By Nancy Adamson
Pollinator Conservation Specialist
Xerxes Society & NRCS
Native bees, wasps, flies, beetles, and many other insects keep Georgia’s forests, fields, and watersheds alive and healthy. Native bees are vital for pollination of most Georgia fruit and vegetable crops, including two of the state’s most valuable fruit, blueberries and watermelons, but also for most of the wildflowers, shrubs, and trees that protect our watersheds and provide food and shelter for lots of other wildlife. Flies, wasps, beetles, butterflies, and moths are also important pollinators, but native bees are especially effective crop pollinators for a variety of reasons.
Georgia has more than 500 native bees, the vast majority of which are solitary species. This means a single female, once she mates, will make and provision nests alone.
Unlike a honey bee colony, that lives through the winter, most of our native bees are only active during the growing season, and overwinter underground or in cavities (as larvae or adults), with the next generation emerging the following season to mate and start the cycle again. Because a solitary bee does not share labor with sisters or a queen, it’s vital that she collects nectar and pollen on every foraging trip—both she and the young she is providing for require the protein in pollen and carbohydrates in nectar.
One reason solitary bees are often more effective pollinators than honey bees on a bee per bee basis is they collect both pollen and nectar every trip, making contact with both the male and female flower parts (a honey bee forager may collect only one). Another reason our native bees are especially effective is that some plants need to be sonicated to release pollen (called “buzz pollination.”)
Plants in the heath family (Ericaceae, which includes blueberries, huckleberries, and sourwood) and nightshade family (Solanaceae, which includes tomatoes, eggplants, and peppers) require buzz pollination, a certain frequency of vibration (via wing muscles) that causes poricidal anthers to release pollen. Most of our native bees, even the smallest sweat bee, buzz pollinate, while honey bees do not. If you stand still for a moment by your tomato plants, you’ll likely see some beautiful green sweat bees belly up below a tomato flower. They may be holding on with their jaws, pollen falling onto their upturned bodies, which they’ll pack into long pollen carrying hairs (scopa) on their legs.
The southeastern blueberry bee, Habropoda laboriosa, is a solitary groundnesting bee that is wholly dependent on blueberries and closely related heath plants for pollen, though it may collect nectar from other plants, like redbud, if needed.
Three species of squash bee, Peponapis pruinosa, Xenoglossa strenua, and Xenogloass kansensis, are wholly dependent on pollen from cucurbits, and often nest in the ground right next to squash plants. Organic growers who use tillage for weed control avoid deep tilling in order to protect groundnesting bee nests (surface tillage may destroy a few, but the vast majority will be alright).
Other native bees are also tremendously effective pollinators of one or both of these plants, including bumble bees, mining or digger bees, various sweet bees, mason bees, and leafcutter bees.
Nick Stewart, a pollinator researcher at Georgia Gwinnett College, has developed a wonderful Bees of Georgia website (http://native-bees-of-georgia.ggc.edu/) and Keren Giovengo of University of Georgia’s Ecoscapes maintains a wonderful set of native plant and land stewardship resources at http://marex.uga.edu/ecoscapes/. Additional pollinator conservation and conservation biological control resources are available from the Xerces Society (http://www.xerces.org/pollinator-conservation/ and http://www.xerces.org/conservationbiocontrol/) and the USDA Natural Resources Conservation Service (http://plants.usda.gov/pollinators/NRCSdocuments.html). Pollinator habitat also supports tremendously beneficial predatory and parasitoid insects. Links to these any many other resources can be found on the Georgia Organics website, as well.
Because we cannot easily move our native bees around, providing habitat, managing to enhance diversity (planting natives, reducing mowing), and avoiding pesticides are the best ways to support pollinators and other insects that benefit crop production and support healthy communities.