The environment can modulate the reproductive pattern of many arthropods by abiotic factors (e.g. temperature, photoperiod, moisture) or by biotic factors (e.g. male-effect, population structure). In the terrestrial isopodArmadillidium vulgare, reproduction is stimulated by environmental factors (e.g. photoperiod) and by the male's behaviour which plays two roles: first accelerating the onset of female reproduction by stimulating vitellogenesis, then mating with a female before the parturial molting. This study is focussed on the influence of male or female presence on the initiation of reproduction. We conclude that the intermittent presence of a male (1 day in 3, or 1 day a week) was as efficient as a permanent contact. The 4th week of the female preparturial inter-molt was the most sensitive time, since the presence of a male during this week only had as much effect as permanent contact. This particular sensitivity can be explained by the vitellogenesis cycle: a male present when the female is beginning the «D» period of its inter-molt (appearance of white plates) accelerates vitellogenesis. Another main conclusion is that female-female intermittent crowding (1 day in 3) also showed a significant acceleration of vitellogenesis. In conclusionArmadillidium vulgareshows various biotic triggers of reproduction, which co-exist with classical abiotic ones. We discuss the relevance of these findings for natural populations, especially when the sex-ratio of the population is highly female-biased because of a parasitic distortion of sex-ratio.