Zizina emelina

Zizina emelina (Z. emelina), formerly Zizina otis emelina, is a butterfly native to Japan and Korea.^[1] Sightings have also been made in the People's Republic of China (PRC) and reported via iNaturalist's community reporting features.

Z. emelina inhabits grasslands in early successional stages^[2] in Japan, Korea,^[3][4][5] and PRC. As a result of land use changes, reduced traditional grassland maintenance, and increased urbanization, their available habitats and their colonies have been reduced by more than half in the past century.^[3][4] Z. emelina feed on Lotus japonicus (L. japonicus) during their larval stage, a native plant which has suffered as a result of diminishing grassland frequency.^[4] However, white clover has been used to substitute L. japonicus, and it has become an important alternative as L. japonicus' frequency decreases.^[6]

Z. emelina live in grasslands resulting from environmental disturbances while the ecosystem recovers. Their habitat and distribution coincide with traditional grassland maintenance, a practice which is being replaced with large-scale agriculture^[7]. As a result, the population of Z. emelina has dwindled to the point of becoming classified in Japan's Red List as 'Endangered'.^[1] In the past century,^[8] the forestry and agriculture industries have had significant detrimental impacts on the species as a result of regular deforestation and afforestation.^[7] Climate change may exacerbate the decline of Z. emelina, as hybridization induced by rapid climate change may lead to population extinctions.^[9] In Korea, Z. emelina is not considered endangered,^[5] however grassland butterflies are at particular risk in urbanized areas.^[10]

Wolbachia is a common endosymbiont among arthropods that causes reproductive alterations, male feminization, and other genetic alterations.^[11] Three strains infect Japanese Z. emelina populations: wEmeTn1, wEmeTn2, and WemeNy1.^[4][11] In Z. emelina, the wEmeTn1 and wEmeTn2 strains pose detrimental effects on reproduction and genetic structure.^[4][11] The Tn2 variant causes the death of males, and it causes females to only produce female offspring.^[4] Tn2 wolbachia has been observed in 9 distinct populations in Japan with an infection rate between 20% and 100%.^[4]

Z. emelina have between five and seven generations annually.^[12][3][5] It is believed that short photoperiods trigger diapause in Z. emelina, and they experience progressive molts during this period.^[13] Temperature also has a direct impact on Z. emelina diapause, suggesting that global temperature increase may be a critical factor in the species' survival.^[13] Rapid environmental change is particularly dangerous for Z. emelina due to its multivoltine life cycle.^[10]