On the male-effect in the terrestrial Crustacean Armadillidium vulgare (Latreille, 1804)

In the terrestrial Crustacean Armadillidium vulgare, the onset of female re production can be sped up by a male-induced stimulation. This male-effect i s mainly characterized by a shortening of the vitellogenesis period, which occurs during the preparturial intermoult. The determinism of this phenomen on, for the first time reported by Jassem in 1982, was investigated here by both experimental and ethological approaches. It was shown that a male dep rived of its copulatory organs is significantly less stimulating than an in tegrated one. On the other hand, a paired female with obturated genital ape rtures is significantly less stimulated. According to the literature, matin g takes place only when vitellogenesis is nearly over and therefore cannot be related to the male-effect. Nevertheless, the ethological approach has r evealed that females are early attractive for males, and that mating postur es can be observed during the whole preparturial intermoult. In fact, insem ination can happen as early as the initiation of the secondary vitellogenes is. Before this stage, short mating postures are still observed but no sper m was found in the female genital ducts (pseudocopulation). However, sperma tozoa and other seminal substances are not implicated in this phenomenon si nce a male unable to ejaculate is as efficient as a normal one. Therefore, it is strongly assumed that the male-effect results from mating postures du ring which male copulatory organs act on mechanoreceptors located in the fe male genital apparatus.