Pesticides Deliver a One-Two Punch to Honey Bees

Phys.Org By Society of Environmental Toxicology and Chemistry August 5, 2019

Researchers conduct semi-field experiments on honey bees. Credit: Lang Chen

Researchers conduct semi-field experiments on honey bees. Credit: Lang Chen

Adjuvants are chemicals that are commonly added to plant protection products, such as pesticides, to help them spread, adhere to targets, disperse appropriately, or prevent drift, among other things. There was a widespread assumption that these additives would not cause a biological reaction after exposure, but a number of recent studies show that adjuvants can be toxic to ecosystems, and specific to this study, honey bees.

Jinzhen Zhang and colleagues studied the effects on honey bees when adjuvants were co-applied at "normal concentration levels" with neonicotinoids. Their research, recently published in Environmental Toxicology and Chemistry, found that the mixture of the pesticide and the adjuvant increased the mortality rate of honey bees in the lab and in semi-field conditions, where it also reduced colony size and brooding.

When applied alone, the three pesticide adjuvants caused no significant, immediate toxicity to honeybees. However, when the pesticide acetamiprid was mixed with adjuvants and applied to honeybees in the laboratory, the toxicity was quite significant and immediate. In groups treated with combined pesticide-adjuvant concentrates, mortality was significantly higher than the control groups, which included a blank control (no pesticide, no adjuvant, only water) and a control with only pesticide (no adjuvant). Further, flight intensity, colony intensity and pupae development continued to deteriorate long after the application comparative to the control groups.

Zhang noted that this study, "contributed to the understanding of the complex relationships between the composition of pesticide formulations and bee harm," and stressed that "further research is required on the environmental safety assessment of adjuvants and their interactions with active ingredients on non-target species."

Sulfoxaflor Continues to be a Killer

CATCH THE BUZZ Michele Colopy, Program Director, Pollinator Stewardship Council, Inc. July 16, 2019


EPA’s announcement1 to expand the use of Sulfoxaflor means expanded loss of managed and native pollinators.  Beekeepers, whose honey bees provide the essential agriculture pollination service for our food supply, have suffered colony losses of 40-90% annually the past ten years.  A horizon scan of future threats and opportunities for pollinators and pollination placed the chemical Sulfoxomine (sulfoxaflor) in the top six priority issues that globally threaten the agricultural and ecological essential service of pollination.

Six high priority issues 
1: corporate control of agriculture at the global scale
2: sulfoximine, a novel systemic class of insecticides (which is sulfoxaflor)
3: new emerging RNA viruses
4: increased diversity of managed pollinator species
5: effects of extreme weather events under climate change
6: positive effects of reduced chemical use on pollinators in non-agricultural settings2

The Pollinator Stewardship Council has expressed our concerns about the registration of Sulfoxaflor for reduced use, and for emergency exemptions. In our legal action about the registration of Sulfoxaflor, the Ninth Circuit Court found in their review that important data concerning the effect upon honey bees from Sulfoxaflor was incomplete.  EPA adjusted the pesticide label, reducing the bee attractive crops on which the chemical could be applied.  However, let’s be concise: the active ingredient, Sulfoxaflor, is toxic to chewing and sucking insects.  Honey bees and other pollinators are chewing and sucking insects.

With over one billion pounds of pesticides used in the U.S. annually,3 the EPA claims there are “few viable alternatives for sulfoxaflor.”   Research is showing the “viable alternatives” are to restore the health of agricultural soils so the beneficial insects and fungi can return and protect the crops.  “Regenerative Agriculture is a system of farming principles and practices that increases biodiversity, enriches soils, improves watersheds, and enhances ecosystem services.”4 By restoring the health of soils, we restore the health of plants, and we restore the health of beneficial insects like pollinators.

In a study conducted from 2004-2009 by the University of Idaho on various methods of control for lygus bugs in alfalfa  it was observed the Peristenus howardi  (and similar species) parasitized lygus bugs ranging from 5% to 80%.   The primary goal of that research was “to conduct studies investigating the feasibility of enhancing lygus bug management in alfalfa seed through several complementary approaches. The individually low levels of lygus bug management provided by newer, more selective alternative compounds and that provided by natural enemies of lygus bugs will be combined in an attempt to provide acceptable levels of lygus management in large plots of alfalfa grown for seed. We will attempt to further enhance natural enemy numbers in these studies through modification of crop habitat (border treatments).”5

These very “border treatments” will now be under threat of contamination from Sulfoxaflor applications, degrading their prospective evidence-based solution of providing habitat for natural predators of crop pests.  Similar border treatments in other crops would be as beneficial.  But the 12-49 feet of blooming crop border could be contaminated with the bee toxic pesticide, Sulfoxaflor.  Blooming field borders support true IPM (Integrated Pest Management), providing costs savings to the farmer in reduced chemical inputs, and conserving crop losses through the pest management of beneficial insects.

