Buzzing with Life: Microbes Inside a Bee’s Gut

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Bees aren’t the only pollinators, but 87% of flowering plants rely on animals for pollination—with bees doing a large share. Their role in global crop production, worth $200 billion annually, makes them a major research focus. In recent years, scientists have turned their attention to bee microbiomes—communities of microbes living in and on bees, including bacteria, fungi, viruses, and archaea—to understand how they support pollination and health in a changing climate.

There are over 20,000 bee species, with 77.4% being solitary, such as mason or mining bees. However, honey and bumble bees, which are social, dominate research—54% of it—even though honey bees aren’t native to the U.S. Despite this, they’re essential to modern agriculture and are more abundant than ever. While native bees were often overlooked due to their lesser economic value, research on these species is growing.

Like humans, bees rely on gut microbiomes for health. A microbiome is a community of microorganisms that live on and inside a larger organism. These microorganisms, or microbes– bacteria, fungi, viruses, etc.– acquired mainly through flowers, aid in digesting tough pollen grains and help bees build fat reserves. Healthy microbiomes also offer protection against pathogens, with bacteria like Lactobacillus acidifying the gut to ward off parasites.

A graphic showing the relative populations of 14 fungal genera on flowers and bee provisions like pollen and honey, and inside bees.

Flowers serve as transmission hubs for both helpful and harmful microbes. For bumble bees, some flower-produced yeasts increase visitation, though possibly at a cost to seed production. Plant pathogens may exploit bees by overwintering in their nests, demonstrating that even mutualisms can have downsides.

Microbiomes vary by geography, bee species, life stage, and social role. For example, queen bees—fed royal jelly—host different microbes like Bombella apis, which survives in that unique diet. During metamorphosis, bees reset their microbiomes and rebuild them through interaction with the colony and environment.

Two graphics showing that bee gut biomes are less diverse when hives are treated with antibiotics and pesticides.

Human activity significantly affects bee health. In apple orchards, fungicides—though deemed safe for adult bees—disrupt brood cell microbiomes. Glyphosate, a widely used herbicide, alters bacterial diversity and reduces bees’ immunity. Contaminants from wastewater, like heavy metals and antibiotics, further disrupt microbial balance. American bees, often treated preventively with antibiotics, show more antibiotic resistance than their European counterparts, raising concerns for long-term health.

Not all findings are bleak. Probiotic and prebiotic supplements—like acacia gum—show promise in strengthening bee immunity and digestion. Probiotics are microorganisms that benefit their host, in this instance, bees, while prebiotics are food for the microorganisms. These additions enhance foraging, pathogen resistance, and overall colony resilience by supporting beneficial gut microbes.

Studying bee microbiomes helps us better protect pollinators. It also reminds us to reduce pesticide use and care for even the smallest organisms. Healthy microbes are crucial—not just for bees, but for entire ecosystems, including our own.

Resources

Bees just wanna have fungi: a review of bee associations with nonpathogenic fungi by Danielle Rutkowski, Makena Wetson and Rachel L. Vannete 

Want to Save the Bees? Focus on Habitat, Not Honey Bees by Rich Hatfield and Matthew Sheperd

Microbiome by Julie Segre

Honey Bee Nutrition by Zachary Huang

In Defense of Plants: Plants, Bees and the Microbes They Share with Quinn McFrederick

Matters Microbial #6: What’s the buzz on honey bee microbes? with Irene Newton

Glyphosate and a glyphosate-based herbicide affect on bumblebee gut microbiota by Marjo Helander et. al

Glyphosate induces immune dysregulation in honey bees by Erick VS Motta, J Elijah Powell and Nancy A Moran

Uptake of the Plant Agriculture-Used Antibiotics Oxytetracycline and Streptomycin by Cherry Radish-Effect on Plant Microbiome and the Potential Health Risk by Lichun Yin et. al

Probiotics positively influence honeybee health, Western research finds by Western University

Effects of Prebiotics and Probiotics on Honey Bees (Apis mellifera) Infected with the Microsporidian Parasite Nosema ceranae by Daniel Borges, Ernesto Guzman-Novoa and Paul H Goodwin

By Lexie Leeser, Agent Associate and Master Gardener Coordinator, Baltimore County, University of Maryland Extension.

The Joys of Garden Surprises

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I celebrate the surprises my garden serves up.  Serendipity is one of the most joyful aspects of gardening.  You just never know what secrets your garden will reveal.

