Identification of a cytokine combination that protects insects from stress.

Growth-blocking peptide (GBP) and stress-responsive peptide (SRP) are insect cytokines whose expression levels are elevated by various stressful conditions such as parasitization and high or low temperatures. Both GBP and SRP are synthesized as precursors and released into the hemolymph, where they are enzymatically processed to active peptides. Injection of active GBP or SRP into early last instar larvae elicits a reduction in feeding and consequent growth retardation in the armyworm Mythimna separata.