STOEHR, Andrew M.; Univ. of California, Riverside: Melanin in immune defense and wing coloration in the cabbage white butterfly, Pieris rapae

The cell-mediated encapsulation response of the arthropod immune system utilizes the pigment melanin. Melanin or its precursors are also used for cuticle sclerotization and coloration. Recent work in some insect species suggests that these different uses of melanin result in trade offs between coloration and immune defense. I tested this hypothesis in the cabbage white butterfly (Pieris rapae) by examining the relationship between melanin-based encapsulation and melanin-based wing pattern elements. Experimentally induced investment in encapsulation in pupae did not result in detectable effects on adult wing coloration, nor did variation in wing coloration correlate with adult encapsulation response. Thus, no support for a melanin-based trade off hypothesis was found in this study.