Culprit Found For Honeybee Deaths In California Almond Groves

PHYS.ORG   By Misti Crane     February 4, 2019

Credit: CC0 Public Domain

Credit: CC0 Public Domain

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.

Explore further: Almond-crop fungicides a threat to honey bees

More information: Andrea Wade et al, Combined Toxicity of Insecticides and Fungicides Applied to California Almond Orchards to Honey Bee Larvae and Adults, Insects (2019). DOI: 10.3390/insects10010020

Provided by: The Ohio State University

How Could the Honey Bee Shortage Affect You?

KWQXNews6 By Akilah Davis    May 18, 2014

Experts say honey bees are more vital than we all realize and the shortage could affect you in ways you might not imagine. The average life span of a worker bee in the summer is six weeks, but that could mean big problems if their life spans are cut short. Without bees pollinating our crops, a lot of them would die off. 

"Honey bees are important to the ecosystem because they pollinate about a third of the crops of the food we eat," said Ronald Fischer, a bee keeper from Illinois.

Fischer has been bee-keeping for over 40 years and says he knows enough to know that if the honey bee shortage continues, it could result in a food desert. 

"Without honey bee pollination you won't get the almonds, apples, citrus. It would be like a food desert out there because you won't be able to get lots of your fruits and vegetables and some of the other products," said Fischer. 

The shortage is the outcome of what's called colony collapse disorder and a lot of factors contribute to it.

"The varroa mite is a mite that sucks on the bees blood and it also brings various viruses with it," said Fischer. "So we've got the varroa mite and viruses, you also have the increase use in pesticides, the neo-nicotine."

That means the weed killer you use to stop them from growing in your yard also stops busy bees from buzzing around.

"None of which is bad by itself, but combine all of them you have an unhealthy hive. When you have an unhealthy hive its susceptible to all these various problems that we have," Fischer explained. 

The shortage is also causing bee keepers like Fischer to take a hit in the wallet and its causing them to pay more for replacement bees. 

"It's about $100 for a three-pound package where you get three pounds of bees and one queen," said Fischer.

That very package used to cost $60.

Our expert says the best way to reverse the trend is plant a bee-friendly garden so bees can pollinate--and cut back on weed pesticides.

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Flowers Linked To Bee Disease Transmission

The following is brought to us by the American Bee Journal   2/25/14

AMHERST, Mass. – Like a kindergarten or a busy airport where cold viruses and other germs circulate freely, flowers are common gathering places where pollinators such as bees and butterflies can pick up fungal, bacterial or viral infections that might be as benign as the sniffles or as debilitating as influenza.

But "almost nothing is known regarding how pathogens of pollinators are transmitted at flowers," postdoctoral researcher Scott McArt and Professor Lynn Adler at the University of Massachusetts Amherst write. "As major hubs of plant-animal interactions throughout the world, flowers are ideal venues for the transmission of microbes among plants and animals."

In a recent review in Ecology Letters with colleagues at Yale and the University of Texas at Austin, McArt and Adler survey the literature and identify promising areas for future research on how floral traits influence pathogen transmission.

As the authors point out, "Given recent concerns about pollinator declines caused in part by pathogens, the role of floral traits in mediating pathogen transmission is a key area for further research." They say their synthesis could help efforts to control economically devastating pollinator-vectored plant pathogens such as fire blight, which affects rose family fruits such as apples and pears, and mummyberry disease, which attacks blueberries.

McArt adds, "Our intent with this paper is to stimulate interest in the fascinating yet poorly understood microbial world of flowers. We found several generalities in how plant pathogens are transmitted at flowers, yet the major take-home from our paper may be in pointing out that this is an important gap in our knowledge."

The authors identified 187 studies pertaining to plant pathogens published between 1947 and 2013 in which floral visitors were implicated in transmission and where transmission must have occurred at flowers or pathogen-induced pseudoflowers. These are flower-like structures made by a pathogen that can look and smell like a real flower, for example. Regarding animal pathogens, they identified 618 studies published before September 2013 using the same criteria.

"In total, we found eight major groups of animal pathogens that are potentially transmitted at flowers, including a trypanosomatid, fungi, bacteria and RNA viruses," they note. Their paper, "Arranging the bouquet of disease: Floral traits and the transmission of plant and animal pathogens," was featured in the publisher's "News Round-Up" of "most newsworthy research."

