<p style="text-align: justify;"><b>Field Testing</b></p>

<p style="text-align: justify;">DBT418 maize has been field tested since 1993 in the major maize growing regions of the United States as well as in Argentina, Canada, France, and Italy. A number of traits (<i>e.g.</i>, yield, grain moisture, final stand count, seedling vigor, plant height) were evaluated to determine how the genetic modifications altered agronomic performance. Very small differences were detected between the non-transformed control and DBT418 maize for grain moisture, seedling vigor, silk growing degree units, stay-green (a senescence rating) and intactness (primarily a measure of intactness of tassels and leaves above the ear). These differences were within the normal range of variation for maize plants and would not be expected to increase weediness. The transgenic line DBT418 provided significant protection from feeding damage from the European corn borer (<i>Ostrinia nubilalis</i>) and Southwestern corn borer (<i>Diatraea grandiosella</i>). Growth inhibition of corn earworm (<i>Heliothis zea</i>) was also observed as a result of silk and ear feeding on DBT418 plants. No significant differences were observed in resistance to a number of other significant insect pests or diseases compared to nontransgenic controls. Field data reports and data on agronomic traits confirmed that DBT418 exhibited the desired agronomic characteristics and did not pose a plant pest risk.</p>

<p style="text-align: justify;"><b>Outcrossing</b></p>

<p style="text-align: justify;">Since pollen production and viability were unchanged by the genetic modification resulting in DBT418, pollen dispersal by wind and outcrossing frequency should be no different than for other maize varieties. Gene exchange between DBT418 and other cultivated maize varieties will be similar to that which occurs naturally between cultivated maize varieties at the present time. In North America, where there are few wild plant species closely-related to maize, the risk of gene flow to other species is remote. Furthermore, none of the sexually compatible relatives of maize in the U.S. are considered to be weeds in the U.S., therefore it is unlikely that introgression of the <i>bar</i> gene would provide a selective advantage to these populations as they would not be routinely subject to herbicide treatments.</p>

<p style="text-align: justify;"><b>Weediness Potential</b></p>

<p style="text-align: justify;">No competitive advantage was conferred to DBT418, other than that conferred by resistance to European corn borer and herbicide tolerance to glufosinate. Maize is not a weed, and resistance to European corn borer or herbicide tolerance will not render maize weedy or invasive of natural habitats since none of the reproductive or growth characteristics were modified.</p>

<p style="text-align: justify;">Cultivated maize is unlikely to establish in non-cropped habitats and there have been no reports of maize surviving as a weed. In agriculture, maize volunteers are not uncommon but are easily controlled by mechanical means or by using other non-glufonsinate containing herbicides as appropriate. <i>Zea mays</i> is not invasive and is a weak competitor with very limited seed dispersal.</p>

<p style="text-align: justify;"><b>Secondary and Non-Target Adverse Effects</b></p>

<p style="text-align: justify;">The history of use and literature suggest that the bacterial Bt protein is not toxic to humans, other vertebrates, and beneficial insects. This protein is active only against specific lepidopteran insects and no lepidopteran species are listed as threatened or endangered species in North America.</p>

<p style="text-align: justify;">Other invertebrates and all vertebrate organisms, including non- target birds, mammals and humans would not be effected by Cry1Ac as these organisms do not have the receptor protein found in the midgut of target insects. Experimental studies demonstrated that soil-dwelling organims (collembola, earthworms) and birds (quail) were not adversely affected by exposure to pollen from DBT418 corn, or as a result of exposure to DBT418 leaf material or Cry1Ac on detritus.</p>

<p style="text-align: justify;"><b>Impact on Biodiversity</b></p>

<p style="text-align: justify;">DBT418 had no novel phenotypic characteristics that would extend its use beyond the current geographic range of maize production. Since the risk of outcrossing with wild relatives in North America is remote, it was determined that the risk of transferring genetic traits from DBT418 to species in unmanaged environments was insignificant.</p>

<p style="text-align: justify;"><b>Other Considerations</b></p>

<p style="text-align: justify;">In order to prolong the effectiveness of plant-expressed Bt toxins, and the microbial spray formulations of these same toxins, regulatory authorities in Canada and U.S. have required developers to implement specific Insect Resistant Management (IRM) Programs. These programs are mandatory for all transgenic Bt-expressing plants, including DBT418, and require that growers plant a certain percentage of their acreage to non-transgenic varieties in order to reduce the potential for selecting Bt-resistant insect populations. Details on the specific design and requirements of individual IRM programs are published by the relevant regulatory authority.</p>

<p style="text-align: justify;">DBT418 maize plants are not likely to eliminate the use of chemical insecticides which are traditionally applied to about 25 to 35% of the total maize acreage planted, since the primary target for most of these applications has been the coleopteran, corn rootworm. DBT418 maize may positively impact current agricultural practices used for insect control by 1) offering an alternative method for control of European corn borer (and potentially other Cry1Ac-susceptible pests of maize); 2) reducing the use of insecticides to control European corn borer and the resulting potential adverse effects of such insecticides on beneficial insects, farm worker safety, and ground water contamination; and 3) offering a new tool for managing insects that have become resistant to other insecticides currently used or expressed in maize, including other Bt-based insecticides.</p>

<p style="text-align: justify;">DBT418 maize, along with glufosinate ammonium herbicides, is expected to positively impact current agricultural practices used for weed control by 1) offering growers a broad spectrum, post-emergent weed control system; 2) providing the opportunity to continue to move away from pre-emergent and residually active herbicides; 3) providing a new herbicidal mode of action in maize that allows for improved management of weeds which have developed resistance to herbicides with different modes of action; and 4) decreasing cultivation needs and increasing the amount of no-till acres. Volunteers of DBT418 can be easily controlled by selective mechanical or manual weed removal or by the use of herbicides with active ingredients other than glufosinate ammonium.</p>
