European Skipper Butterfly (Thymelicus lineola) Associated with Reduced Seed Development of Showy Lady’s-slipper Orchid (Cypripedium reginae)

Peter W. Hall, Paul M. Catling, Paul L. Mosquin, Ted Mosquin


It has been suggested that European Skipper butterflies (Thymelicus lineola) trapped in the lips of the Showy Lady’s-slipper orchid (Cypripedium reginae) may interfere with pollination. This could occur through blockage of the pollinator pathway, facilitation of pollinator escape without pollination, and/or disturbance of the normal pollinators. A large population of the orchid at an Ottawa Valley site provided an opportunity to test the interference hypothesis. The number of trapped skippers was compared in 475 post-blooming flowers with regard to capsule development and thus seed development. The presence of any skippers within flowers was associated with reduced capsule development (P = 0.0075), and the probability of capsule development was found to decrease with increasing numbers of skippers (P = 0.0271). The extent of a negative effect will depend on the abundance of the butterflies and the coincidence of flowering time and other factors. Counts of skippers trapped in flowers were found to follow closely a negative binomial distribution (P = 0.8656).


Cypripedium reginae; Thymelicus lineola; Showy Lady’s-slipper; orchid; European Skipper; butterfly; pollination; pollinator interference; negative binomial distribution; Ottawa Valley

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