Traditionally, research on flower evolution has focused largely on selection by pollinators, but as McArt and colleagues point out, pollinators that also transmit pathogens may reduce the benefits to the plant of attracting them, depending on the costs and benefits of pollination. The researchers say more work is needed before scientists can know whether a flower's chemical or physical traits determine the likelihood that pathogens are transmitted, for example, and whether infection by pathogens is an inevitable consequence of pollinator visitation.

"Plant pathologists have made great strides in identifying floral traits that mediate host plant resistance to floral pathogens in individual systems; synthesizing this literature can provide generality in identifying traits that mediate plant-pathogen dynamics. From the pollinator's perspective, there has been surprisingly little work elucidating the role of flowers and floral traits for pathogen transmission. Given recent concerns about pollinator declines caused in part by pathogens, understanding the role of floral traits in disease transmission is a key missing element," say McArt and colleagues.

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Growing Insects: Farmers Can Help to Bring Back Pollinators   By Richard Conniff   2/3/14

With a sharp decline in pollinating insects, farmers are being encouraged to grow flowering plants that can support these important insects. It’s a fledgling movement that could help restore the pollinators that are essential for world food production.

For the last few years, Richard Rant has agreed to let researchers introduce strips of wildflowers among the blueberry plants on his family’s farm in West Olive, Michigan. It’s part of an experiment to see if the wildflowers can encourage pollinating insects and, in a small way, begin to reverse the worldwide decline in beneficial insects. It’s also a pioneering effort in the nascent movement to persuade farmers to grow insects almost as if they were a crop. 

That movement is being driven by news that is disturbingly bad even by gloomy environmental standards. Insects pollinate 75 percent of the crops used directly for human food worldwide. They contribute $210 billion in agricultural earnings. But honeybees are now so scarce...


Honey Bees and Extinction

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey    11/7/13 

"Would the extinction of honey bees lead directly to the extinction of humans?"

That's a recent question posed on Quora, where folks can ask questions and receive answers.

The answer is "no."

"We are a resilient species that existed before beekeeping...


Visit the Kathy Keatley Garvey Bug Squad blog at:

Just what makes that little old ant… change a flower's nectar content?

Science Daily  April 24, 2013

Ants foraging on nectar transmit yeasts that change sugar-chemistry and may affect subsequent pollinator (Bee)  visitations and plant fitness

Ants play a variety of important roles in many ecosystems. As frequent visitors to flowers, they can benefit plants in their role as pollinators when they forage on sugar-rich nectar. However, a new study reveals that this mutualistic relationship may actually have some hidden costs. By transmitting sugar-eating yeasts to the nectar on which they feed, ants may be indirectly altering the nectar-chemistry and thus affecting subsequent pollinator visitations.

Many species of plants benefit from interacting with ants, and some even secrete special sugary substances to attract ants. Plants produce sugar, in the form of nectar, and in exchange ants provide services such as pollination or protection from herbivores.

The main components of nectar that attract pollinators include three dominant sugars—sucrose, fructose, and glucose—and amino acids (or proteins). The chemical composition of nectar differs among plant species and has been thought to be a conservative trait linked to pollinator type. For example, plants pollinated by hummingbirds tend to have nectar with high amounts of sucrose. In addition, nectar composition is thought to be regulated by the plant.

"When people think about how flowers are pollinated, they probably think about bees," notes Clara de Vega, a postdoctoral researcher at the Estación Biológica de Doñana, Spain. "But ants also pollinate flowers, and I am interested in the role ants play in pollination since it is still poorly understood."

De Vega joined forces with Carlos M. Herrera, an evolutionary ecologist at the Estación Biológica de Doñana, to investigate the relationship between ant pollinators and nectarivorous yeasts. Nectar-dwelling yeasts, which consume sugars, have recently been discovered in the flowers of many temperate and tropical plant species. De Vega and Herrera have already discovered that some ant species not only carry certain types of sugar-metabolizing yeasts on their bodies, but they also effectively transmit these yeasts to the nectar of flowers they visit.

In their most recent work, published in the American Journal of Botany (, De Vega and Herrera investigated whether flowers visited by these ants differed from flowers that were not visited by ants in their sugar chemistry, and whether sugar-chemistry was correlated with the abundance of ant-transmitted yeasts found in the nectar.






By excluding ants from visiting inflorescences of a perennial, parasitic plant, Cytinus hypocistis, and comparing the nectar chemistry to inflorescences that were visited by ants, the authors tested these ideas experimentally.

When the authors compared the sugar content in the nectar of flowers visited by ants versus those enclosed in nylon mesh bags to exclude ants, they found that nectar of flowers exposed to ants had higher levels of fructose and glucose, but lower levels of sucrose compared with the ant-excluded flowers.

