Drifted dinner: Investigating herbicide drift’s impacts on herbivorous insects in arboreal ecosystems

Herbicides are necessary for weed management in agricultural systems; however, improper use can lead to unintended harm. Herbicide drift occurs when droplets of herbicide move through the atmosphere from the application site to be deposited in distant locations. Most research focuses on herbicide drift’s effects on agriculture, particularly the herbicide dicamba’s tendency to damage unresistant crops; however, tree species such as white oaks (Quercus alba L.) and other fruit, nut, and ornamental species are also susceptible to drift damage. However, further investigation is necessary to determine whether the dramatic visual damage on affected trees extends to higher trophic levels, and observing the insects feeding on the leaves, phloem, and xylem of these trees is the first step. Through a collaboration between the University of Missouri, Lincoln University, the United States Forest Service, and the Missouri Department of Conservation, we will apply 1/200th the application dose of 2,4-D amine — reflective of that found in precipitation — to white oak trees grown in a controlled greenhouse. We will then allow Polyphemus silk moth (Antheraea polyphemus Cramer) caterpillars and adult oak lace bugs (Corythucha arcuata Say) to consume the leaf tissue in separate assays, followed by examining the caterpillars’ nutritional uptake and the oak lace bugs’ survival and fecundity. We hypothesize that insects that eat the control leaves will have the highest nutritional uptake, survival, and fecundity, and insects that eat the leaves treated at bud burst will have the lowest.