Does the presence of conspecific adults influence the embryonic development of Lymnaea columella?

JULIETA PUJADAS; PREPELITCHI LUCILA; WISNIVESKY MARÍA CRISTINA

Rio de Janeiro

Congreso; XI ICMAM International Congress of Medical and Applied Malacology; 2012

Brazilian Society of Malacology

Snails belonging to genus Lymnaea are the known intermediate host of Fasciola hepatica. Prevention and control of fasciolosis can be improved by the knowledge of its biology. The aim of the present work is to assess if the presence of conspecific adults affects the embryonic development of Lymnaea columella, the main intermediate host of F. hepatica in Northeastern Argentina. We worked with 8 egg capsules (48 eggs) deposited by L. columella from Berón de Astrada, Corrientes Province, Argentina and maintained in the laboratory. The 8 egg capsules were randomly distributed in two experiments: P=Presence and A=Absence of conspecific adults that were replicated twice. “P” treatments consisted of 2 egg capsules each (P1=6 and 7 eggs; P2=4 and 6 eggs) and 15 L. columella adults each; “A” treatments consisted of 2 egg capsules each (A1=8 and 6 eggs; A2=6 and 5 eggs). Treatments were conducted simultaneously and performed in glass aquaria with filter and aerated water, at 22ºC, under a 12:12 light:dark photoperiod. Beginning on the oviposition date (to) and every two days, water was changed, all embryos were measured and dates of hatching were recorded. In “A” treatment none of the embryos could hatch. In “P” treatments, 82.6% of the embryos successfully hatched and their median time of development was 14.0 days (1stQ=11.0; 3rdQ=15.5 days). At the beginning of development, no differences were found in the size of the embryos between treatments (t(0-2)=0.3mm and t(3-4)=0.4mm; p>0.05). From day five after laying onwards, embryos in “P” treatments were significantly bigger than embryos in “A” treatments: t(5-7)=0.6 vs 0.4mm, U=103, p