A novel T-maze assay to evaluate chemical irritants on Lumbricus terrestris

Abstract

Earthworms have a profound effect on the soil they inhabit, but our current understanding of the chemical factors and molecular mechanisms that attract or repel earthworms from a specific area of soil is limited. In this study, we developed a soil T-maze assay allowing for the examination of earthworm behavioral responses to repellent chemicals. This tests earthworms individually, and thus the potential confounds of worms being influenced by conspecifics signals are avoided. Canadian nightcrawlers (Lumbricus terrestris) can detect the canonical Transient Receptor Potential Ankyrin 1 (TRPA1) agonist, allyl isothiocyanate (AITC), but not the canonical Transient Receptor Potential Vanilloid 1 (TRPV1) agonist capsaicin. In the T-maze assay L. terrestris avoided TRPA1 activators AITC, cinnamaldehyde and menthol in a dosage dependent manner. The single subject T-maze assay is a useful tool to study the avoidance of earthworms to chemical compounds and provides behavioral evidence for a TRPA1 ortholog in L. terrestris.