Among many researchers working to save the honeybees, Daniel Swale, Ph.D., brings a unique perspective: his expertise in killing insects.
Honeybees face an array of threats, from habitat loss to environmental toxins from insecticides. Millions and millions of dollars go toward funding research to better understand these threats and their impact.
“[The University of Florida] has some excellent scientists and world-class facilities working on bees,” said Swale, the Associate Director of Training and Special Projects at the University of Florida Emerging Pathogens Institute.
He cites Jamie Ellis, Ph.D., and Cameron Jack, Ph.D., both from the UF Institute of Food and Agricultural Sciences. “A lot of great work, particularly on bee biology and ecology comes out of Jamie’s research program, and Cameron’s group has done fantastic on honeybee toxicology and mite control.”
Unfortunately, the sustainability of the managed honeybee industry is challenged by many different factors, such as loss of land, pesticides, diseases and infestation with bee pests. Ongoing research helps scientists and beekeepers better understand these issues, but it’s unlikely that these stressors will go away any time soon.
Swale, an associate professor at UF IFAS, has decided to take these circumstances as a given and focus on ways to mitigate their impact. With that mindset, Swale’s lab secured funding from the United States Department of Agriculture to find ways to enhance honeybees’ immune systems.
“We know that bees are dying for a number of different reasons, and it’s accepted among the field that viruses play a large, if not the largest component of honeybee health issues,” Swale said.
He works at the intersection of physiology, the study of how the body works, and toxicology, the study of the effect of poisons. Combining these two to create physiotoxicology, Swale researches how to exploit an insect’s body functions and drug the system.
“So, we can understand a unique physiological system and utilize that to poison a pest insect, such as a mosquito or tick, prevent transmission of pathogens that cause disease,” Swale explained.
While the lab sometimes develops insecticides, the researchers can also use their physiology expertise to enhance a body function.
“The other side of it is actually the same thing,” Swale said. “You’re still putting a drug into a system to alter the function of it. But, in the case of honeybees, it’s to help it.”
Enhancing honeybees’ immune systems
If you’ve heard of free radicals before, you likely know of them as a bad thing. Health experts recommend eating antioxidant-rich foods like fruits and vegetables to protect your body from free radicals. These unstable oxygen molecules are a natural byproduct of cell processes.
The negative reputation of free radicals is partially deserved since they can damage cells in large quantities, contributing to conditions like diabetes, heart disease and cancer. But at lower concentrations, free radicals help cells communicate with each other and defend the body against infection.
Like blood pressure or insulin levels, free radicals hit a sweet spot in healthy bodies. Swale’s team wondered if they could stimulate the production of free radicals to help honeybees resist diseases.
“Can we push that system right to the edge?” Swale asked. “Where we’re able to maximize its benefit and, in this case, enhance the immune system.”
The research team used a compound called pinacidil to alter potassium channels. Bees, humans and most living things use these proteins to control the distribution of potassium across cells. With pinacidil, Swale’s team stimulated potassium channels to produce more free radicals.
The lab spent two years doing large field studies with 90 full-sized honeybee colonies. They mixed pinacidil into sugar water for some of the colonies and left others untreated for comparison. Bees that consumed the treated sugar water had spread it to others as they moved in and out of the hive.
Then, the researchers exposed the colonies to six different viruses. Pinacidil had essentially eliminated virus infection not only in the individual bee, but also the entire colony.
Helping honeybees while poisoning pests
“We like bees. We do a lot to help the bees,” Swale said. “But most other insects give us diseases. They bite us, they’re nuisances. They kill our pets, kill our livestock and they’re massive economic burdens.”
The United States has applied insecticides like malathion and naled for decades to control mosquitoes. In addition to causing annoying, itchy welts, mosquito bites transmit viruses that cause dengue, yellow fever, chikungunya and Zika.
“Insecticides are a good thing. They save a lot of lives,” Swale said. And the process of creating them is ultimately the same as designing a therapeutic treatment for honeybees. “You develop a chemical and you get it to bind to a target site to elicit some sort of response in a selective manner. You get the phenotype you want in the target insect, but no negative consequences to non-target organisms.”
Swale understands why people may be wary of insecticides, especially out of concern for how they may affect the bees. Swale is fond of honeybees and personally keeps 20 colonies.
But he also recognizes the tangible benefits of insecticides, such as reducing the spread of disease and protecting the food we eat.
There is a balance to be found, Swale said. “It helps to be strategic about application. It doesn’t have to be all or nothing.”
Counties across Florida apply mosquito sprays at night, for example, when there is no bee activity.
As for the next big breakthrough in honeybee health, Swale sees a bright future ahead for therapeutics that either target varroa mites or help honeybees resist viruses.
Written by: Jiayu Liang