Field Experiment I. Environmental Pesticide Concentrations
- 1 Introduction
- 2 Summary
- 3 Background
- 4 Goals
- 5 Procedure
- 6 No foundation
- 7 Apiaries
- 8 Sample Collection
- 9 Test Results
- 10 Bee Kill
- 11 Pesticide Mitigation
- 12 Budget
- 13 Funding
- 14 Notes
This experiment will measure insecticide, fungicide and herbicide levels in honey bees (Apis mellifera), wax and bee bread (pollen) in three different environments:
- Agriculture (Rural farmlands)
- Urban (Suburb in small city)
- Pristine (National Forest)
This is part of the Science, Technology, Engineering and Math ("STEM") and Long Term Environmental Research programs at Rabun Gap Nacoochee School. A Bayer CropScience award and other interested donors provided the funding for this experiment.
Pesticide levels in apiaries were measured in agricultural, urban and pristine locations. To eliminate contamination from old equipment or wax foundation, packages of bees installed in new woodenware without foundation were used. At the end of the season, samples of bees, wax and pollen were removed from the hives and sent to the USDA for pesticide screening. Two insecticides and a fungicide were in the pollen from the agricultural area. Nothing was detected in the bees or wax. No pesticides were detected in the pollen from both the National Forrest and the suburbs near Athens, Georgia.
Researchers have raised concerns about pesticide levels found in the hive. Some literature (citation needed) suggests that pesticide use around the home in an urban setting is higher than a rural farming environment.
Beekeepers often send small sample sizes to the USDA Laboratories which can limit the level of detection (LOD). Sampling technique can concentrate or dilute concentrations.
Most pesticides, being non-polar molecules, are not detected in honey, but are more likely to be found in the wax which acts as the liver to absorb toxins.
Measure the pesticide levels in bees and wax in apiaries in three different environments: Agricultural, Urban, Pristine.
- How clean is clean? Is it possible to raise bees with no detectable levels of pesticides in the hive?
- What are the pesticide levels in an urban environment?
- How dirty is dirty? What are the pesticide levels in a hive near agriculture?
- Where are the highest levels of pesticides in the hive? In the home (urban) or rural farms (agriculture)?
Six 3 lb packages of bees were purchased from a commercial beekeeper and installed in new equipment without foundation. They were initially fed 1.5 to 3 gallons of food grade sugar syrup. Two hives (a primary and a backup) are located in three different environments:
- Near intensive farming in Rabun Gap, Georgia, USA.
- In a subdivision in Athens, Georgia, USA.
- In a pristine area of the Nantahala National Forest near Franklin, North Carolina, USA, at the top of a watershed, with minimal human disturbance for a two mile radius.
At the end of August, the colonies will be destroyed. The bees will be gassed with CO2, flash frozen, and sent to labs to measure the amount of various pesticides in the bees. The wax will be separated from the honey. The wax will be sent to the USDA National Science Laboratories, Gastonia, North Carolina, USA and analyzed for pesticides.
After email discussions with the USDA NSL, the procedure was changed. Instead of destroying the hive, a sample of bees, wax and pollen was taken from each hive.
Frames with foundation could potentially introduce outside pesticides and contaminants. Wax foundation is "recycled." Beekeepers send their surplus wax (often from uncapping the comb) to bee equipment suppliers who use it to produce foundation. Even plastic foundation is coated with wax. Some pesticides have a long life, in excess of twenty years. Studies have shown (need citation) that "new" foundation contains detectable levels of pesticide. Some of the pesticides that have been found in wax such as coumaphos and fumagillinwere intentionally introduced into the hive by beekeepers to kill parasites.
To maintain the integrity of this experiment, only new wooden frames with no foundation, not even a starter strip, were used.
Apiaries were set up in three different environments: agriculture, urban and pristine.
Rabun Gap, Georgia, USA - Population Density of Rabun County: 44/sq mi (17/km²)
Package 1 installed April 11, 2016
Package 2 installed ______________
Athens - Clark County, Georgia, USA - Population: 119,980; Population Density of Clark County: 851.5/sq mi (328.8/km²) (2013).
Package 1 installed March 30, 2016 (Queen did not take.)
