From greenhouse to field: effects of elicitor-mediated induction of plant defense on fall armyworm (Spodoptera frugiperda) and two-spotted spider mite (Tetranychus urticae)

Plants respond to insect herbivory and damage by triggering signal pathways that result in the production of secondary metabolites that have been shown to reduce insect fitness, deter feeding, and attract beneficial insects.  Additionally, many organic and inorganic chemicals have shown to affect plant response to pathogen and/or herbivorous arthropod attack and damage when applied as a foliar spray or soil drench. The effect of selected elicitors on the induction of plant defenses were determined by measuring the growth of fall armyworm, Spodoptera frugiperda, on four important crops under greenhouse conditions. As demonstrated in other studies, application of jasmonic acid (JA) consistently reduced the growth of fall armyworm, particularly in cotton and soybean. These observations inspired two additional experiments: 1) to determine the effectiveness of adjuvants in increasing activity of JA for inducing defenses of cotton and corn under greenhouse conditions, and 2) a field experiment to determine the effect of JA on the establishment and growth of populations of two-spotted spider mite, Tetranychus urticae, on cotton. There was no consistent increase in the effectiveness of JA applied with an adjuvant compared to JA alone, and two-spotted spider mite population growth was equal for the standard acaracide and JA treatments.