Determination of wheat bug (Eurygaster spp.) damage in durum wheat (Triticum durum L.) by electrophoresis and rapid visco analyser

The degradation effects of wheat bug protease(s) on glutenin proteins of durum wheat cultivars were investigated by electrophoresis and modified rapid visco analyser (RVA) test. Glutenin patterns of the bug damaged durum wheats changed substantially due to bug protease(s). Although high molecular weight glutenin subunits (HMW-GS) of three cultivars (Ege, Svevo, and Zenith) disappeared after 60 min of incubation, the HMW-GS of other two cultivars (Diyarbakir and Firat) were still visible even after the longest incubation period at medium damage level. It shows that there was an intercultivar variation in susceptibility to hydrolysis by bug proteolytic enzymes. Low molecular weight glutenin subunits of all cultivars decreased substantially after 30 min of incubation. The RVA curves indicated a clear reduction in viscosity in semolina samples with both medium and high damage levels as compared to their respective undamaged (control) samples. There were significant correlations (p < 0.001) between bug damage level and viscosities at 3 min (r = −0.765), at 4.5 min (r = −0.549) and at 10 min (r = −0.835), breakdown value (r = −0.534) and decay rate (r = 0.600). Consequently, hydrolysis rate of wheat bug protease(s) can be determined by modified RVA technique without much more chemicals, procedures and expensive equipments.