Genetic sources of pheromone variation inColias eurytheme butterflies.

The courtship pheromone ofColias eurytheme butterflies varies greatly among males in both the quantities and relative proportions of its three chemical components [n-heptacosane (C27), 13-methylheptacosane (13MH),n-nonacosane (C29)]. Narrow-sense heritabilities were high for the blend of 13MH and C27 and for the component quantities in one population (Kansas) but were low for the other population tested (Arizona). Genetic correlations between the three components were high in both populations, indicating a substantial degree of additive genetic influence on the component blends. High variability among populations in phenotypic correlations suggests that much of the male-to-male variation in the courtship pheromone may be attributable to environmental or developmental sources. Pheromone phenotypes do not seem to be associated with alba genotype.