IDENTIFICATION OF RELEASE PRODUCTS OF CORPORA ALLATA OF MALE AND FEMALE ARMYWORM MOTHS, PSEUDALETIA-UNIPUNCTA

The release of juvenile hormones (JH) by female and JH acids (JHA) by male corpora allata (CA) of Pseudaletia unipuncta was monitored in vitro using a radiochemical assay. Separation and quantification of the homologues was accomplished by HPLC and liquid scintillation counting of collected fractions. At emergence, CA of females maintained at 25-degrees-C, 16 h light: 8 h dark (16L:8D) released only trace amounts of JH. On days 1-2, JH III remained virtually undetectable, but similar, low quantities of JH I and JH II were released. Between days 3 and 7, an increase in the release of each homologue was observed, the largest being for JH II. Similarly, the amount of JH released by CA of females maintained at 10-degrees-C, 12L:12D, increased as a function of age up to 25 days following emergence, with JH II again being the most abundant homologue. However, even after 25 days, the levels observed at 10-degrees-C were considerably less than those seen at 25-degrees-C. Under conditions of 25-degrees-C, 16L:8D, males exhibited a pattern of JHA release similar to that described for females, with the exception that JHA I rather than JHA II was generally the dominant homologue. CA from male moths held for 5-25 days at 10-degrees-C, 12L:12D, released little JHA III, but comparatively high and similar amounts of JHA I and II. However, contrary to the continuous age-related increase seen in females, JHA release peaked on day 10 and subsequently declined. We discuss these results in the context of ovarian development, pheromone production, calling behaviour and migration in armyworm females, and we argue that JH or JH acid regulates the maturation of the pheromonal communication system in males.