Sunday, June 19, 2016

Bees and Biodiversity

Bombus ternarius, Tricolored bumble bee on mountain mint
 Recently I discussed the idea of allowing dandelions on the lawn to benefit pollinators. I pointed out that such practice only benefits a handful of generalist pollinators, but not the specialists. The latter can be more numerous than the former when they are all counted. They also account for the wide diversity of nature.
Bombus impatiens, Common Eastern Bumble Bee on blanket flower

Andrena cornelli, Azalea andrena on azalea
Let me expand on the concept of biological diversity or, as it is often called by ecologists, biodiversity. There are 4,000 species of bees in North America, from the familiar, big and plump bumble bees to tiny bee species that remain unnoticed to all except to those who study bees. Bear in mind that even bumble bees aren't just one single species but about 46 in North America.

Augochlora pura on thistle
Nomada, cuckoo bee on spring beauty
Bee species vary not only in size but in many other ways. Some are active from early spring to the end of fall. Others complete their whole cycle in just a few weeks and remain dormant the rest of the year. Some are adapted to different climates and cover a large area, others are more limited in their geographic distribution.

There are even some species, called cuckoo bees, that don't bother raising a family. Instead, just as cuckoo birds, lay their eggs in the nests of other bees.

Some bees have a long tongue that enables them to reach into fairly deep throated flowers. Others can only visit flowers that are relatively flat and open. Finally, some are very particular about the flowers they visit.They collect pollen from only one species of plants (monolectic) or a few related species (oligolectic). They may visit a wider range of flowers for nectar, but only their choice plants will satisfy their pollen needs.
Agapostemon splendens on seaside goldenrod

Lasioglossum pilosum on coneflower
Losing a few of these specialists may not be catastrophic, but it is preferable to preserve as many of them as possible. A rich variety of species confers resilience to an ecosystem. This is why it is important to have a wide range of specialists along with the handful of generalists. One way to help the specialists is to plant a variety of native plants to ensure that some of them satisfy their needs.
Colletes on Cerceris canadensis
Bombus perplexus, confusing bumble bee on common milkweed
Long horned bee on sunflower

 All images © Beatriz Moisset

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2016