While Pollinator Stewardship Council appreciated the initial revised Sulfoxaflor label as an improvement over the previous label, limiting the use of the pesticide after bloom on mostly non-bee attractive crops,  Sulfoxaflor is still a bee toxic pesticide with unknown synergisms when tank-mixed.  With little to no data on the degradates of Sulfoxaflor, and no research of tank mixes with Sulfoxaflor, it remains a bee toxic pesticide contaminating bee forage through drift and residue.  With the expansion of the use of Sulfoxaflor EPA is ignoring the threats to essential agricultural and ecological pollination services, and to the very livelihood of beekeepers tasked with providing the managed honey bees to pollinate our crops.

1 EPA Registers Long-Term Uses of Sulfoxaflor While Ensuring Strong Pollinator Protection,

2 Brown MJF, Dicks LV, Paxton RJ, Baldock KCR, Barron AB, Chauzat M, Freitas BM, Goulson D, Jepsen S, Kremen C, Li J, Neumann P, Pattemore DE, Potts SG, Schweiger O, Seymour CL, Stout JC. 2016. A horizon scan of future threats and opportunities for pollinators and pollination. PeerJ 4:e2249

3 Pesticides Use and Exposure Extensive Worldwide, Michael C.R. Alavanja, Dr.P.H., Rev Environ Health. 2009 Oct–Dec; 24(4): 303–309. ,

5 MANAGEMENT OF LYGUS SPP. (HEMIPTERA: MIRIDAE) IN ALFALFA SEED, University of Idaho,  National Institute of Food and Agriculture, 2004-2009,

Bee Alert: Is a Controversial Herbicide Harming Honeybees?

Yale Environment 360 By Michael Balter May 7, 2019

A honeybee pollinates a blossom in an almond orchard in McFarland, California. DAVID KOSLING/ USDA

A honeybee pollinates a blossom in an almond orchard in McFarland, California. DAVID KOSLING/USDA

Recent court cases have focused on the possible effects of glyphosate, found in Monsanto’s Roundup, on humans. But researchers are now investigating whether this commonly used herbicide could also be having adverse effects on the health and behavior of honeybees.

Is one of the world’s most widely used herbicides a danger not only to annoying weeds, but also to honeybees? While debates rage over whether certain powerful insecticides are responsible for so-called colony collapse disorder — or even whether bee populations are declining at all — recent research suggests that glyphosate, the active ingredient in weed killers such as Monsanto’s Roundup, could be having subtle effects on bee health.

Glyphosate has been in the news in recent months, but not for its possible harm to bees. Rather, some studies have suggested an association between exposure to glyphosate and higher risk of non-Hodgkin lymphoma (NHL), a cancer of the white blood cells. Glyphosate garnered headlines last August when a jury in California awarded groundskeeper DeWayne Johnson a massive judgement against Monsanto’s parent company, the German pharmaceutical giant Bayer. Johnson, along with more than 13,000 other plaintiffs, alleges that glyphosate caused his case of NHL.

But concerns about glyphosate are not limited to humans. Researchers have been accumulating evidence that glyphosphate may also be having deleterious effects on the environment and be harmful to fish, crustaceans, and amphibians, as well as to beneficial bacteria and other microorganisms in soil and water.

A University of Texas study reported evidence that glyphosate disrupts microorganisms in the guts of bees.

In recent years, a number of studies have concluded that glyphosate could also be hazardous to bees. Although the herbicide does not appear as toxic to bees as some other pesticides (notably neurotoxins known as neonicotinoids), researchers have found that glyphosate may impact bees in more subtle ways — for example, impeding the growth of bee larvae, diminishing bees’ navigational skills, altering their foraging behavior, or even disrupting their gut microorganisms, known as the microbiome.

The research is controversial because defenders of glyphosate use have long argued that it is benign in the environment. The herbicide is uniquely designed to target an enzyme that plants need to grow. That enzyme is essential to the so-called shikimate pathway, a metabolic process required for the production of certain essential amino acids and other plant compounds. However, the shikimate pathway is also used by some bacteria and other microorganisms, raising the possibility that glyphosate could have widespread and unexpected effects on a variety of natural organisms.

In a September study in the Proceedings of the National Academy of Sciences, Nancy Moran, an evolutionary biologist and entomologist at the University of Texas, Austin, and her coworkers found evidence that glyphosate disrupts microorganisms found in bees’ guts.

