SEASONAL REPRODUCTION IN HEMILEPISTUS-REA UMURI (AUDOUIN, 1826), A TERRESTRIAL ISOPOD OF SEMIARID ZONES

In Hemilepistus reaumuri (Audouin, 1826), a monogamous desert isopod, control of reproduction by external factors is studied in females from a Tunisian population. In the wild, females perform only one brood (i n May). In contrast to isopods submitted to temperate climates (long d ay species), H. reaumuri is unsensitive to photoperiod. Onset of repro duction is dependent on temperature: it occurs only when temperature i s higher than 15 degrees C (between 15 degrees C and 20 degrees C). Mo reover, at 25 degrees C, the lag time of the onset of reproduction is shortened by 50% in comparison with the delay obtained at 20 degrees C . Whereas an isolated female remains in sexual rest, the presence of a male (even separated from the female by a wire netting) speeds up vit ellogenesis following by moult. The beginning of burrow digging is wel l correlated with the initiation of reproduction (second phase of vite llogenesis).