Has vertebrate chemesthesis been a selective agent in the evolution of arthropod chemical defenses?

Arthropods use a variety of chemical substances to repel potential predators, but how did they arrive at the suite of chemicals that they use? One way to explore this question is to map chemically defended arthropod species in a multidimensional "compound" space. Clustering within this space indicates species that share similar combinations of chemical compounds and can reflect a phylogenetic signal, common biochemical pathways, or both. More important for this study, clustering can help to identify allomone targets. We herein compare common arthropod allomones with known vertebrate trigeminal irritants. We argue that the degree of overlap between these two groups of compounds indicates that chemesthesis was an important determining factor in the evolution of many arthropod allomones. The multidimensional scaling methods used may also allow the identification of new irritant receptors.