Effect of different barley cultivars on nutritional physiology of Tribolium castaneum (Coleoptera: Tenebrionidae)

Red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a cosmopolitan and serious pest of cereal grains and their products in storage. In this research, nutritional indices and digestive enzymatic activity of T. castaneum fourth instar and adults were studied on ten barley cultivars (Fajr30, Behrokh, Sahra, Makuyi, Neek, Lout, Bahman, Nosrat, Abidar, and Sahand) at 30 ± 1 °C, relative humidity of 75 ± 5% and darkness conditions. The results showed that fourth instars and adults reared on cultivars Makuyi and Fajr30 had the lowest weight gain, efficiency of conversion of ingested food (ECI), relative growth rate and growth rate (GR) values. However, T. castaneum fed on cultivar Lout showed the highest weight gain, ECI and GR. The highest amylolytic activity of larvae was on cultivar Bahman, whereas the lowest activity was on cultivars Makuyi and Neek. Amylolytic activity of adults was the highest on cultivar Makuyi, and the lowest on cultivar Lout. Moreover, proteolytic activity of fourth instar was the highest when larvae were fed on cultivar Sahra and the lowest when they were fed on cultivars Behrokh and Makuyi. The highest proteolytic activity of adults was on cultivar Abidar, and the lowest on cultivar Bahman. The results of this study indicated that cultivars Fajr30 and Makuyi were less nutritive and cultivar Lout was more nutritive to T. castaneum. Therefore, more attention should be paid to manage the pest on cultivar Lout as a susceptible cultivar.