Anti-Herbivory For Fall Armyworm And Corn Earworm Management

Panek, Bryan

Anti-Herbivory For Fall Armyworm And Corn Earworm Management

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Author:: Panek, Bryan
Graduate Program:: Agricultural and Environmental Plant Science (MS)
Degree:: Master of Science
Document Type:: Master Thesis
Date of Defense:: February 21, 2024
Committee Members:: Surinder Chopra, Thesis Advisor/Co-Advisor
Majid R Foolad, Committee Member
Erin Connolly, Program Head/Chair
Maxim J Schlossberg, Committee Member
Gary Felton, Committee Member
Keywords:: Flavonoids
Maize
Fall Armyworm
Corn Earworm
Breeding
Abstract:: Spodoptera frugiperda (J.E. Smith) (Fall Armyworm, FAW) and Helicoverpa zea (Boddie) (Corn Earworm, CEW) are notoriously devasting polyphagous insect pests of numerous crop plant hosts, such as maize, sorghum, sugarcane, and tomato, leading to direct adverse effects on domestic and global agricultural production. Currently, FAW and CEW control and management are implemented through Bacillus thuringiensis (Bt) transgenic cultivars, pesticides, and regional methods of control (hand picking, botanicals, and wood ash used as a biopesticide). As field-evolved resistance to Bt crops and pesticides continues to drive selection pressures, innovative measures are required to control and manage FAW and CEW. Flavonoids may be one of the novel approaches researchers have been looking for to combat these evolving pest pressures. Flavonoids are polyphenolic secondary metabolites found throughout the plant kingdom and involved in cellular signaling, free radical quenching, antimicrobial defense, insect anti-herbivory, etc. The research in Chopra laboratory has been focused on understanding the genetics of specific classes of flavonoids that have shown promises in controlling insect pests in sorghum and maize. In this thesis, I will explore the spatial and temporal accumulations of flavonoids in maize (Zea mays L). and their effects on FAW and CEW herbivory behavior. Maize (Zea mays L.) stands as a titan among crops. From its humble origins in the Teosinte fields of Mesoamerica, it has ascended to become the most widely produced and versatile cereal grain on Earth. Its golden kernels nourish billions, fuel industries, and even find themselves woven into the very fabric of cultural identities. In Chapter 1, I introduce flavonoids in plants and maize, explaining their beneficial effects on plants and their nutritional consumption for animals, people, and livestock. I continue by introducing plant breeding and its tremendous impact on agriculture and grain yield improvements. I continue Chapter 1 by reviewing FAW and CEW, their life cycles, field-evolved resistance to Bt crops and pesticides, and these veracious pests' social and economic impacts. Finally, I end Chapter 1 with a short section on my trip to the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and how entomologists and breeders perform their screening for FAW resistance in five mandated crops. In Chapter 2, I investigate the spatial and temporal accumulations of 3-deoxyanthocyanidin flavonoids and anthocyanins in maize near-isogenic lines (NILs) and parental inbred lines. To achieve this task, I extracted flavonoids and spectroscopically analyzed planted seed, harvested seed, and leaf tissue from the whorl at three distinct stages of maturity, husk tissue, and examined the extraction via photo spectroscopy. Also, in Chapter 2, I performed detached tissue feeding assays on FAW and CEW from greenhouse and field-raised plants to evaluate the efficacy of flavonoid expression lines compared to non-flavonoid expressing lines. To better understand the breeding value of these NILs and parental lines, Chapter 2 also examines the associated grain yield between pigmented and non-pigment lines. Similarly to Chapter 2, Chapter 3 discusses the spatial and temporal accumulations of flavonoids, anti-herbivory efficacy, and grain yield but in flavonoid-expressing hybrids and backcrosses instead of NILs and parental tester lines. These projects' sheer size and effort will help emphasize the monumental task of understanding the complexities associated with flavonoid accumulations and their possible efficacy as an anti-herbivory agent.

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