REGULATION OF SEX-PHEROMONE BIOSYNTHESIS IN 2 NOCTUID SPECIES, SPODOPTERA-LITTORALIS AND MAMESTRA-BRASSICAE, MAY INVOLVE BOTH PBAN AND THE VENTRAL NERVE CORD

In order to understand better the mechanism of regulation of pheromone production in moth species, we performed ELISA analyses to detect and follow pheromone biosynthesis activating neuropeptide-like immunoreac tivity (PBAN-IR) in different tissues of the two noctuidae species, Sp odoptera littoralis and Mamestra brassicae. Male S. littoralis and bot h male and female M. brassicae brain-subesophageal ganglion (Br-SEG), corpora cardiaca-corpora allata complex, and terminal abdominal gangli on extracts showed the presence of PBAN-IR during both the photophase and the scotophase. However, PBAN-IR was found only in scotophase in f emale hemolymph. Analysis of extracts of Br-SEG, terminal abdominal ga nglion, and hemolymph after HPLC fractionation showed that the most im munoreactive fraction in all the extracts exhibited the same retention time as Hez-PBAN, suggesting that similar PBAN-like material is prese nt in all these tissues. In vivo studies demonstrated that severing th e ventral nerve cord in IM. brassicae anterior to the terminal abdomin al ganglion impaired normal sex pheromone production by third-scotopha se females, as was previously shown in S. littoralis. Additionally, PB AN-IR levels were lower in hemolymph samples obtained at the peak of p heromone production in both S. littoralis and M. brassicae females tha t had the ventral nerve cord severed compared with sham operated anima ls. These results, along with earlier reported data, indicate that con trol of pheromone production in both species may involve both PBAN (Or PBAN-like peptides) and the ventral nerve cord and support the hypoth esis that a neural input from the ventral nerve cord triggers the rele ase of the pheromonotropic peptide(s) into the hemolymph, which then a cts directly on the pheromone gland to stimulate pheromone biosynthesi s. (C) 1998 Wiley-Liss, Inc.