EFFECT OF SYNTHETIC PBAN AND DERIVED PEPTIDES ON SEX-PHEROMONE BIOSYNTHESIS IN HELIOTHIS-PELTIGERA (LEPIDOPTERA, NOCTUIDAE)

The activity of synthetic Heliothis zea PBAN (Hez-PBAN) and four shorter peptides on the sex pheromone biosynthesis in Heliothis peltigera was investigated in order to characterize their biological potency, and to determine the structure-activity relationship. Hez-PBAN (PBAN 1-33) is very potent and stimulates sex pheromone biosynthesis at the picomolar range both in photophase and scotophase. Removal of eight amino acids from the N-terminal region of the peptide Hez-PBAN had only a minor effect on the biological activity. A shorter fragment of Hez-PBAN, lacking 18 amino acids from the N-terminus, was less active. Two short peptides, consisting of eight and six amino acids, derived from the C-terminal region of Hez-PBAN had very little biological activity. In addition, it was found that PBAN 1-33 undergoes oxidation during storage. The oxidation of the peptide resulted in a loss of its biological activity, which could be restored by reduction with N-methylmercaptoacetamide. Unlike PBAN 1-33, PBAN 9-33 did not lose activity as a function of time, and its activity was fully preserved after prolonged storage. The results indicate that PBAN 1-33 and PBAN 9-33 have similar activities, and that the sequence containing the eight N-terminal amino acids is not essential for the biological activity of Hez-PBAN on the biosynthesis of H. peltigera sex pheromone.