Insecticides

Synthetic Pyrethriod Insecticide

Synthetic pyrethroids are synthesized derivatives of physically occurring pyrethrins that are in use from pyrethrum, the oleoresin extract of dried chrysanthemum flowers. The insecticidal belongings of pyrethrinsare derived from ketoalcoholic esters of chrysanthemic and pyrethroic acids. These acids are strongly lipophilic and quickly enter many insects and paralyze their nervous system. Both pyrethrins and synthetic pyrethroids are sold as profitable pesticides used to control pest insects in agriculture, homes, communities, restaurants, hospitals, schools and as a topical head lice cure. Various formulations of these insecticides are often combined with other chemicals, known as synergists, to increase potency and persistence in the environment. While chemically and toxicologically alike, pyrethrins are very sensitive to light, heat and moisture. However, the pyrethroids, the synthetic analogues of obviously occurring pesticides, were urbanized to capture the effective insecticidal activity of this botanical insecticide, with increased constancy in light, yielding longer residence times. They are not easily absorbed through the skin, but are captivated through the gut and pulmonary membrane.

Tested and reliable: Tests of some pyrethroids on laboratory animals disclose striking neuro toxicity when administered by injection or verbally. Systemic toxicity by inhalation and dermal absorption is low. The acute toxicity, ranges from low to high, depending on the exact formulation. Low toxicity is attributed to two factors like limited absorption of some pyrethroids and rapid biodegradation by mammalian liver enzymes. Insects, without this liver function, exhibit greater susceptibility to the chemicals. Pyrethroids interfere with the ionic conductance of nerve membranes by prolonging the sodium current. This stimulates nerves to free repeatedly causing hyper excitability in poisoned animals. The synthetic pyrethroids are neuropoisons acting on the axons in the peripheral and central nervous systems by interacting with sodium channels in mammals and insects. The major systems for metabolism include breakage of the ester bond by esterase action and oxidation at various parts of the particle. Induction of liver microsomal enzymes has also been observed.

Sing of poisoning: Signs and symptom of poisoning by pyrethroids may take numerous forms. Because of the similarities to basic pyrethrum, pyrethroids can act as dermal and respiratory allergens. Contact to pyrethroids has resulted in contact dermatitis and asthma like reactions. People, especially children, with a history of allergies or asthma are particularly sensitive and a strong cross reactivity with ragweed pollen has been recognized.

Insecticides