<p style="text-align: justify;"><b>Field Testing</b><br>
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Filed trials were performed at a total of 32 locations in the United Stated during 2002 and 2003 with a number of different hybrids all containing the MIR604 event. As controls, non-transgenic segregants with the same genetic background were used at each site, as well as a range of conventional maize hybrids. For the majority of the traits assessed, there were no statistically significant differences and for the few traits where there was a significant difference, these differences were not consistent between sites over the two years of trials. The range of values for the agronomic characters, even when statistically significantly different from the controls, was within the range of values expected for maize hybrids and was thus not considered biologically significant.<br>
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MIR604 hybrids and their non-segregant controls were exposed to various corn pathogens and susceptibility was measured revealing no significant differences in disease susceptibility. Insect efficacy trials were conducted in field plots that were infested with naturally occurring populations of corn rootworm, with populations enhanced by use of trap crops the preceding season, or artificially infested with rootworm eggs.<br>
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The outcome of these studies indicated that, except for reduced damage to roots caused by corn rootworm, the agronomic performance of MIR604-derived hybrids was similar, and for most traits, equivalent to their nontransformed near isogenic counterparts. In contrast to the similarity in most agronomic parameters, the yield performance of MIR604-derived hybrids in the presence of corn rootworm pressure was significantly increased relative to corn hybrids lacking this trait.<br>
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<b>Outcrossing</b><br>
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Since pollen production and viability were unchanged by the genetic modification resulting in MIR604, pollen dispersal by wind and outcrossing frequency should be no different than for other maize varieties. Gene exchange between MIR604 maize and other cultivated maize varieties will be similar to that which occurs naturally between cultivated maize varieties at the present time. In the United States, where there are no plant species closely-related to maize in the wild, the risk of gene flow to other species appears remote. Feral species in the United States related to corn cannot be pollinated due to differences in chromosome number, phenology (periodicity or timing of events within an organism’s life cycle as related to climate, <i>e.g</i>., flowering time) and habitat.<br>
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Maize (<i>Zea mays</i> ssp. <i>mays</i>) freely hybridizes with annual teosinte (<i>Zea mays</i> ssp. <i>mexicana</i>) when in close proximity. These wild maize relatives are native to Central America and are not present in the United States, except for special plantings. <i>Tripsacum</i>, another genus related to <i>Zea</i>, contains sixteen species, of which twelve are native to Mexico and Guatemala. Three species of <i>Tripsacum</i> have been reported in the continental United States: <i>T. dactyloides</i>, <i>T. floridanum</i> and <i>T. lanceolatum</i>. Of these, <i>T. dactyloides</i>, Eastern Gama Grass, is the only species of widespread occurrence and of any agricultural importance. It is commonly grown as a forage grass and has been the subject of some agronomic improvement (i.e., selection and classical breeding). <i>T. floridanum</i> is known from southern Florida and <i>T. lanceolatum</i> is present in the Mule Mountains of Arizona and possibly southern New Mexico. Even though some <i>Tripsacum</i> species occur in areas where maize is cultivated, gene introgression from maize under natural conditions is highly unlikely, if not impossible. Hybrids of <i>Tripsacum</i> species with <i>Zea mays</i> are difficult to obtain outside of the controlled conditions of laboratory and greenhouse. Seed obtained from such crosses are often sterile or progeny have greatly reduced fertility.<br>
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<b>Weediness Potential</b><br>
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The introduced traits in MIR604 are not expected to cause MIR604 maize to become a weed. No competitive advantage was conferred to MIR604 that would render maize weedy or invasive of natural habitats, since none of the reproductive or growth characteristics were modified and no significant differences in these traits were noted in the field trials. Cultivated maize is unlikely to establish in non-cropped habitats and there have been no reports of maize surviving as a weed. <i>Zea mays</i> is not invasive and is a weak competitor with very limited seed dispersal. Volunteers can occur in fields, the year following cultivation, when maize is grown in rotation with other crops. Although maize volunteers are a minor weed problem, these can cause harvesting problems.<br>
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<b>Secondary and Non-Target Adverse Effects</b><br>
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Three sources of data were used to evaluate the environmental safety of the modified Cry3A (mCry3A) <i>Bacillus thuringiensis</i>-related insect control protein expressed in MIR604. First, experimental data was used to establish how the spectrum of activity of mCry3A differs from native Cry3A. These data suggest that the toxicity of mCry3A differs from native Cry3A only in the intended increase in activity against certain pest species in the genus <i>Diabrotica</i> (Coleoptera: Chrysomelidae). Secondly, data on the spectrum of activity of native Cry3A was reviewed to provide evidence about the likely spectrum of activity (<i>i.e</i>., the hazard) of mCry3A. As the previous studies showed that mCry3A and native Cry3A differ only in the intended increase of activity of mCry3A to certain <i>Diabrotica</i> species, the toxicity of native Cry3A is a good predictor of the hazard of mCry3A to non-target organisms (NTOs).<br>
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From the native Cry3A data it was predicted that mCry3A is unlikely to be hazardous except to certain species in 3 families of Coleoptera: the Chrysomelidae (leaf beetles, flea beetles and rootworms), the Curculionidae (weevils and snout beetles) and the Tenebrionidae (darkling beetles). The third source of data which was then used to test this hypothesis, was single-species laboratory studies exposing representative NTOs to concentrations of mCry3A in excess of the expected environmental concentrations of mCry3A resulting from the proposed cultivation of MIR604. Test species were chosen to represent taxa that might be exposed to mCry3A from tissues of MIR604, or taxa related to the western and northern corn rootworm. In addition, test species were selected to include functional groups found in agricultural fields and other habitats into which mCry3A might spread: birds, freshwater fish, predators and parasitoids of crop pests, soil invertebrates and pollinators.<br>
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<b>Impact on Biodiversity</b><br>
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Analysis concluded that MIR604 maize exhibited no traits that would cause increased weediness and that cultivation would not lead to increased weediness of other maize or sexually compatible species, nor would cultivation be likely to harm non-target organisms. Based on this conclusion, there was no apparent potential for a significant impact on biodiversity.<br>
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