The threshold level (5 % plants damaged) to trigger lepidopteran pest control applications was never reached for the MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM maize hybrids in any study. This was expected given the intrinsic lepidopteran and coleopteran IR traits in these two hybrids conferred by the expression of Bt-derived proteins in the plant. As expected, no differences were detected between MON-ØØ6Ø3-6 and the conventional isohybrid maize for insect damage since neither plant material contains IR traits; both were affected equally by lepidopteran or coleopteran insect pests and both received chemical insect-control applications in these trials. Consequently, the threshold level (5 % plants damaged) to apply an insect-control treatment was reached once or twice during the growing season for MON-ØØ6Ø3-6 and the conventional isohybrid controls. These observations are consistent with those by Finger et al. (2011), Areal et al. (2013), and Blanco et al. (2014), thus confirming that GM IR and HT maize hybrids could be utilized as a beneficial alternative tool in IPM programs in Mexico. The reduction in use of additional insecticide applications to control lepidopteran pests such as fall armyworm (Spodoptera spp.) would help reduce the amount of insecticide active ingredients used per year in Mexico and would result in production cost savings for growers. In addition, use of GM IR hybrids may provide benefits associated with the reduction of pesticide loads in the environment.