Helping Pollinators in Peril
Honeybees are one of the most essential and observable pollinators of agricultural crops. As their population has begun to decline recently in North America and Europe, scientists and environmentalists alike are concerned about pollinator shortages.
Contributors to the decline are climate change, habitat destruction and pathogens, such as Nosema ceranae and Nosema apis, and the use of pesticides and fungicides, which contaminate pollen and make honeybees more susceptible to infection by Nosema species, according to a 2013 study led by Dennis vanEngelsdorp, an assistant research scientist with the University of Maryland department of entomology. Published in the journal PLOS ONE, the research suggests that the interaction of these factors appear to strengthen the negative effects. The Nosema species can cause complete collapse of honeybee colonies.
In addition to the social honeybees, several types of solitary native bees are responsible for the pollination of about 60 percent of the total flowers in North America: mason, green sweat, mining and leafcutter. Pollination produces fruits, vegetables, nuts, seeds, spices and of course, honey. Native, social bumblebees are the only pollinators of tomatoes. Our food supply, and therefore our very survival, depends upon pollinators.
We can help the plight of the pollinators by adding diversity to our yards and gardens, even with something as simple as a container garden on a balcony. Adding low-growing, flowering plants in front of foundation shrubs or hedges also provides opportunities for pollination. In the vegetable garden, we can add a flowering mix, including plants in the parsley family along the edge, as well as annuals like marigolds and herbs such as thyme and lavender.
Bees prefer the flower colors purple, blue, violet, white and yellow, and although they do not see red, they can see ultraviolet patterns on not visible to humans in normal light. The patterns, along with other cues like scent, are believed to guide the bees into the flower. Plants with tubular flowers attract skipper butterflies and sphinx moths. Hummingbirds like large red or orange tubes that produce ample, dilute nectar.
Flowers from the daisy family are rich in nectar and pollen. Spring choices include the purple coneflower, blackeyed Susan, sweet alyssum, dandelion and wild geranium. Joe Pye weed and cardinal flowers are good mid-summer selections, and asters and goldenrods do well in the fall. Native plants work well because local pollinators have evolved alongside them. Some newer cultivars may have been bred for beauty at the expense of pollen or nectar production; for instance, double-flowered varieties are sterile and their pollen or nectar is usually inaccessible or blocked.
Most bees forage within 100 to 200 yards from their nests, so the availability of nesting habitat is another important factor for bee survival. Most native bees nest underground in well-drained soil; bumblebees, for instance, prefer rocky sites. Some mason bees nest in holes in brick and limestone; gardeners can purchase or build mason bee houses and install them with entrance holes facing east or southeast. Leafcutter bees nest in dead branches of trees; when pruning, leaving patches of dead plant stalks at the edge of the garden provides nesting for them, as well as overwintering shelter for other beneficial insects, such as ladybugs and praying mantises, and cocooning habitat for caterpillars.
Avoiding the use of pesticides and fungicides may be one of the most helpful things we can do for pollinators. Most pesticides, even organic ones, are not selective and will kill beneficial insects and pollinators. Do not use neonicatoids, not even for ash trees. Avoid spraying neem oil on flowers to control Japanese beetles because it will kill bees and pollinators. Use sustainable and manual (hand) methods of pest and disease control whenever possible.
Proper plant pruning, mulching, non-chemical weed control and removal of diseased plant parts makes plants stronger and more fertile by increasing water and nutrient availability and reducing pests and diseases, while protecting pollinators and providing them a thriving habitat.
Diane Olson-Schmidt owns LaceWing Gardening and Consulting Services. For more information, call 414-793-3652 or email LaceWinggdcs@att.net.