Abstract
BACKGROUND Terrestrial snails are one of the most damaging threats to sustainable agriculture. Chemical control using molluscicides is the main approach used to combat these agricultural pests. Metaldehyde is the active ingredient in most snail control products in use. However, its toxicity indices and mode of action have scarcely been investigated. For the first time, we characterized the metaldehyde contact toxicity indices against the white garden snail Theba pisana. The biochemical impact of metaldehyde on acetylcholinesterase (AChE), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), alkaline phosphatase (ALP) and glutathione S-transferase (GST) activities and the lipid peroxidation (LPO) level was investigated.
RESULTS The median lethal dose (LD50) values at 24, 48 and 72 h of treatment were 11.33, 8.53, and 6.87 mu g g(-1) body weight (BW), respectively; while, the median lethal time (LT50) values were 88.16, 55.85, and 25.67 h when doses of 6, 8, and 12 mu g g(-1) BW were applied, respectively. In the snails treated with 2.83 and 5.67 mu g g(-1) BW (1/4 and 1/2 LD50 at 24 h of treatment) and 2.13 and 4.27 mu g g(-1) BW (1/4 and 1/2 LD50 at 48 h of treatment), higher AChE, GST, AST, ALT, and ALP activities as well as higher levels of LPO were observed compared with that of untreated snails.
CONCLUSION Metaldehyde displayed dose- and time-dependent contact toxicity. The biochemical results suggest that metaldehyde may have neurotoxic and cytotoxic actions in terrestrial snails. Application of metaldehyde in ways that could control pest snails and slugs and reduce its negative impact on the environment are discussed.