Detecting the conspecific: herbivory induced olfactory cues in the fall armyworm (Lepidoptera: Noctuidae)

Authors: INGBER, DAVID - University Of Delaware; Christensen, Shawn; Alborn, Hans; HILTPOLD, IVAN - Agroscope

Submitted to: Metabolites
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2021
Publication Date: 8/30/2021
Citation: Ingber, D.A., Christensen, S.A., Alborn, H.T., Hiltpold, I. 2021. Detecting the conspecific: herbivory induced olfactory cues in the fall armyworm (Lepidoptera: Noctuidae). Metabolites. 11, 583. https://doi.org/10.3390/metabo11090583.
DOI: https://doi.org/10.3390/metabo11090583

Interpretive Summary: Fall armyworm (Spodoptera frugiperda) is a pest of many economically important crops such as corn, cotton, sorghum, rice, and a variety of pasture and turf grasses. Larval feeding damage is especially severe in corn, where yield losses can range from 17% to as high as 72%. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL in collaboration with researchers at the University of Delaware studied how corn plants respond to damage caused by fall armyworm and identified plant chemicals that have direct anti-feedant activity. Additionally, the scientists discovered several volatile compounds that may act as deterrents against female fall armyworms trying to lay their eggs. These chemicals could be used in spray applications or be expressed in crops through genetic modifications (transgenics). Such practices could provide an effective means of pest management and alleviate economic losses that corn growers experience due to fall armyworm.

Technical Abstract: The fall armyworm, Spodoptera frugiperda (Smith), is a polyphagous pest whose larval feeding threatens several economically important crops worldwide with especially severe damage to corn (Zea mays L.). Field-derived resistance to several formulations of conventional pesticides and Bt toxins have threatened the efficacy of current management strategies, necessitating the development of alternative pest management methods and technologies. One possible avenue lies in the use of volatile organic compounds (VOCs) and metabolites that are produced and sequestered by plants as a response to larval feeding. The effects of conspecific larval feeding on fall armyworm oviposition preferences and larval fitness were examined using two-choice oviposition experiments, larval feeding trials, metabolomics, and VOC analyses. There was a significant preference for oviposition on corn plants that lacked larval feeding damage, and larvae fed tissue from damaged plants exhibited reduced weights and head capsule widths. All larval feeding promoted significantly increased metabolite and VOC concentrations compared to corn plants without any feeding. Metabolite differences were driven primarily by linoleic acid (which is directly toxic to fall armyworm) and tricarboxylic acids. Several VOCs with significantly increased concentrations in damaged corn plants were known oviposition deterrents that warrant further investigation in an integrated pest management context.