Forager bees ‘turn on’ gene expression to protect against microorganisms, toxins

UC Davis News & Information   November 9, 2015

Forager bees, like this one feeding on lavender nectar, "turn on" genes that could help protect the hive and honey against microbes and toxins. (Kathy Keatley Garvey)When honeybees shift from nurse bees to foragers, or from caring for the brood to foraging for nectar and pollen, the bees “turn on” gene expression with products that protect against microorganisms and degrade toxins, three University of California, Davis, scientists have discovered.

Their findings on bee immunity and toxin metabolism are published today inScientific Reports by the Nature Publishing Group.

“First, the results suggest that forager bees may use antimicrobial peptides — short sequences of amino acids with general activity — to reduce microbial growth in stored food resources,” said Rachel Vannette, assistant professor, UC Davis Department of Entomology and Nematology. “This would be a largely unrecognized way that bees protect honey and potentially other stored resources from microbial spoilage. Second, this work shows that forager bees produce toxin-degrading enzymes in nectar-processing tissues.

“This may allow forager bees to degrade many different kinds of compounds in nectar, before it is stored,” Vannette said. “Bees also vary in their ability to do this; foragers have a greater ability to degrade a variety of compounds than nurses. This may have implications for hive health and management.”

The scientists found the change in the bees’ nectar-processing tissues, but not in the gut. The scientists surmised that the exposure to bacteria or yeasts in the environment may trigger this change, but they did not examine it in the study.

“It had been well known that the division of labor in a honeybee colony is supported by extensive differences in brain gene expression between bees that perform different jobs,” said Gene Robinson, director of the Institute for Genomic Biology and Swanlund Chair of Entomology, University of Illinois at Urbana-Champaign, who was not involved in the research. “This new research shows nicely that this genomic differentiation extends beyond the brain; different complements of active genes in a variety of tissues make each bee better suited for the job it needs to perform.”

The journal article, titled “Forager Bees (Apis Mellifera) Highly Express Immune and Detoxification Genes in Tissues Associated with Nectar Processing,” is the work of senior author Brian Johnson, assistant professor, UC Davis Department of Entomology and Nematology; and co-authors Abbas Mohamed, graduate student researcher in the Johnson lab and a member of the Pharmacology and Toxicology Group, and Vannette, who joined the UC Davis Department of Entomology this fall after serving a postdoctoral fellowship at Stanford University. At Stanford, Vannette examined the role of nectar chemistry in community assembly of yeasts and plant-pollinator interactions.

Johnson, whose research interests include animal behavior, evolution, theoretical biology and genomics, recently began long-term research on the honeybee immune system and the causes and consequences of economically important diseases or syndromes such as colony collapse disorder.

The team plans to follow up with functional assays to examine the potential of these gene products to reduce microbial growth and degrade a variety of natural and synthetic compounds.

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Karate Kick!

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey    July 7, 2014

If you've ever watched a karate competition, you've probably seen the roundhouse kick, tornado kick, the reverse roundhouse kick or the flying side kick.

But have you ever seen a bee do that?

We were photographing sunflower bees on our Mexican sunflowers (Tithonia) yesterday, trying to catch the territorial dive-bombing. We were shooting with a Canon E0S 7D equipped with a 100mm macro lens. Settings: ISO, 1600. Shutter speed,  1/1400 of a second. F-stop, 10.

If bees could engage in humanlike conversation, imagine this dialogue:

"This flower is mine! Get off! I want my ladies to have that flower!"

"No, it's not! It's mine. I was here first! Leave me alone!"

For awhile, a large bee, a male longhorned bee, Svastra obliqua (as identified by native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis), appeared to be the "king of the mountain." It held its resource.

Suddenly, faster than my shutter speed, a smaller bee of a different species, a male longhorned bee, Melissodes (probably Melissodes agilis, Thorp said) headbutted Svastra,  a scene reminiscent of a World Cup play.

One swift kick by Mr. Svastra and a surprised Mr. Melissodes shot straight up in the air, whirling end over end. 

Roundhouse kick? Tornado kick? Reverse roundhouse kicK? Flying side kick?

Whatever it was, the "bee master" won.

And he wasn't even wearing a black belt.

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The Power of Red

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey   2/6/14

There's a heartfelt reason why Friday, Feb. 7 is "UC Davis Wears Red Day."   

It's about raising awareness for heart disease, the No. 1 killer of both men and women. It's a battle we need to fight with an arsenal of weapons.

Spearheading the campuswide initiative is Chancellor Linda Katehi, partnering with Dr. Amparo...


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Bugfest at Dixon May Fair May 8-12

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey

[If you're in the Sacramento area check out the Dixon May Fair May 8-12.]

If you think that every insect on a flower is a honey bee, you should see what the UC Davis Department of Entomology is showcasing at the Dixon May FairMay 9-12.

You'll not only see honey bees in a bee observation hive, but specimens of bumble bees, cuckoo bees, carpenter bees, long-horned bees, squash bees, plasterer bees, mining bees, leafcutter bees, wool carder bees and sweat...


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