Influence of Abiotic Factors on Anti-reproductive Activity of Bait-containing Papain in Lymnaea acuminata

Aims: To investigate the anti-reproductive action of papain against Lymnaea acuminata with respect to abiotic factors. Snail Lymnaea acuminata is the intermediate host of Fasciola species, which causes endemic fasciolosis in cattle and human population. Fasciolosis is a disease of ruminants worldwide which shows most widespread distribution in comparison to other vector-born parasitic disease.
Study Design: Baits were prepared from starch or serine (20Mm) in 2% agar-agar solution with papain the active component of Carica papaya (40% and 80% of 24h LC50). Each regimen of 5 liter water was kept in six aquaria separately, containing 20 snails in each aquarium. Bait containing papain was added in each aquarium except control. Control bait was without papain. After every 24 h, up to 96 h, the total number of eggs laid by the snails was counted in each aquarium. At every 24h spawns were observed for hatching and survival of embryos. Temperature, pH, dissolved oxygen and dissolved free carbon dioxide of different regimen of water were measured, simultaneously. After 96h, the ovotestis and/ or nervous tissue were dissected out and protein [22], free amino acids [23], nucleic acids [24] and enzyme AChE [25,26] activity were then measured.
Place and Duration of Study: Malacology Laboratory, Department of Zoology, DDU Gorakhpur University, Gorakhpur – 273009, U.P., India.The present study was carried outinbetween November- 2011 to October- 2012.
Results: Feeding of baits containing papain with starch and serine (40% and 80% of 24h LC50) caused a significant reduction in fecundity, hatchability and survival of young snails. Maximum (1036 eggs/20 snails) and minimum (175 eggs/ 20 snails) fecundity were observed in June-2012 and February-2012, respectively. There was significant (P =.05) positive correlation in between the sublethal concentration of baits containing papain (starch/ serine) and variation of temp/pH/CO2 of water in each month of the year2011-12. Protein, amino acid, DNA and RNA in the ovotestis of L. acuminata were significantly decreased when they were fed to bait containing 80% of 24h LC50 of papain + serine in different months of 2011 and 2012. Maximum reduction in protein (26.31 % of control), amino acid (28.83% of control), DNA (42.34% of control) and RNA (34.10% of control) level were measured in the ovotestis of L. acuminata fed to bait containing 80% of 24h LC50 of papain + serine. Feeding of bait containing 80% of 24h LC50 of papain + starch caused maximum reduction in the level of protein (28.97% of control), amino acid (56.77% of control), DNA (42.05% of control) and RNA (29.31% of control) in the ovotestis of L. acuminata. There was a significant (P=.05) positive correlation between the fecundity in different months and the corresponding AChE activity in the nervous tissue of the snail. Feeding of bait containing 80% of 24h LC50 of papain + serine caused maximum inhibition in AChE activity (41.71% of control) was observed in snail exposed to in the nervous tissue of L. acuminata in December2011. Feeding of bait containing 80% of 24h LC50 of papain + starch caused maximum inhibition in AChE activity (31.92% of control) in the nervous tissue of L. acuminata in June 2012.
Conclusion: Papain altered the reproductive capacity of snails. The anti-reproductive action against L. acuminata significantly altered with respect to the change in the abiotic factors in different months of the year Nov-2011toOct-2012.