Pyrethrums

Pyrethrums Pyrethrins are an extract of the pyrethrum daisy Chrysanthemum

cinaeriofolium. (Chrysanthemum flowers) They are the most widely used botanical insecticide. They are the active ingredient of many household sprays and home vegetable-garden preparations. Chemists have built upon the basic pyrethrins molecules, producing a whole new class of useful pesticides--the pyrethroids. These are synthetic pyrethrins with improvements, such as extended persistence or the ability to control other pests, that make them more suitable for pest management. Pyrethroids have been the fastest-growing class of new insecticides over the past decade and include products such as permethrin, which last much longer. The Advantages of Pyrethrins are that they are highly irritating to insects and provides rapid "knockdown." Pyrethrins are often is the active ingredient in "wasp and hornet" sprays. One of the Disadvantages of Pyrethrins are that they have a short residual effect, hence the need for longer lasting synthetic versions (the pyrethroids) that don’t break down in sunlight in just a few hours.

Another naturally occurring material, often used in conjunction with permethrin products, is “Piperonyl Butoxide”. When Piperonyl Butoxide is combined with pyrethin as a synergist, it gives it faster knock down. Piperonyl Butoxide is derived from Sassafras trees

As mentioned above natural pyrethrins work good but only for just a short time; hours, when exposed to sunlight. Consequently we at Bugaboo prefer to fill our arsenal with pyrethroid products, synthetic pyrethrins. Some of these are as follows:

Examples of Synthetic Pyrethrins

What is Cyfluthrin? Cyfluthrin is a member of the pyrethroid chemical class (a synthetic Pyrethin). insecticide that has both contact and stomach poison action. Cyfluthrin, the main active ingredient in INTRUDER HPX, which is considered to be moderately toxic to mammals. It contains just .10% Cyfluthrin, .05 pyrethrins, and .05% Piperonyl Butoxide. Although Cyfluthrin is an irritant to human skin, especially facial skin, it is not considered to have high dermal toxicity. Although Cyfluthrin is a skin and eye irritant in humans, pyrethroid poisonings are rare. The main reason for cyfluthrin’s low toxicity in humans, is that it is rapidly broken down in the human body by liver proteins, and eliminated quickly out of the body. Also, pyrethroids are not well absorbed into the bloodstream, contributing to their moderate acute toxicity in mammals. There was no evidence of carcinogenicity in rats or mice. Cyfluthrin is of low toxicity to upland game birds and waterfowl. However, Cyfluthrin is highly toxic to marine and freshwater organisms. Cyfluthrin is not considered a threat to contaminate groundwater. INTRUDER HPX also contains Pyrethrins and Piperonyl Butoxide which is derived from Sassafras trees.

The following article on Pyrethrums / Pyrethrins by D. R. Maciver, Laboratory Manager at Fairfield American Corporation in Newark, New Jersey is also very informative.

Despite the many advantages that chemical pesticides provide in controlling plant pests, most have serious limitations as well. Not only do they have to be applied carefully because of possible hazards to humans and animals, but insects often develop resistance to them very quickly And yet there is an insecticide available that has neither of these drawbacks. It is safe and effective, and it has been in use for years without any sign of insect resistance developing. And new means are being devised for improving it and making it more effective.
The insecticide is natural pyrethrum, Extracted from a daisy grown mainly in Kenya, it has been in use in the West since the early twentieth century. At one time pyrethrum powder was mixed with kerosene to create a sprayable liquid insecticide. Today pyrethrum flowers are processed into extracts to serve domestic, industrial and agricultural needs. Insecticides using natural pyrethrum as active ingredient include Fairfield American's Pyrenone.