Monsanto's Roundup at a store in San Rafael, California. The product's manufacturer maintains that glyphosate is safe when used as directed.JOSH EDELSON/AFP/ GETTY IMAGES

Monsanto's Roundup at a store in San Rafael, California. The product's manufacturer maintains that glyphosate is safe when used as directed.JOSH EDELSON/AFP/GETTY IMAGES

Mature bees have eight dominant gut bacterial species. Those strains are responsible for such benefits as promoting weight gain and providing resistance to harmful pathogens. The University of Texas team found almost all of them declined when the bees were exposed to concentrations of glyphosate commonly found in the environment. Young worker bees exposed to glyphosate were more susceptible to dying from infections. Moreover, the gut bacteria were more sensitive to the effects of glyphosate if the bacteria possessed an enzyme known to play a key role in the shikimate pathway.

Bayer disputes research findings suggesting Roundup or glyphosate is hazardous to bees. Utz Klages, Bayer’s head of external communications, says the “good news is that honeybee colonies are not in decline and rumors of their demise are greatly exaggerated.” Klages notes that regulatory authorities in a number of countries, including the United States, Canada, and the nations of the European Union, “have determined that glyphosate is safe when used as directed.”

A number of studies have suggested that glyphosate is not highly toxic to bees, including research performed by Monsanto and several other agrochemical companies. That research considered the “realistic worst-case” exposures to the herbicide and found no significant effect on bee mortality. Similarly, a series of studies led by Yu Cheng Zhu, a research entomologist at the U.S. Department of Agriculture, concluded that glyphosate did not seem to kill bees outright. “We did not find an unusual number of dead bees after spraying a bee yard with Roundup a few times each year,” Zhu said.

Scientists have found that glyphosate appears to interfere with the growth and survival of honeybee larvae.

But Walter Farina, a researcher at the University of Buenos Aires in Argentina, says that the very fact that glyphosate is not immediately toxic to bees facilitates the harm it does. “Since glyphosate does not cause lethal effects, it can enter the colony and [be] assimilated by the younger individuals,” Farina says. “The negative effects of [glyphosate] are worse for younger bees, promoting an increased disorganization of the collective task within the hives.”

Farina and his team have looked at some of these effects in Argentina, where glyphosate is intensively used in agriculture. In a 2014 study, published in The Journal of Experimental Biology, they found that the “appetitive behavior” of honeybees — including how well they could detect sucrose and their ability to learn and remember where food sources were located — was significantly diminished after exposure to doses of glyphosate commonly found in farmlands.

In a second study, published in 2015 in the same journal, Farina’s team used harmonic radar to track how long it took honeybees to find their way back to their hives. They found that exposure to relatively low doses of glyphosate appeared to hinder the bees’ ability to navigate back to the hive, and concluded that glyphosate “impairs the cognitive capacities needed to retrieve and integrate spatial information for a successful return.”

A farmer in Argentina, where glyphosate is used intensively, sprays a soybean field in Entre Rios province in February 2018. PABLO AHARONIAN/AFP/ GETTY IMAGES

A farmer in Argentina, where glyphosate is used intensively, sprays a soybean field in Entre Rios province in February 2018. PABLO AHARONIAN/AFP/GETTY IMAGES

In other research, scientists have found that glyphosate appears to interfere with the growth and survival of honeybee larvae. For example, in a studypublished last year in the Journal of Agricultural and Food Chemistry, Pingli Dai of the Institute of Apicultural Research in Beijing, China, and his colleagues found that elevated exposures to glyphosate can lower both the weight of bee larvae and the larval survival rate. This study also showed that glyphosate markedly decreased the diversity and richness of bacteria in the larvae’s intestines, indicators of reduced resilience.

As concerns about how glyphosate may be affecting honeybees mount, researchers are getting a boost from funding agencies that see this as an important research avenue. In March, the National Science Foundation awarded nearly $1 million in grant money to researchers at Virginia Tech and Eastern Washington University to further study the honeybee microbiome.

Meanwhile, Moran, at the University of Texas, says her lab has done follow-up confirmatory experiments using antibiotics to target the honeybee gut bacteria, with similar results on bee mortality as in the previous experiments. She emphasizes that these results have little to say so far about how important a factor glyphosate might be in the declines in bee populations. “We have to say that we don’t know at this point,” she says. “Our results suggest that it is worth studying further, which is what we are doing, and hope others will do also.”

Asian Citrus Psyllid Treatment Program in Whittier

The California Department of Food and Agriculture will be conducting treatments in the Whittier area for Asian citrus psyllid (ACP) suppression, due to the detection of citrus trees infected with Huanglonging (HLB) disease.  They will begin treatments on Monday, March 18, 2019 and the treatment will last approximately  2-3 weeks.  See the following map of the area they will be working in. All citrus trees will be treated within the area boundaries using Tempo SC Ultra and Merit 2F.  

See the CDFA website for additional information on the ACP/HLB program:
Pesticide Regulation
Protecting Bees Tips
Asian Citrus Phyllid Whittier Map Enhanced

If you have any questions regarding their program, you can contact:

Celestina Galindo
Environmental Program Manager
California Department of Food and Agriculture
Pest Detection and Emergency Projects