Constitutive and induced structural defenses in horsenettle were negatively affected by inbreeding. Reduced flower production and internode length on damaged plants compared to controls suggests that defense induction entails significant costs.

The observed preferences are consistent with our previous findings regarding the constitutive and induced volatile profiles of inbred and outbred horsenettle plants and their effects on plant-herbivore interactions. They furthermore correspond to differences in host-plant quality predicted by previous work and, thus, suggest that naive larvae of M. sexta can accurately assess aspects of host-plant quality via olfactory cues perceived at a distance.