1 ), naïve caterpillars showed a highly significant preference for the herbivore-induced black poplar odor ( N = 44, χ 2 = 26.27, P < 0.001), whereas the experienced caterpillars oriented towards the odor of undamaged leaves ( N = 33, χ 2 = 5.12, P = 0.024).
Experienced caterpillars spent a longer time in arms permeated with either DMNT or ( Z )-3-hexenyl acetate than in control arms ( N = 25, Z = −2.623, P = 0.009 and N = 22, Z = −2.256, P = 0.024, respectively), but avoided benzyl cyanide, and they showed a strong trend towards the avoidance of salicyl aldehyde ( N = 22, Z = −1.997, P = 0.046 and N = 22, Z = −1.834, P = 0.067, respectively).
The odor of the caterpillars and their frass was attractive for naïve caterpillars in comparison to clean air ( N = 30, χ 2 = 8.53, P = 0.003), and attraction was marginally significant in the case of experienced caterpillars ( N = 23, χ 2 = 3.52, P = 0.060).