Pollinator Foraging, Experimental Nectar-robbing and Plant Fitness in Impatiens capensis

Bombus vagans workers were observed collecting nectar from two populations of Impatiens capensis. Approximately one half of the flowers in one population had their standing crops of nectar removed in a manner simulating nectar-robbing by bumblebees. The other population served as a control. Bombus vagans employed arearestricted searching behavior in both populations. The increased frequency of longdistance bee flights associated with the abundant low-quality reward blossoms in the nectar-robbed patch served to increase neighborhood size relative to the control area. Pollen was transported greater distances because of nectar thievery, thus making it more likely that the main purpose (i. e., genetic variability via outbreeding) of the chasmogamous flowers of I. capensis was achieved. Because seed set was statistically indistinguishable for robbed and unrobbed blossoms, nectar-robbing may thus actually enhance female fitness in L capensis.