Nutritional indices and digestive proteolytic and amylolytic activities of Trogoderma granarium (Coleoptera: Dermestidae) on seed of different cereals

The khapra beetle, Trogoderma granarium (Everts), 1898 is one of the damaging pests of different stored cereal grains in Iran. In this research, effect of four cereal grain species including wheat (varieties N-91-9 and Aftab), barley (varieties Dasht and Oxin), maize (varieties AR and 704), and rice (varieties Hashemi and Fajr) was studied on nutritional indices and digestive proteolytic and amylolytic activities of T. granarium fifth instar at 33±1˚C, relative humidity of 65±5% and a photoperiod of 14: 10 (L: D) h. The results showed that the highest food consumption by larvae was observed on wheat N-91-9 and the lowest value was seen on maize 704 and rice Fajr. The relative growth rate was the highest on wheat N-91-9 and barley Dasht. The highest proteolytic activity was in larvae fed on wheat Aftab, barley Dasht and rice Hashemi, and the lowest activity was in those fed on rice Fajr. The amylolytic activity of larvae fed on varieties Dasht, N-91-9, Hashemi and AR was significantly higher than those fed with other tested cereals. The results of this study indicated that barley Dasht and both wheat varieties tested were relatively more favorable than other examined cereals for feeding of T. granarium larvae.