Insulin-like and testis ecdysiotropin neuropeptides are regulated by the circadian timing system in the brain during larval-adult development in the insect Rhodnius prolixus (Hemiptera)

► Insulin-like peptides (ILPs) are localized in 3 distinct groups of brain neurons. ► Testis ecdysiotropin (TE) is co-localized in 2 of the groups. ► Release of ILPs is initiated by feeding and occurs rhythmically in vitro and in vivo. ► Axons of ILP/TE neurons closely associate with axons of clock neurons. ► Rhythmicity in neurohormones is apparently regulated by axons of the brain clock.