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

https://phys.org/news/2019-02-culprit-honeybee-deaths-california-almond.html

OSU Webinar: Bee Foraging in Rural Areas During Corn Planting

Join us for our free monthly beekeeping webinar on Wednesday, August 20th at 9AM EASTERN / 6AM PACIFIC: Bee Foraging in Rural Areas During Corn Planting
Reed Johnson, Assistant Professor, The Ohio State University 

Dr. Johnson will discuss the issues surrounding corn planting and honey bee health. He will address neonicotinoid pesticides and their effects on bees, as well as current research efforts in Ohio and elsewhere.

All webinars are free, and pre-registration is not required. To join this free webinar, follow the link and LOG IN AS A GUEST at about 8:55AM (EASTERN) 5:55AM (PACIFIC) on August 20th.

Bee Lab Webinar Link
https://carmenconnect.osu.edu/r7v7zmbhr1y/

* Please note, our webinar link changed this summer. If you had bookmarked or saved a previous link, please update with this link.

This and each monthly webinar will be recorded and archived on the Ohio State Bee Lab website the day of the session. We currently have about two dozen webinar recordings archived.

Corn Dust Research Consortium (CDRC) Calls for Cooperative Measures to Support Honey Bees, Beekeepers, and Farmers

Bee Culture's CATCH THE BUZZ by Kim Flottum   1/30/14

R. Thomas (Tom) Van Arsdall, Director of Public Policy

The non-profit Pollinator Partnership (P2) today released the 2013 Preliminary Report and Provisional Recommendations of the Corn Dust Research Consortium (CDRC), a multi-stakeholder initiative formed to fund research with the goal of reducing honey bee exposure to fugitive dust emitted from planter fan exhaust during mechanical planting of treated corn seed. The report can be found at http://www.pollinator.org/PDFs/CDRCfinalreport2013.pdf with provisional recommendations starting on page 23.

The CDRC participating organizations include the American Seed Trade Association, the American Honey Producers Association, the American Beekeeping Federation, the Association of Equipment Manufacturers, Bayer CropScience, the Canadian Honey Council, the Farm Equipment Manufacturers Association, the National Corn Growers Association, the Pollinator Partnership, Syngenta, and the University of Maryland. These organizations came together to fund and oversee research projects in 2013 to better understand ideas for mitigating risks to honey bees from exposure to fugitive dust emitted from fan exhaust from machinery during corn planting.

The CDRC funded three research teams, led by Dr. Reed Johnson of Ohio State University, Dr. Mary Harris of Iowa State University, and Dr. Art Schaafsma, University of Guelph on behalf of the Grain Farmers of Ontario. It is hoped that the preliminary results and provisional recommendations will inform best practices for the 2014 planting season. Additional research in subsequent seasons will be needed to replicate and...

Read more at: http://home.ezezine.com/1636/1636-2014.01.30.16.10.archive.html

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