Sublethal concentration (0.3 ppm) of Topas (fungicide) with active ingredient Penconazole (10%) was tested in combination with Schistosoma mansoni infection on the hermaphrodite gland of adult Biomphalaria alexandrina snails and its egg laying capacity. The obtained results indicated that, the mean number of eggs/snail/week of infected and treated-infected snails was significantly lower than that of control group. The reproductive rate was also greatly reduced by a percentage of 41.3%, 78.9% and 95.9% in treated, infected and treated-infected groups, respectively. Some of egg masses laid by treated snails showed morphological abnormalities with percentage of 15.7% during the experimental period. Topas treatment elicited various histopathological changes on hermaphrodite gland of infected and non-infected B. alexandrina snails. The gland acini became deformed, separated by loose connective tissue and degeneration of male and female gametogenic cells was also observed.
Key words: Fungicide, Topas, Egg laying, Histology, Egg masses abnormalities.