Cytokine which promotes survival following infection by Sindbis virus by suppressing the immune deficiency pathway (PubMed:26739560). Following infection by the enteropathogenic bacteria E.carotovora limits intestinal stem cells proliferation (PubMed:30036358). When secreted from muscle or adipose tissue, can attenuate age-related intestinal tissue degeneration by inhibiting apoptosis (PubMed:30036358). Secreted into the hemolymph. Detected in hemolymph (at protein level). Also expressed in the fat body and is probably synthesized in the fat body and secreted into the hemolymph. Expressed in muscle and fat body with levels increasing in the adult stage. By viral infection with Drosophila C virus (DCV), feline herpesvirus (FHV), Sindbis virus (SINV) and vesicular stomatitis virus (VSV). Strongest induction occurs with SINV and VSV. Highest levels of induction occur 6-24 hours after infection with levels declining steadily until 96 hours after infection. Induction requires the dorsal-related immunity factor Dif but does not require the myeloid differentiation primary response protein MyD88 (PubMed:26739560). By muscle tissue stress (PubMed:30036358). Contains two subdomains, SD1 and SD2. SD1 is composed of an antiparallel beta-sheet covered by an alpha-helix and displays a ferredoxin-like fold. SD2 displays a new protein fold made of loops connected by four disulfide bridges. Mutants have a shortened lifespan and succumb more rapidly than controls to SINV infection (PubMed:26739560). RNAi-mediated knockdown in fat body leads to accelerated aging of the intestine with intestinal stem cell hyperproliferation, epithelial dysplasia and accelerated induction of apoptosis in the aging midgut (PubMed:30036358). RNAi-mediated knockdown in muscle had no impact on systemic intestinal tissue aging (PubMed:30036358). The name 'Diedel' is the German translation of Tweedle and is based on the fictional Lewis Carroll characters Tweedledum and Tweedledee due to the presence of two subdomains within the protein. Belongs to the Diedel family.