How to choose more user friendly Insecticides.

A Community Health

How to Control Mosquitoes

Part 4: Pyrethroids Insecticides

Chrysanthemum flowers

The flower of Pyrethrums from the plants Chrysanthemum cinerariaefolium and C. coccineum, familia Asteraceae, produce natural chemical pyrethrins,
pyrethrins are contained in the seed cases, which is grown commercially to supply the insecticide, pyrethrins are a pair of natural organic compounds that have potent insecticidal activity. pyrethrin I and pyrethrin II, the chemical structure of pyrethrins is the basis for a variety of synthetic insecticides called pyrethroids.

Pyrethrin I

Pyrethrin II

Pyrethrins are neurotoxins that attack the nervous systems of all insects. when present in amounts not fatal to insects, they still appear to have an insect repellent effect, pyrethrins are harmful to fish, birds, and mammals, including human beings. In human beings, pyrethrin irritates the eyes, skin, and respiratory systems, and it may cause other harmful effects.
pyrethrins are gradually replacing organophosphates and organochlorides as the pesticide of first choice.

Pyrethroids : Synthetic Pyrethrins

Pyrethroids are synthetic chemical compounds similar to the natural chemical pyrethrins, pyrethroid chrysanthemic acid is produced industrially in a cyclopropanation reaction of a diene as a mixture of cis- and trans isomers followed by hydrolysis of the ester, they are common in commercial products such as household insecticides and insect repellents, in the concentrations used in such products, they are generally harmless to human beings but can harm sensitive individuals. They are usually broken apart by sunlight and the atmosphere in one or two days, and do not significantly affect groundwater quality except for being toxic to fish.

Pyrethroids are axonic poisons (see Note*) that work by keeping the sodium channels open in the neuronal membranes of insects, the sodium channel is a small hole through which sodium ions are permitted to enter the axon and cause excitation. as the nerves cannot de-excite, the insect is paralyzed.
pyrethroids are usually combined with piperonyl butoxide, a known inhibitor of key microsomal oxidase enzymes, this prevents these enzymes from clearing the pyrethroid from the body of the insect, and assures the pyrethroid will be lethal and not merely a paralyzing agent. Insects with certain mutations in their sodium channel gene may be resistant to pyrethroid insecticides.

(Note*) Insecticides are neurotoxin, attack the nervous system of insects. There are two main parts of the nervous system: the nerve fibers, called axons, which carry small electrical impulses, and the synapse, the microscopic gap between nerve fibers (axons), because each nerve fiber ends at a synapse, the nerve impulse must be carried across the synapse chemically. The pesticides that attack the synapse are called synaptic poisons, and that attack the nerve fiber (axon) itself are called axonic poisons.

Allethrin

Cyfluthrin

Transflutrin

Commercial Pyrethroid Insecticides / Repellants

[1] Allethrins, [2] Bifenthrin, [3] Cyfluthrin, [4] Cypermethrin, [5] Deltamethrin, [6] Permethrin, [7] Prallethrin, [8] Rasmethrin, [9] Phenothrin or Sumithrin, [10] Tetramethrin, [11] Tralomethrin, [12] Transflutrin, [13] Imiprothrin.

[1] Allethrins are a pair of related synthetic compounds used in insecticides, they are first synthetic pyrethroids, synthetic forms of a chemical found naturally in the chrysanthemum flower.

[2] Bifenthrin a 4th generation pyrethroid, is insoluble in water, has high persistence in soil (half life = 7 days - 8 months), it is the longest residual termiticide currently registered on the market.

[4] Cypermethrin is fast-acting neurotoxin in insects, easily degraded on soil and plants but can be effective for weeks when applied to indoor inert surfaces, exposure to sunlight, water and oxygen will accelerate its decomposition.

[5] Deltamethrin is one of the safest classes of pesticides: synthetic pyrethroids, the most popular and widely used insecticides in the world and have become very popular with pest control operators and individuals in the United States in the past five years, mammalian exposure to deltamethrin is classified as safe, this pesticide is highly toxic to aquatic life, particularly fish, and therefore must be used with extreme caution around water. Deltamethrin is also one of the primary ingredients in ant chalk.

[6] Permethrin does not repel insects but works as a contact insecticide, causing nervous system toxicity that leads to the death or "knockdown" (out of the air) of the insect. effective against mosquitoes, flies, ticks, and chiggers, permethrin has low toxicity in mammals, is poorly absorbed by the skin, and is rapidly inactivated by ester hydrolysis. Permethrin should be applied directly to clothing, shoes, bed nets and camping gear or other fabrics not to skin, permethrin-treated clothing repels and kills ticks, mites, mosquitoes, and other arthropods and retains this effect after repeated laundering, the spray form is nonstaining, nearly odorless, and resistant to degradation by heat or sun (long-lasting repellent) and maintains its potency for at least 2 weeks. Combination of permethrin-treated clothing and skin application of a DEET-based repellent creates a formidable barrier against mosquito bites.

[8] Resmethrin is a pyrethroid insecticide with many uses, including control of the adult mosquito population.

[9] Phenothrin, also called sumithrin, is a synthetic pyrethroid that kills adult fleas and ticks, it has also been used to kill head lice in humans. phenothrin is often used with methoprene, an insect growth regulator that interrupts the insect's biological life cycle by killing the eggs.

[11] Tralomethrin has potent insecticidal properties; it kills by modifying the gating kinetics of the sodium channels in neurons, increasing the length of time the channel remains open after a stimulus, thereby depolarizing the neuron for a longer period of time, this leads to uncontrolled spasming, paralysis, and eventual death.

[12] Transfluthrin can be used in the indoor environment against flies, mosquitoes and cockroaches, it is a relatively volatile substance and acts as a contact and inhalation agent.

Examples :
((1)). Baygon indoor Insecticide, to kill: mosquitos Aedes aegypti, Culex quinquefasciatus, flies Musca domestica, and cockroaches: Blatella germanica, contains: [13] Imipothrin 0,05%, [4] Cypermethrin 0,10%, [12] Transfluthrin 0,06%.
((2)). Baygon indoor Insecticide, to kill: mosquitos Aedes aegypti, Culex quinquefasciatus, and flies Musca domestica, contains: [6] Permethrin 0,10%, [7] Prallethrin 0,04%, [12] Transfluthrin 0,04%.
((3)). Raid Max indoor Insecticide, to kill: mosquitoes, flies, and roaches, contains: [3] Cyfluthrin 0,06%, [12] Transfluthrin 0,06%.
Raid is the brand name of a line of insecticides produced by SC Johnson, first launched in 1956, the initial active ingredient was the first synthetic pyrethroid, Alethrin.

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