Differential responses of herbivorous insect species to protease inhibitorsfrom barley and strawberry

Abstract: In this study has been analysed the in vitro inhibitory activity of cystatins from barley(HvCPI1 to HvCPI-13) and strawberry (FaCPI-1) against different species of insects that rely oncysteine-like proteases for digestion. These proteins presented different capability to inhibit theactivity of cathepsin L-like protease activities in the different species tested, being HvCPI-6 themost effective inhibitor. Gelatin-containing gels showed most of the multiple protease formsdetected in the insect extracts were partially or even totally inhibited by this barley cystatin.Besides, the in vivo effect of this HvCPI-6 was analysed on two aphid species by feeding assayswith supplemented artificial diets.