Study: Biotech Corn Kills Monarch

[Jeffrey A. Caldwell]

Paul, thanks for posting this -- these do sound like logical studies to make in this
case.

Paul Cherubini wrote:

> Clay Taylor wrote:
> >
> > Paul - how much of that $100,000 spent by "the industry" actually
> > went into the field studies?  In light of the potential gains "the industry"
> > stands to make from such a study, only spending $100K seems to be a pretty
> > small investment.  How thorough were their methods in investigating the
> > differences you point out between laboratory Vs. field testing of Monarchs
> > and Bt corn?
>
> Below are the results that were gained from the $100,000+ worth of
> biotech industry funded studies conducted last summer.
> These results were copied and pasted from the following website:
> http://www.fooddialogue.com/monarch/newresearch.html
>
> MILKWEED DISTRIBUTION
>
> Milkweed density is highest in roadsides.
> Dr. Doug Buhler, research agronomist at the USDA-ARS, and Dr. Robert
> Hartzler, associate professor and Extension weed scientist in the Agronomy
> Department at Iowa State University found that Iowa roadsides had 48
> common milkweed patches per hectare, while corn and soybean
> fields had only seven patches per hectare. They concluded that common
> milkweed in roadsides may be especially important to monarchs due to
> the frequent occurrence of milkweed in roadsides and
> the uniform distribution of roadsides across the landscape. In another
> survey, Hartzler and Buhler also found that the majority of milkweeds
> along roadsides were distant from field edges. Milkweed density was
> approximately twice as high adjacent to the road (186 patches per hectare)
> and in the center of the roadside (165 patches per hectare) as it was next to
> the field edge (89 patches per hectare).
>
> About 50 percent of corn and soybean fields were reported to have some
> milkweed present, although usually appearing in small patches. Because
> the plants can be poisonous to livestock and compete with crops for sunlight,
> nutrients and water, farmers try to eliminate milkweeds from
> fields with the use of crop rotations, plowing, disking and herbicides.
>
> FEW MILKWEEDS WERE FOUND VERY CLOSE TO CORNFIELDS
>
> Researchers from several universities and industry surveyed the occurrence
> of milkweeds along roadsides in Iowa, Nebraska, Illinois, Indiana and
> Maryland. Dr. David Isenhour, entomologist for Monsanto Company,
> reported that survey results showed from 15 to 41 percent of roadside
> milkweeds were adjacent to cornfields. In addition, the Iowa surveyors
> found only 19 percent of roadside milkweeds occurred within 1 to 3
> meters of the field edge. Considering both proximity
> and location, less than 8 percent of roadside milkweeds were found
> to be exposed to meaningful amounts of pollen.
>
> MONARCHS PREFER MILKWEED AWAY FROM CORN
>
> Tests by Dr. John Losey, Cornell University assistant professor of
> entomology, show that monarchs avoid laying eggs on milkweed
> surrounded by corn. Losey placed potted milkweeds by themselves
> or surrounded by corn plants and found that monarch adults preferred
> to lay eggs on milkweeds in the open. If this is typical behavior for
> monarchs in natural environments, then larvae would be less common
> on milkweeds very close to cornfields.
>
> When given a choice between feeding on milkweed leaves with no
> pollen or high levels of Bt pollen, the majority of monarch larvae
> chose no pollen, reported researchers from
> USDA-Agricultural Research Service (ARS) and Iowa State University.
>
> MONARCH MIGRATION AND BT POLLEN SHED MAY NOT
> COINCIDE
>
> Scientists acknowledge that exposure to Bt pollen varies from region
> to region. Dr. Galen Dively, pest management specialist and professor
> of entomology at the University of Maryland, monitored Maryland
> cornfields and monarch development in 1999. He found that corn plants
> had completed pollen shed before monarch caterpillars were first
> observed feeding on milkweed.
>
> Dively saw adult butterflies during the short period of pollen shed,
> but since they feed on plant nectar, not pollen, they are not affected
> by Bt corn. Similarly, Dr. John Foster, professor of
> entomology at the University of Nebraska, observed that by late
> July, corn pollination in Nebraska was 95 percent complete before
