Campus Units

Iowa Monarch Conservation Consortium

Document Type

Article

Publication Date

10-2001

Journal or Book Title

Proceedings of the National Academy of Sciences USA

Volume

98

Issue

21

First Page

11913

Last Page

11918

DOI

10.1073ypnas.211234298

Abstract

To assess the likelihood that monarch larvae will be exposed to Bacillus thuringiensis (Bt) pollen, we studied milkweed and monarch densities in habitats which comprise much of the land available to breeding monarchs, e.g., cornfields, cornfield edges, other agricultural fields, and nonagricultural areas, in four regions of the monarch breeding range. We found that monarchs use milkweed in cornfields throughout their breeding season, and that per plant densities are as high or higher in agricultural habitats as in nonagricultural habitats. As a result of the prevalence of agricultural land, most of the monarchs produced in the upper Midwest are likely to originate in cornfields or other agricultural habitats. There was a greater temporal overlap between susceptible monarchs and corn anthesis in the northern than the southern part of the summer breeding range, because of earlier pollen shed in the south. The importance of agricultural habitats to monarch production suggests that, regardless of the impact of genetically modified crops, agricultural practices such as weed control and foliar insecticide use could have large impacts on monarch populations.

Comments

This article is from Proceedings of the National Academy of Sciences USA; 98 (2001); 11913-11918; doi: 10.1073ypnas.211234298

Rights

Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.

Copyright Owner

National Academy of Sciences

Language

en

File Format

application/pdf

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