It’s a tale that many of us first heard in elementary school science: a bee flies onto a flower, sucks nectar from the flower’s center, collects pollen on its body and quickly moves on to the next plant, where the pollen is transferred into the stigma. In a perfect exhibit of mutualism, a dependency among species in which all those involved benefit, pollination simultaneously ensures that the pollinator species sustains the energy to survive and that the pollinated species produces seeds that will grow into the next generation of plant. 

As many of us know, though, bees aren’t the only pollinator species. Among the ranks of pollinators there exist bees, small mammals, bats, birds, moths, butterflies and countless other species which benefit from this mutualistic relationship.  According to the USDA, this process alone is at the base of nearly $18 billion in annual crop production revenue in the United States.

A troubling trend is emerging however. In July, the International Union for Conservation of Nature (IUCN), declared the Danaus plexippus plexippus species of butterflies, also known as the migratory monarch butterfly, to be endangered. Almonds, thirsty crops that also rely heavily on pollination, have struggled in recent years as a result of intense droughts in California, a state that produces nearly 80% of the world’s almonds. Tomato plants, which don’t require pollinators but do benefit from them, are notoriously heat sensitive. In California, where a quarter of the world’s tomatoes are grown, yield dropped nearly 23% from 2015 to 2021. 

Dr. Gloria K. Muday, the Charles M. Allen Professor of Biology at Wake Forest, researches tomato plants specifically. Muday’s research on tomatoes initially centered around plant hormones but has evolved into attempting to understand how antioxidants known as flavonols could potentially increase a tomato’s resilience to increasingly high temperatures.

“We started out thinking much more about hormones that control plant growth and development, as well as the molecular mechanisms by which they do that,” Muday said. “We accidentally got involved in climate change.”

As lab assistants began cutting open one particular mutant variety of tomato Muday’s lab was growing in the Campus Garden, they noticed something surprising: there were far fewer seeds than a typical, nonmutant tomato plant contains. Muday and other lab members noticed that seed counts were particularly low when the weather was warmest. 

“The reason that they had no seeds was that the pollen produced by the mutant plant was not very good and it was exquisitely sensitive to elevated temperatures,” Muday says. 

Muday explains that her lab has come to the conclusion that the lack of seeds is directly related to the mutant tomatoes’ lack of flavonols, a specific type of chemical compound found in many plants, which acts as an antioxidant.

“Plants produce these compounds as sunscreens to protect them from the oxidation that happens when light hits them,” Muday said.

Without flavonols, tomatoes are much more prone to heat stress and their reproductive capacities in particular are compromised. Ultimately, this means that flavonols may be a key component in combating climate-induced heat stress in not only tomatoes but other core crops like rice and corn as well. If scientists like Muday can bioengineer a variety of tomato that produces more flavonols, it is likely that those varieties will be less susceptible to heat-induced reproductive damage. 

On the pollinator side, Wake Foresters are searching for solutions as well. As ZSR Library Specialist and avid beekeeper David Link explains, rising temperatures are largely concerning because it alters honey bees’ strategies for weathering the cold, a fact he says will lead to the necessity for more human-managed hives.

“Honey bees store nectar/honey in the hive to survive during the cold winter months when there is no nectar/carbs to harvest,” said Link. “With warmer temperatures, honey bees are flying for longer periods when there is no nectar to harvest.  Bees will leave the hive pumped on carbs to go searching for nectar and return empty, so they have to eat again upon return.  Their stored carbs are depleted quicker and many hives die of starvation before the first blooms providing nectar arrive in the spring.” 

Link maintains 10 hives between Campus Gardens and Reynolda Gardens, 12 more hives within half a mile of campus and numerous others in the greater Winston-Salem area. He expresses concern about the effects of pesticide use as well, an area that Dr. Susan Fahrbach’s lab is investigating.

Fahrbach, who is the Reynolds Professor of Developmental Neuroscience in the Wake Forest Biology Department, says that the biggest threat to bees is not a rise in temperatures alone; bees aren’t native to North America and live in a variety of different climates around the world. Fahrbach believes that this makes bees uniquely suited to adapt to rising temperatures. 

Her lab is studying the neurological and gastroenterological effects of pesticide use on honey bees.

“Honey bee populations have incredible genetic diversity, so I’m not so worried about their capacity to adapt,” Fahrbach said with regard to the life of the honey bee. “[However], the honey bee’s ability to regulate the temperature [of the hive] assumes everything else (besides temperature) will be equal. If the plants they depend upon are not flowering at traditional times or in traditional abundance…that could be a problem [for honey bees].” 

Alternatively, Fahrbach’s primary concern when it comes to human impacts on bees lies mainly in the realm of pesticide use. While certain levels of pesticides are nonlethal to bees, Fahrbach and her team believe that bee behavior is being affected by sublethal doses, something that could alter a bee’s productivity when it comes to pollination. 

“Modern pesticides that spread throughout [the entirety] of the plant are called systemic insecticides. They are designed to be very safe for humans and mammals…but widespread use of neuroactive pesticides results in a lot of sub-lethal exposures [of insects to pesticides],” Fahrbach says. “Exposure to a sublethal dose [of pesticide] reliably causes a change in the brain [of honey bees, but] we have [yet] to link that to something that the bee does.” 

While Muday and Fahrbach’s research may seem only distantly connected from a biological standpoint, the thread that connects them lies in the relationship between pollen and pollinators. If plants like tomatoes can’t produce ample amounts of viable pollen, pollinators like honey bees can’t spread pollen. If the behavior of honey bees and other pollinators is threatened by pesticide use, they will put not only themselves but also plants at risk. 

Scientists say that one of the biggest challenges in the fight against climate change will be maintaining ample food supplies. As populations of pollinator species like the monarch butterfly dwindle, we may become increasingly reliant on the adaptability of bees in order to pollinate crops. With this in mind, are we, as Susan Fahrbach is examining, putting bees at risk through our use of pesticides? Will Muday’s findings about the sunscreen-like effect of flavonols be a key factor in reducing heat stress among core crops? 

Time will only tell what humanity’s response to pollen and pollinators in peril will be, but in the meantime, Wake Foresters continue to exhibit Pro Humanitate in action. Whether it’s through in-depth scientific research on bees and tomatoes or beekeeping in gardens on campus, members of the Wake Forest community are combating the issue of pollination head-on.