UTTAR PRADESH JOURNAL OF ZOOLOGY

Pupae of the common Indian mosquito, Culex fatigans, survive in 100% sea water and its various dilutions and the time involved (62.33 - 63 hours) in development and emergence of imago is not affected. When pupae are placed in NaNO,, NaNO„ Na₂SO₄, NII,NO, and NI-14C1 solutions iso-osmotic with 0.65% NaCI solution, no significant difference in respect of emergence period is observed in distilled water (65 h), 0.94% NaNO, (64.66 h) and 0.88% N1-1,N0, (65 h), but the difference is highly significant (P < 0.001) in other solution, being minimum (62 h) in 0.76% NaNO₂ and maximum (67.66 h) in 0.59% NI-14C1 solution. Pupae are resistant to different levels of osmotic pressure of pure and diluted sea water, but iso-osmotic solutions of different electrolytes having dierent ionic activities have a significant effect on the duration of time for development and ecloston.