ECDYSTEROID INDUCTION OF SEX-PHEROMONE BIOSYNTHESIS IN THE HOUSEFLY, MUSCA-DOMESTICA - ARE OTHER FACTORS INVOLVED

Removal of the corpora allata-corpora cardiaca complex from female houseflies within 8 h of adult emergence did not inhibit sex pheromone production as measured by the amount of (Z)-9-tricosene (Z9-23:Hy) produced or the incorporation of labelled acetate into pheromone components. Treatment of intact females with precocene II did not have a permanent effect on sex pheromone production but temporarily retarded egg development and depressed mating. Sequential treatment of males with the juvenile hormone analogue methoprene followed by 20-hydroxyecdysone or 20-hydroxyecdysone followed by methoprene showed that methoprene did not synergize the effects of 20-hydroxyecdysone on inducing sex pheromone production. Male insects which had their heads removed one day after emergence, were treated with 20-hydroxyecdysone on day 3 followed by a 2 h incubation with labelled acetate on day 4 incorporated radioactivity into Z9-23:Hy, indicating that a head factor was not required for sex pheromone induction. RH 5849, a non-steroidal ecdysteroid agonist induced low levels of Z9-23:Hy production in males, as demonstrated by radio-gas-liquid chromatography and by gas chromatography-mass spectrometry. These results show that juvenile hormone neither induced nor modified sex pheromone production in the housefly. Ecdysteroids or their agonist, by themselves, induce sex pheromone production in the housefly.