Entomology, Department of


First Advisor

Judy Wu-Smart

Second Advisor

Autumn Smart

Date of this Version

Winter 12-2022


Tokach R. T. (2022). Adverse health impacts on honey bee (Apis mellifera L.) colonies from a contaminated environment and resources. University of Nebraska-Lincoln, Lincoln, NE.


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Entomology, Under the Supervision of Professors Autumn Smart and Judy Wu-Smart. Lincoln, Nebraska: December 2022

Copyright © 2022 Rogan T. Tokach


Honey bees (Apis mellifera L.) continue to experience high annual declines due to a combination of factors including pesticides. Due to increasing agricultural intensification has led to a reliance on systemic pesticide treated seed which can brought back to the colony in pollen and nectar. Treated seed is not subject to the same guidelines as pesticide applications reducing the regulations on the disposal of treated seed. In 2015, an ethanol plant in Mead, Nebraska began processing expired treated seed for ethanol production. Subsequently, the University of Nebraska-Lincoln Bee Lab started seeing 100% colony failure in apiaries surrounding the plant.

To examine the effects on colony function in this polluted environment compared to other landscapes, queenless colonies were established and allowed to requeen themselves after given resources from “deadout” or contaminated colonies from Mead, Nebraska or from a control site. Colonies given contaminated combs produced fewer overall queen cells and were less likely to successfully requeen themselves compared to those given control resources. These results indicate pesticide laden resources impact queen rearing capacity.

Exposure to pesticides can have sublethal impacts on individual worker aging, queen behavior, and gene expression. Using apiary locations or sites as treatments, small observation hives with age-marked worker bees were set up to monitor bee behavior at the contaminated site and a control site. Results showed significant differences in the onset of critical hive tasks and worker bees at the contaminated site accelerated their aging process resulting in lower brood care and pollen processing by young bees and more precocious foraging which leads to shorter worker longevity. Queen locomotion was largely unaffected, but egg-laying rate was reduced for queens in the contaminated site. These results indicate environments contaminated with widespread systemic pesticide pollution can have differential, subtle, and cascading effects that disrupt critical behaviors and colony functions, reduce overall productivity, and increase risk for colony failure.

Advisors: Autumn Smart and Judy Wu-Smart

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Entomology Commons