Pyrethrin II

Pyrethrin-II-2D-skeletal

Pyrethrin II is one of the six pyrethroids that are naturally occurring compounds found in the flowers of Chrysanthemum cinerariifolium and other Chrysanthemum species. Pyrethrins, including Pyrethrin II, are highly regarded for their use in insecticide formulations due to their effectiveness in controlling a wide range of insect pests while being relatively safe for humans and other mammals. Pyrethrin II, specifically, is known for its potent insecticidal activity, which is attributed to its ability to disrupt the neurological system of insects, leading to paralysis and death.

Chemistry

Pyrethrin II is a natural organic compound characterized by its chemical structure that includes a cyclopropane carboxylate and a chrysanthemic acid ester linked to a pyrethrolone moiety. This structure is responsible for its insecticidal properties, as it interacts with the sodium channels in nerve cells, prolonging their activation and causing the nervous system to malfunction. The chemical is sensitive to light, air, and moisture, which can lead to rapid degradation and a decrease in efficacy. This sensitivity necessitates careful formulation to maintain its insecticidal activity.

Mode of Action

The mode of action of Pyrethrin II involves targeting the sodium channels in the neuronal membranes of insects. By binding to these channels, Pyrethrin II prevents their closure, leading to prolonged sodium ion exchange and continuous nerve impulse transmission. This results in hyperexcitation of the nervous system, paralysis, and eventually death of the insect. This mode of action is similar to that of synthetic pyrethroids, which are designed to mimic the insecticidal activity of natural pyrethrins but with enhanced stability and efficacy.

Uses

Pyrethrin II is widely used in the formulation of insecticides for household, agricultural, and veterinary applications. Its rapid action and low mammalian toxicity make it an ideal component in products aimed at controlling mosquitoes, flies, fleas, moths, and other pests. Pyrethrin II is often combined with other insecticides or synergists, such as piperonyl butoxide, to enhance its efficacy and overcome insect resistance.

Safety and Environmental Impact

Pyrethrin II is considered to be of low toxicity to humans and other mammals when used as directed. However, it can cause allergic reactions in some individuals, and care should be taken to avoid inhalation or direct contact with the skin. In the environment, Pyrethrin II is rapidly degraded by sunlight and microorganisms, minimizing its long-term impact. However, it is highly toxic to aquatic organisms, including fish and invertebrates, necessitating careful management of runoff and disposal of products containing pyrethrins.

Regulation

The use of Pyrethrin II, like other insecticidal compounds, is subject to regulation by various national and international agencies to ensure its safe and effective use. Regulations may include restrictions on application rates, target pests, and approved uses, as well as guidelines for handling, storage, and disposal to protect human health and the environment.