Pupal Color Polyphenism Regulated by Temperature and Photoperiod in the Asian Comma Butterfly, Polygonia c-aureum (Lepidoptera: Nymphalidae)

To investigate the effects of environmental factors on pupal coloration of the Asian comma butterfly Polygonia c-aureum L., newly hatched larvae were reared and allowed to reach pupation under different temperature and photoperiodic conditions. Pupal colors which developed after pupal molting were classified into 5 types of dark brown, brown, yellowish-brown, light yellow, and brilliant yellow on the basis of the coloration of the ventral side of pupae. Under long-day conditions, developmental ratios of combined dark brown and brown types in male and female pupae were respectively 68% and 70% at 16 degrees C, 42% and 7% at 23 degrees C, and 0% and 0% at 32 degrees C. Under short-day conditions, developmental ratios of combined dark brown and brown types in male and female pupae were respectively 43% and 29% at 20 C, and 29% and 7% at 32 degrees C. Pupal color development in P. c-aureum was significantly affected by temperature and not by photoperiod, although short-day conditions induced pupae that were slightly darker than long-day pupae at 32 degrees C. A higher temperature induced pupae of lighter types than did a lower temperature under the same photoperiodic conditions. Between the sexes, pupal coloration of males showed a tendency towards a slightly darker type than that of females at all tested photoperiodic and temperature conditions. However, there were no significant differences between male and female pupae. These results indicate that pupal color polyphenism in P. c-aureum is co-regulated by 2 factors, mainly temperature and to a small degree photoperiod, as environmental cues, suggesting that these 2 factors contribute to regulating phenotypic plasticity in life history traits of P. c-aureum.