Buzzing the Gauntlet: Improving Honey Bee Risk Assessment

With new annual colony loss data being released (see BIP Box, June 2017) we are reminded of the four Ps that give our bees the most trouble for a decade now –they are Parasites, Pathogens, Poor Nutrition and Pesticides. Those of us working to improve bee health are concentrating on those four areas, and stakeholders have continued to step up to make a difference in the decade since CCD raised the alarm about honey bee health. Assessing the risks that pesticides pose to bees and applying mitigations are critical challenges to pesticide regulators (both federal and state), that can directly impact the beekeeping industry. High quality research takes time to plan and execute, and it can be quickly outpaced by the development of new chemistries, delivery methods and applicator preferences such as mixing compounds. That is why it is important for our industry to keep pace with the latest research, including supporting studies that form the basis of the current understanding of risk to bees. We know that honey bees can forage up to several miles from their hives, often pollinating a variety of important crops, many of which might be treated with pesticides at various times. On these foraging trips, pollinators may be exposed to these pesticides. But what are the risks? There are many options to quantify and mitigate exposure risks, but until recent years, mandatory risk assessments did not include data from immature honey bee laboratory studies. It is critically important in determining chronic and sub lethal effects to immature honey bees from compounds that may not affect adult bees the same way. In recent years, beekeepers concerned about increased hive losses have been working with the EPA and Registrant Companies to develop better methods of assessing pesticide risks from pesticides. 
 
Accordingly, Project Apis m. supports additional and continued research to determine what pesticide exposure levels could result in effects, and whether those effects match symptoms seen under field conditions. Following this approach, we have had great successes determining practices to minimize the potential harm to bees, including recent work by Dr. Reed Johnson, who has explored the role of specific tank mixes used in almonds which were harming bees- particularly honey bee larvae. (Very good web presentation here) This discovery was promptly used by the Almond Board of California to refine management recommendations to protect bees. This is an example of how responsive applied research can make a difference for all stakeholders.
 
Likewise, many groups are working to determine how to test chemicals to best assess risks to bees, which can inform chemical registration and proper use. This month we are sharing an example of a laboratory approach for determining toxicity to honey bee larvae, which will serve as one of the standard toxicity studies required for pesticide regulation in the U.S. (and most of the world).

Larval toxicity test, photo courtesy of University of Florida

The following article summarizes a collaborative global effort of academia, agrochemical industry, regulatory agencies and independent labs, to standardize a testing protocol which determines pesticide risk to honey bee larvae. As beekeepers, we know effects on any cohort can ultimately impact the colony, and effects to honey bee brood, including eggs, larvae and pupae (capped brood), are no exception. Ideally we would test all bees, in all settings, at all stages, to make the best decisions, but how do you eat an elephant? One bite at a time! This particular test; the 22-day chronic larval toxicity test, has been challenging to standardize, and as you can see from complete report, a huge effort was required just to be sure that laboratories can successfully complete the study. Independent labs across the world were invited to participate and 15 of them took on the task to generate these data. I invite you to take a look and see what goes into incremental improvements to a method like this, and appreciate the scientists who are dedicated to this kind of work. This is an example of cooperation by many stakeholders to advance our understanding of pesticide risk, developing new methods to protect pollinators.
 
Honey Bee Larval Toxicity Test Protocol Development Summary
​Dr. Dan Schmehl, Pollinator Safety Scientist, Bayer Crop Science
 
A recent effort by the Pollinator Research Task Force1 (PRTF) validated the use of a method for evaluating the chronic toxicity of a compound (e.g., a pesticide) to an immature honey bee for use in a risk assessment. Substantial data on the honey bee toxicity (i.e., what level causes an effect) and exposure (i.e., what concentration and amount they encounter in the environment) on both the adult and immature stages of development are required prior to conducting a thorough risk assessment for a pesticide. Currently, established methodology exists for measuring acute oral and contact toxicity of a pesticide on adult honey bees, and for measuring acute toxicity on honey bee larva. Developing a robust study design for evaluating chronic exposure of a compound to immature honey bee development has been challenging due to high mortality in the controls (control = no pesticide present).

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Read the Full Report:  Results of the Honey Bee (Apis mellifera L.) Toxicity Following Chronic (Repeated) Exposure International Ring Test Performance