Effectiveness of Sorghum and Maize Flavonoids Against Pests
Open Access
- Author:
- Lesko, Tyler
- Graduate Program:
- Agricultural and Environmental Plant Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- February 21, 2023
- Committee Members:
- Surinder Chopra, Thesis Advisor/Co-Advisor
Gary Felton, Committee Member
Erin Connolly, Program Head/Chair
Ruairidh James Hay Sawers, Committee Member
Michael S. Wolfin, Committee Member - Keywords:
- fall armyworm
maize
sorghum
flavonoids
plant defense
secondary metabolites
mushrooms - Abstract:
- Sorghum (Sohum bicolor (L.) Moench) and maize (Zea mays L.) are economically important cereal crops with a wide array of applications beyond food. Therefore, pest pressure can be extremely detrimental to individual farmers and the economy. Our current strategies of management typically involve the heavy use of chemicals with limited modes of action. However, since plants are sessile, they have evolved defensive strategies such as the use of secondary metabolites. One group of secondary metabolites, flavonoids, are polyphenolic compounds with many subclasses that are primarily used for pigmentation. Research into these compounds has shown them to possess pesticidal properties on a wide range of pests. One subclass of sorghum and maize flavonoids, 3-deoxyanthocyanidins (3-DAs) was the focus of this work. Extraction of 3-DAs from flavonoid-rich sorghum material showed several chemical species present, namely apigeninidin, luteolinidin, and several derivatives. We tested these compounds in vivo and in vitro against the fall armyworm (Spodoptera frugiperda), a polyphagous lepidopteran pest. The extract was added to an artificial diet and sprayed on susceptible maize leaves to test exogenous application efficacy. Fall armyworm larvae had a significant decrease in body weight and an increase in mortality when fed on food sources containing flavonoids. The efficacy of endogenously produced 3-DAs in maize tissue was tested using detached leaf-feeding assays from different maize growth stages. Feeding on flavonoid-rich material showed a significant decrease in average body weight and an increase in mortality of FAW. Possible mechanisms were explored including damage to the matrix surrounding the caterpillar’s midgut and changes in the microbial composition of the larval fore and midguts. Since 3-DAs were shown to be effective against insect and fungal pests of cereals, the efficacy of sorghum 3-DAs against mushroom pests was explored. Extracted sorghum 3-DAs were tested on the fungal pathogen Lecanicillium fungicola (responsible for Verticillium Dry Bubble). Applications of the extract on fully colonized tubs of Agaricus bisporus did not reduce the total yield, however, it did reduce the number of bubbles that formed by half. The extracted 3-DAs were also tested on two mushroom insect pests trghat can vector L. fungicola, fungus gnats, Lycoriella ingenua, and mushroom phorids, Megaselia halterata. One minute exposure to extract residue caused a significant increase in mortality for both flies after 24 hours. Overall, the use of 3-DAs extracted from sorghum biomass is a promising alternative to synthetic pesticides for mushroom pests.