In the nematode Caenorhabditis elegans, an insulin receptor signaling pathway regulates adult life span and developmental arrest at the dauer larval stage. Here we show that the
unc-64 and
unc-31 genes also function in this pathway. These two genes are involved in mediating Ca2+-regulated secretion. Mutations in
unc-64 and
unc-31 increase adult life span and cause constitutive dauer formation. Both phenotypes are suppressed by mutations in
daf-16, which also suppresses other mutations in this pathway. We present evidence that the site of action of
unc-64 is neuronal, suggesting that a neurosecretory signal regulates life span and dauer formation.