GENETIC IMPROVEMENT OF MAIZE AND PEARL MILLET FOR RESISTANCE TO INSECTS AND AFLATOXIN
Location: Crop Genetics and Breeding Research
Title: Foliar resistance to fall armyworm in corn germplasm lines that confer resistance to root- and ear-feeding insects
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2011
Publication Date: December 15, 2011
Citation: Ni, X., Chen, Y., Hibbard, B.E., Wilson, J.P., Williams, W.P., Buntin, G., Ruberson, J.R., Li, X. 2011. Foliar resistance to fall armyworm in corn germplasm lines that confer resistance to root- and ear-feeding insects. Florida Entomologist. 94(4):971-981.
Interpretive Summary: A holistic approach to developing new corn germplasm that shows reduced multiple insect damage in different plant tissues at various growth stages has been examined in a series of field studies recently. In the present study, we examined whether corn germplasm lines resistant to ear- and root-feeding insects would confer resistance to leaf feeding insects. The study showed that a western corn rootworm-resistant, and one of the two corn earworm-resistant corn germplasm lines showed moderate resistance to leaf feeding by the fall armyworm. In addition, the rootworm-resistant corn germplasm also showed attraction to predators of insect pests at whorl stage on the corn plants. This experiment demonstrates two interesting leads for our further examination of the complex of corn germplasm-insect pest-natural enemy interactions; The first one is that the development of germplasm that confers resistance to multiple leaf-, root-, ear-feeding insects at various growth stages is plausible; and the other one is that the attractions of corn plants to predators of insect pests (such as, lady bugs) should be included in the field selection of corn germplasm lines for the least insect pest injury.
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 foliage resistance to fall armyworm [Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)] 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 ‘EPM6’], and four germplasm entries with different levels of fall armyworm resistance (‘Mp708’, ‘Ab24E’, ‘FAW7061’ and ‘FAW7111’) were also included for comparison in the study. All plants were manually infested with 15-20 neonate fall armyworms per plant, and insect injury was rated 7 and 14 d after the infestation using a rating scale of 1-9 ranging from the lowest to the highest amount of damage. Among the eight entries, FAW7061 and Mp708 were the most resistant, and Ab24E, EPM6, and B37*H84 were the most susceptible to fall armyworm feeding. The western corn rootworm-resistant CRW3(S1)C6 and corn earworm-resistant SIM6 showed moderate resistance to fall armyworm feeding, which was at the same level as FAW7111. Surveys for the diversity and abundance of natural enemies in each experimental plot were also conducted 7 d after S. frugiperda infestation. CRW3(S1)C6 and Ab24E had the highest and lowest natural enemy abundance, respectively. However, there was no direct correlation between S. frugiperda injury ratings and natural enemy 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 natural enemies, and reduce pest populations and crop damage is also discussed.