Sensitization after Brief Pre-Exposure in a Moth Figure 6. Proboscis extension reflex (PER) responses to sucrose (SUC) of males pre-exposed to gustatory and olfactory stimuli. A) pre-exposure to SUC and QUI, test with 0.03 M SUC. B) pre-exposure to SUC ipsi- or contralateral antenna, test with 0.03 M SUC. C) pre-exposure to PHE, test with 0.03 M SUC. D) responses of males to SUC after a non-specific mechanical stimulus, test with 0.1 M SUC. Columns show the percentage of males extending the proboscis when one of their antennae was contacted with a toothpick soaked with a SUC solution. Within each frame (A, B, C, D), the percentage of PER responses were significantly different between columns with different letters (Chi-Square, p,0.05). Numbers at the bottom of bars indicate numbers of tested males. Sensitivity to SUC was intra-modally increased by pre-exposure to SUC and QUI, and cross-modally increased by pre-exposure to PHE. doi:10.1371/journal.pone.0034141.g006 Figure 7. Proboscis extension reflex (PER) responses to different test-concentrations of sucrose (SUC) of males pre-exposed to sucrose (1 M SUC) and quinine (0.1 M QUI). Each point represents the percentage of males extending their proboscis when their antennae were contacted with different concentrations of SUC. The number of tested males is n = 40 for each data point. Dashed boxes enclose values that do not differ significantly (Chi-Square tests, p,0.05). Sensitivity to SUC was higher in males pre-exposed to SUC and QUI, showing a stronger difference with na¨ıve males at low doses. doi:10.1371/journal.pone.0034141.g007 PLoS ONE | www.plosone.org 7 March 2012 | Volume 7 | Issue 3 | e34141