Fig. 4

S. stercoralis free-living adults show distinct short-term behavioral responses to bacteria. a Overlaid tracks of individual S. stercoralis free-living adults in a single-worm bacterial chemotaxis assay. Worms were tracked for 20 min or until they left the assay arena. Black crosses represent starting points. For each assay arena, the red circle (left) depicts the experimental zone containing bacteria and the black circle (right) depicts the control zone containing the media control. In the case of the LB control assay, both the experimental zone and the control zone contained LB media. b Worms spent more time in the experimental zone when the experimental zone contained E. coli. **p< 0.01, Kruskal-Wallis test with Dunn’s post-test. The only significant difference is noted. c Worms spent more time in the E. coli lawn than they did in the P. fluorescens lawn. Only animals that reached a bacterial lawn were included in this analysis. d Worms spent more time in the control zone when the experimental zone contained P. fluorescens. *p< 0.05, Kruskal-Wallis test with Dunn’s post-test. The only significant difference is noted. e Worms displayed similar navigational patterns regardless of the bacteria present, as quantified by the distance ratio (total pathlength ÷ linear displacement from the initial point to the final point). No significant differences were detected (Kruskal-Wallis test). n = 24–30 worms for each condition. Graphs show medians (solid lines) and interquartile ranges (dashed lines). All statistical comparisons are relative to the LB control assay