Comparative study on biochemical indices of silkworm (Bombyx mori L.) hybrids for their thermal stress

The larvae of silkworm, Bombyx mori L., were used to determine the activities of catalase (CAT), peroxidase (POD), glutathione-s-transferase (GST) and some macromolecules such as; protein and triglyceride after treatment at 24°C and 39°C. The larvae of fifth instars were treated at 39 ° C for 8 h. The humidity of experiment was set at 55% at 24˚C and increased to 75% at 39˚C. The hemolymph and fat body were removed after four days. Some economic indices were assessed like weight of one male cocoon shell, percentage of male cocoon shell, weight of male cocoon, weight of one female cocoon shell, percentage of female cocoon shell, weight of female cocoon and their mortalities. Results indicated that the higher temperature reduced all the economic indices and the amount of macromolecules. The heat also increased the activities of antioxidant enzymes. The comparison between the antioxidant enzymes and economic indices indicated that Chinese hybrid 67 is more tolerant to temperature.