D3134: Can drought shield hay grasses from fall armyworm pest?

Forage and hay grasses for livestock feed are a major industry across the United States. In Texas alone, in 2008, 4.4 million acres of hay were harvested, estimated at $1 billion. Fall armyworms (Spodoptera frugiperda) are a major pest of many crop species including hay grass pastures in Texas. Fall armyworm infestations can damage entire fields within in two or three days, causing major losses. Many regions across the U.S. are experiencing increasingly severe weather conditions, including less predictable rainfall events and droughts. Because water is an essential resource for plants, drought stress can negatively impact plants in a variety of ways. For example, waters tress can reduce plant growth, alter plant nutrients, and alter plant defense chemicals. The goal of this research is to investigate how water stress affects the interactions between hay grass and fall armyworms. More specifically, I am evaluating insect preference and performance on two different varieties of grass grown for hay in Texas (pearl millet—which is a drought tolerant variety—and brown top millet—which prefers wetter soils) under irrigated and drought stressed conditions. I predict that fall armyworm will perform better and prefer wellwatered plants over water-stressed plants. I expect water-stressed plants to have elevated defense levels and reduced nutrient contents that negatively affect fall armyworm. To test this hypothesis, I am conducting choice tests and performance bioassays with fall armyworm. I am also analyzing plant growth and defense traits. This research will provide better insights into plant resistance against fall armyworm across different environmental conditions.