Figure 3. Larvae reared on 0.2 M (light grey) and 0.3 M (dark grey) tested: (left) for untrained preference between Pure (white) and NaCl (shaded) substrate at a concentration 0.025 higher than their food, i.e., 0.225 M and 0.325 M respectively; (right) for odour preference after associative training with the corresponding substrates, tested on Pure.

* denotes a significant difference from zero (the calculated confidence interval of the sample mean with (0.05/2) does not include 0, see text). In both cases an aversive substrate has a positive reinforcement effect.