Last fall, I dug and divided a large clump of great blue lobelia because it needed more shade. When I lifted the clump, it collapsed into 13 pieces with barely there, weeny roots. I dutifully planted each, watered, and prayed. 

Closeup of a lobelia stem with open purple flowers.
Great blue lobelia is a lovely native plant.

Nothing came up this spring.  Ah well, I tried.  But I noticed some distinct sprouts last week.  Lobelia!  Four had survived the move, so I did a little happy dance. Never had I had a transplant take that long to emerge.  Never.  It just goes to show you that nature has her own plans – and timeline.  Gardeners need pocketfuls of patience.

I love clustered bellflowers.  Deep purple globes of tiny blooms wave atop 2 foot stems, guaranteeing oohs and aahs.  I finally got my hands on one, planted it and waited with anticipation.  It just sat there.  Refused to bloom.  For two years I waited, watching leaves unfurl but no blessed blossoms.  The third year it bloomed.  I nearly threw it a party. 

But not all surprises are good.  I now know that rhizomatous plants like bellflowers can be beasts, spreading aggressively by sneaky underground stems.  Some are invasive and should be evicted.   So proceed with caution and do your research.  The word “vigorous” on any plant tag should give you pause. 

Sometimes it isn’t the garden that surprises us, but its unexpected guests. One year I was filling a small water bowl in a container garden when I had a sense of being watched. A frog was nestled in the shallow bowl looking smug.  I smiled, said “howdy,” and watered around him. Now that container was four feet up on an elevated deck so getting there took some effort.  Did he use the steps?  Climb the coral honeysuckle?  He never said.  But I do know that frogs drink through their skin so he needed that water. So every day for two weeks I added water to his bowl as he shuffled a bit to the side for his daily refill.  Every day I grinned, grateful for the whimsical start to my day.

Ever have an alligator on your computer?  Last week I noticed a flash of orange on my keyboard.  A quarter-inch-long spiky ladybug larva was looking for lunch.  These orange and black beneficial insects eat thousands of aphids, scales, thrips and mites.  I gently relocated him from my fingertip to the garden and wished him happy hunting.

Close-up top-view of a ladybug larva consuming an aphid.
Alligator-like ladybug larva eating aphids.

Sometimes our brush with nature is a literal brush. I was reading on my patio yesterday and spied a squirrel peeking out at me from a drape of spiderwort.  A friendly fellow, he walked right under my chair, brushing my leg with his fluffy tail on his way to some hickory nuts. 

Close-up of an Eastern grey squirrel on a branch.
Eastern grey squirrels can both vex and charm.  

Whether you call these God-winks or close encounters of the natural kind, they are gifts, the most delightful of surprises.  They keep us watching, noticing, learning and reveling in the wondrous world around us.

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension.  Read more by Annette.

Q&A: What are these things on our basil stems?

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A basil plant with portions of the lower stems tightly packed with tan to brown bumps that can't be scraped off. The bumps are adventitious roots.
Adventitious roots growing on basil stems

Q. I have this “something” growing on my basil and some flowers in my garden. At first, I thought it was eggs from an insect, but when I scraped them, they appeared to actually be part of the plant. Did some kind of bacteria create these nodes? I was hoping you would be able to identify them and perhaps give me a solution.

A. Fortunately, these “bumps” are not a problem and don’t require any solution.  They are adventitious roots that sometimes grow along the stem of a plant. They are not part of the actual root system but would grow into roots if covered with soil.  They often appear in very wet or
humid conditions, and we definitely have had higher than usual humidity!  The following University Extension link will provide additional information.
https://extension.umd.edu/resource/bumps-or-swelling-vegetable-stems/

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.

It’s Too Darn Hot: Garden Schemes for Sweltering Days

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Sticky.  Sticky.  Sticky.  When the temps soar into the 90s, my garden game plan changes. I set my alarm a little earlier to water newly planted plants or those suffering in the heat.  Thank you, rain barrel. I water early so the leaves don’t go to sleep wet at night, a red banner invitation for fungal issues. I’ve snaked a soaker hose through my boxwoods, shallow-rooted plants that stress out in drought.  So I turn on the water and set a timer to give them a good weekly deep soak. As I’m on my watering rounds, I look for interlopers.  In the cool of the morning, my trusty trowel and I are rogueing out sneaky chameleon plant and other weeds.  

