D3061: Entomopathogenic nematodes reduce cotton plant resistance to fall armyworm herbivory

dwelling insect pests. Recent studies have reported that EPNs can induce resistance in the systemic tissue of some crop species, making these plants more resistant and less attractive to aboveground-feeding insect herbivores by changing various physiological responses or inducing systemic defenses. The objective of this study was to determine how EPNs (Heterorhabditis bacteriophora) affect systemic defense responses in cotton (Gossypium hirsutum). We predicted that cotton plants exposed to EPN treatments would induce higher concentrations of defensive terpenoids and would be more resistant to fall armyworm (Spodoptera frugiperda) herbivory than control plants. In contrast, our results indicate that EPN treatment reduced cotton defenses and that these plants were more susceptible to herbivory. Overall, these findings suggest that while EPNs can be used for biological control of pests, there may be unintended consequences for plant resistance.