JUVENILE HORMONES - THEIR ROLE IN THE REGULATION OF THE PHEROMONAL COMMUNICATION-SYSTEM OF THE ARMYWORM MOTH, PSEUDALETIA-UNIPUNCTA

Recently, much effort has been devoted to the elucidation of the neuro -endocrine mechanisms regulating the biosynthesis and emission of sex pheromones in the Lepidoptera. The available data indicate that the ho rmonal mechanisms involved vary considerably among species. For exampl e, compelling evidence that juvenile hormones (JH) play a role in the control of sex pheromone production has been presented only for the ar myworm moth, Pseudaletia unipuncta. In this species, females that are allatectomized at emergence neither produce nor release pheromone, but both activities are restored following replacement therapy with synth etic JH. However, injection of synthetic JH into neck-ligated females does not induce pheromone biosynthesis, whereas treatment with either a brain homogenate or synthetic PBAN results in a rise in the pheromon e titer. These results indicate that the role played by JH is an indir ect one and that the tropic factor is a PBAN-like substance. Studies o n in vitro JH biosynthesis by isolated corpora allata of P. unipuncta have shown that the low JH output observed early in the life of adult females coincides with the absence of both calling behavior and pherom one production. The subsequent increase in the rates of JH biosynthesi s correlates with the onset of pheromone production and release. We ha ve therefore proposed that JH titers must pass a threshold level befor e the circadian release of PBAN and calling behavior can begin. Furthe rmore, recent experiments suggest that the continuous presence of JH i s necessary for calling behavior to be maintained once initiated. Last ly, we present data suggesting a role for JH or JH acids in the recept ivity of P. unipuncta males to the female sex pheromone. (C) 1994 Wile y-Liss, Inc.