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2-Plants: Field tests proof hazards of Bt-pollen on Monarch butterflies

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TITLE:  Non-target effects of Bt corn pollen on the Monarch
SOURCE: Iowa State University, Laura Hansen
DATE:   May 25, 1999

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Monarch Butterflies and Bt Corn
Iowa State University Extension

May 25, 1999 - Data from Iowa State University Department of
Entomology shows a relationship between the mortality of first
instars (larvae) of the monarch butterfly (Lepidoptera: Danaidae)
under field conditions with Bt corn. Laura Hansen, graduate
research assistant, and John Obrycki, professor of entomology,
presented a poster at the North Central Branch meetings of the
Entomological Society of America on March 29, 1999. An abstract
of the data is available on the NCB Web site.

For further information contact:
Laura Hansen
Room 4 - Insectary Building
Iowa State University
Ames, IA 50011
voice: (515) 294-1999


          *****     text from NCB web site     *****

Non-target effects of Bt corn pollen on the Monarch butterfly
(Lepidoptera: Danaidae)

*L. Hansen, Iowa State University, Ames , IA 50011 and
J. Obrycki, Iowa State University, Ames, IA 50011
Contact e-mail: 

The expression and dispersal of Bt toxin in the pollen from
transgenic crop plants may pose a risk to non-target
Lepidopterans. When Bt corn pollen lands on the leaves of plants
in and around corn fields, it exposes non-target Lepidopteran
larvae feeding on these plants to Bt toxins. In Iowa, where the
landscape is dominated by row-crop agriculture, areas effected
could include a significant portion of non-cultivated areas,
including remnant prairies, roadside ditches and wetlands. The
monarch, Danaus plexippus (Lepidoptera: Danaidae) was chosen as
the non-target Lepidopteran species for this study because it is
a common butterfly species that feeds on several species of
milkweed, Asclepias. Asclepias syriaca (Asclepiadaceae) commonly
grows in road ditches, grassy areas between fields, and within
corn fields, so it is likely to have Bt corn pollen deposited
upon it.

The first step of this study was to determine the amount of corn
pollen deposited on A. syriaca leaves within and adjacent to a Bt
corn field at 0 m, 1m, and 3m. The highest levels of pollen
deposition was found on plants within the corn field, and lowest
levels found at three meters from the edge of the corn field.
Leaf samples taken from within and at the edge of the corn field
were used to assess mortality of first instar monarch, D.
plexippus exposed Bt and non-Bt corn pollen. Within 48 hours,
there was 19% mortality in the Bt corn pollen treatment compared
to 0% on non-Bt corn pollen exposed plants and 3% in the no
pollen controls.

Date: 3/29/99 - Time: 8:00 - Section: C - Type: Poster - Number:
Order: Lepidoptera - Family: Danaidae - Species: Danaus plexippus
Order: Asteridae - Family: Asclepiadaceae - Species: Asclepias



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