Estudo do crescimento e da reprodução de Bradybaena similaris (Férussac) (Mollusca, Xanthonychidae) em laboratório

Abstract

G rowth and reproduction of Bradybaena similaris (Férussac) (Moi-lusca, Xanthonychidae) in laboratory conditions. Biologica l aspects of Bradybaena similaris (Férussac, 182 1) were studied, such as: onset of sex ual maturity, occ urrence of self-fertilization, oviposi tion, incubation period, eclos ion rate and shell lengt h measurement at different stages of developme nt. It was noted that in isolated B. similaris the minimum and max imum ti me for reaching sexual maturity were 109 and 180 days, respectively. When kept in groups, the minimum time was 78 days. The occ urrence of self-fertili zation was observed in 18,4% ofspec imens. The total number of eggs per oviposition varied fro m one to 38 (average: 3,5 ± 7, 15), the total number of eggs per mollusc varied from one to 39 (average: 7,0 ± 10,21) and the total number of oviposition per moll usc vari ed form one to six (averege: 2,0 ± 1,27). Thirty oviposit ions (894 eggs) were fo ll owed and the minimum eclos ion time of the young was 14 days, the maximum eclosion time was 35 days and the average 23 ,69 days. The eclosion average percent was 8 1,22. As to the shelllength in different growth stages , it was observed that in B. sil1lila ris the length ofthe shell was similar unti l 30 days for age. After this period iso lated specimens acquired a greater growth rhythm when compared to that of grouped specimens. The maximum shell length of isolated spec imens was 17,4 mm whereas grouped spec imens reached 14,5 mm. In this specie, individ uais that were kept grouped became sex uall y mature earlier than isolated ones. Individ uais kept isolated reach larger length of shell. In the moment of the sex ual maturity, the Iength of the shell in the individuais tha were kept isolated was smaller than the grouped. KEY WORDS. Bradybaena similaris, biology, growth , reprod ucti on 8 radybaena similaris (F é ru ssac, 1821) é um a esp éc ie d e m o lusco d e inter-esse pa ras ito lóg ico, a tu a nd o co m o h os p e d e i ro inte rm e di á ri o d e Eurytrema coelomaticum Giard & Bille t , 1882 (PINHE IRO & AM ATO 1995), Postharmostomum gallinwn W ite nbe rg, 1923 (DUARTE 1980) e d e Angiostrongylus costaricensis M o rera & C ésp e d es, 1971 (R AMBO et aI. 1997). Este m o lus c o e nco ntra-se di s-tribu íd o princ ipalme nte nas re giões tro picais , dissemi n a do p e lo c o m é rci o d e p lan-tas. O co rre n a Am é ri ca d o N o rte, Centra l e d o Sul ; n o Bras il , é e ncontrad o d esd e o A m a p á a té ao Ri o Gra nd e d o Sul.