Members of the UF/IFAS Honey Bee Research and Extension Laboratory in collaboration with researchers located at the Federal University of Rio Grande do Norte in Brazil conducted a research project studying the effects of contact exposure to pesticide residues in beeswax on adult honey bees. Below is a summary of the research as well as a link to the full publication.

Background

Environmental pesticide exposure has been implicated in high gross loss rates in managed western honey bee ( mellifera) colonies. This exposure can occur through contact with and ingestion of agricultural pesticides or treatments for honey bee pests, which cause hive products, including honey, pollen, bee bread, and beeswax to accumulate pesticide residues. Honey bees continuously contact beeswax within the hive, a route of exposure that is understudied compared to exposure through the ingestion of nectar and pollen, despite pesticides presence in much higher concentrations in beeswax compared to other routes.

Purpose

The purpose of this research was to determine how the survival of honey bees over a 30-day trial is affected by contact exposure to environmentally relevant concentrations of pesticide residues found in beeswax. In particular, researchers examined the impact of the pesticides amitraz, chlorothalonil, clothianidin, coumaphos, imidacloprid, and tau-fluvalinate on honey bee mortality, using dimethoate as a positive control. The experiment lasted a total of 30 days.

Key findings

• Data suggest that tau-fluvalinate negatively impacts adult honey bee survival; there were minor reductions in survival in the short term, but no conclusive evidence to determine the lasting impact of chlorothalonil on bees. Amitraz, clothianidin, coumaphos, and imidacloprid did not impact honey bee survival in this experiment.
• Dimethoate was shown to be an effective positive control for beeswax residue exposure studies with 100% mortality in dimethoate-exposed bees, which aligns with previous findings.
• Pesticide exposure through contact with beeswax may be less harmful to bees than pesticide exposure through the ingestion of water, nectar, and pollen in relatively short-term experiments, such as this.
• More research is necessary to determine any effect pesticides may have on adult bees via contact exposure to contaminated beeswax.

Significance

Contact exposure to pesticides in beeswax has been less studied than exposure through ingestion. This research improves our understanding of how pesticide-contaminated beeswax affects adult honey bee mortality, revealing another way pesticides harm bees. This knowledge can help beekeepers protect their colonies and support the environment and crops that rely on pollination.

To read this publication, visit: https://academic.oup.com/etc/article/44/8/2181/8129571

This blog was written by UF/IFAS Honey Bee Research and Extension Laboratory employee, Katie Shealy and revised by Amy Vu and Cody Prouty.

Cody Prouty, Cameron J Jack, Gerbson A Mendonça, James D Ellis, Contact exposure to environmentally relevant pesticide residues in beeswax may affect honey bees in a laboratory setting, Environmental Toxicology and Chemistry, Volume 44, Issue 8, August 2025, Pages 2181–2185, https://doi.org/10.1093/etojnl/vgaf123

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