Enhanced expression of stress-responsive cytokine-like gene retards insect larval growth

► We identified a novel gene encoding a cytokine-like peptide in the host insect larvae parasitized by parasitoid wasp. ► Synthetic cytokine-like peptide activated plasmatocytes to enhance their adhesiveness on a foreign surface. ► Injection of synthetic peptide repressed feeding activities of test larvae and caused subsequent growth retardation. ► The gene expression was also enhanced by various stressors such as injury, ligation, and heat treatment. ► The enhanced gene expression was observed only in damaged larvae but not in recovered larvae after heat stress.