Antibiotic overuse might be bad for bees

Too much of a good thing

bees, some with pink dots on their backs
Bees treated with antibiotics (pink) were less likely to survive than a control group (green)Vivian Abagiu/U. of Texas at Austin

Bees are gutsy little beasts. They're the optimistic, plant-protecting, soccer-playing marvels of the insect world.

And their actual guts are great models for the human microbiome. Both bees and humans acquire their gut bacteria socially, humans initially through their mother, and bees from other bees in the hive. Bees' microbiomes set them apart from their cousins in the insect world—most bugs pick up their bacteria from the environment, not from their housemates.

That similarity means that humans and bees can face similar risks to their microbiomes as well. In a paper published Tuesday in PLOS Biology researchers found that antibiotic ingestion alters the bacterial colonies living in the bee gut—just as the antibiotics we take change our own microbiomes.

Beekeepers often use antibiotics to treat their colonies for a condition called foulbrood, a bacterial infection capable of destroying an entire hive.

In many cases—just like in humans—antibiotic treatments are great news for bees. But there’s not a lot of research into interactions between those antibiotics and the ‘good’ bacteria that live inside bees’ guts. So researchers decided to take a look.

“The aim of the study definitely was not to give advice about the best beekeeping practices or to tell people how to treat their bees,” says Kasie Raymann, lead author of the paper. “The aim of the study was for us to better understand the role of the microbiota in the biology of bees, and more generally understand the consequences of disrupting the microbiome in an animal host.”

They treated one set of bees with a standard bee antibiotic, and left another set as a control group, feeding them sugar water. They painted tiny, colorful dots on the bees' backs in order to tell them apart, then returned them to the hive. After a week of observation, the researchers found that two-thirds of the non-treated bees were still thriving in the hive, while only one-third of the antibiotic-treated bees were still alive.

Humans tend to have thousands of different kinds of bacteria inside our guts, but bees only have 8-10 types. So it's a much more delicate ecosystem: killing off some of those bacteria can have a profound effect on the microbes that are left.

Raymann also found evidence that treated bees were more susceptible to a bacterial pathogen called Serratia, suggesting that while antibiotics might help treat some infections they could leave bees more vulnerable to others.

And that's not all. Just like antibiotic overuse in humans can lead to antibiotic resistant diseases, the same thing can happen in bees, and that's worrying in a population facing far larger threats of habitat loss and insecticides.

“I don’t want to recommend how to use antibiotics,” Raymann says, adding: “I do think that antibiotics should be used with care.”

More research is needed to fully understand the interaction between antibiotics and bee microbiomes. Raymann is interested in continuing the research, hoping to look into how bacterial metabolisms change after antibiotic treatments, or how long it might take for a bee microbiome to recover from an antibiotic treatment—if it can at all. And in addition to helping us save the bees, these insights could one day be tied to similar research on our own guts.