Issue: Plant Pesticides Impact less
on Non-target Organisms
Genetically modified plants that produce
their own plant pesticides include Bt cotton, Bt corn, Bt sweet corn,
and Bt potatoes. These plant pesticides are very selective. For example,
the type of Bt in Bt corn only controls the caterpillars of some moths
and butterflies. The type of Bt in Bt potatoes controls Colorado potato
beetles. In addition, the Bt is inside the plant, so only insects that
feed on the plant or plant parts are exposed to the plant pesticide. An
exception to this is with the pollen from Bt corn which is wind blown.
Some Bt-corn pollen also contains the Bt toxin. It has been shown in the
laboratory to reduce the survival of monarch caterpillars that have been
feed on milkweed plants that were dusted with this pollen. However
field studies indicate negligible impact of corn pollen containing Bt on
monarch butterfly larvae.
But it is important to keep in mind that
these genetically modified crops that produce their own plant pesticides
require fewer pesticide sprays. Most of the commonly used insecticide
used on these crops are referred to as broad spectrum insecticides. They
are generally as toxic to non-target organisms as they are to the target
pest. Plants that produce their own plant pesticides are more selective
in terms of controlling pests without damaging non-target organisms. Their
impact on non-target organisms is further reduced because they require
fewer broad spectrum pesticide sprays.