Fig. 7. Thermal preference in N2 (grey bars) and CB4856 (black bars) is not influenced by food quality. Control (C): thermal gels seeded with E. coli strain OP50 were incubated at room temperature overnight. Ultra-violet (UV): prepared as for control then subjected to UV radiation to kill the bacteria. Heat (H): bacteria grown in liquid culture overnight, killed via exposure to high temperature, concentrated, and applied to thermal gels to approximate a live lawn. Mean thermal preferences are based on 3–8 replicates with an average of 144 individuals per replicate for a total of 3446 observations. Values are least square means ± 2 s.e.m. Treatments not sharing the same letter are significantly different (P<0.05; Tukey HSD).