Fig. 5

Steinernema scapterisci shows temperature- and age-dependent changes in response to odorants, CO₂, and host odor. a Infective juveniles (IJs) incubated at 15 °C or 25 °C for several months showed attraction to CO₂ and insects. n = 4–8 trials for each condition. b IJs were grown at room temperature (22 °C ± 1 °C) and incubated at either 15 °C or 25 °C. For both temperature treatments, IJs showed a gradual shift in their CO₂ response from repulsive to attractive with increasing age; n = 8–16 trials for each condition. c IJs showed a shift in their responses to potential insect hosts that corresponded with their changing response to CO₂; n = 6–8 trials for each condition. d IJs were grown at room temperature (22 °C ± 1 °C) and incubated at 15 °C for 4–5 weeks until their responses to CO₂ shifted to attraction. IJs were then swapped to 25 °C or maintained at 15 °C for another 4–5 weeks. The responses of IJs to several of the tested odorants differed as a function of temperature, suggesting olfactory plasticity occurs independently of the change in CO₂ response valence. * P < 0.05; *** P < 0.001 relative to the initial 4–5 week IJ population; two-way ANOVA with Dunnett’s post-test; n = 6 trials for each condition. e, f IJs were grown at 25 °C and either temperature-swapped to 15 °C and back to 25 °C (e) or maintained at 25 °C (f) and tested for their responses to two selected odorants. Responses to these odorants changed as a function of age and/or temperature. * P < 0.05; ** P < 0.01; *** P < 0.001 relative to day 0 IJs; two-way ANOVA with Dunnett’s post-test; n = 8 trials for each condition. For all graphs, error bars represent standard error of the mean (SEM). Mean, n, and SEM values for each assay are listed in Additional file 7: Dataset S1