Is cotton’s chemical defense enough to stop a hungry locust?

This study investigated whether gossypol, a sesquiterpene aldehyde produced by cotton (Gossypium hirsutum), differentially deters feeding in the Central American locust (Schistocerca piceifrons, CAL) and the American bird grasshopper (S. americana, ABG). Newly molted final instars of both species removed from the stock colony cages on the day of molting and starved for 24 hours before the assays. Then, they were allowed to feed on filter paper discs with 5% sucrose (as a feeding stimulant) plus either 0.1% or 1% gossypol. Control discs contained sucrose only. Each treatment included 20 individuals per species (N = 120 total). Feeding deterrence was assessed by calculating the proportion of disc weight consumed. Data were analyzed using ANCOVA with the factors: gossypol concentration, species, sex, trial, and initial insect weight, along with a species x concentration interaction. Wilcoxon tests with Bonferroni correction were used for pairwise comparisons. Gossypol deterred feeding in both species, but CAL consumed significantly more gossypol-treated discs than ABG at both concentrations, suggesting a greater tolerance. There was no significant difference in control disc consumption between species. These findings indicate a significant species x concentration interaction, with CAL displaying reduced sensitivity to gossypol’s deterrent effects. This tolerance may reflect an adaptive advantage for CAL when feeding on cotton, raising concerns about its potential role as an emerging pest. Given its ability to tolerate a key chemical defense of cotton, CAL could represent a growing threat to U.S. cotton production, warranting increased monitoring and consideration in integrated pest management strategies.