Water droplets on the surface of a soaker hose.
Soaker hoses put water right where plants need it.
Photo credit: Annie Lemarie
Leaves and one flower of the chameleon plant.
Chameleon plant is a sneaky weed that requires vigilance.
Photo credit:  Kristen Bell

Where, where, where did that dogbane come from?  I really thought I had it all.  A sneaky mimic of young common milkweed, I sometimes miss it.  “Off with its head,” I say with glee. I’m a “while I’m here” gardener.  So if I see ground ivy lurking at the base of boxwood, I nab it.  The same goes for vinca resprouts in my woodland bed.  Begone!

If I notice tomato leaves touching my straw and newspaper mulch, I snip them off.  Rain can splash fungal spores from the soil onto leaves which is why most tomato troubles start from the bottom up. I cut off the lower branches of my tomato plants a month ago, but I try to stay vigilant with a trim here and there. It’s amazing what you can get done in a half hour in the garden.  Even 15 minutes.  And it’s oh-so-much more pleasant in the cool of the morning. 

Irregular brown lesions on tomato leaves caused by early blight disease.
Snipping off lower tomato leaves decreases the chance of early blight. 
Photo credit:  Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org

When the heat drives me indoors, I catch up on my garden journal.  A binder with a page for each plant, it’s my garden diary.  I note care basics when I add new plants, and add updates and photos as the seasons pass. I also update my garden maps, rough diagrams of my beds. Maps help me find plants in my densely planted beds and see opportunities to add new plants. As I look out my window, I see a lot of green, but few flowers in a native plant bed. I’m happy with the contrasting forms and textures, but there’s just not enough color.  So I’m making a note to add more late June-July blooms.

Today’s high heat also inspired me to organize all the garden stuff in my sun porch.  I tend to drop and go as I come and go and it’s looking a little rough. So, I’ve organized my pots and tags, tools and twine in my repurposed cabinet and storage bench. So that’s where that was!

I hope I’ve given you a few ideas for keeping your green thumb—and your plants—happy as we enter the heat of summer.    

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.

What’s the Buzz Going On in My Front Yard?

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Early spring, you might notice curious little mounds of finely textured soil dotting your lawn or garden beds. If you look closer, you may even catch a tiny bee poking its head out of a hole like a groundhog (although one that doesn’t eat your plants) on the first day of spring. Don’t be alarmed and don’t stomp them out. They’re native ground-nesting bees, and if you’re lucky, they might be the charming, adorable, and important cellophane bees.

A cellophane bee looking at the camera at the opening of her nest in bare soil.
Cellophane bee emerging from nest

Meet the cellophane bee

Cellophane bees (Colletes sp.) are solitary, ground-nesting native bees that emerge in early spring. They are generalist pollinators, visiting a wide variety of plants, including early blooming trees, native wildflowers, and even some fruits and vegetables.. They’re medium-sized bees with a somewhat fuzzy appearance and are often mistaken for honey bees, though they lack the social structure and communal hive of honey bees.

Top view of a female cellophane bee creating a tunnel in bare soil to build a nest for her brood.
Cellophane bee digging tunnel

What makes cellophane bees stand out among other bees is their unique nesting behavior. Female cellophane bees dig slender vertical tunnels into well-drained or sandy soil, creating brood cells lined with a natural waterproof secretion. This lining hardens into a thin, clear layer that looks and functions like cellophane, hence its name. It helps protect developing larvae from moisture and microbial threats.

A small hole in bare soil with a low mound of soil piled up around the hole. The hole was made by a cellophane bee.
Cellophane bee hole

Now, why all the buzzing around?

Cellophane bees are solitary, meaning each female builds and provisions her own nest. However, individuals may choose the same area, leading to what looks like a large colony. This clustering behavior can surprise homeowners who suddenly see dozens of small holes in one relatively small patch of soil. While it may seem like they are swarming, these bees are not defending a hive, so they have no reason to sting unless directly handled or severely threatened, and even then, only the females can sting, and they are typically extremely docile. Because they tend to stay close to their nesting sites, they can be incredibly effective at pollinating your immediate landscape. These bees are also a reminder that supporting pollinators isn’t just about planting flowers. It’s also about providing habitat for them, and in this case, a patch of sandy soil.