> monarch eggs were observed on milkweeds in the vicinity of corn.
> He added that rain, dew and irrigation all tend to wash off the pollen.
>
> Pennsylvania State University researchers, using computer models
> and historical climatic information, found that a more mixed picture
> should be expected across the entire region of monarch migration.
> Dr. Dennis Calvin, associate professor of entomology at Penn State,
> reported very little overlap of pollen shed in the early larval stages in
> Pennsylvania and greater overlap in the late larval stages and as adults.
> Calvin and his colleagues will continue to examine when and
> to what extent pollen shed may overlap monarch development, but
> he expects that overlap will vary greatly.
>
> POLLEN MOVEMENT
>
> Corn pollen doesn¹t travel far. Due to its large particle size (90 to
> 100 microns), most corn pollen deposits stay within the
> cornfield, said Dr. Stuart Weiss of Stanford University. He noted
> that at wind speeds of 5 meters per second (11 miles per hour) or less,
> most pollen grains fall close to the field edge.
>
> The volume of pollen falls off sharply just a few feet away from
> cornfields, reported Dr. Mark Sears, chair of the University of Guelph¹s
> Department of Environmental Biology. Using pollen traps set on poles
> about the height of milkweed, Sears and his colleagues determined that 90
> percent of pollen grains traveled less than 5 meters (16.5 feet) from the
> field edge. Because pollen density dropped off rapidly a short distance
> from the field edge, ³The risk to monarch larvae is very minimal,² he said.
>
> Likewise, Dively also set out to measure how much pollen lands on
> milkweed leaves in and around Maryland cornfields. He, too, found the
> pollen drops off rapidly beyond the field edge. He reported that pollen levels
> on milkweed within the field at the end of full pollination run between
> 200 and 250 pollen grains per square centimeter. Going outside the field,
> within the first 3 meters (10 feet), the pollen level drops 90 percent ­ to
> 20 to 30 grains per square centimeter.
>
> Milkweed leaves capture only 30 percent of available pollen, reported
> Dr. John Pleasants, professor in the Department of Zoology and Genetics
> at Iowa State University. Wind speed and direction also affect pollen
> deposition, as illustrated in Figure 6, which shows an Iowa field that
> experienced prevailing winds from the south. Like his colleagues,
> Pleasants found the pollen levels decrease rapidly going away from
> the field edge and that uncommonly ³high² pollen
> densities (150 grains per square centimeter) were not found on milkweeds
> just 2 meters (6.6 feet) from a Bt cornfield.
>
> NECESSARY POLLEN LEVELS TO EFFECT MONARCH LARVAE
>
> Typical pollen levels had little to no effect
> Different types of Bt corn pollen seem to have varying degrees of toxicity,
> Iowa State University and USDA researchers reported. Feeding trials with
> monarch larvae and two types of Bt pollen ­
> YieldGard (MON810) and StarLink (CBH351) ­ indicated that leaves with
> high pollen densities of 150 grains per square centimeter had no effect on
> larval weight or survivorship. Pleasants and Dr.
> Richard Hellmich showed that pollen densities dropped to harmless levels
> beyond 1 meter (3 feet) from the edge of the field. Thus, the potential effects
> on monarch caterpillars that may be present very near to pollinating corn would
> be limited. However, KnockOut and NatureGard varieties (Event 176),
> which represents just 2.5 percent of Bt corn, was more toxic, with higher
> mortality rates and lower weight gains.
>
> University of Nebraska professor of entomology Dr. Blair Siegfried performed
> a feeding study in which young caterpillars were administered various
> concentrations of purified Bt proteins in an artificial diet. The caterpillars were
> more sensitive to some proteins and less sensitive to others. At
> high concentrations of the most toxic Bt protein, the larvae all died.
> At moderate concentrations, inhibited growth was observed.
>
> These findings are no surprise since the original Nature article already
> demonstrated toxicity in lab conditions when caterpillars consumed large
> amounts of the most toxic Bt protein. Again, the
> question at hand is how toxicity and exposure work together to determine
> risk in a real-world situation.