Reproduction in the frog Aubria subsigillata (Dumeril 1856): hormonal injection and captive breeding technique.

Abstract

Aubria subsigillata (Dumeril 1856) is a frog under increasing threat that is intensely harvested by Beninese people. The aim of this study was to develop a captive breeding program to repopulate the natural habitat of frogs in Benin Republic in view to conserve anuran biodiversity. The methodology adopted consisted of combining broodstock not injected with ovulin (hCG) in netted cages (natural reproduction) and broodstock injected with ovulin in tanks (assisted reproduction). In vitro fertilization of unfertilized female eggs by male milt was also carried out (controlled reproduction). In natural reproduction, A. subsigillata eggs or tadpoles are not produced. The concentration of 0.2 IU/g administered by intra-femoral injection resulted in the release of gametes in both sexes. Assisted reproduction enabled eggs to be obtained from the three coupling tanks after a post-injection lag time varying between 93 and 94 hours (Tank one = 304 eggs; Tank two = 125 eggs; Tank three = 56 eggs) and at a water temperature of 26°C; however, there was no incubation of eggs. For controlled reproduction, the average time between injection and first spermiation was 13 hours for males and 27 hours for females post-injection at a temperature of 28.5°C. Fecundity varied between 56 and 329 eggs. The eggs had an average weight of 1 mg and were incubated between 164 and 168 hours after fertilization. However, the incubation rate decreased on the 5^th day due to infection of the eggs by Saprolegnia sp. These results suggest that the experiment is partially viable: while hormonal stimulation can induce spawning and fertilization under controlled conditions, the success of incubation and development remains limited, highlighting the need for improvements in biosecurity and egg management to ensure full viability of captive breeding efforts.