Summer 2025: Symbiont-Mediated Detoxification of Phenethyl Isothiocyanate in Grasshoppers

Project title: "Toxin Lethality and Symbiont-Mediated Detoxification of Phenethyl Isothiocyanate in Grasshoppers"

Abstract: Plant-insect interactions have a profound effect on the adaptation of plants and insects alike, as well as a greater effect on the food web they are a part of as a whole. Plants adapt to insect herbivory, and insects adapt to the plants defenses in turn. Secondary plant metabolites are created that act as deterrents or toxins to insects. Insects have innate mechanisms to remedy this, including avoidance behaviors and producing enzymes to break down the toxins, but an emerging idea is that insects form symbiotic relationships with bacteria housed in their guts that break down the toxins in their food. Phenethyl isothiocyanate (PEI) is a toxin produced by plants in the Brassicaceous family after the leaf tissue is damaged. I investigated whether PEI is detrimental to chewing insect Schistocerca americana, as well as if the gut microbiome moderates these negative impacts of PEI on the insect, providing evidence that generalist insects could utilize bacterial symbionts to degrade toxins in their diet. This was achieved by feeding the insects toxin treated diets, as well as feeding them a known bacterial degrader to act as a gut symbiont to test for an effect. I found that consumption of PEI by S. americana leads to a decrease in weight gain over time and increased mortality in higher concentrations, though acquisition of a known toxin bacterial degrader did not confer clear benefits to the host.

This research was conducted at The University of Texas at Arlington through the Ravenscraft lab and the McNair Scholars program. It has been presented at the McNair Scholars Research Conference in Waco, TX, McNair Research
Symposium in Arlington, TX, and at Entomology 2025 in Portland, OR. In addition, this work won the "Friends of the UTA Libraries - McNair Scholars Scholarship" in Fall 2025.