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Title:Chronic contact exposure to realistic soil concentrations of a neonicotinoid insecticide represents a potentially important and unexplored route of exposure for ground nesting bees
Author(s):Anderson, Nicholas L
Advisor(s):Harmon-Threatt, Alexandra N.
Contributor(s):Francis, Bettina M.; Allan, Brian F.
Department / Program:Entomology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Ground-nesting bees
Contact exposure
Contaminated soil
Sublethal effects
Mushroom bodies
Abstract:In the face of widespread declines, the non-target effects of pesticides on ecologically and economically important bees are an area of growing concern. One class of pesticides that has gained considerable attention over the past two decades is the neurotoxic neonicotinoid insecticides. Neonicotinoids are a widely used group of compounds that are often applied preemptively to protect plants from pestiferous insects. Due to their systemic nature, they are found throughout treated plants, including in pollen and nectar. This has led to an ever expanding literature concerning the effects of these chemicals when consumed by bees. However, much of the applied active ingredients are not absorbed by treated plants, return to the soil as plant material decomposes, and persist in soils due to their relatively long half-lives. Neonicotinoid contamination of soil represents a potentially important, yet under explored, route of exposure for bees, the majority of which nest in the ground. The aims of this thesis are to examine this route of exposure and to determine potential sublethal effects. In chapter 1, I explore the effects of chronic contact exposure during to realistic soil concentrations of imidacloprid - the most widely used neonicotinoid - on pre- and post- overwintering development speed, mass, and immature and adult longevity. In chapter 2, I focus on the effects of this type of exposure on adult bee mushroom body growth. The results presented here suggest that neonicotinoid contamination of soils represents a potentially important route of exposure for ground nesting bees. A number of sublethal effects were detected in response to treatment with chronic contract exposure to imidacloprid including: reduced development speed at low and intermediate concentrations, increased conservation of starting nest cell (food provision and egg) biomass, and changes to immature and adult longevity. Population-level and ecological consequences of these effects are discussed, as well as implications for habitat restoration and bee conservation.
Issue Date:2017-04-24
Rights Information:Copyright 2017 Nicholas Lee Anderson
Date Available in IDEALS:2017-08-10
Date Deposited:2017-05

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