Evaluation of maize germplasm from Saint Croix for resistance to leaf feeding by fall armyworm

Authors: Abel, Craig; Coates, Brad; Scott, Marvin

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2018
Publication Date: 3/21/2019
Citation: Abel, C.A., Coates, B.S., Scott, M.P. 2019. Evaluation of maize germplasm from Saint Croix for resistance to leaf feeding by fall armyworm. Southwestern Entomologist. 44(1):99-103. https://doi.org/10.3958/059.044.0111.
DOI: https://doi.org/10.3958/059.044.0111

Interpretive Summary: The fall armyworm is a pest of maize, damaging developing leaves and ear tissue which reduces the crop's yield potential. Economically viable control of this pest is challenging and years of insecticide use has selected for resistance to several classes of insecticide and Bt-maize grown in Brazil, Puerto Rico and the southeastern U.S. The discovery and use of native sources of maize resistance to this pest is needed. For this study, maize collected from Saint Croix, U.S. Virgin Islands, was tested for resistance to leaf feeding fall armyworm. Thirteen maize entries were grown in the field and each plant was infested with 75 fall armyworm larvae. Damage to the maize leaves was recorded at 7 day and 14 day. There were statistically significant differences for the entries tested. Four populations of maize collected from Saint Croix had less leaf damage and were considered moderately resistant to fall armyworm. Within these maize populations, individual plants exhibited variability in their response to fall armyworm feeding, indicating that selection under fall armyworm feeding pressure could result in the development of maize germplasm with high levels of resistance.

Technical Abstract: Maize is a preferred host of fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera:Noctuidae), with larvae primarily feeding on developing leaves and ear tissue, reducing yield potential. The fall armyworm (FAW) is resistant to several classes of insecticide, Cry1Ab Bt-maize in Brazil, and Cry1F Bt-maize in Brazil, Puerto Rico and the southeastern U.S. Native sources of plant resistance to this pest are available for public use, but there remains a need to discover and develop new sources of resistance to this pest. The objective for this study was to test maize germplasm collected from Saint Croix, U.S. Virgin Islands, for resistance to leaf feeding by the FAW. Plants were grown in the field and infested at a high level, i.e. 75 larvae per plant. FAW leaf feeding damage ratings were given at 7 day and 14 day and differed significantly for the 13 maize entries tested. FAW ratings at 14 days for entries Saint Croix Group 1 (5.8 ± 0.5), Saint Croix Group 3 (5.6 ± 0.5), Saint Croix 2 (5.6 ± 0.5), and Saint Croix 7 (6.0 ± 0.5) were not significantly different from one another and were moderately resistant. Individual plants within these populations were variable for leaf feeding resistance, receiving ratings between 4 and 7. It should be possible to select for higher levels of FAW leaf feeding resistance within these populations.