Package 2 installed April 11, 2016
Package 3 installed May 12, 2016
Wayah Bald, Nantahala National Forest, Macon County, North Carolina, USA
Two 3 lb packages installed May 9, 2016.
During the afternoon and evening of Monday September 5, 2016, the entrance of the hives in Athens, GA and Wayah Bald, NC were screened and the hives brought back to Rabun Gap-Nacooche School campus. The entrance screens were kept in place until the next morning when the hives were opened and samples of empty comb, comb with pollen, and bees were taken.
Initially, due to the high cost of pesticide residue analysis ($396 per sample for the general pesticide screen), samples of bees, wax and bee bread (pollen) were tested only from the rural farmland apiary at Rabun Gap-Nacoochee School. We felt that if nothing was found in them, there would be no point in further testing. Base on the findings in the next section, Agriculture Pesticides Concentrations, only the bee bread (pollen) from the other two locations was tested.
Agriculture Pesticide Concentrations
|Agricultural Pesticides in Pollen|
|Cyhalothrin total||564||1.0||Insecticide (pyrethroid)|
|1. parts per billion|
2. Level of Dectection in ppb
- No pesticides were found in the bees. USDA Pesticide Report on Bees
- No pesticides were found in the wax. USDA Pesticide Report on Wax
- Two insecticides and a fungicide were found in the pollen. See table to right. USDA Pesticide Report on Pollen
The Cyhalothrin is of particular concern. "It is highly toxic to bees, for which the oral LD50 is 38 ng/bee, and the contact LD50 is 909 ng/bee.
At the found concentration of 564 ppb (.564 micrograms/gram) .068 grams (68 milligrams) of this pollen contains 38 ng of cyhalothrin, the LD50.
In the research article High Levels of Miticides and Agrochemicals in North American Apiaries: Implications for Honey Bee Health, Table S1. Summary of pesticide detections in 887 North American beehive and related samples, cyhalothrin was detected in 7.8% of the samples with a mean value of 5.6 ppb and a peak of 71 ppb. Our levels (564 ppb) were so much higher than the 71 ppb peak found in this study, one state insecticide inspector said our levels are "off the chart".
Urban Pesticide Concentrations
No pesticides were detected in the pollen samples from a subdivision in Athens, Georgia. USDA Pesticide Report on Pollen
Pristine Pesticide Concentrations
No pesticides were detected in the pollen samples from the top of Wayah Bald mountain, Franklin, North Carolina surrounded by the Nantahala National Forrest. USDA Pesticide Report on Pollen
After the samples were removed from the hive, beekeepers in the area reported dead bees in front of their hives. These dead bees were not sampled and tested for pesticides as we did not plan nor budget for this event.
A worker bee consumes on average 3.4–4.3 mg pollen per day, with a peak at the age of nursing. (Crailsheim et al., 1992). Using their hypopharyngeal glands and enzymes, nurse bees process pollen into a high-quality larval food (Moritz and Crailsheim, 1987) that allows honey bee larvae to grow rapidly. A study by Haydak (1935) found that each larva needed 100 mg of pollen to complete development from the larval stage to the pupal stage on through to adult emergence. Honey Bee Nutrition, MAAREC Publication 1.4 February 2015.
We speculate that these dead bees are not foragers that brought the pollen back, but nurse bees that ate the pollen to produce the "milk" or "jelly" to feed to the larva. As calculated above, consumption of only 68 milligrams of pollen would kill 50% of the bees.
Similar bee kills have been experienced in prior years in late summer to early fall. About 6 acres of sweet corn is planted each week. The corn is sprayed with the insecticide Warrior (Cyhalothrin) at night to minimized bee exposure. The strategy obviously wasn't working.
- Do not grow corn on campus.
- Move the bees after sourwood flow.
- Apply a bee repellent to the corn.
- Plant an alternative pollen or nectar source.
A follow up, Field Experiment II. Alternative Forage Pesticide Mitigation, is being conducted to test the timing, planting method and spacing. required acreage.
|Eight 3 lb packages of bees at $99 each||$792|
|Feeders and syrup||$150|
|Battery/solar charger for bear fence||$150|
|Remote hive monitoring cellular data fees||$200|
|Pesticide Testing at USDA||$1980|
Funding was provided by an award from Bayer CropScience, a donation from the Macon County Beekeepers Association, and gifts from private donors.