CONDITIONAL OUTCOMES OF INTERACTIONS: THE POLLINATOR–PREY CONFLICT OF AN INSECTIVOROUS PLANT

Insectivorous plants benefit from trapped, dead insects as a source of nutrients. On the other hand, most insectivorous plants depend on free‐moving, live insects as pollen vectors for sexual reproduction. In Pinguicula vallisneriifolia Webb, the spatial and temporal coincidence between flowers and the first distal leaves presents a potential conflict between the plant–pollinator and plant–prey systems. To examine this possibility, I combined an extensive regional survey to identify the pollinator assemblages and to analyze prey capture with a local intensive study to investigate the mechanisms of interference between the two systems. I analyzed the possible conflicting functions of pollination vs. insectivory under contrasting abiotic scenarios. Field observations and experiments confirmed the pollinator role of small flower visitors and the interference between the plant–pollinator and plant–prey systems. The degree of this interference is determined by the size and foraging behavior of pollinators, given that only small pollinators become entangled on leaves. Plants in bloom had a greater probability of capturing thrips than did plants without flowers. Because P. vallisneriifolia is pollen limited, the capture of small pollinators depleted the availability of the resource that limited plant reproduction. The pollinator–prey conflict is, however, environment specific, because the shadiness of the microsite where the plant grows determines both the distribution and abundance of different‐sized insect species and the retention capacity of the mucilage. The present results indicate that plant–pollinator and plant–prey interactions can be strongly determined by species‐specific ecophysiological responses of flying insects and sessile plants to abiotic characteristics of the environment. The physical environment affects the outcomes of plant–animal interactions and, ultimately, the balance between mutualistic and antagonistic systems.