Articles Published in the American Bee Journal

Project Description

PRI’s Dr. Susan Kegley and Dr. Tim Brown are collaborating to write articles that explore cutting-edge bee research and policy. These articles offer advanced reviews on topics pertinent to bee health and pesticide use that are both concise and accessible to the lay-person.

Read the full articles below to learn more about effects of bee-toxic pesticides. Please visit the American Bee Journal website to for more articles on beekeeping and Apis mellifera.

Introducing “The Curious Beekeeper”

Welcome to the first installment of The Curious Beekeeper, a new resource for beekeepers on developments in bee health and pesticide use. As part of an ongoing education effort about key factors affecting the health and productivity of these vital pollinators, the National Honey Bee Advisory Board is partnering with the Pesticide Research Institute to develop a series of articles for the American Bee Journal and Bee Culture Magazine. Each month, we will delve into a new topic, ranging from a closer look at how bees might be exposed to pesticides, to an assessment of new regulatory action on pesticides, to reviews of the most recent studies in the scientific literature, while providing the background necessary to fully understand the issues at hand.

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The Dose Makes the Poison…or Does It?

In our first installment of The Curious Beekeeper, we discussed the differences between the newer systemic pesticides, including neonicotinoid insecticides and certain fungicides, and the previous generation of pesticides, such as organophosphate and carbamate insecticides. Both the newer and older pesticide classes exhibit acute toxicity toward honey bees and other pollinators in the form of bee kills as a result of foliar applications. However, residues of the newer systemic pesticides are incorporated into pollen and nectar because they are taken up through the leaves (from foliar treatments) or through the roots (from soil or seed treatments) and distributed throughout the entire plant. Many of these systemic pesticides are also long-lived, with residues remaining in soils and plant materials for months to years following application. These attributes all contribute to the exposure of bees to low levels of systemic pesticides over an extended period of time, and can lead to significant adverse effects on colony health and productivity.

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Control or Chaos:  Designing Scientific Bee Studies That Make Sense

Not all scientific research is created equal, and a primary goal of The Curious Beekeeper is to provide beekeepers with a strong foundation for critically evaluating the new studies on bee health. The difficulty is that a beehive is a complex system. As a beekeeper friend said to me once, “Beekeeping isn’t rocket science . . . it’s MUCH harder.” We have to agree with that one!

The unsustainable colony losses we’ve seen over the last 5–10 years is potentially linked to a number of different factors, including pesticide exposure, Varroa mites, viruses, and bee nutrition. How can researchers untangle the issue when there are so many possibilities? This is where scientific principles are being brought to bear on the problem to help understand cause and effect, as well as potential interactions between factors.

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Going the Distance:  Scientific Bee Studies That Make an Impact

Carefully designed scientific bee studies are invaluable tools for the practicing beekeeper. Without them it is nearly impossible to analyze the effects of different stressors on long-term colony health and make meaningful, informed decisions. In our previous installment of The Curious Beekeeper we discussed a series of flawed studies analyzing the effects of honey bee exposure to the new neonicotinoid insecticide sulfoxaflor. Some of the experiments designed to better understand the effects of sulfoxaflor exposure on brood development failed to follow a complete brood cycle. In addition, one of the key studies used a control hive (no exposure to sulfoxaflor) that was infested with Varroa to make comparisons against mite-free hives exposed to sulfoxaflor. Because the two colonies were not comparable in terms of mite infestation status, it was therefore impossible to draw any conclusions regarding the effect of sulfoxaflor on brood development from these experiments.

For this fourth article in our series, we counter our previous example with a study that goes the distance, with procedurally sound experiments that lead to defensible conclusions. Here we dissect the experimental design and evaluate the results from a notable 2012 study co-authored by Joseph Riddle and his colleagues at Michigan State University (MSU), Jeff Pettis at USDA, and Xianbing Xie from Nanching University analyzing the effects of long distance transport on the physiology of honey bees. As the first investigation of its kind, the study was designed to evaluate the two extremes in the level of transport, where one group of bees was transported while a comparison group (the negative control) was not moved at all.

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Metabolites and Breakdown Products: The Enduring Legacy of Bee-Toxic Pesticides

see no evil monkeyWhen it comes to the safety and efficacy of pesticides, the parent pesticide generally receives the lion’s share of attention from researchers, the chemical industry and regulators. This isn’t too surprising given that the mode of action for pesticide products is intimately tied to the chemical and toxicological profile of the active ingredient. However, pesticide active ingredients do break down in the environment to one or more different chemicals. While some degradation products are less toxic than the parent chemical, higher toxicity degradates may also be generated. This means that, when evaluating the impacts of pesticides on honey bees, it is important to know exactly what chemicals are present.

