Biochemical estimations:

      Exposure of snail to sub lethal doses i.e. 40% and 80% of 24h LC₅₀ of both the plant extract either singly or in binary mixtures for 96h caused significant alterations in the level of total protein, total free amino acids, glycogen and nucleic acids and activity of enzyme protease in nervous and hepatopancreas tissue of the snail Lymnaea acuminata (Table 3 and Fig.1 and 2). Total protein, glycogen and nucleic acid levels were significantly reduced, while total free amino acid level and activity of enzyme protease was significantly enhanced after the exposure to sub lethal doses in both the body tissues.

After exposure to sublethal doses (40% and 80% of 24h LC₅₀) of methanolic extract of stem bark of Lantana indica, total free amino acid level was induced to 118% to 135% and 124% to 138% and activity of enzyme protease was induced to 128% to 141% of control in nervous and hepatopancreas tissue of snail respectively while reduction in total protein level was significantly reduced to 78% to 59% in nervous  and 76% to 56% in hepatopancreas tissue, glycogen was to 71% to 50% in nervous and to 64% to 47% in hepatopancreas tissue, DNA level to 83% to 66% in nervous and to 76% to 65% in hepatopancreas tissue, RNA  level was to 75% to 63% in nervous and to 73% to 60% of control respectively, in hepatopancreas tissue of snail Lymnaea acuminata (Table 3).

After exposure to sublethal doses (40% and 80% of 24h LC₅₀) of methanolic extract of stem bark of Alstonia scholaris, total free amino acid level was induced to 117% to132 % and  122% to 140% and activity of enzyme protease was induced to 131% to 144% of control in nervous and hepatopancreas tissue of snail respectively, while reduction in total protein level was significantly reduced to 82% to 68% in nervous  and 80% to 62% in hepatopancreas tissue, glycogen was to 75% to 69% in nervous and to 73% to 53% in hepatopancreas tissue, DNA level to 85% to 67% in nervous and to 82% to 63% in hepatopancreas tissue, RNA  level was to 81% to 65% in nervous and to 78% to 64% of control in hepatopancreas tissue of snail Lymnaea acuminata respectively (Fig. 1).

After exposure to sub lethal doses (40% and 80% of 24h LC₅₀) of binary mixture of methanolic extract of stem bark of Lantana indica+Alstonia scholaris in 1:1 ratio, total free amino acid level was induced to 134% to 153% in nervous and 138% to 156% in hepatopancreas tissue and activity of enzyme protease was induced to 135% to 149% of control in nervous and to 133% to 147% in hepatopancreas tissue of snail respectively while reduction in total protein level was to 75% to 47% in nervous  and 70% to 46% in hepatopancreas tissue, glycogen was to 52% to 44% in nervous and to 52% to 40% in hepatopancreas tissue, DNA level to 78% to 58% in nervous and to 76% to 51% in hepatopancreas tissue, RNA  level was to 81% to 62% in nervous and to 78% to 61% of control respectively, in hepatopancreas tissue of snail Lymnaea acuminata (Fig. 2).

Students‘t’ test showed that these biochemical changes were significantly (p<0.05) time and dose dependent. Seven days withdrawal experiment shows, there was highly significant (p<0.05) recovery in all the above biochemical parameters in both the tissues of snail Lymnaea acuminata.