Insulin-like peptides are mainly produced by brain mNSCs in insects. (A) Detection of bombyxin-II and dilp2 mRNA in the larval brain by in situ hybridization. bombyxin-II and dilp2 expression is observed in four and seven pairs of mNSCs in Bombyx and Drosophila, respectively. (B) Detection of Bombyxin-II and DILP2 localization in the larval brain by immunostaining. Bombyxin-II produced by mNSCs (white arrows) are axonally transported to the CA. DILP2 produced by mNSCs (white arrows) are axonally transported to the CC (yellow arrow) on the ring gland, and further transported to the dorsal vessel (yellow arrowhead). DILP2 signal can also be detected in specific sets of neurons within the brain (white arrowhead). CA, corpora allata; CC, corpora cardiaca; RG, ring gland.