Provided herein are screening methods for identifying arthropod repellent compounds based on modulation of ionotropic receptors, including an Ir40a receptor, an Ir93a receptor and an Ir25a receptor. Further provided are screening systems related to these methods. Such systems may include a sample that has one or more of the ionotropic receptors; and one or more compounds that each is a repellent for at least one arthropod species, wherein the one or more compound each modulates the activity of such ionotropic receptor(s). Further provided are one or more compounds identified using the screening methods described herein, and compositions containing such compounds.