DGE analysis of changes in gene expression in response to temperature and deltamethrin stress in the silkworm (Bombyx mori)

The silkworm (Bombyx mori) is an important insect for various industrial applications and is also a model insect for the order Lepidoptera. The silkworm is more resistant to deltamethrin at high temperatures than at low temperatures. To elucidate the role of the negative temperature coefficient of deltamethrin in the silkworm, digital gene expression (DGE) analysis was performed for the identification of differentially expressed genes in silkworms challenged with deltamethrin at different temperatures. Compared with deltamethrin exposure at 30 degrees C, silkworms treated at 20 degrees C exhibited more severe stress responses, and gene sets associated with peptidoglycan recognition protein (PGRP), mucin, and antimicrobial peptides (AMPS) were downregulated dramatically. Similarly, a decrease in genes related to reactive oxygen species scavenging was also detected, which may have resulted in an imbalance between radical-generating and radical-scavenging systems. These results indicated that the lower. mortality rate after deltamethrin treatment at high temperature was caused by a series of gene alterations (quantitative increases) rather than qualitative changes. (C) 2015 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society. Published by Elsevier B.V. All rights reserved.