Interestingly, in flowers visited by ants, there was a high correlation between yeast cell density and sugar content. Nectar that had higher densities of yeast had more fructose and less sucrose, suggesting that the types of yeasts change the sugar content of the nectar. Flowers that were excluded from ants did not have any yeast in their nectar.

"Our study has revealed that ants can actually change the nectar characteristics of the flowers they are pollinating," says de Vega. "The microorganisms, specifically yeasts, that are present on the surface of ants change the composition of sugar in the flower´s nectar."

"This means that nectar composition is not completely controlled by the flower—it is something created in cooperation with the ants that visit the flower," she notes. "We also think that these ant-transported yeasts might have the potential to affect plant reproduction."

Indeed, if a plant cannot control the sugar content of its nectar, then it may lose some of its target pollinators, which would potentially affect overall seed set and plant fitness.

Moreover, if introducing these yeasts to nectar changes the chemistry of the very components that serve to attract pollinators, then perhaps ants are indirectly changing the foraging behavior of subsequent flower visitors and thereby affecting seed dispersal patterns.

This study has revealed an additional layer in the complex association between ants and flowering plants, as pollinating ants alter sugar-nectar chemistry in flowers via sugar-consuming yeasts. But the story does not end here. De Vega plans to continue researching the role that these nectarivorous yeasts play on the reproduction of plants.

 "I plan to study the whole interaction of plants, yeasts, and pollinators—how are they interrelated and what mechanisms shape these relations?"

Story Source:
The above story is reprinted from materials provided by American Journal of Botany, via EurekAlert!, a service of AAAS.

Almond pollination prices, pollinators and growers heat up - An Editorial

(The following is brought to us by CATCH THE BUZZ (Kim Flottum) Bee Culture, The Magazine of American Beekeeping, published by A.I. Root Company.) 

It’s been a somewhat contentious pollinating season in California this season so far. Growers have been reluctant to dig deeper to get good colonies, and beekeepers have had a tough time getting colonies in good shape at the prices offered. 

Future shortages were apparent last summer, even last spring at the end of the season when I was there because water was already a problem in many foraging areas…not only in California but in much of the country. Nutrition, or basically sources of enough good food was one of the keys in a season-long struggle to just keep up.

Beekeepers were faced with either unavailable but good mite control, or expensive but good mite control, but either way the cost of keeping a colony alive kept increasing. Moreover, just the overall cost of getting a colony to strong-enough-strength has gone up, and growers have been unwilling to accommodate those costs, even considering the fact that the price of almonds just keeps increasing…both because of worldwide demand and a short crop last year because of water shortages.

Without adequate compensation there is little incentive for beekeepers to spend more money on colonies ahead of time unless some provision is made to cover those expenses. Several have said it’s safer to work hard on fewer colonies than to gamble on providing more colonies…recall our article last year comparing almond pollination, producing an almond crop, and a game of 5 card draw.

So this season some colonies are in California weaker than they were planned to be, some colonies are in California empty of bees altogether, and some colonies of bees are in California that weren’t planning on being there at all just to fill the gap of fewer colonies and the promise of gold in the orchards fixing the problems created by weaker colonies and more almonds that got planted this year. Florida has sent something like 100,000 colonies this year, up about 20% according to Ag. officials there. Not enough to threaten the orange honey crop, or the orange crop itself, but a bigger chunk than ever….from one coast to another. 

So forever, honey bee colonies in almond orchards have been viewed as a commodity by almond growers…no more and no less than fertilizer, water or insecticide. Simply one more input to a successful crop. So what happens when that input says NO? With honey heading towards $3+/pound, shipping going up (those Florida beekeepers picked up the tab for sending those bees to California you know, which comes right off the bottom line of the profit column…what the heck happened to cost plus freight?), other crops vying for the attention of all those bees on the east coast in good shape, and the price of a pollinating colony going up about 15% in the last year generally… I don't care what the Almond folks think...this is 2013...not 1993.

It’s been a tough year so far and it’s going to be another tough year, even if everything goes right, because it costs a beekeeper lots of money to catch up, and even lots of money to stay even, and there will be still more almonds to pollinate next year. From where I sit the beekeepers have just seen your call, and raised.   And the answer better be right because lots and lots of almond customers are watching your next move. Screw it up, play hard ball, and the demand goes south because they won't know if there will be a crop next year and they won't bet on you again...see the bet, spend the money and you can be pretty sure customers will feel safe in putting in orders. 

Your call....