Natural pyrethrum, despite its power and safety, has certain limitations The fact that it is imported means it comparatively expensive. Moreover, some insects - houseflies for example - are able to detoxify modest amounts of the poison in their bodies. These tend to recover from any but the heaviest doses. In addition, natural pyrethrum tends to break down in sunlight, rapidly losing its effectiveness after outdoor use. Researchers have dealt with the detoxification problem by combining pyrethrum extract with a liquid synergist, piperonyl butoxide, which fools the insect's metabolism so that it doesn't break down pyrethrum in the body. Mixed with this chemical, a small amount of pyrethrum can control insects effectively.
As for the tendency of the substance to degrade in sunlight, this has turned out to be a blessing in disguise. Pyrethrum is considered biodegradable and is sought for sensitive applications like the post-harvest treatment of fruits and vegetables. Natural pyrethrum is so safe that the U.S. Government approves its use on such insect-prone foods as tomatoes, even while they are on their way to the supermarket or processing plant. And in 1946 the city of Amsterdam added pyrethrum to the municipal water supply to kill a population of insects that were threatening 'to choke the system. The insects were destroyed, while humans continued to drink, wash and cook with the treated water without suffering any harm.

Because of its safety, pyrethrum has long been preferred for household and agricultural applications. But recent research is revealing new power and new uses for this old and tested insecticide. Combined with a synergist, natural pyrethrum is one of the fastest-acting insecticides known. Even before it kills, it knocks down and paralyzes insects almost immediately. When it encounters pyrethrum, the insect is thrown into a state of nervous disorder. It runs from its hiding place and scuttles around erratically, or adopts a confused flight pattern. Both responses show that the insect has lost all control of its central nervous system. This contact effect is called activation. Recent practice exploits the activation effect by adding small mounts of pyrethrum to a routine residual agricultural formulation.
Pyrethrum activates hidden insects, driving them from cover and into contact with the main insecticide. This "flushing" action has been most successful in the control of such hard-to-hit pests as the cotton bollworm and the gypsy moth.

Recently, researchers have identified a subtle effect that occurs even before activation takes place: jamming. The jamming phenomenon suggests new uses for pyrethrum in the battle against malaria. To show how jamming works, you need only a cage full of voracious female mosquitoes and some extremely brave volunteers. Those who put their bare arms in the cage can expect to get some 20 to 50 bites per minute. But if the cage is exposed to trace amounts of pyrethrum for only five minutes and the arm is reinserted, no bites are recorded, even though the insects otherwise seem completely normal. Apparently small amounts of pyrethrum can jam the "black box" of the insect's food-searching mechanism: The insect forgets to eat as it were. Because of this effect, low-level pyrethrum applications have been shown to reduce the risk of malaria carried by indoor mosquitoes

There's more to pyrethrum's bag of tricks. The reason is not fully understood, but insects do not become resistant to natural pyrethrum. After decades of use, no insect population has ever developed significant pyrethrum resistance. Intense study of the pyrethrum, molecule has produced the related synthetic materials, pyrethroids. But so far science has not devised a synthetic that combines the speed, effectiveness, activation effects and biodegradability of natural pyrethrum. Over 85% of the world's pyrethrum comes from Kenya, where it is grown by thousands of family farmers organized into cooperatives. Other suppliers are Ecuador, New Guinea, Tanzania and Rwanda. Because of factors ranging from weather conditions to competition from other cash crops, the pyrethrum supply often swings wildly from dearth to glut.
The Kenyan government is' presently acting to stabilize pyrethrum production, and has set up the Pyrethrum Board of Kenya to accomplish this. Pyrethrum is the country's fourth-largest export and forms an important part of its mixed agricultural economy. Stability in the industry is sorely needed. A recent survey sponsored by the United Nations International Trade Center stressed the importance of pyrethrum, and estimated its growth potential to exceed that of any other botanical insecticide. If production can be brought more into line with demand, we are likely to encounter pyrethrum more often in the near future - both alone, and as an adjunct to traditional residual insecticides.

Don MacIver is an English-trained organic chemist and entomologist. He headed the information bureau for the Kenyan pyrethrum industry for 15 years, and edited and published the journal Pyrethrum Post. He now lives in the United States and serves as laboratory manager for Fairfield American Corporation.
Flowers from which pyrethrum is extracted are still harvested by hand in Kenya. The extract is prepared at a plant in Nakuru, Kenya, and shipped by air to the U.S.