By Laurie Zitterkopf, Nebraska Extension Master Gardener Volunteer
Bumble bees are declining, and protecting existing habitat and creating and maintaining new habitat are some of the most immediate and productive steps that can be taken to conserve these pollinators. These habitats also support other native pollinators and beneficial insects.
Where populations of pollinators have declined, there is a parallel decline in insect-pollinated plants. Bumble bees and other native pollinators are needed to pollinate our native forbs (flowers).
Habitat fragmentation, grazing, pesticide use (insecticides and herbicides), and pests and diseases are some of the challenges facing the bumble bees.
Habitat Fragmentation: Extensive tillage and plant monocultures can be detrimental to bumble bee populations. It is helpful to provide bee habitat throughout farmed areas, including wind breaks, tree rows with shrubs and underplanted with native forbs and bunch grasses.
Grazing: Timing and intensity of grazing, and type of livestock are all important predictors of the number of bumble bee species present on a site.
Pesticide Use: The use of insecticides and herbicides is detrimental to a healthy community of pollinators. Insecticides by design kill insects, but sublethal does can affect their foraging and nesting behaviors, and herbicides reduce floral diversity. The greatest pesticide use (measured as pounds of active ingredient applied per acre) takes place on the homeowners’ landscapes. Homeowners have access to a wide array of pesticides with little regulation of their use, and lack education about the effects of these chemicals.
Pests and Diseases: The commercial bumble bee industry has greatly increased its output of bumble bees for greenhouse pollinators. In the 1990s, queen bees were sent to Europe, where it is thought they picked up the pathogen N. bombi and brought it here. If you are going to purchase insects, be careful not to spread introduced pests and diseases to our native pollinators.
The flight season of different bumble bee species varies, but generally queens emerge in the late winter or early spring and the colony continues through to early fall. This requirement makes bumble bees sensitive to differing management practices throughout the course of the year. Plant for all-season blooms.
Careful selection of plants that are beneficial to bumble bees is essential to creating valuable habitat. Native plants are an excellent choice to provide nectar and pollen sources. They provide several benefits:
- Bumble bees coevolved with native plants.
- Once established, native plants typically need less maintenance (less water, fertilizers and pesticides).
- Native plants usually do not spread to become weedy species in natural areas.
Protecting, restoring, enhancing, or creating new bumble bee habitat is the best way to conserve populations of these animals. Individual landowners can make a direct contribution to bumble bee conservation. Every property has the potential to support habitat and thus become a refuge for bumble bees. Where can you create a bumble bee habitat in your yard?
Resource: Conserving Bumble Bees, Xerces Society