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Document Type

Thesis - University Access Only

Award Date

2015

Degree Name

Master of Science (MS)

Department

Plant Science

First Advisor

Adrianna Szczepaniec

Abstract

Transgenic maize that expresses toxins derived from the bacterium Bacillus thuringiensis (Bt) has been used to control corn rootworm since 2003. However, the widespread use of Bt maize has recently selected for resistance to the toxins Cry3Bb1 and mCry3A in populations of western corn rootworm, which has created concern over the spread of Bt resistance in western corn rootworm populations throughout the United States. The goal of this study was to test the effectiveness of three YieldGard®, Herculex®, and Agrisure® maize hybrids in suppressing damage caused by corn rootworm larvae in maize fields in eastern South Dakota and to survey the current species composition of corn rootworm in the state. These field experiments and surveys were conducted over two years in two locations in the state. We also wanted to assess the corn rootworm-related management issues from the perspective of crop consultants in South Dakota. This was accomplished by soliciting the consultants’ input through a survey conducted in 2014 during an extension event organized by South Dakota State University. We found that Cry3Bb1 and mCry3A toxins did not effectively control corn rootworm, as unexpected damage to maize roots and high numbers of adult beetles were discovered in maize expressing these toxins. However, Cry34/35Ab1 toxins did vii successfully suppress damage to roots and beetle emergence. We also found that the majority of beetles collected in our surveys were western corn rootworm. Results from the crop consultant survey suggest that corn rootworm damage to Bt maize is widespread throughout the eastern half of South Dakota, implying that resistance to Bt maize may be evolving in western corn rootworm populations in this area. Overall, this research increases our knowledge of possible Bt resistance in our state, which can lead to recommendations for successful corn production and sustainable management of corn rootworm in South Dakota.

Library of Congress Subject Headings

Corn--Disease and pest resistance--Genetic aspects
Western corn rootworm--Control--South Dakota
Hybrid corn

Description

Includes bibliographical references (pages 37-40)

Format

application/pdf

Number of Pages

47

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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