Reasons floral fidelity is important for bees and plants

Floral fidelity makes honey bees special. While many pollinators flit from one plant species to another, honey bees doggedly pursue flowers of a certain species.

So when the new day dawns, worker bees Sue and Marianne, Betsy and Josephine grab their flight plans and wing out the front door. Sue is visiting dandelions, Marianne and Betsy are working on apples, and Josephine has cherries in mind. They each collect just one species of pollen. This is great for plants because the pollen that lands on the stigma is the type needed for fertilization. How this benefits the honey bee is less clear.

Nevertheless, an entire foraging trip will be spent on that single flower type. In fact, individual bees are likely to keep collecting the same pollen for many days. Only when the source dries up does the forager switch to something else.

This fidelity to one pollen type at a time means the plant has a better chance of being completely pollinated. Bees that forage on any plant they come across have mixed pollen types on their bodies, so the chances of a plant receiving the right type of pollen are less.

Floral fidelity requires large numbers of flowers

Floral fidelity is the reason you seldom see honey bees on small plantings. If you have just a few flowers of several different species, the flowers are more likely to be visited by native pollinators than by honey bees. A honey bee forager wants to see at least two basket-loads of pollen—probably more—before she starts to collect.

Much research has gone into floral fidelity. Examinations of pollen loads show that only about six percent of the pollen is inconsistent with the rest of the load. And some of the six percent may have been introduced accidentally. For example, pollen could have been deposited on a flower by the wind—or perhaps by a different pollinator—where it remained until it was inadvertently picked up by a honey bee.

You can clearly see the results of floral fidelity

You don’t need a laboratory analysis of pollen pellets to know floral fidelity exists. Instead, just take a look. Pellets have distinct colors—sundry shades of white, yellow, orange, blue, and gray. Each pellet is made from one color, not mixed up like M&Ms.

However, this is not true of all bee species. You can often see loads of pollen on bumble legs that have layers of different colors. It’s apparent that when they finished with one plant, they went on to a different species of plant with a different color of pollen.

The advantages of floral fidelity to the bee are less clear

Probably the biggest benefit to the honey bee is the efficiency of pollen collection. Instead of flying here and there and everywhere, randomly searching for pollen, the bee keeps working the flowers on one plant until the supply of pollen is used up.

By staying on one plant, a honey bee needs to fly less distance, and flying is an activity that requires lots of energy. If you watch carefully, you can often see honey bees walking, rather than flying, from flower to flower on a blooming tree or shrub.

Each honey bee unloads the pollen from her own legs

Whereas nectar is transferred from bee to bee before it is stored in a honeycomb, pollen-carrying bees must store their own pellets. Somehow, the foragers feel their way around inside the dark hive and find an available cell. They back up to the cell and scrape one leg with the other until the pollen pellet drops into the cell.

The photos of brilliantly-colored pellets were graciously provided by Phillip Cairns at MudSongs.org.

Rusty
Honey Bee Suite