By Katie Pratt
Bumblebees dart in and out of hives inside Brent Cornett's greenhouse in rural Laurel County. Without them. Cornett, '01, would not have such an abundance of bright, red tomatoes that play a role in his family's diversified farming operation. Shortly after installing the greenhouse this past winter, he hot his first beehive with help and guidance from Ric Bessin, University of Kentucky extension entomologist, and Steve Berberich, UK horticulture extension associate. He chose bumblebees, because they more efficiently pollinate nursery plants.
"In an enclosed environment without wind and rain to carry the pollen, tomatoes will not self-pollinate," Cornett said. If you don't have hives, your other option is to hand pollinate by either shaking the blossoms or using a leaf blower, which is very labor intensive and expensive."
Pollinators, which include bees, butterflies, hummingbirds, bats, beetles, and flies, are responsible for pollinating nearly 75 percent of crops. But many pollinators are facing dire futures, as their populations decline. In the past five to 10 years, researchers estimate that pollinator populations have dropped between 30 and 60 percent, depending on the pollinator. Much of the attention has focused on colony collapse disorder in honeybees, but they face decline for many other reasons including parasitic mites, pesticide issues, lack of nutrition, stress, and illness. Native bee populations—bumblebees, mason bees, and many other solitary bee species—are on the decline too. Monarch butterfly populations have also steadily declined over the past few decades. Habitat loss due to urban and suburban sprawl is one of the main reasons for the declines in all pollinator species.
Faculty, staff, and students in the College of Agriculture, Food, and Environment take these statistics seriously and have developed many efforts to protect pollinators and rebuild their numbers, so farmers like Cornett can continue to be successful and consumers can continue to have the nutritious foods that pollinators help produce.
Some answers to honeybee health may be in their behavior, UK assistant professor Clare Rittschof is a honeybee neuroscientist. She studies the brain mechanisms that control bee behavior, particularly aggression.
"Honeybee aggression is a cool behavior to study for a few reasons—it is a highly socially coordinated, sophisticated behavior, and it is tied to their health," Rittschof said.
When they feel threatened, honey bees release a special pheromone that alerts the hive to danger. The bees respond in numbers with a coordinated attack. Rittschof is studying how bees perceive those cues, and how information is encoded in the brain to lead to a change in behavior. She is also interested in understanding why colonies show such remarkable differences in their tendency to respond to aggressive cues.
Rittschof has found that honeybee aggressive response is tied to their environment—workers from colonies that are more aggressive tend to transmit that information to young developing bees, making them more aggressive as well. She is studying the brain mechanism that controls that decision, as well as physiological changes in other tissues. In a surprise finding, more aggressive bees tend to be more tolerant of pesticides, perhaps because they may be better at detoxifying harmful compounds. Rittschof is testing that hypothesis across honeybees with different aggression levels by assessing physiological patterns in the insect-equivalent of the liver.
Understanding these mechanisms could actually improve bee health. Rittschof's group has found aggressive bees are healthier in many ways. They tend to forage more, survive the winter better, and have fewer parasitic mites in their hives. Other labs have found that aggressive bees make more honey and more baby bees, or brood.
"The honeybee is a great example of the ways in which behavior can be used to infer individual health," she said. "Clearly, behavior has a strong physiological basis, and it reflects processes going on throughout the organism in tissues other than the brain."
Students in Professor Daniel Potter's Urban Landscape Entomology lab are studying ways to increase urban habitats for pollinators. This could help rebuild populations in areas that have seen the steepest decline due to development. They are also studying ways to manage lawn and landscape pests without harming bees and other beneficial insects.
One of the research priorities for graduate students Adam Baker and Bernadette Mach is to determine which plants are the most attractive to pollinators and develop recommendations for homeowners, landscape managers, and nursery professionals.
Monarch butterfly larvae are picky; they feed only on milkweeds. The adult butterflies also need flower nectar to fuel their annual long-distance migrations.
