by Katie Navarra
Honey bees are the most widely known pollinator species. However, recent research shows there are numerous pollinator species and that the more diverse the species the increased pollination benefits. “There are thousands of bee species, some are solitary, some nest in the ground, others in twigs and trees,” explained David Crowder, Assistant Professor of Entomology at Washington State University.
During an eOrganic webinar, Crowder and Elias Bloom, a Ph.D. student in Entomology working in Crowder’s lab, discussed the diversity of native bees in farming systems and the roles they may play in supplement or replacing honey bees for pollination services.
“The decline of bees is a major issue globally,” Crowder added. Protecting all pollinators, including wild bees, is like providing insurance against the loss of honey bees. “If anything happens to honey bees or another species, when a rich, diverse population is present, it offsets the decrease in population,” he added.
Though findings from experimental tests are limited, the available studies suggest that as the number of pollinator species increases, seed production is also greater. “Only when there were up to 9 or 10 bee species is the efficiency similar to that of manual pollinating,” he said.
Many people are surprised to learn that surface flies, butterflies and even some beetles may also be beneficial pollinators. A study completed in Indonesian pumpkin crops supports this theory. From the research that is available, it’s also been noted that diverse pollinator species complement one another and work in a symbiotic relationship. “There is some evidence that wild bees pollinate some crops such as blueberries, tomatoes and squash better than honey bees,” he said.
A Federal Pollinator Task Force has been created to devise strategies to improve pollinator health. “Pollinator health matters,” Crowder emphasized.
Understanding what constitutes a healthy bee community is and practices that have the potential to improve or harm bee community habitats are important to supporting the viability of pollinators.
What is a healthy bee community?
A healthy bee community includes an abundance of bees in sheer number and a varying assortment of species. “Evenness, meaning no one bee species dominates and stability, especially for farms growing lots of crops is key,” Crowder said.
While pollinators may visit many different flowering plants, they favor certain crops over others. “Some bees may have plant preferences, which is why diversity is so important,” Bloom said, “for example, green bees prefer plants like asters.”
Diversified organic production can make it difficult for bee communities to effectively to do their job since plants bloom at different times throughout the growing season. “Honey bee (population) builds up over the entire growing season and spikes at the end of the season. Sweat bees are the second most abundant bee in the late part of the farming season,” he said.
Environmental factors may also impact the presence and effectiveness of pollinators. “They (pollinators) vary based on landscape context. There are fewer in urban areas than rural farming areas,” he added, “however, the functional role of the bee doesn’t change in rural vs. urban areas.”
Enhancing native pollinator habitat can encourage higher populations and promote pollinator health. Bloom observed some farms planting floral mixtures as a buffer strip to increase the diversity of the pollinator group. Though it’s unknown the effects plowing has on ground nesting bee populations, it’s worth considering. “Approximately 70 percent of bees nest in the ground so we’re also looking into creating bee beds,” he said.
Bloom will continue his research on Western Washington farms through the 2015, 2016 and 2017 growing seasons. Collecting bee samples is time consuming work done either through netting or by setting out blue vane traps or bee bowls.
“We’ve been fairly successful identifying bees to the genus level with a taxonomic key,” he said. Bees collected in Western Washington have revealed approximately 200 genera of bees. “About 25 percent of the community were Bombits, bumble bees, and another 25 percent were Apis, honey bees,” he said.
To learn more about the pollinator species on your farm, Bloom encourages farmers to study the insects visiting your crops. Connecting with pollinator experts in your local area can also be helpful. Information is available at the North American Pollinator Protection Campaign at www.pollinator.org .
To hear the webinar in its entirety, visit www.extension.org .