FIGURE 1.

Schematic overview of questions that are addressed in this study. The horseradish flea beetle, Phyllotreta armoraciae, sequesters glucosinolates from its brassicaceous host plants and is thus able to overcome plant myrosinase activity. Here, we investigate the impact of plant myrosinase activity on glucosinolate sequestration (I), and the effect of glucosinolate hydrolysis on beetle weight and energy reserves (II). Further, we analyze possible mechanisms that may facilitate sequestration by influencing plant myrosinase activity: a rapid uptake of ingested glucosinolates from the gut (III), the inhibition (IV) and digestion (V) of plant myrosinases, and gut pH conditions (VI).