Revista Brasileira de Milho e Sorgo (Apr 2002)
RESISTANCE OF BT TRANSGENIC MAIZE (Zea mays L.) TO FALL ARMYWORM, Spodoptera frugiperda (SMITH) (LEPIDOPTERA: NOCTUIDAE)
Abstract
In Brazil, the use of transgenic maize (Bt) might reduce the yield loss caused by insect pest, equivalent to 500 million dollars. The objective was to evaluate the Bt maize hybrids available in the American market to fall armyworm (FAW), Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), resistance. Nine maize hybrids, expressing the Cry 1F, Cry 1A(b), Cry 1 A(c) and Cry 9C Bt toxins and one native resistance hybrid (MP 704 X 707) were compared, in the field, with susceptible pairs in a completed randomized block design with split plot and 4 replications. The artificial infestation was implemented 33 days after planting and the evaluations were based on the number of surviving larvae at 10 and 15 days after infestation, larval weight and leaf damage score. All studied variables indicated significant differences (P≤0,05) among the hybrids. Also, significant differences were observed between some Bt maize and the controls, except for the maize hybrid expressing Cry 9C toxin. The hybrid 2722 IMI, expressing the toxin Cry 1F, was the most resistant cultivar (immune) and the ones expressing the Cry 1A(b) toxin and the native resistance were intermediate. In general, the transgenic maize hybrids yielded 32% more than the susceptible non-Bt.
