Nectar robbers are animals that take nectar from flowers without contacting the sexual parts of the flower; they rob the flowers of nectar without pollinating them. In this sense, they are considered cheaters of the pollination system. In most cases of nectar robbing, a different kind of animal robs than pollinates: bee robbers taking nectar from hummingbird-pollinated flowers, for instance. In the case of Impatiens (jewelweed), the same species of bumble bees are both robbing and pollinating. Even more surprising, some of the same individuals are both robbing and pollinating. This observation flies in the face of currently accepted ideas of mutualism between plants and their pollinators. The proposed research will determine how bees make behavioral decisions as they forage among jewelweed flowers. Does nectar level in flowers determine which behavior they will perform? Does previous visitor history of the flower affect their behavior? How does age and experience of the bees influence their behaviors? Intensive observations of marked bees will reveal individual behavior patterns. Manipulating the nectar level of flowers will allow the testing of the strength of the relationship between reward level and behavior.
It has traditionally been thought that the relationship between plants and their pollinators is a prime example of mutualism: a tight relationship in which both members benefit. The behaviors of bumble bees at flowers of jewelweed suggest that this mutualism may not be as strong, or more subject to exploitation, than previously thought. This research will help us understand what is apparently a unique system of cheating and benefiting, one that currently defies the simple categories of mutualism or antagonism.