Most activity happens over a brief few weeks in the spring. Once the females have mated, dug their tunnels, and stocked the brood cells with pollen and nectar, they seal them up and die off, leaving the next generation to develop underground until the following year. By early summer, all visible signs of their presence have vanished and moved underground where the larvae develop, until next spring’s return.

Live and let buzz

Let the bees live, but also support their habitat:

  • Leave some bare or lightly vegetated ground in sunny, undisturbed areas, grassy yards, or pathways. Over-mulching or frequent tilling can destroy nesting sites.
  • Avoid using broad-spectrum insecticides when pollinators are active.
  • Plant native early bloomers to provide nectar and pollen when cellophane bees emerge.
  • Resist the urge to mow or disturb nesting areas for a few weeks during peak activity (typically March through May). Mowing can destroy nesting sites and cause tunnels to collapse.
  • Educate neighbors and fellow gardeners about these beneficial bees, so they are not confused with infestations and treated as such.

 So, if you catch sight of a tiny bee carefully peaking its head out of a little dirt tunnel in your yard this season, take a moment to appreciate it. That bee is one of Maryland’s native pollinators, doing its part to keep your garden and the larger ecosystem buzzing with life.

Written by: Hayden Schug, AgFS Educator and Julia Rycyna, Home Horticulture Educator, both with UME, Charles County. Photo credits: Hayden Schug. Article previously published in the University of Maryland Extension Charles County Connection newsletter.

New beginnings in the garden

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Bean seedlings in my new vegetable garden

Are gardens and landscapes ever finished? Completed? Done?

Of course not. Gardens are in a constant state of change. Some of them (vegetable gardens, for example) we plant anew each year. Other areas we might fill up with trees and shrubs and perennials, and think we’ve created something permanent. But… trees grow, and shade grows with them. Plants die, or plants get bigger or spread faster than we expected. Unpredictable seedlings come up, and might be weeds, or might be something new and exciting that found its way in.

I’ve had some significant gardening changes this year, along with the normal state of constant flux. For one thing, we took down a tree near our driveway (it was an invasive species, and also persistently dropped things on our cars in a super-annoying way) and now we have an area in pretty full sun where it was partial before. So of course we’ve put in a new vegetable garden!

View of the new garden in early June

I had a perennial bed there, but it had become choked with liriope and Spanish bluebells, so I dug those out and threw them away, and transplanted what flower bulbs and native perennials I could locate during the winter months. My son constructed the new garden, which has a base of landscape fabric and pea gravel (to discourage anything from re-emerging from underneath) and consists of three 3’x6’ raised beds that are close to 18” high (no landscape fabric under these), plus plenty of room for containers. It’s surrounded by a six-foot wire fence to discourage animal invaders. The raised beds are made with pressure-treated lumber (now considered to be safe for food gardens) and handy concrete corners they slot into. The soil in the raised beds was dug from the surrounding area (some excavation was necessary to put in that base layer) and supplemented with homemade compost. Some weeds are popping up (along with volunteer tomatoes and mystery cucurbits), but I’m glad not to have to buy topsoil and compost

I’m going to use the new garden for vegetable plants I have trouble growing in my community garden plot, because of pests and diseases that are hard to keep at bay there. This year I’m growing beans and winter squash, plus a few other things! It’ll be interesting to find out how much produce I can grow in a relatively small space.

The herb spiral in early June, with new plants

In another area of my yard I have an herb spiral that was put in seven or eight years ago, next to a gravelly slope where I’d had great success growing rosemary. But this was a particularly bad winter for that marginally hardy Mediterranean herb, and when I checked in early spring, all of the plants were very, very dead. I’ve replanted new rosemary in pretty much the same place (sunny, great drainage, protected from wind) so hopefully it will live at least a few more years.

The herb spiral itself had been taken over by lavender, so it was basically a glorious lavender hill, with no room for anything else to grow. I don’t think the winter completely killed the plants (lavender is surprisingly tough, at least the hardier cultivars) but they were badly enough off that I decided it was time to take them out. I’ve added new soil into the herb spiral and begun planting more herbs. No lavender this time! I have room for it in other places where it can grow into shrubs.

Marjoram, thyme, and lemon verbena in the recovered herb spiral

Changes happen every year in the garden—big ones or small ones, but always some. Enjoy the early summer weather as you transform your own gardening spaces, one small task or one giant refreshment at a time.

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.