OHIO VALLEY — Native bees play a crucial role in pollination, but are often overshowed by honeybees. Honeybees produce wax and honey as well as pollinate, and their hives are large. Native bees are solitary bees and do not produce anything of interest to humans, but their contribution to pollination, especially of early crops should not be overlooked.
Once such bee is the Mason (species Osmia). Sometimes called orchard bees, as they are often seen buzzing around blooming fruit trees and berries in early spring. They are very independent, producing their own offspring and gathering their own food. While they often nest close to each other, they are only focused on their own nest.
They were named for the way they build their nesting chambers with “masonry” products. Using mud and clay, they use existing holes found in nature to place pollen and an egg inside, then seal the entrance with a mud wall.
Mason bees emerge from their cocoons inside the chambers in early spring, as they prefer cooler temperatures and wet conditions. Once they emerge, they mate and begin the search for empty holes and begin their efforts at stocking the nests. Females collect the preferred food, fruit tree pollen and some nectar, and bring it to their nests, where they knead it into a ball, mixing it with nectar and their own saliva. The egg is laid on top of the mixture and then sealed. They begin the process again, until they have five to eight cells or nests. When this is completed, they seal the entrance to the hole with a thicker mud wall. The larvae grow and metamorphose into pupae and later on into adults. Mason bees are gone by early summer, hibernating over the winter inside their cocoon.
According to the U.S. Department of Agriculture, successful pollination does not require a large population. About 250 to 300 female bees per acre are recommended if there are no other bees present. Backyard orchards of a few dozen trees may be adequately pollinated with 50 female bees.
Their efficiency is due to the fact that Mason bees land directly on the reproductive structures of the fruit tree blossom. They collect pollen on the underside of their abdomen, simply put, on their belly. With the abdomens of foraging female bees loaded with pollen, the repeated and direct contact with the anthers and stamens of the blossom results in pollen transfer.
Since female bees collect pollen while constructing nests to provide food for bee larvae, the key to heavy pollination is to promote maximum nesting activity.
Social bees, such as honey bees, will respond to threats on the colony from people or animals by stinging. The protection of the hive is so important that worker bees will give their lives to protect it. In contrast, orchard bees have little to defend and will only sting in self-defense.
Chris Blank, Gallia County Bee Inspector, said that while the Mason bee is a hardy native species, there is cause for concern from the effects of pesticides.
Mason bees are active outside of nests only during the spring and early summer, so they are unlikely to be directly affected by spraying that occurs at other times of the year.
“The concern for these bees are the systemic pesticides sprayed at other times of year,” Blank said.
Neonicotinoid pesticides are a growing area of concern because they can become persistent in plants and be transferred to bees via pollen or nectar.
“Pesticides sprayed on raspberries and fruit trees can become systemic in plant tissues, so even though they might not be affected by the spraying itself, it is in the plants they visit,” Blank said. “Native bees have small colonies, so they are vulnerable to a reduction in size.”
While it is difficult to study the impact of pesticides on Mason bees due to their solitary nature, amounts found in nectar and pollen are likely to cause neurological impairment affecting memory and such behaviors as foraging, which in turn affects reproduction, according to the Conservation and Management of North American Mason Bees.
Any effort to support Mason bees and other pollinators is a positive step to ensuring their survival. Blank encourages gardeners to attract these native bees to their own gardens by developing nesting places and proper soil conditions. Many resources can be found online or in books at your local library.
“You don’t have to be a bee-keeper to encourage these bees to make their home in your yard,” Blank said. “They just need a place to nest, and plants with pollen and nectar, and they will take care of themselves.”
This is the third is a series of articles on bees in the Ohio Valley. Special thanks to Chris Blank and the U.S. Department of Agriculture.
Lorna Hart is a freelance writer for Ohio Valley Publishing. She can be reached at [email protected]