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The Effects of Pathogen‐Induced Pseudoflowers and Buttercups on Each Other's Insect Visitation

Roy, B. A.
Ecology 1994 v.75 no.2 pp. 352-358
Arabis, Diptera, Puccinia, Ranunculus, color, flowers, insects, nectar secretion, odors, plant pathogenic fungi, pollination, pollinators, rust diseases
Pseudoflowers induced by the rust fungus Puccinia monoica on Arabis spp. are flower—like in color, shape, size, nectar production, and scent. Pseudoflowers attract insects that aid the rust's reproduction in a way that is analogous to pollination in flowering plants. I explored the effects of pathogen—induced pseudoflowers and co—blooming buttercups (Ranunculus inamoenus) on each other's insect visitation by comparing visitation in single—species plots and mixtures. Visitation to pseudoflowers was greater in mixtures containing buttercups than in pseudoflowers plots of the same density, and visitation to buttercups was also greater in the mixtures than in pure buttercup plots. Because fungal pseudoflowers and buttercups both appeared to receive greater visitation when associated with each other than when alone, and both species produce food for insect visitors, this interaction could be described as Mullerian floral mimicry. However, several characteristics of this system do not fit standard definitions of mimicry: (1) pseudoflowers are not necessarily mimicking any particular species but instead may be generalized flower—mimics, (2) flower visitors may not always mistake pseudoflowers for flowers but may actually choose them, and (3) under some circumstances pseudoflowers and flowers may compete for visitors. Competition in favor of pseudoflowers is most likely when flies are the primary flower visitors or on the rare occasions when pseudoflowers are common relative to other species.