Study sites in maize production areas were located within five ecoregions: (i) 9.5.1.2 = Tamaulipas coastal plain with xerophile vegetation or without apparent vegetation; (ii) 10.2.2.8 = floodplains of the Yaqui, Mayo, and Fuerte Rivers with xerophile shrubs and mesquite; (iii) 10.2.3.3 = floodplains and rolling hills of the Vizcaíno and Magdalena Deserts with xerophile sarco-sarcocrassicaule and halophytic vegetation; (iv) 10.2.4.1 = central plains of the Chihuahuan Desert with xerophile-halophytic microphyllus vegetation; and (v) 14.3.1.2 = Sinaloa coastal plain with low thorny forest (INEGI-CONABIO-INE 2008) (Supplementary Table 1, Fig. 1). Thirty-six studies, 19 Experimental Phase (smaller trials) and 17 Pilot Phase (larger trials), were conducted across maize production regions of the Mexican states of Sinaloa, Sonora, Chihuahua, Coahuila and Durango (Comarca Lagunera), Tamaulipas, and Baja California Sur during the 2009–2013 crop seasons (Supplementary Table 2).Fig. 1Map of level IV ecological regions (ecoregions) of Mexico where GM field studies were conducted during 2009–2013