ABSTRACT

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°, 20°, 25°, 30° and 35°C and room temperature (20.02–31.75°C) which showed maximum survivability at 20°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°C and as longer as 125 days at 20°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.

Abbreviations: °C: degree Celsius; mm: millimeter; mg: milligram; ml: milliliter; LSD: Least Significant Difference; ANOVA: Analysis of variance.

摘要

蜗牛中间宿主Indoplanorbis exustus对鼻血吸虫、S. spindale、S. indicum、amphistomes、棘口虫等幼虫阶段的易感性取决于它们的年龄、体重和其他湖泊学特性。所以，大量健康的性成熟I. exustus蜗牛从阿萨姆邦的不同水源中随机收集，并释放到预先准备好的生物平衡水族箱中，以保持在实验室条件下以了解生物学和发育情况。每组70只新孵化的蜗牛在实验室保持在15°、20°、25°、30°和35°C的恒温和室温（20.02-31.75°C）下，在20°时表现出最大的存活率C。发现壳直径 (10.63 ± 0.162 mm) 和体重增加 (435.83 ± 23.367 mg) 的最高增长率是在室温下 6^日周龄。蜗牛在 30°C 下早 50 天就性成熟，在 20°C 下长达 125 天。发现波动的室温更有利于繁殖力，其中从 1033 个卵簇中孵化出多达 22833 个卵。因此，可以得出结论，温度在调节生存能力、生长、性成熟和繁殖力方面发挥了重要作用。

缩写： °C：摄氏度；mm：毫米；mg：毫克；ml：毫升；LSD：最小显着差异；方差分析：方差分析。