With research plots at The Arboretum and 18 different monarch waystation gardens he's installed at the college's Spindletop Research Farm. Baker is assessing which milkweed species and garden configurations are the most attractive to monarch butterflies. He is also spearheading a project to help golf courses establish monarch butterfly habitat in their out-of-play areas.
"Recent research has shown that 50 percent of all monarchs that migrate to overwinter in Mexico come through the Midwest, which includes Kentucky, so it's important that we do our part to provide habitat they can use as stepping stones," Baker said. "Our research demonstrates that monarchs do indeed find and use these waystations in urban areas."
He has found swamp, common, and showy milkweeds are the most attractive to monarchs, whereas butterfly milkweed, despite its name, is especially good for bees.
Mach assessed about 75 species of flowering trees and shrubs at 375 sites around Lexington and Cincinnati and documented the numbers and types of bees that visit them. From her findings, she developed a bee-friendly plant list for the Ohio Valley. Released this past spring, it is the first comprehensive study of its kind. The list is available on Potter's lab website, https://entomology.ca.uky.edu/Dpotterlab.
"This list allows the land care professionals and homeowners to participate in meaningful bee conservation efforts using science-based plant recommendations," Mach said. "It can also stimulate interest in pollinator-friendly plants and spur sales of such plants by Kentucky nursery producers and garden centers."
It's not just Kentucky yards that are becoming more pollinator friendly. The Kentucky Transportation Cabinet is also making sure the state's highways provide pollinator habitats, and CAFE is helping in the effort.
Joe Omielan, a research scientist in the Department of Plant and Soil Sciences, collaborates with cabinet personnel Mike Smith, '83, and Steve Kempf, both roadside environmental administrator, on managing invasive weeds along the roadways. When cabinet personnel began installing the gardens, Omielan began working with them to find an effective herbicide rate that would control weeds and allow the pollinator friendly plants to establish and thrive.
"It is very difficult to keep weeds out of pollinator beds. There's not a lot of information on how to do it and not a lot of herbicide products we can use, and that's what Joe is doing," Smith said. "When I talk to states that don't have the relationship that we do with their university, they are envious of us because we have someone who can look at these new products and figure out how to best use them."
Since the 2014 presidential memorandum on pollinators, which called for public-private partnerships and greater citizen engagement, the Kentucky Transportation Cabinet has installed more than 80 pollinator gardens and monarch waystations along the state's highways with plans to install more.
"It took awhile for the plants to germinate, but now we have a fairly diverse mix out there. It's only going to get better," Kempf said.
Ric Bessin has been a proponent of bees since he was a child growing up in a family that raised bees. Not only does he offer advice to farmers like Cornett, but he has been very active in statewide policy to improve pollinator conditions. He and Ricky Yeargan, senior extension associate for UK Ag Programs, were UK's representatives to a statewide group that developed the Kentucky Pollinator Protection Plan. The plan outlines best management practices for beekeepers, pesticide applicators, and landowners, ways to increase pollinator food sources, and ways to educate the public on the importance of pollinators.
At the college's Horticulture Research Farm in Lexington, Bessin works with horticulture professor Mark Williams on best management practices and applied research projects. Together, they develop ways to improve pollination for high-value fruit and vegetable crops like cantaloupe and acorn squash while keeping insect pests away.
They have developed a system where organic growers can plant cucurbit crops under low tunnels. The screens over these tunnels help keep insect pests like the cucumber beetle at bay. To pollinate the plants, however, they must place bees underneath the screens.
"This system works well for a high value crop, and pollinators are critical for us to get the yields we want," Williams said.
In 2016, Bessin and Williams found just how important bee timing was, as delayed pollination resulted in reduced yield. They are trying to determine the optimal time to release pollinators in this system, which could have important yield and economic consequences for growers.
Outreach and innovative research efforts like this at the College of Agriculture, Food and Environment are key to ensuring a brighter future for both pollinators and humans.