In some cases, foraging bees are exposed to toxic mixtures of the active ingredient and its various degradates. Inside the beehive, stored pollen or nectar that was brought into the hive containing a single pesticide active ingredient may later contain a mixture of the active ingredient and the degradation products that formed over time. This mixture may pose a significant risk of colony impairment for hives using stored food sources during fall and winter months.

In this installment of The Curious Beekeeper, we delve into the intricacies of pesticide degradation products—what they are, their relative toxicity to honey bees, and implications for monitoring pesticide residues in the environment—for several widely used, bee-toxic pesticides.

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Sampling for Pesticide Residues, Part I: Deciding What to Sample

After the large bee kill in almonds this spring, many beekeepers were interested in finding out more about what role pesticides might have played in the losses. In this installment of The Curious Beekeeper, we provide some guidance on sampling for pesticide residues, with a focus on what type of sample should be taken, either from inside the hive or from the environment in which the bees may have been exposed. We also provide perspective on the advantages and disadvantages of the different sample types. In a subsequent article, we’ll talk more about the actual logistics of sampling, analysis, and interpretation of results.

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Sampling for Pesticide Residues, Part II:  Sampling Logistics and Interpretation of Results

In the last Curious Beekeeper article, we talked about the different kinds of samples that could be taken—bees, pollen, wax, honey, plants, soil, water—and described the advantages and disadvantages of analyzing each. In this installment of The Curious Beekeeper, we provide logistical guidance on taking samples from your apiary without contaminating the samples through contact with other materials or another sample. We also outline best practices for documenting the process and provide insight on interpreting and using sample results.

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Running the Risk, Part I: An Overview of Honey Bee Risk Assessment Basics

BeeOnOnionThe decline in pollinator populations and the crisis of unsustainable losses in managed honey bee colonies in several regions of the world has pressured regulatory agencies to revamp pesticide risk assessment methods for honey bees. While some countries are beginning to require more rigorous risk assessment protocols for honey bee exposure to pesticides, there is still considerable uncertainty involved in the process and wide gaps in the information needed to fully understand pesticide risks to bees.

In this installment of The Curious Beekeeper, we provide part I of Risk Assessment 101—a general overview of pesticide risk assessment for pollinators, including information on how regulatory agencies determine a reference dose for bees and estimate bee exposures. In Part II next month, we will take a look at the more involved Tier II and Tier III studies and compare EPA’s new pollinator risk assessment guidance published in June of 2014 to the methods currently used in Canada, and the European Union.

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Running the Risk, Part II: The Higher Tiers of Honey Bee Risk Assessment and Comparisons between the U.S., Canada and Europe

In the last installment of The Curious Beekeeper, we provided an overview of the basics of pesticide risk assessment for pollinators. In this article, we introduce you to the higher tier risk assessment methods that are being used to assess risks to entire colonies rather than just individual bees. We also compare the new US EPA pollinator risk assessment guidance published in June 2014 to the methods currently used in Canada , and the European Union, and provide recommendations for minimizing the current uncertainties in assessing the risk of pesticide exposure to bees.

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Chemical Synergies:  When 1 + 1 does not equal 2

The agricultural environment is a source of chemical exposure for bees, with pesticides, their degradation products, and other ingredients in pesticide products (adjuvants, solvents, and other chemicals added to formulated products) dominating the scene. Because multiple pesticide products are applied to a crop, honey bees foraging on or near the crop will typically bring multiple chemicals back to the hive in pollen, nectar and/ or water. In-hive miticides are also part of the picture. Indeed, most analyses of hive materials (pollen, wax, bees, honey) taken from beehives in agricultural areas show that multiple agricultural and miticidal chemicals are present. As we think about the potential effects of these chemicals on bee health, it becomes clear that we need to know not only how the individual chemicals affect bees, but also whether the mixture alters the toxicity of individual components. There are three possibilities:

1. Additive: Toxicity is simply the sum of the toxicity across the individual components;

2. Antagonistic: The mixture is less toxic than the sum of its components would suggest; and

3. Synergistic: The mixture is more toxic than the sum of its components would indicate.

In this Curious Beekeeper article, we’ll explore the occurrence of synergistic effects, where 1 + 1 is greater than 2.

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More to come!