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

11919

Last Page

11924

DOI

10.1073ypnas.211287498

Abstract

The density of corn pollen on leaves of milkweed plants inside and outside of cornfields was measured in several studies from different localities. The purpose was to obtain a representative picture of naturally occurring pollen densities to provide a perspective for laboratory and field studies of monarch larvae feeding on milkweed leaves with Bt corn pollen. Pollen density was highest (average 170.6 grains per cm2) inside the cornfield and was progressively lower from the field edge outward, falling to 14.2 grains per cm2 at 2 m. Inside the cornfield, and for each distance from the field edge, a frequency distribution is presented showing the proportion of leaf samples with different pollen densities. Inside cornfields, 95% of leaf samples had pollen densities below 600 grains per cm2 and the highest pollen density observed was 1400 grains per cm2, which occurred in a study with a rainless anthesis period. All other studies had rainfall events during the anthesis period. A single rain event can remove 54–86% of the pollen on leaves. Leaves on the upper portion of milkweed plants, where young monarch larvae tend to feed, had only 30–50% of the pollen density levels of middle leaves.

Comments

This article is from Proceedings of the National Academy of Sciences USA; 98 (2001); 11919-11924; doi: 10.1073ypnas.211287498

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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