Nav: Home

Culprit found for honeybee deaths in California almond groves

February 04, 2019

COLUMBUS, Ohio - It's about time for the annual mass migration of honeybees to California, and new research is helping lower the chances the pollinators and their offspring will die while they're visiting the West Coast.

Each winter, professional beekeepers from around the nation stack hive upon hive on trucks destined for the Golden State, where February coaxes forward the sweet-smelling, pink and white blossoms of the Central Valley's almond trees.

Almond growers rent upwards of 1.5 million colonies of honeybees a year, at a cost of around $300 million. Without the bees, there would be no almonds, and there are nowhere near enough native bees to take up the task of pollinating the trees responsible for more than 80 percent of the world's almonds. The trouble was, bees and larvae were dying while in California, and nobody was sure exactly why. The problem started in adults only, and beekeepers were most worried about loss of queens.

Then in 2014, about 80,000 colonies - about 5 percent of bees brought in for pollination - experienced adult bee deaths or a dead and deformed brood. Some entire colonies died.

With support from the Almond Board of California, an industry service agency, bee expert Reed Johnson of The Ohio State University took up the task of figuring out what was happening. Results from his earlier research had shown that some insecticides thought safe for bees were impacting larvae. Building on that, Johnson undertook a new study, newly published in the journal Insects, that details how combinations of insecticides and fungicides typically deemed individually "safe" for honeybees turn into lethal cocktails when mixed.

Johnson, an associate professor of entomology, and his study co-authors were able to identify the chemicals commonly used in the almond groves during bloom because of California's robust and detailed system for tracking pesticide applications. Then, in a laboratory in Ohio, they tested combinations of these chemicals on honeybees and larvae.

In the most extreme cases, combinations decreased the survival of larvae by more than 60 percent when compared to a control group of larvae unexposed to fungicides and insecticides.

"Fungicides, often needed for crop protection, are routinely used during almond bloom, but in many cases growers were also adding insecticides to the mix. Our research shows that some combinations are deadly to the bees, and the simplest thing is to just take the insecticide out of the equation during almond bloom," he said.

"It just doesn't make any sense to use an insecticide when you have 80 percent of the nation's honeybees sitting there exposed to it."

The recommendation is already catching on and has been promoted through a wide array of presentations by almond industry leaders, beekeepers and other experts and has been included in the Almond Board's honeybee management practices. Many almond growers are rethinking their previous practices and are backing off insecticide use during almond bloom, Johnson said.

That's good news for bees, and doesn't appear to be harming the crops either, he said, because there are better opportunities to control problematic insects when almonds are not in bloom.

"I was surprised - even the experts in California were surprised - that they were using insecticides during pollination," Johnson said.

While these products were considered "bee-safe," that was based on tests with adult bees that hadn't looked into the impact they had on larvae.

"I think it was a situation where it wasn't disallowed. The products were thought to be bee-safe and you've got to spray a fungicide during bloom anyway, so why not put an insecticide in the tank, too?"

Insecticides are fairly inexpensive, but the process of spraying is labor-intensive, so growers choosing to double up may have been looking to maximize their investment, he said.

"The thing is, growers were using these insecticides to control a damaging insect - the peach twig borer - during this period, but they have other opportunities to do that before the bees enter the almond orchards or after they are gone," Johnson said.

This research could open the door to more study of fungicide and pesticide use on other bee-dependent crops, including pumpkins and cucumbers, Johnson said.
-end-
Other Ohio State researchers who worked on the study were Chia-Hua Lin and Colin Kurkul. Andrea Wade and Erzsebet Ravasz Regan of the College of Wooster were also co-authors.

CONTACT: Reed Johnson, 330-202-3523; Johnson.5005@osu.edu

Written by Misti Crane, 614-477-2964; Crane.11@osu.edu

Ohio State University

Related Bees Articles:

To buzz or to scrabble? To foraging bees, that's the question
A team of UA biologists has discovered that for a hard-working bumblebee, foraging for pollen versus nectar is very different -- and tougher than you might think.
Nicotine enhances bees' activity
Nicotine-laced nectar can speed up a bumblebee's ability to learn flower colors, according to scientists at Queen Mary University of London (QMUL).
Scientists say agriculture is good for honey bees
Scientists with the University of Tennessee Institute of Agriculture evaluated the impacts of row-crop agriculture, including the traditional use of pesticides, on honey bee health.
Honey bees have sharper eyesight than we thought
Research conducted at the University of Adelaide has discovered that bees have much better vision than was previously known, offering new insights into the lives of honey bees, and new opportunities for translating this knowledge into fields such as robot vision.
Overuse of antibiotics brings risks for bees -- and for us
Researchers from The University of Texas at Austin have found that honeybees treated with a common antibiotic were half as likely to survive the week after treatment compared with a group of untreated bees, a finding that may have health implications for bees and people alike.
Flies and bees act like plant cultivators
Pollinator insects accelerate plant evolution, but a plant changes in different ways depending on the pollinator.
Bees can learn to use a tool by observing others
Simply by watching other bees, bumblebees can learn to use a novel tool to obtain a reward, a new study reveals.
Stingless bees have their nests protected by soldiers
Attacks by robber bees result in the evolution of larger guard bees and thus promote the division of labor in the hive.
Save the bees? There's an app for that
A new mobile app can calculate the crop productivity and pollination benefits of supporting endangered bees.
Sweat bees on hot chillies: Native bees thrive in traditional farming, securing good yield
Farming doesn't always have to be harmful to bees: Even though farmers on the Mexican peninsula of Yucatan traditionally slash-and-burn forest to create small fields, this practice can be beneficial to sweat bees by creating attractive habitats.

Related Bees Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Setbacks
Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".