Field Testing
The genetic modification resulting in transgenic maize event MIR162 was not intended to affect a specific agronomic or phenotypic characteristic except to confer resistance to certain lepidopteran insect pests. Grain yield and agronomic performance of MIR162 maize (field corn) hybrids were evaluated in a series of trials across a total of 16 locations over two years. In addition to inspections for disease and insect damage, qualitative and quantitative comparisons for a number of morphological and agronomic traits were made between MIR162 hybrids and non-transgenic control hybrids. The traits chosen for agronomic comparison were those typically observed by professional maize breeders and agronomists, covering a broad range of characteristics that encompass the entire life cycle of the maize plant. The agronomic performance and phenotypic data generated for MIR162-derived hybrids and their corresponding near isogenic non-transgenic control hybrids suggest that the genetic modification resulting in event MIR162 did not have any unintended effect on plant growth habit and general morphology, lifespan, vegetative vigour, flowering and pollination, grain yield, or disease susceptibility.
Potential for Increased Weediness or Invasiveness
Maize has lost the ability to survive in the wild due to its long process of domestication, and needs human intervention to disseminate its seed. Although maize from the previous crop year can over-winter and germinate the following year, it cannot persist as a weed. In contrast to weedy plants, maize has a pistillate inflorescence (ear) with a cob enclosed with husks. Consequently seed dispersal of individual kernels does not occur naturally. The phenotypic comparison of event MIR162-derived hybrids and non-transgenic hybrids did not reveal any consistent biologically meaningful differences in vegetative vigour, time to maturity and seed production. These data support the conclusion that event MIR162-derived hybrids are unlikely to form feral persistent populations, or to be more invasive or weedy than conventional maize hybrids.
Altered Plant Pest Potential
The intended effects of expression of the Vip3Aa20 and PMI proteins are unrelated to plant pest potential, and maize itself is not a plant pest in the United States or Canada. In addition, agronomic characteristics of MIR162-derived hybrids were not consistently significantly different than near-isogenic non-transgenic hybrids and indicated that growth habit of maize had not been unintentionally altered as a result of the genetic modification. Field observations did not indicate modifications to disease and pest susceptibilities.
Potential Impacts on Non-target Organisms
An assessment of risk for nontarget organisms and endangered species that might be exposed to the Vip3Aa20 protein in MIR162 maize was performed. Extensive nontarget organism studies were performed with 12 different species representative of wild birds, wild mammals, pollinators, above ground arthropods, soil-swelling arthropods, aquatic organisms and farmed fish. No adverse effects were observed in any study that exposed representative nontarget organisms to Vip3Aa proteins. The concentration of Vip3Aa tested in the studies was sufficient to achieve margins of exposure of ? 1 for all but one species based on realistic expected environmental concentrations.
There is a weight of evidence that at concentrations in MIR162 maize, the toxicity of Vip3Aa20 will be limited to certain species of Lepidoptera. Its receptor-mediated mechanism of action and absence of activity in bioassays with multiple species outside of the order Lepidoptera support this conclusion. The comparison of hazard and exposure data corroborate the hypothesis that Vip3Aa20 is not harmful to nontarget organisms at concentrations likely to result from cultivation of MIR162, and provide a weight of evidence that Vip3Aa20 in MIR162 maize will have no harmful effects on populations of potentially exposed nontarget organisms.
The only endangered lepidopteran with potential for exposure to insecticidal proteins in maize is the Karner blue butterfly (Lycaeides melissa samuelis), which is listed as extirpated (a wildlife species that no longer exists in the wild in Canada, but exists elsewhere in the wild) in Schedule 1 of the Species at Risk Act. Even should Karner blue butterfly populations be recovered in the wild in Canada, exposure to maize pollen from MIR162 would be minimal because of the large separation between populations of its food plant (wild lupine; Lupinus perennis) and cultivated maize, and because maize anthesis usually occurs after the Karner blue has finished feeding.
Potential Impact on Biodiversity
Event MIR162 has no novel phenotypic characteristics which would extend its use beyond the current geographic range of maize production in the United States and Canada. Since maize does not out cross to wild relatives in the United States or Canada, there will be no transfer of novel traits to unmanaged environments. MIR162 maize provides excellent protection against feeding damage caused by A. ipsilon, H. zea, S. albicosta, and S. frugiperda. For this reason, its introduction will impact current maize insect control practices in a very positive way, having the potential to displace conventional insecticide applications for control of these pests. Therefore, the potential impact on biodiversity of MIR162 is equivalent to its unmodified counterparts.
