The wing melanization with 20-hydroxyecdysone modulation in Idea leuconoe clara (Lepidoptera: Nymphalidae)

Temperature-induced changes in the physiological signals altered the wing coloration in Bicyclus anynana (Butler, 1879). The morphogenetic hormone 20-hydroxyecdysone (20E) increases with temperature and regulates the seasonal morph formation of the species. Although melanization in Idea leuconoe clara Butler (Lepidoptera: Nymphalidae) can be induced by temperature shock at 10, 35, and 40 °C, the relationship between this phenomenon and 20E remains unexplored. This study hypothesizes that the melanic phenotype of I. leuconoe clara is affected by distinct hormonal responses under extreme temperatures. The 20E levels were measured at the 3% and 20% pupal development stages of I. leuconoe clara under temperature shock. The relationship between 20E and melanization was investigated through hormone injection. The results demonstrated that the relationship between melanization under cold shock and 20E was negative and that 20E regulated the degree of melanin deposition rather than the patterning of melanized areas. This study investigates the effects 20E on wing melanization under extreme temperatures in I. leuconoe clara. Future studies could further determine the melanic changes in pigment and structural coloration through transcriptomic analysis and scanning electron microscopy based on the temperature shock procedure.