Effect of the plant azole pinnate on survival, growth rate fecundity and hatchability of egg-masses of Biomphalaria alexandrina snails

ABSTRACT

Data indicated that Azolla pinnata plants variously reduce the growth rate of Biomphalaria alexandrina snails expressed as net increase in shell diameter [direct or indirect exposure]. The plant density plays an important role in this respect. The higher the plant density, the lower the growth rate and vice versa. Indirect exposure of newly hatched B. alexandrina resulted from exposed treated eggs reduced the growth rate of these snails. Data revealed that direct and/or indirect exposure to the abnormal high density [50,000 plants/L] resulted in complete killing of B. alexandrina snails after 2 weeks from continuous exposure. Snails exposed directly to Azolla at 50,000 and 25,0000 plants/L failed to lay eggs. On the other hand, snails exposed to 10,000 plants/L laid few eggs, resulted in low reproductive rate [57.94] compared with unexposed ones [110.6]. The same results were recorded with hatchability of Biomphalaria eggs