One of the best ways to assure pollination will occur on farms is to make certain there is a vibrant, healthy native bee population in the area. That’s the official word, according to Cornell University researchers.
Native bees can be growers’ hedge against declining honey bee populations. “If growers can ensure they have a decent enough native bee population to pollinate their apples, they don’t have to solely rely on honey bees,” said Maria van Dyke, research and outreach director of the Cornell University entomology department’s Danforth Lab.
van Dyke doesn’t think honey bees are headed for extinction. However, she has heard of farmers whose pollinators were unable to fulfill contracts because their bees were the victim of a spray incident at another site.
Native bees, like the melandrena, offer some advantages over their domesticated brethren. “Similar in size to honey bees, they prefer visiting members of the Rosaceae plant family (nearly all major tree fruits) and maple trees, which means they are more likely visiting more than just multiple trees in the same species in one foraging bout,” she said.
Because honey bees don’t readily hang upside down underneath leaves, they undergo a learning period when dropped off in blueberry fields and still emerge as less efficient cross-pollinators than native bees. “Native bees are totally adapted because they evolved with wild blueberries and readily go upside down and get all up in the stamens of those flowers,” van Dyke said.
Rutgers University researcher Rachael Winfree found honey bees engage in a behavior called “nectar-robbing” when confronted with unfamiliar flowers. “They will bite the base of the flower and just suck out the nectar without even touching the anthers,” said van Dyke.
Natives are not without disadvantages. Because they live in hives and are easily transportable, honey bees are far more mobile than native bees. Honey bee reproductive capacity is much higher than that of native bees. Natives typically produce from 20 to 40 offspring each year, while single hive populations range from 20,000 to 30,000 bees.
That said, van Dyke knows of farmers in New York’s Finger Lakes and Lake Ontario regions, as well as one of the Cornell University orchards, whose managers no longer sign contracts with pollinators because native bees handle the load. The necessary components of that situation are plentiful bee habitat and bee forage as well as spray programs executed with bee survival in mind.
Build Habitat for Native Bees
Growers can build plentiful habitat in areas where it is absent or lacking. It is a relatively easy process since about 70 percent of native bees are ground dwellers.
“Large-sized orchards with no bee habitat will have maybe 15 to 20 percent native bee visitations, while orchards where the surrounding bee habitat is good and integrated pest management is practiced experience 60 to 70 percent native bee visitations,” said Cornell’s Maria van Dyke.
Logs and snags, sand pits, soil piles, even raised beds or planting boxes will serve this purpose. Avoid using nesting blocks because the holes drilled in them for bee nesting are hard to keep clean and often fill with dirt or fungus; wasps compete with bees for their use, too.
To build a ground nest, clear vegetation from a small patch of level or sloping ground that is sunny and well-drained. Sandy loam soils are best, said van Dyke. Shallow till once and keep surrounding vegetation down. In areas where soils are heavier, dig a 2-foot pit and refill it with a sandy loam potting soil. Planting native wildflowers nearby will attract the bees to nest. Provide forage sources to for bees. Seeding meadows, road edges, hedgerows, wind breaks and fence lines with inexpensive flowering seed, such as clover, will provide necessary forage throughout the growing season.
Be patient, advised van Dyke. “It will take about three years for the nests to populate.”