Vanishing Act: Scientists Find Possible Clue to Disappearing Bees

University of Texas at Austin      By Nancy Moran     March 14, 2017

In the winter of 2004/05, many beekeepers across America went to check on their honeybee hives and were shocked to find most of the adult bees had vanished, leaving behind the queen and immature bees. Millions of bees mysteriously disappeared, leaving farms with fewer pollinators for crops.

Colony collapse disorder, as it was later dubbed, has continued to vex beekeepers year after year — and there’s still no effective solution. Explanations for the phenomenon have included exposure to pesticides, habitat loss and bacterial infections. But now, a new study from The University of Texas at Austin suggests that antibiotics could play a role.

Researchers found that honeybees treated with a common antibiotic were half as likely to survive the week after treatment as a group of untreated bees. The antibiotics cleared out beneficial gut bacteria in the bees, making way for a harmful pathogen, which also occurs in humans, to get a foothold. The research is the latest discovery to indicate overuse of antibiotics can sometimes make living things, including people, sicker.

Vanishing bees is cause for concern because many of our most cherished food crops are pollinated by honeybees including almonds, apples, avocados, blueberries, carrots, cranberries, onions, squash, and watermelon. And that’s not to mention honey itself.

In large-scale U.S. agriculture, beekeepers typically apply antibiotics to their hives several times a year. The strategy aims to prevent bacterial infections that can lead to a widespread and destructive disease that afflicts bee larvae, called foulbrood.

“Our study suggests that perturbing the gut microbiome of honeybees is a factor, perhaps one of many, that could make them more susceptible to declining and to the colony collapsing. Antibiotics may have been an underappreciated factor in colony collapse.” 

-Nancy Moran, professor of integrative biology at UT Austin and co-author of the study published March 14 in the journal PLOS Biology.

To learn more, read the press release: “Overuse of Antibiotics Brings Risks for Bees — and for Us

https://news.utexas.edu/2017/03/14/scientists-find-possible-clue-to-disappearing-bees-1

Sick Honeybees May be Nursed By Doctors

BBC Earth News    By Richard Gray   October 25, 2014

They are among the most industrious creatures on the planet, but honeybees still struggle when they’re ill. Once a disease takes hold inside a hive, the bees can become sluggish and disorientated, and many may die.

Now it seems honeybees may have a way of helping to keep their workforce healthy - by employing bees that feed "medicinal honey" to other members of the hive.

A group of worker bees called "nurse bees", if they are infected with a parasite, selectively eat honey that has a high antibiotic activity, according to Silvio Erler of the Martin Luther University Halle-Wittenberg in Halle, Germany and his colleagues.

These bees are also responsible for feeding honey to the larvae and distributing it to other members of the colony. So it's possible they are the hive's doctors, prescribing different types of honey to other bees depending on their infection. If that is true, it could be a big part of how bees fight disease. 

Doctor, I'm sick, could you prescribe me some honey? (Credit: The Picture Pantry / Alamy)

Doctor, I'm sick, could you prescribe me some honey? (Credit: The Picture Pantry / Alamy)

In Erler's study, nurse bees infected with a gut parasite calledNosema ceranae were given a choice of honeys. Three were made from the nectar of plants - black locustsunflower andlinden trees - while a fourth was honeydew honey made from the secretions of scale insects or aphids. Each of the honeys was known to have antibiotic activity.

Bees with greater levels of infection tended to eat more of the sunflower honey, which had the strongest antimicrobial activity. It reduced the level of infection in the bees that ate it by 7%, compared to the honey from the linden trees.

"Honeys are full of micronutrients, alkaloids and secondary plant compounds that are good for both bees and humans alike," says Mike Simone-Finstrom of North Carolina State University in Raleigh. One study suggested they can increase the activity of honeybees' immunity genes, boosting their ability to fight disease.

A separate study from September by Erler's group suggests that different honeys are effective against different diseases. While sunflower honey is good at preventing the growth of bacteria that cause American foulbrood in bees, it is less effective against bacteria associated with European foulbrood. However, linden honey was more effective against these bacteria. 

Disease spreads fast in densely-packed beehives (Credit: Todd Huffman, CC by 2.0)

Disease spreads fast in densely-packed beehives (Credit: Todd Huffman, CC by 2.0)

"The in-hive worker bees might be in an exceptionally important position to distribute honey selectively in the colony that affects their own health but potentially also that of other nestmates," says Erler.

His team is now investigating whether nurse bees select honeys from different sources depending on the infection they are fighting. If this turns out to be the case, it will reveal a level of medical care within honeybee hives not seen before.

With honeybees under threat from disease, climate change, pollution and new farming techniques, Erler says their medicinal abilities could prove invaluable. "Apiculturists might take advantage of specific honey flows to protect their colonies against specific diseases," he says.

But we mustn't overstate the medicinal role of honey, says Francis Ratnieks of the University of Sussex in Brighton. "If after six days of feeding just one type of honey you only get a 7% effect on infection, I would reckon that the effect in a hive would be less. Bees collect honey primarily as a food supply, not as medication." 

Dead honeybees are a source of dangerous infections (Credit: Jannis Tzimopulos / Alamy)

Dead honeybees are a source of dangerous infections (Credit: Jannis Tzimopulos / Alamy

Honeybees do have other sources of medicine besides honey. For example, they collect resin from plants and incorporate it into their nests, where it may help combat fungal parasites. In 2012 Simone-Finstrom and a colleague showed that bees infected with fungal spores collected more of the resin.

Honeybees, along with other insects like ants, also display "hygienic" behaviour: workers carry dead members of the colony far away to avoid an infection spreading. Ratnieks is trying to breed honeybees that do this more often, to produce colonies that are more resistant to disease.

Bees are far from the only animals that can self-medicate. While humans reach for an aspirin to combat a headache, many primates including chimpanzees eat bitter bark and rough leaves that may help kill off parasites in their guts. Goats eat vegetation high in tannins when they are suffering from intestinal worms. Woolly bear caterpillars fight parasitic flies by eating plants rich in toxic chemicals, while wood ants incorporate antimicrobial resin from conifer trees in their nests.

Read at http://www.bbc.com/earth/story/20141025-honeybees-play-doctors-and-nurses