The Pierid Red-Egg Syndrome

Abstract

1. Among crucifer-feeding pierid butterflies, members of the inflorescence-feeding guild lay red or orange eggs and engage in apparent egg-load assessment, while members of the leaf-feeding guild lay yellow to white eggs and do not. The egg color and female behavior are convergent in members of the subfamilies Pierinae and Euchloinae. (2) Patterns of host utilization on weedy crucifers are seemingly inefficient, resulting in artificial shortages of oviposition sites. This could reflect "phylogenetic inertia," the oviposition behavior being appropriate to the dispersion of the original, nonweedy hosts. (3) In one experiment, Pieris protodice and Euchloe ausonides engaged in apparent interspecific egg-load assessment within the inflorescence-feeding guild. Competition among species in this guild is probably rare in North America but may occur more commonly in North Africa. (4) Pieris sisymbrii populations on serpentine barrens have a heavy impact on their exclusively native hosts, species of Streptanthus, some of which have evolved apparent mimicry of butterfly eggs as a defense mechanism.