfly species new to science. Lepidochrysops liberti sp. nov. (Lycaenidae) flies in the extensive mosaic of natural clearings in sub-montane forest above 1100 m a.s.l., whereas Ceratrichia fako sp. nov. (Hesperiidae) locally inhabits the forested narrow gullies in the same vegetation zone. Observations on the habitat and behaviour of both species are also presented.
The lycaenid butterfly, Shijimiaeoides divina (Lepidoptera: Lycaenidae), has been listed in Korea as a class II endangered wild species since 2012. Therefore, the mitogenome sequence is necessary to better understand genomic characteristics of the species. The 15 259-bp complete mitochondrial genome of the species consists of a typical set of genes, including 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes, and 1 major non-coding AT-rich region, with an arrangement typical of Ditrysia (trnM-trnI-trnQ between the AT-rich region and ND2). The 379-bp A + T-rich region has a trnK-like sequence. Phylogenetic analysis using 13 protein-coding genes of the families Lycaenidae and Riodinidae with outgroups from species in Nymphalidae indicates that each family is a strong monophyletic group and that S. divina, belonging to Polyommatinae, is correctly placed as a sister to the within-subfamilial species Cupido argiades with the highest support.
Sequencing complete genomes of all major phylogenetic groups of organisms opens unprecedented opportunities to study evolution and genetics. We report draft genomes of Calephelis nemesis and Calephelis virginiensis, representatives of the family Riodinidae. They complete the genomic coverage of butterflies at the family level. At 809 and 855 Mbp, respectively, they become the largest available Lepidoptera genomes. Comparison of butterfly genomes shows that the divergence between Riodinidae and Lycaenidae dates to the time when other families started to diverge into subfamilies. Thus, Riodinidae may be considered a subfamily of Lycaenidae. Calephelis species exhibit unique gene expansions in actin-disassembling factor, cofilin, and chitinase. The functional implications of these gene expansions are not clear, but they may aid molting of caterpillars covered in extensive setae. The two Calephelis species diverged about 5 million years ago and they differ in proteins involved in metabolism, circadian clock, regulation of development, and immune responses.
There have been only a few reports on the directional reflection of light by butterfly wings. Here, we systematically investigated this phenomenon in a lycaenid butterfly, Chrysozephyrus smaragdinus,in which males have bright green wings based on structural coloration. We used a device that measures intensities of light in hemispherical space by vertical shifting of a sensor and horizontal rotation of the stage carrying the wing, which is illuminated from the top, to determine the direction of light reflected by the fore- and hindwings. The orientation and curvature of wing scales were also examined microscopically. The forewing of this species reflected light shone from the top largely forward, whereas the hindwing reflected it slightly forward. This difference was attributed to the tilt angles of the wing scales. Light reflection by the forewing was relatively weak, and widely scattered, whereas that by the hindwing was rather concentrated, resulting in higher reflectance. This difference was attributed to difference in the curvature of the wing scales on the two wings.
Butterflies (Papilionoidea), with over 18,000 described species , have captivated naturalists and scientists for centuries. They play a central role in the study of speciation, community ecology, biogeography, climate change, and plant-insect interactions and include many model organisms and pest species [2, 3]. However, a robust higher-level phylogenetic framework is lacking. To fill this gap, we inferred a dated phylogeny by analyzing the first phylogenomic dataset, including 352 loci (> 150,000 bp) from 207 species representing 98% of tribes, a 35-fold increase in gene sampling and 3-fold increase in taxon sampling over previous studies . Most data were generated with a new anchored hybrid enrichment (AHE)  gene kit (BUTTERFLY1.0) that includes both new and frequently used (e.g., ) informative loci, enabling direct comparison and future dataset merging with previous studies. Butterflies originated around 119 million years ago (mya) in the late Cretaceous, but most extant lineages diverged after the Cretaceous-Paleogene (K-Pg) mass-extinction 65 mya. Our analyses support swallowtails (Papilionidae) as sister to all other butterflies, followed by skippers (Hesperiidae) + the nocturnal butterflies (Hedylidae) as sister to the remainder, indicating a secondary reversal from diurnality to nocturnality. The whites (Pieridae) were strongly supported as sister to brush-footed butterflies (Nymphalidae) and blues + metalmarks (Lycaenidae and Riodinidae). Ant association independently evolved once in Lycaenidae and twice in Riodinidae. This study overturns prior notions of the taxon’s evolutionary history, as many long-recognized subfamilies and tribes are para- or polyphyletic. It also provides a much-needed backbone for a revised classification of butterflies and for future comparative studies including genome evolution and ecology.