June 16, 2024
Obtaining samples ASAP and knowing how to preserve the evidence is key to detecting and proving a pesticide kill but resources are scarce.
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In May, NHBA contacted Dr. Scott McArt;

Meet the Faculty: Scott McArt | CALS

Dr. Scott McArt
Associate Professor
Department of Entomology
4132 Comstock Hall

College of Agriculture and Life Sciences
Cornell University

Ithaca, NY 14853
Office: 607-255-1377
Lab website:
CU pollinator network:
Chemical Ecology Core Facility:

And asked him several questions regarding the sampling and preservation of samples for suspected exposure of bees/beehives to pesticides.  His answers and advice follow below.

First, most pesticides are fairly stable at -20C (a normal freezer) and are even more stable at -80C (an ultralow lab freezer). In general, my advice is that samples can be stored for up to ~6 months at -20C without worry, and for several years at -80C without worry.

Outside of freezer storage, pesticide degradation happens more quickly, but is highly variable depending on the environmental matrix. Pesticides in cold soils can have half-lives of a year or more, while pesticides in bees that are in the sun can have half-lives of a few minutes or hours. When investigating a bee kill, it’s best to sample dying bees or very recently dead bees (i.e., dead within the past few minutes or hours) and also to sample the most recently deposited pollen cells in the hive. Recently deposited pollen can sometimes be even more informative that bees, in part because bees actively metabolize pesticides via their detoxification enzymes. Wax can also be informative, but pesticides persist in wax for many years, so wax is the most difficult matrix to consider when trying to identify a single acute exposure event. That said, wax can be useful for getting a somewhat wholistic picture of chronic exposure.

In terms of threshold values, this is currently a contentious topic. Guidance from the EPA on this topic can be found here:

And here’s a recent paper we published that uses the EPA’s threshold values:

In the analysis below, we used a sublethal risk assessment approach to complement the EPA’s lethal risk assessment threshold approach:

Sublethal risk assessments are conducted by the FDA for drugs (e.g., we’re concerned about drugs that may give us cancer) but they aren’t currently conducted by the EPA for pesticides. Almost every academic researcher who works on this topic feels this is an oversight by the EPA. One example is highlighted in this article:

And this article shows why omitting sublethal risk assessment can result in negative consequences for pollinator populations (the article also highlights why post-registration monitoring, which isn’t currently required by the EPA or EFSA, would be informative):

Now the unfortunate side of this is that analytical laboratories to analyze samples are in short supply.  First, there are none in NH that I have been able to find, or that Dr. McArt knows of. Second, his laboratory at Cornell does conduct a comprehensive analysis of 92 pesticides currently at a cost of $120/ sample! Dr. McArt knows of no one who is doing it cheaper than he is.  Other laboratories that provide similar services include;

Our national USDA pesticide testing lab is in Gastonia, NC:

There are also private labs that operate multiresidue analyses. For example:

George Argiriou

Business Development Manager

Eurofins Microbiology Labs

2430 New Holland Pike, Suite D-215

Lancaster, PA 17601

Phone:  610-816-4327


Silliker Inc., Illinois Laboratory (they also have a lab in Allentown, PA)

3600 Eagle Nest Drive, North Building

Crete, IL 60417

PHONE: RCS 877-777-6375

FAX:  708-367-0698  

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