Myths vs Facts
Sometimes it's difficult to tell a myth from a fact. When myths are repeated enough, the perception is they might be true. Below are some of the most commonly asked questions about pyrethrum and factual answers. Hopefully they will help clarify some common misperceptions.
Where does pyrethrum come from?
Pyrethrum is found in the Chrysanthemum plant, Chrysanthemum cinerariifolium. Pyrethrum is found at particularly high concentration within flower structures known as achenes which are located in the flowerhead of the Chrysanthemum.
What are the differences between pyrethrum, pyrethrins and pyrethroids?
Pyrethrum is the extract from the flowerhead of the Chrysanthemum plant. The six esters known collectively as pyrethrins are found within the pyrethrum extract. The pyrethrins are the active ingredient in pyrethrum that kills insects.
Pyrethroids are synthetically produced compounds with a chemical structure that is similiar to the structure of one of the pyrethrin esters. They kill insects by a similiar mode of action, but do not come from flowers.
How does pyrethrum kill insects?
Pyrethrum induces a toxic effect in insects when it penetrates the cuticle and reaches the nervous system. The pyrethrins that compose pyrethrum bind to sodium channels that occur along the length of nerve cells. Sodium channels are responsible for nerve signal transmission along the length of the nerve cell by permitting the flux of sodium ions. When pyrethrins bind to sodium channels, normal function of the channels is obstructed thereby resulting in hyperexcitation if the nerve cell and, consequently, a loss of function of the nerve cell. The shutdown of the insect nervous system and insect death are most often the consequences of insect exposure to pyrethrins.
What happens to pyrethrum in the environment?
Pyrethrum does not persist for a long time in the environment. The active chemicals in pyrethrum, pyrethrins, are degraded by high temperature and UV light.
What kind of insects can be controlled with pyrethrum based products?
Pyrethrum is a broad spectrum insecticide. Meaning it will affect a wide range of insects; including beneficials.
How long have pyrethrins been used for insect control?
Pyrethrins have been used in insect control for more than 160 years.
Will pyrethrum/ins degrade or become less potent during storage?
Most products are packaged in containers that do not let UV light through, and indicate they should be stored in a cool, dry place. Under these conditions most products should maintain their potency for a couple of years. If the product is subjected to high temperature or UV light, there can be some degradation of the pyrethrins. As with most products, you should only purchase what you need, and for best results use it within the season it is purchased.
How safe is Pyrethrum?
Pyrethrum has been extensively studied for its effects on people and the environment. Like all insecticides, pyrethrum is used to have a toxic effect on insects. Thus it is not correct to say that pyrethrum is "safe." At the same time, we are confident that pyrethrum has a very good toxicity profile. For mammals, doses that elicit toxic reactions are significantly larger than the exposures people typically experience in using pyrethrum based products.