Evaluation of germplasm lines of maize for resistance to fall armyworm and southwestern corn borer leaf-feeding damage

Authors: Woolfolk, Sandra; Matthews, Gerald - Boo; WILLIAMS, WILLIAM - Retired ARS Employee

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2023
Publication Date: 7/14/2023
Citation: Woolfolk, S.W., Matthews Jr, G.A., Williams, W.P. 2023. Evaluation of germplasm lines of maize for resistance to fall armyworm and southwestern corn borer leaf-feeding damage. Southwestern Entomologist. 48(2):347-352. https://doi.org/10.3958/059.048.0208.
DOI: https://doi.org/10.3958/059.048.0208

Interpretive Summary: Maize (corn) is an economically important crop, and its production in 2020 was 1,162 billion tons. Two important pests of corn are fall armyworm and southwestern corn borer. Fall armyworm larvae attack all above-ground parts of corn plants from the seedling stage to maturity while southwestern corn borer larvae attack plants from inside whorls, on developing ears, and tunnel within the stalks of the plants. The USDA-ARS have developed germplasm lines to control these two pests. There were corn lines that have not been released. Thus this study sought to evaluate a group of germplasm lines that were developed by USDA-ARS, but not released, for leaf feeding damage by fall armyworm and southwestern corn. The corn lines were planted in field experiments and the plants were artificially infested at the whorl stage of growth with newly-hatched larvae of fall armyworm or southwestern corn borer. The damage on leaves was evaluated 14 days after infestation. The leaf feeding rating scores differed significantly among the lines in both 2020 and 2021 for both insect species. The non-released “Mp” lines showed better than moderate resistance to resistant to leaf damage for fall armyworm, and moderate resistance for southwestern corn borer. These lines may be useful in producing breeding crosses with other resistant lines.

Technical Abstract: Maize is an economically important crop, and its production in 2020 was 1,162 billion tons. Two important pests of maize are fall armyworm [Spodoptera frugiperda (J.E. Smith)] and southwestern corn borer (Diatraea grandiosella Dyar). Fall armyworm larvae attack all above-ground parts of maize plants from the seedling stage to maturity while southwestern corn borer larvae feed within plant whorls, on developing ears, and tunnel within the stalks. The objective of this study was to evaluate a group of germplasm lines that were developed by USDA-ARS, but not released, for leaf feeding damage by fall armyworm and southwestern corn borer and to compare the damage sustained to lines we had previously released. The maize lines were planted in replicated field trials. Plants were artificially infested at the whorl stage of growth with neonates of fall armyworm or southwestern corn borer and evaluated for leaf-feeding damage at 14 days post infestation. The leaf feeding rating scores differed significantly among the lines in both 2020 and 2021 for both insect species. From the 13 non-released “Mp” lines evaluated, the rating scores for combined years ranged from 2.37 (Mp97:155) to 3.14 (Mp68:616) for fall armyworm and from 3.42 (Mp97:155) to 4.64 (Mp97:161) for southwestern corn borer. The non-released “Mp” lines exhibited better than moderate resistance to resistant to leaf damage for fall armyworm, and moderate resistance for southwestern corn borer. These lines may be useful in producing breeding crosses with other resistant lines or with lines that have other desirable traits.