MON863 X MON810 (OECD identifier: MON-ØØ863-5 x MON-ØØ81Ø-6) maize is an F1 hybrid resulting from the hybridization of two insect-resistant maize lines: MON863 (OECD identifier: MON-ØØ863-5) which is resistant to coleopterans, such as the Corn Rootworm, and MON810 (OECD identifier: MON-ØØ81Ø-6), which is resistant to lepidopterans, such as the European Corn Borer. This stacked maize hybrid is a product of traditional plant breeding, and therefore is not automatically subject to regulation in all jurisdictions as are transgenic plants resulting from recombinant DNA technologies. Certain jurisdictions may request notification in advance of the release of a stacked hybrid, or may request information to conduct an environmental and food safety assessment.  Examples of jurisdictions that require either notification or information about stacked hybrids prior to their release into the environment, and for use in human food and livestock feed are Canada and Japan.<br> <br>The stacked hybrid MON863 X MON810 expresses two novel insecticidal proteins: Cry3Bb1, a delta-endotoxin which confers resistance to coleopterans, and the delta-endotoxin Cry1Ab which confers resistance to the lepidopterans.  Cry3Bb1 is produced by the <i>cry</i>3Bb1 gene from MON863, and Cry1Ab, by the <i>cry</i>1Ab gene from MON810.  The novel traits of each parent line have been combined, through traditional plant breeding, to produce this new hybrid.  For a full description of each parent line please refer to the individual product descriptions in the crop database for <a href="dbase.php?action=ShowProd&data=MON863&frmat=LONG"><b>MON863</b></a> and <a href="dbase.php?action=ShowProd&data=MON810&frmat=LONG"><b>MON810</b></a>.<br>The inserted genes and their gene products have a history of safe use, and have undergone review and approval by several regulatory agencies.  No interactions among the gene products or negative synergistic effects are expected in the stacked hybrid.  Neither Cry1Ab, nor Cry3Bb1 are enzymes and therefore have no effect on plant metabolism.  These Cry proteins are therefore not expected to interact within, nor affect the metabolism of the stacked hybrid.  <br>Studies were conducted to compare the resistance to coleopterans and lepidopterans in the stacked hybrid and each parental line.  There were no statistically significant differences in the levels of resistance to the target insects between the stacked hybrid and either of the parental lines.  Non-target insects that were found to be unaffected by the insecticidal proteins in MON863 and MON810 were also unaffected by the combination of the proteins in the stacked hybrid.  Thus, the hybridization of MON863 and MON810 did not affect the expression levels of the <i>cry</i>1Ab and <i>cry</i>3Bb genes, and there was no observed synergistic effect of simultaneous exposure to both proteins.  <br>Heterosis is expected in F1 hybrids.  An example of heterosis is a substantial increase in yield in the F1 hybrid compared to the parental lines.  The stacked hybrid MON863 X MON810 is therefore expected to display heterosis, as would any conventional F1 hybrid.  Heterosis in this hybrid is not expected to be caused by the introduced genes, since the gene products are not expected to affect plant metabolism, or interact synergistically.