What type of pesticides inhibit cholinesterase in animals?

Organophosphates are a class of pesticides that work by inhibiting cholinesterase, an enzyme essential for the normal functioning of the nervous system in both insects and mammals. This chemical interference disrupts the breakdown of the neurotransmitter acetylcholine, leading to an accumulation of this neurotransmitter, which can cause overstimulation of the nervous system. As a result, exposed organisms may exhibit symptoms ranging from tremors and paralysis to, in severe cases, death.

Carbamates also inhibit cholinesterase but are generally considered to have a different mechanism of action and are a distinct category from organophosphates. Pyrethroids and neonicotinoids, while effective against pests, do not inhibit cholinesterase; pyrethroids disrupt the function of sodium channels in nerves, and neonicotinoids act on nicotinic acetylcholine receptors but do not affect cholinesterase activity. Therefore, organophosphates are specifically noted for their role in cholinesterase inhibition, making them the correct choice for this question.