Ants as Flower Visitors and their Effects on Pollinator Behavior and Plant Reproduction

Ants regularly visit flowers, but they may decrease plant reproductive success by competing with pollinators or damaging reproductive structures. However, how ants may exert these costs needs further clarification. In Chapter 1, I review the literature, finding that flower-visiting ants often have neutral effects on plant fitness. In Chapter 2, using artificial flowers with male and female function, I investigate how interference competition between flower-visiting Myrmica rubra ants and Bombus impatiens bumblebees changes pollen analogue movement patterns. Ant presence and scent significantly reduced pollen analogue donation and reception because bees avoided flowers with ant cues. In Chapter 3, to assess the frequency of palynivory among ants, I conducted an acetolysis survey of 75 neo- and paleo-tropical ant species. Ants consistently contained low numbers of pollen grains, suggesting opportunistic pollen consumption may be widespread. Altogether, ant visitation may be costly, but the mechanism depends on the plant, pollinator and ant identities.MAS