Pheromonotropic activity of naturally occurring pyrokinin insect neuropeptides (FXPRLamide) in Helicoverpa zea

Insect neuropeptides, having the common C-terminal sequence FXPRLamide (X = V, T, S, or G), were tested for pheromonotropic activity in the moth, Helicoverpa zea. Dose-response studies indicated that locustamyotropin-II or locustapyrokinin-II induced production of more pheromone than was stimulated by the pheromone biosynthesis activating neuropeptide of this moth. Other peptides showed various degrees of pheromonotropic activity. The data indicated that substitution of the variable amino acid in the C-terminal pentapeptide sequence resulted in significant differences in pheromonotropic activity. However, the overall structure of the peptide was also found to be of importance.