No flowers? No problem. Bees have other ways of finding sugar

What’s a bee to do when there are very few flowers available and it needs a sugar fix? Wild bees may be responding to climate change and urban expansion by relying on insects to get the sweet stuff, according to a study by Joan Meiners, a Ph.D. student in the University of Florida IFAS School of Natural Resources and Environment.

Non-honey bees, which live in holes in the ground instead of in hives, are the primary pollinators in wild habitats such as national parks and provide valuable pollination services in croplands, Meiners said. “These solitary bee species develop in the ground for about 11 months, and then come out to visit flowers for nectar and pollen—which they need for energy and to reproduce,” she said.

Climate change has caused some flower species to bloom at different times than they have in the past, Meiners said. This causes a potential mismatch in bees and flowers meeting at the right time. With urban development also reducing the number of wildflower habitats, wild bees could come out of the ground to find very little food available to them.

When this happens, Meiners discovered that some wild bees turn to plant-feeding insects for food. The plant-feeding insects suck out nutrients from their host plant, and then secrete a nutrient-rich carbohydrate known as honeydew that is similar to nectar sugar, Meiners said. “We are the first to study solitary bees feeding on honeydew while they wait for more flowers to bloom,” she said. “And one of the most interesting things about this behavior is that these bees can find the honeydew without any colorful petals or scents to guide them there.”

Meiners and other researchers observed 42 species of wild bees visiting nonflowering shrubs during early spring, and determined that these bees were accessing sugary honeydew secretions from insects without the aid of standard cues like floral color, scent, or humidity. “We think of bee foraging as being all about flowers. But it appears that bees improvise when they can’t find flowers by eating sugar from honeydew, and that they have ways of finding these sugars that might involve watching the activity of other bee foragers instead of just looking for flowers,” Meiners said. “They still need pollen from flowers to reproduce. But feeding on honeydew may be a way for them to survive until flowers bloom when the timing is off.”

Solitary wild bees are important to the environment because they conduct most of the pollination in wild habitats, Meiners said. Insects, primarily bees, are responsible for 90 percent of animal-mediated pollination, which helps flowers reproduce, she said. “A crop plant may fail to produce fruit or seeds if it is not visited by a bee. With honeybees on the decline, we need wild bee species to help pick up the slack,” she said

Meiners’ next study, set for spring 2018, will further explore wild bee honeydew foraging by asking: Of all the bee species present in the environments studied, which ones are using honeydew and which are not? Are there patterns or traits common to the bee species using honeydew that can help us understand how important these sugars are to them?

Source: University of Florida (Beverly M. James)