FOLIAR RESISTANCE TO FALL ARMYWORM IN CORN GERMPLASM LINES THAT CONFER RESISTANCE TO ROOT- AND EAR-FEEDING INSECTS

A holistic approach to developing new corn germplasm that confers multiple insect resistance in various plant tissues at different growth stages was examined. Eight corn germplasm lines were examined for their foliar resistance to fall armyworm [Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)1 and natural enemy attraction at V6-V8 (or 6-8 leaf) stages in 2008 and 2009. Four corn germplasm lines with known levels of resistance to root- and ear-feeding insects ['CRW3(S1)C6', 'B37*H84', 'SIM6' and 'EPM61], and four germplasm entries with different levels of S. frugiperda resistance ('Mp708', 'Ab24E', 'FAW7061' and 'FAW7111') were evaluated in the study. All plants were manually infested with 15-20 neonate S. frugiperda larvae per plant, and injury was rated 7 and 14 d after infestation. Based on cluster analysis of S. frugiperda injury rating and predator survey data, 'Mp708' and 'FAW7061' were the most resistant, whereas 'Ab24E' and 'EPM6' were the most susceptible to fall armyworm feeding. The western corn rootworm-resistant 'CRW3(S1)C6' showed resistance to S. frugiperda feeding. Surveys for the diversity and abundance of predators of S. frugiperda in each experimental plot were also conducted 7 d after infestation. 'CRW3(S1)C6' and 'Ab24E' had the highest and lowest predator abundance, respectively. However, there was no direct correlation between S. frugiperda injury ratings and predator abundance. The current study demonstrated the feasibility of developing foliage-, root-, and ear-feeding insect-resistant germplasm covering multiple corn growth stages. In addition, the possibility of utilizing plant volatiles to attract predators, and reduce pest populations and crop damage is discussed.