Foraging behaviors of skin-penetrating nematodes.

<p><b>A</b>. IJ motility in the absence of chemosensory stimulation. Motility varies across species (<i>P</i><0.0001, one-way ANOVA), with <i>Str. stercoralis</i> being the most active (<i>P</i><0.01, one-way ANOVA with Tukey-Kramer post-test). n = 6–9 trials for each species. For this graph and subsequent graphs with multiple species, red = skin-penetrating; gold = passively ingested; blue = entomopathogenic. Of the three entomopathogenic species, <i>Ste. carpocapsae</i> is considered an ambusher, <i>Ste. glaseri</i> is considered an active cruiser, and <i>He. bacteriophora</i> is considered a less active cruiser <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004305#ppat.1004305-Downes1" target="_blank">[15]</a>. Statistical analysis is shown in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004305#ppat.1004305.s007" target="_blank">Table S1</a>. <b>B</b>. Unstimulated vs. heat-stimulated mean speeds of mammalian-parasitic IJs. Heat-stimulated IJs were exposed to an acute 37°C stimulus and tracked at 37°C. ***, <i>P</i><0.001; *, <i>P</i><0.01, unpaired t test or Mann-Whitney test. n = 5–10 trials for each species. <b>C–D</b>. Heat stimulates local search behavior. <b>C</b>. Representative tracks for <i>Str. stercoralis</i> and <i>Str. ratti</i> from 20 s recordings at room temperature versus 37 s recordings at room temperature versus 37°C. <b>D</b>. Movement patterns at room temperature versus 37°C. Distance ratios were calculated as the total track length divided by the maximum displacement attained during the 20 s recording period. A distance ratio of 1 indicates travel in a straight line s recording period. A distance ratio of 1 indicates travel in a straight line; a distance ratio of >1 indicates a curved trajectory. ***, <i>P</i><0.001; **, <i>P</i><0.01, Mann-Whitney test. n = 5–10 trials. <b>E</b>. Nictation frequencies of IJs. Nictation was defined as standing or waving behavior of at least 5 s in duration over the course of a 2 min period. Nictation frequencies varied among species (<i>P</i><0.0001, chi-square test). <i>N. brasiliensis</i> showed a nictation frequency comparable to <i>Ste. carpocapsae</i> (<i>P</i>>0.05, chi-square test with Bonferroni correction) and greater than <i>Str. stercoralis</i> or <i>Str. ratti</i> (<i>P</i><0.01, chi-square test with Bonferroni correction). Statistical analysis is shown in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004305#ppat.1004305.s010" target="_blank">Table S4</a>. n = 20–28 IJs for each species. For all graphs, error bars indicate SEM.