Rule #1: ‘Prevention is better than Cure’
Name: Cypermethrin (Class II Pyrethroid Pesticide)
Cypermethrin is a Synthetic Pyrethroid, a derivative of naturally occurring pyrethrins[1] (taken from pyrethrum: the oleoresin extract of dried chrysanthemum flowers), first synthesized in 1974 and has risen to become one of the most important insecticides in wide-scale use.
J.P Leahey wrote in his book ‘The pyrethroid Insecticides’ that no insecticide is perfect “but the pyrethroids come close”[2].
Exposure to sunlight, water and oxygen accelerates the decomposition of many insecticides, being synthetic, cypermethrin is one of a handful of light-stable synthetic pyrethroids, yielding longer residence times. Studies has shown that residue from cypermethrin can last for 84 days when applied to indoor inert surfaces such as walls, floors and furniture.
Cypermethrins chemical structure is loosely based upon Pyrethrins. Cypermethrin is a complex molecule, with eight different ways in which the atoms are arranged in three dimensions, these are called isomers. Cypermethrin is a mixture of all eight isomers making it, on a molecular level, one of the most complex insecticides.
Cypermethrin: Summary effect on insects
Cypermethrin behaves as a fast-acting neurotoxin affecting the peripheral and central nervous system of insects by binding with and disrupting the correct functioning of their ion chaNnel, altering the membrane potential and sodium ion permeability ultimately leading to death.
Cypermtherin: On the central nervous systems of insects?
Never impulses travel along nerves when the nerves become momentarily permeable to sodium atoms, which allows sodium to flow into the nerve. Cypermethrin delays the ‘closing of the gate’ allowing sodium to flow. This results in multiple nerve impulses instead of the usual single impulse, in turn, these impulses cause the nerves to release neurotransmitter acetylcholine and stimulate other nerves. At the same time, Cypermethrin also inhibits the y-aminobutyric acid receptor, causing excitability and convulsions whilst also inhibiting calcium uptake by the nerves and its monoamine oxidase (an enzyme which breaks down neurotransmitters). Cypermethrin also affects the enzyme adenosine triphosphatase, which is involved in cellular energy production, the transport of metal atoms and muscle contractions. In short, Cypermethrin interferes with the ionic conductance of erve membranes by prolonging the sodium current, stimulating nerves to discharge repeatedly causing hyper-excitability.
[1] The insecticidal properties of pyrethrins are derived from ketoalcholic esters of chrusanthemic and pyrethroic acids, these acids are strongly lipophilic and rapidly penetrate many insects and paralyze their nervous system.
[2] Leahey, J.P. (ed.), The Pyrethroid Insecticides, Taylor & Francis, London, 1985