Native bees: The “other” pollinators we depend on

Friday, March 14, 2014

In the last few years we’ve been hearing a lot about the loss of honeybees and their hives. A looming pollination crisis is stretching across the globe. If honeybees disappear, we’ll face an historic calamity threatening many of the seed-derived foods we need to survive.

As ecosystem assaults mount — with climate chaos disrupting the synchrony between bee emergence and plants’ blooming times, systemic pesticides killing bees and human activity causing massive losses of habitat — bees earnestly go about their business.

They may not know it, but bees are a keystone species of life on land. Like us, bees need healthy food and a disease- and poison-free environment within which to nurture their young.

If we are to save the bees, it will require many thoughtful actions aimed at restoring their habitat. Strategies to assure pollinator survival must include helping native bees, as well as European honeybees. (Honeybees were brought here by English settlers in the 1600s.)

My primary focus is to protect and create native bee habitats that satisfy their critical needs. With 5,000 species of native bees in North America, of which 356 are in Massachusetts, we have our work cut out for us.

Unlike honey beekeepers, who harvest sweet evaporated nectar and aromatic wax to make candles, native beekeepers keep no honey or wax, and need far fewer tools. Yet both share a common objective: They assist bees that help flowering plants to reproduce. Bees carry male pollen to female stigmas of the same species, thus fertilizing the flower ovum that produces the miracle of seeds. Our food supply — including fruits, vegetables and herbs, and even meat and milk from plant-eating animals — depends on this crucial interaction.

Throughout millions of years of co-evolution, plants developed clever strategies to attract pollinators. Their flower petals, decked out with colors, shapes and patterns signal and guide bees to their nectar, the bees’ reward. For their part, bees have evolved body hairs to which pollen readily attaches. Bees gather both pollen and nectar to feed their larvae while the plant plays the fertilization odds: the success rate is only about two percent.

But before they gather these provisions bees need a place to lay eggs. About 90 percent of native bee species are solitary nesters; 70 percent of those nest in the ground, preferring well-drained soil in sunny, dry locations. The remaining 30 percent of solitary bees lay their eggs in woody materials. (Warm and dry conditions help keep developing pupae and cocoons from succumbing to mold and rot.)

Each female provisions one egg at a time with a ball of pollen and nectar, aptly named bee bread. Once females are bred in the spring, their first order of business is nest making. Ground-nesting females dig a hole about a foot deep before branching down snug corridors to lay a single egg in each chamber. This feat has been equated to a human bare-handedly digging a 50-foot hole, unearthing one armful at a time, while maintaining a shoulder-width opening.

A tad less daunting is the task of tunneling by wood-nesting bees. Often they will move into large beetle-larva excavations or hollow stems of reeds and grasses, or they may burrow into the pithy stems of various woody plants. Mason bees, also called blue orchard bees, are the stars in this realm. As native beekeepers we can readily assist these highly efficient pollinators with nesting materials. Even though mason bees have powerful mandibles, given the choice between easy-to-dig pith or empty hollow cylinders, they prefer the latter in the form of reeds, bamboo or even manufactured paper tubes.

North Americans have been tending these relatively easy-to-manage native bees for at least 15 years. These pioneer citizen-scientists have opened a way to restore pollinator habitat in landscapes ranging from backyards to farms. Fortunately there are suppliers offering a variety of nesting options, including ready-to-use pupated cocoons. The company Crown Bees, for example, in line with their food security mission, offers to buy back excess cocoons so they can eventually help orchardists and farmers meet their larger-scale pollination demands. Meanwhile, gardeners, small-scale farmers and other land managers are filling gaps in pollination by propagating native bees.

Another big help to pollinators is growing bee-friendly plants. Native bees and native plants, having co-evolved here, fit hand in glove. When we fulfill the pollinators’ nutritional needs, the success rate of native plants increases and we get closer to securing good pollinator habitat. Native bees have also grown accustomed to many non-native plants. Consulting a pollination specialist can help in making good planting choices.

But sourcing bee-safe plants isn’t simple these days. Large-scale plant nurseries that supply retailers have applied systemic pesticides to the potting soils of their so-called bee-friendly plants. Be careful and ask questions before you purchase. On my website (www.pollinatorswelcome.com) I have listed bee-safe nurseries and questions to ask your supplier. In addition, the sidebar to this column provides a list of “Top 10 Tips for Pollinator Proliferation.” If we all chip in, we just might change the course of history.

Tom Sullivan, owner of Pollinators Welcome, designs for pollinators and helps people attract them to their landscapes. He gives talks on creating habitats for native bees and consults with people interested in the link between food, pollinators and meadows. His next two talks are on Feb. 15th at the Hadley Garden Center and Feb. 26 for the New England Wild Flower Society and the Hitchcock Center for the Environment at Nasami Farm in Whately. Space is limited for the Feb. 26 talk; registration is required.

For more information or to register, go to www.newfs.org/ learn/catalog/bot5044 or call the Hitchcock Center at 413-256-6006.

Earth Matters, written by staff and associates of the Hitchcock Center for the Environment at 525 South Pleasant St., Amherst, appears every other week. For more information go to www.hitchcockcenter.org, call 256-6006 or write to column@hitchcockcenter.org.