Influence of temperature on survivability, growth, sexual maturity and fecundity of the Indoplanorbis exustus and its associated schistosomes in Assam, India

The susceptibility of larval stages of Schistosoma nasale, S. spindale, S. indicum, amphistomes, echinostomes, etc., in Indoplanorbis exustus, the snail intermediate host, depends on their age, body weight and other limnological properties. So, a good number of healthy sexually mature I. exustus snails were collected randomly from different water sources of Assam and released in previously prepared biologically balanced aquaria to maintain in laboratory condition to know the biology and development. The newly hatched snails numbering 70 in each group were maintained at laboratory at a constant temperature of 15 degrees, 20 degrees, 25 degrees, 30 degrees and 35 degrees C and room temperature (20.02-31.75 degrees C) which showed maximum survivability at 20 degrees C. The highest growth rates in terms of shell diameter (10.63 +/- 0.162 mm) and body weight gain (435.83 +/- 23.367 mg) were found to be at room temperature at 6(th) week of age. The snails became sexually mature as early as 50 days at 30 degrees C and as longer as 125 days at 20 degrees C. Fluctuating room temperature was found to be more conducive for fecundity wherein as many as 22833 numbers of eggs were hatched out from 1033numbers of egg cluths. It can be concluded that temperatures, therefore, played an important role in regulating survivability, growth, sexual maturity and fecundity.