Genetically modified corn on Spodoptera frugiperda and Helicoverpa zea control in Sinaloa, Mexico

Corn hybrids Agrisure Viptera 3111 and Agrisure 3000 GT with the Cry1Ab, Vip3Aa20 and mCry3A proteins of Bacillus thuringiensis (Bt) provided by Syngenta Agro were tested for fall armyworm and corn earworm control at El Dorado and Navolato, Sinaloa using a Proc ANOVA with 8 treatments and 3 replicates. Davis scale (1= no damage to 9= severe damage) was used to evaluate armyworm and length (cm) of damaged corncobs for corn earworm evaluation. Spodoptera frugiperda. At El Dorado, Agrisure Viptera 3111 and Agrisure Viptera 3111 with Crop Protection (CP), had an average of 1 on Davis scale and are considered to be highly resistant to the pest whereas the isoline presented damages of 3.53 and 2.89 with and without chemical control respectively; on the other hand, no damaged was found on the Bt corn and the isolines had 64.4 and 56.7 % of damaged plants with and without insecticide treatment respectively. A high armyworm population was found at Navolato; Agrisure 3000 GT and Agrisure 3000 GT + CP showed damage of 1.34 and 1.13 respectively on Davis scale and 13.3 and 7.8 % damaged plants that are also resistant to the pest if compared with their isolines that had 3.87 and 4.97 damage on Davis scale and 66.7 and 76 % affected plants for the same hybrids respectively. Helicoverpa zea. Agrisure Viptera 3111 and Agrisure Viptera 3111 + CP at El Dorado had 40 and 46.7 % damaged cobs with small galleries of 0.33 and 0.45 cm long respectively, whereas the isolines had 93.3 damaged cobs with galleries averaging 2.1 and 2.2 cm long without and with insecticide treatment respectively finding galleries up to 7 cm long. At Navolato, Agrisure 3000 GT with and without chemical control had low infestation levels of corn earworm with average galleries of 0.27 cm and 0.45 cm long with a 36.7 and 56.75 % of corncobs with damage; on the other hand, the isolines had galleries of 4.37cm with insecticide treatment and 5.5 cm without treatment and up to 12 cm long in the last one with a high 96.7 and 100 % cobs with damage for the same materials respectively. Bt Agrisure Viptera 3111 and Agrisure 3000 GT probe to be resistant to both pests; damage found is due that the insects must feed to be affected by the bacteria endotoxin.