Piretroidok

Piretroidok, known in English as pyrethroids, are a class of synthetic insecticides developed as stable, more persistent analogs of natural pyrethrins. They were introduced in the mid-20th century and have since become among the most widely used insecticides in agriculture, public health, and domestic pest control.

Chemically, pyrethroids are ester derivatives of chrysanthemic or related acids, and they are commonly categorized into Type I and Type II. Type I pyrethroids lack an alpha-cyano group; Type II possess it, which influences potency and duration of action. They are generally lipophilic and designed for improved stability compared with natural pyrethrins.

Mechanism of action involves targeting voltage-gated sodium channels in insect neurons, delaying channel closing and causing prolonged depolarization and repetitive nerve firing. This leads to paralysis and death of the insect. Type II pyrethroids are typically more potent and longer-lasting, and can produce distinct neurotoxic signs in mammals at high exposures.

Applications and formulations cover a broad range of pests, including agricultural crops, stored products, and disease vectors. Common formulations include emulsifiable concentrates, wettable powders, and granules, used in field sprays, indoor residual sprays, and spot treatments. Resistance management emphasizes rotating modes of action and integrating non-chemical methods.

Safety and environmental considerations: pyrethroids generally have low acute mammalian toxicity but can cause nervous-system symptoms with high exposure. They can be toxic to aquatic organisms and some non-target insects such as bees, especially with improper use. Persistence varies by compound and environment, with degradation accelerated by sunlight and microbial action. Regulatory status and permitted uses vary by country and context.