| dc.description.abstract | The fall armyworm (Spodoptera frugiperda) is a highly polyphagous agricultural pest native to the Western Hemisphere. This species is comprised of two morphologically identical, but genetically distinct strains, commonly referred to as the corn strain (C-strain) and the rice strain (R-strain). These strains have a sympatric distribution and may show a slight difference in their host ranges. Although the same species, these two strains respond differently to commonly used insecticides, and thus can be considered unique agricultural pests. Implementing strain specific pest management plans is a future goal to better control this species in the field.
Here, I applied ecological and genetic tools to uncover new insights about fall armyworm populations in the United States (US) that can be used to inform pest management plans. Specifically, I had three primary objectives. First, I used population genomics to characterize the population structure of fall armyworms in the central US and identify genomic patterns of gene flow between the C- and R- strain. Second, I developed new diagnostic tools for differentiating between fall armyworm strains, and then demonstrated how these tools can be used to study strain behavior in the field. Last, I compared the nutritional ecology of fall armyworm lab colonies to field populations to determine the utility of lab colonies as models to understand the behavior and physiology of field insect populations.
In addition to providing new diagnostic tools to differentiate between fall armyworm strains, my research provides novel insights into the pre- and postzygotic mechanisms underlying reproductive isolation between strains. Growers and researchers often assume a fall armyworm’s strain based on the host plant on which an insect is feeding. However, my data indicates that both C- and R- strain individuals often occupy the same fields, highlighting the importance of using molecular diagnostic tools to differentiate between these strains. Finally, I show that laboratory colonies of fall armyworms exhibit significant differences in their physiology and behavior when compared to the wild population, and should be used with caution when drawing generalize conclusions about field derived insect populations. | en |
