An analysis of beeswax in managed honeybee hives in New York found a wide variety of pesticide, herbicide and fungicide residues — exposing current and future generations of bees to long-term toxicity.
The study, published in the Journal of Veterinary Diagnostic Investigation, notes that people may be similarly exposed through contaminated honey, pollen and wax in cosmetics. Though the chemicals found in wax are not beneficial to humans, the small amounts in these products are unlikely to pose a major risk to human health, as compared to their impact on bees.
Bees reuse wax over years, causing chemicals to accumulate, including those that are no longer in use in New York but remain in beeswax.
“Because pesticides can accumulate in wax, it’s important for beekeepers to keep removing old wax every few years and having the bees replace it to make sure the colonies and the bee products remain healthy,” said Karyn Bischoff, associate professor of practice at Cornell University and the study’s lead author.
Toxic residues get into beeswax from nectar and pollen of plants that have been sprayed with pesticides, and from drugs and pesticides that beekeepers apply to hives to improve bee health. Healthy bees are vital to New York’s economy and agriculture: the state’s beekeeping industry generated close to $11 million worth of honey in 2020 and annually generates $300 million in pollination services to agriculture.
Pesticides were found in all 72 managed honeybee colony samples analyzed and researchers tallied up to 34 fungicides, 33 insecticides and 22 herbicides, with each wax sample averaging about 18 residues. Wax sent by commercial beekeepers contained the most residues.
“Commercial beekeepers had the most pesticides, which makes sense because those bees are exposed to a lot of different crops, and farmers may use different pesticides for each,” Bischoff said.
The most common chemicals, found in 86% of samples, were acaricides — a class of insecticides that beekeepers use to protect honeybees from varroa mites. These mites are associated with very high bee losses over winter.
Almost every sample (98.6%) contained piperonyl butoxide, a compound that makes animals, insects and fungi more sensitive to insecticides and fungicides, making them more effective. Systemic insecticides (placed on seeds before planting and spreading to all parts of a plant as it grows), called neonics, were also common in samples.
Understanding which contaminants are impacting domestic honeybees may help researchers better protect other pollinators, including wild bees and other insects, as well as birds and bats, Bischoff said.
The New York State Environmental Protection Fund and the U.S. Department of Agriculture funded the research.