Co-Authors:
Fan, Y., Department of Entomology, The Hebrew Univ., P.O. Box 12, 76100, Rehovot, Israel
Rafaeli, A., Department of Stored Products, Volcani Center, P.O. Box 6, 50250, Bet Dagan, Israel
Moshitzky, P., Department of Entomology, The Hebrew Univ., P.O. Box 12, 76100, Rehovot, Israel
Kubli, E., Zoological Institute, Univ. Zurich-Irchel, W., Zürich, Switzerland
Choffat, Y., Zoological Institute, Univ. Zurich-Irchel, W., Zürich, Switzerland
Applebaum, S.W., Department of Entomology, The Hebrew Univ., P.O. Box 12, 76100, Rehovot, Israel
Abstract:
Sex peptide (SP) and Ductus ejaculatorius peptide (Dup) 99B are synthesized in the retrogonadal complex of adult male Drosophila melanogaster, and are transferred in the male seminal fluid to the female genital tract during mating. They have been sequenced and shown to exhibit a high degree of homology in the C-terminal region. Both affect subsequent mating and oviposition by female D. melanogaster. SP also increases in vitro juvenile hormone (JH) biosynthesis in excised corpora allata (CA) of D. melanogaster and Helicoverpa armigera. We herein report that the partial C-terminal peptides SP8-36 and SP21-36 of D. melanogaster, and the truncated N-terminal SP6-20 do not stimulate JH biosynthesis in vitro in CA of both species. Both of these C-terminal peptides reduce JH-III biosynthesis significantly. Dup99B, with no appreciable homology to SP in the N-terminal region, similarly lacks an effect on JH production by H. armigera CA. In contrast, the N-terminal peptides SP1-11 and SP1-22 do significantly activate JH biosynthesis of both species in vitro. We conclude that the first five N-terminal amino acid residues at the least, are essential for allatal stimulation in these disparate insect species. We have previously shown that the full-length SP1-36 depresses pheromone biosynthesis in H. armigera in vivo and in vitro. We now show that full-length Dup99B and the C-terminal partial sequence SP8- 36 at low concentrations strongly depress (in the range of 90% inhibition) PBAN-stimulated pheromone biosynthesis of H. armigera. In addition, the N-terminal peptide SP1-22, the shorter N-terminal peptide SP1-11 and the truncated N-terminal SP6-20 strongly inhibit pheromone biosynthesis at higher concentrations. (C) 2000 Elsevier Science Ltd.