INS and bacterial infectious disease: Insulin, p38 MAPK, Wnt, DBL-1/TGF-β, ELT-2, and PCD are important signals required for the control of innate immunity against bacterial infection in nematodes (Kurz and Tan, 2004; Irazoqui et al., 2008; Arvanitis et al., 2013; Zhi et al., 2017b; Head et al., 2017).