Daniel Dixon

Date of Award

January 2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Earth System Science & Policy

First Advisor

Haochi Zheng

Abstract

North Dakota supports the highest number of honey bee colonies in the US due to its abundance of floral resources, but threats from land-use change and pesticide applications have altered the quantity and quality of those resources in recent years. This thesis explored landscape scale pesticide use trends from both spray applied and seed treated insecticides on lands within 1.6km of ~13,000 registered apiaries North Dakota from 2001 to 2015. The regional application of five spray applied insecticides was collectively modeled using InVEST’s Habitat Quality Model during years of heightened land-use change. In these models, regional application rates were converted and normalized to relative risk values which degrade the quality of pixels adjacent to where applications occurred. Results from 2006 to 2014 suggest decreases in the quantity and quality of beneficial natural land covers such as grasslands surrounding apiary sites due to shifting land-use and changing spatial pesticide applications. Conservation scenarios were designed to better understand the effectiveness of strategic placement of conservation land within apiary site buffers by utilizing apiary density as a guide in the year 2014. Comparing baseline and scenario outputs led to the discussion of policy at regional and field levels to improve quantity and quality of resources for honey bees. More generalized modeling of neonicotinoid use from corn and soybeans resulted in spatial outputs that mirrored those from spray applied insecticides. Threats to apiaries in the forms of pesticide use and land-use change occurred collectively east of the Missouri River where land-use change has been most pronounced. The ecosystem service benefits of grassland as sources of forage and as a refuge from pesticide exposure were discussed.

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