Results: 

 Toxicological observations

LC₅₀ (24h) doses of methanolic extract of stem bark of Lantana indica and Alstonia scholaris in the laboratory conditions (Chauhan, 2009)

 

In pond

Behavioral change was seen after few minutes of exposure to the extracts. In initial 30-45 minutes snails were started to aggregating, and they started crawling on each others. As poison enters in the body of snails, there was a muscular twitching and snails become spirally twisted, which resulted ataxia, convulsion, paralysis and finally death of snails. In control groups, there were no such behavioural response and symptoms occur and there was no death also. The contraction of the body within the shell and no response to a niddle probe were taken as evidence of snail death.

             The toxicity of both plant extracts were time and dose-dependent against snail Lymnaea acuminata. There was a significant negative correlation between LC₅₀ values and exposure periods (Table 1 and 2). Thus with increase in exposure periods the LC₅₀ of methanol extract of L. indica stem bark decreased from 41.28 mg/L (24h); >30.35 mg/L (48h); >21.38 mg/L (72h); >14.73 mg/L (96h); and 55.19 mg/L (24h); > 40.29mg/L (48h); > 31.48 mg/L (72h); >23.20 mg/L (96h) in the case of A. scholaris (Table 1). Similarly the LC₅₀ value of binary mixture of L. indica+A. scholaris of this extract in 1:5 ratio decreases from 28.53 mg/L (24h); > 27.02 mg/L (48h); >24.86 mg/L (72h); >23.65 mg/L (96h) and 22.76 mg/L (24h); > 20.59 mg/L (48h); >18.87 mg/L (72h); > 17.78mg/L (96h) in the case of 1:1 ratio (Table 2).

            The steep slope value given in the toxicity table was steep and the heterogeneity factor was less than 1.0, which indicates that the results found fall within 95% confidence limits of LC values. The regression test (‘t’ ratio) was greater than 1.96 and the potency estimation test (‘g’ value) was greater than 0.5 at all probability levels.