What is the toxic principle in slug and snail bait?

The toxic principle in slug and snail bait is metaldehyde, which acts as a potent neurotoxin when ingested by slugs and snails. It disrupts normal neurological function, leading to increased muscle contractions, convulsions, and ultimately can result in the death of these pests.

Metaldehyde's primary mechanism involves the enhancement of neurotransmitter release at synapses, resulting in hyperactivity and seizure-like symptoms in animals that ingest the bait. This compound is particularly hazardous not only to invertebrates but also poses risks to pets and wildlife if consumed in significant quantities.

The other substances mentioned do not possess the same neurotoxic properties associated with metaldehyde. For instance, calcium carbonate is commonly used as an antacid and is not toxic in the concentrations found in slug bait. Acetaminophen, while toxic to certain species such as cats and dogs, is not typically used in slug and snail baits. Iron phosphate, on the other hand, is often regarded as a less toxic alternative to metaldehyde and is safer for use around pets and wildlife. Thus, metaldehyde stands out distinctly as the toxic agent in slug and snail bait formulations.