Effect of pyrethrum on CNS and haemolymph monovalent (Na(+), K(+)) cations and also on the level of CNS acetylcholine and activities of esterase and choline acetyltransferase in the insect Schizodactylus monstrosus drury.

The organic compound pyrethrum is recognised as a highly neurotoxic insecticide. Experiments were conducted to see whether the substance influences the central nervous system and haemolymph cationic (Na(+), K(+)) concentrations and also to examine changes in acetylcholine concentration and the activities of esterase and choline acetyltransferase. Pyrethrum treatment exhibits dissimilar changes in respect of sodium and potassium ion concentrations in the haemolymph and CNS of the carnivorous, orthopteran insect Schizodactylus monstrosus. Application of pyrethrum insecticides decreased the activities of esterase and choline acetyltransferase but increased the concentrations of acetylcholine. The release of the neurotransmitter acetylcholine is related to the ionic balance in the nerve membrane. The changes in the level of both sodium and potassium when exposed to pyrethrum impair the ionic balance in the nerve membrane, and for that matter the nerve conductor is blocked due to non release of acetylcholine ultimately causing paralysis of the insect concerned.