Secondary plant substances like flavonoids found in host plant tissues or/and environmental contaminants, like cadmium, can pose a common challenge for polyphagous herbivore pests. Earlier pre-exposure experience, with specific stressor, lasting even through many generations may affect the response to the other stressor. In this study, combined the effect of cadmium and extracts of some common spices (ordered according to total flavonoid content: lovage >
mentha >
basilium), on Spodoptera exigua larvae from two strains, control, and cadmium (selected with a sublethal concentration of cadmium for 160 generations) were examined. The developmental parameters (survival and growth rate during two last larval stages), the detoxification enzymes (non-specific esterases and glutathione transferases) activity and concentration of the energetic substances (carbohydrates, glycogen, lipids, and proteins) were recorded in the larvae. Individuals from two tested strains had varying responses (in survival rate, change in detoxification enzyme activity) to the plant extracts, particularly when exposed also to the metal. Treatment with Cd and plant extract, alone or together, generally enhanced the non-specific esterases activity in the examined individuals, but dependently on strain origination. But, the control strain individuals seemed to be more sensitive than cadmium strain animals.