Insecticide pyrethrum

Andreas Buxtorf and Max Spindler. Fifteen Years of Geigy Pest Control. Basel, Switzerland J. R. Geigy S.A., 1954. Source for Geigy woolen specialty natural insecticides delousing during World War I pre-DDT insecticides pyrethrum and rotenone as controls and visit to United States. 

Areas of application Mode of action How obtained Remarks Aphids, blossom weevils and other weevils, tortricids, winter moth, bugs, noctuid moths Contact, ingestion and inhalation insecticide Pyrethrum is produced from chrysanthemums and contains piperonyl butoxide as an additive which increases UV stability Very broad spectrum of action Not completely harmless to beneficials Pyrethrum is poisonous to fish Sprays consisting of pyrethrum alone are also commercially available (e.g. Spruzit)... 

Sulfur ylides can also be used in the synthesis of chrysanthemate esters (72) from hept-2-enoates (73) (Scheme 27). The natural insecticide pyrethrum is a complex chrysanthemate ester, and the formation of trans-chrysanthemic acid is consequently important for the synthesis of many synthetic pyrethroid insecticides. 

Permethrin is a synthetic derivative of the insecticide pyrethrum, which was obtained originally from Chrysanthemum cinerariaefolium. Neurotoxicity associated with this compound is extremely rare. A 5% cream (Acticin, Elimite, others) is available in the treatment of scabies. This is used as an 8- to 12-hour or overnight application. A 1% permethrin cream rinse (NIX) also is available for the treatment of lice. 

The natural insecticide, pyrethrum traditionally has been considered to have the qualities of the ideal insecticide because it is a powerful insecticide and harmless to mammals under normal use conditions. However, the natural pyrethroids are too unstable outdoors to find use as agricultural insectides. In 1949 the first synthetic pyrethroid, allethrin, was announced (see Table 29.14). It acted more rapidly and effectively than the natural material, particularly on the common housefly but on other species it was less active. This initiated the search for related materials with a combination of properties that would eventually lead to commercial insecticides that could be used in outdoor agricultural applications. The discovery of permethrin by Michael Elliot in 1973 showed that pyrethroids could be found that were stable to outdoor environments. Permethrin also had exceptionally high insecticidal action (0.1 lb ai/A). 

Figure 8.3 Antique container of pyrethrum powder. Labeled here as an insecticide, pyrethrum powder was also used as a repellent. (From GIttIns, J., and Trask, B.H., Wing Beats, 16 (4), 16-20, 2005.)...

The edible parts of parsnips contain a chemical of insecticidal and strong synergistic nature. This chemical, present in a concentration of about 200 p.p.m., was isolated and identified as 5-allyl-l-methoxy -2, 3-methylene-dioxybenzene or myristicin. Its toxicity to various insects (fruit flies, etc.) was established and compared with pyrethrum and aldrin. A second chemical, identified as 2-phenylethyl isothiocyanate, was found in the edible parts of turnips and rutabaga, which also have been consumed for centuries by humans without obvious harm. 

Godin et al. (10), working on the effect of insecticidal activity of pyrethrum flowers from fresh and dried flowers, showed that extracts from fresh flowers had little or no greater effect on pyrethroid content and insecticidal activity than extracts from dried flowers with drying temperatures up to 80 °C. However, some of all the pyrethrin was lost at 120°C. The principal loss was in pyrethin I and not pyrethin II. 

The biochemistry or mode of action of pyrethrum is not as well known as its chemistry. There are several theories of the toxic action of pyrethrum. Lauger et al. (26) consider that a highly effective contact insecticide must possess a toxic component (toxaphore) and must have groups attached which absolutely insure pronounced lipid solubility. They consider in the case of pyrethrins that in the cyclopro-... 

By employing C14-labeled pyrethrum, it has been determined that at 35 °C. the rate of penetration of pyrethrum is more than twice that at 15°C. Cockroaches prostrate at 15 °C. can be returned to normal by transferring them to 35 °C., a process which can be repeated for several hours. Since cockroaches transferred from 35° to 15°C. became prostrate more rapidly than those held continuously at 15°C., the insecticide (or some metabolic toxin) was probably in the vicinity of its site of action at 35 °C. but was ineffective. 

Both cis- and trans-chrysanthemic nitriles and amides were resolved into highly enantiopure amides and acids by Rhodococcus sp. whole cells [85]. The overall enantioselectivity of reactions of nitriles originated from the combined effects of a higher (lJ )-selective amidase and a (IJ )-selective nitrile hydratase (Figure 6.29). Chrysanthemic acids are related to constituents of pyrethrum flowers and insecticides. 

Another extremely important military requirement that is not usually associated with civilian requirements is stability in prolonged storage under adverse conditions. For example, the first lots of fly spray that were shipped to North Africa, in 1942, contained pyrethrum as the principal active ingredient. It was not possible to store this material under cover and much of it remained under constant exposure to the intense tropical sun, undoubtedly deteriorating very rapidly. Covered storage facilities are the exception rather than the rule in a combat theater of operations, and all insecticide compounds furnished to the military forces should withstand this type of storage. 

After mothproofing wool, the next logical step for Geigy was to invent an insecticide that killed more kinds of pests. Imported natural insecticides made from plants, including pyrethrum from tropical chrysanthemums, rotenone from a tropical vine, and nicotine from tobacco, could be quite expensive they were also not persistent and were easily destroyed by light and heat. American and European attempts to synthesize their active ingredients had failed. Arsenic compounds remained the only cheap and effective insecticides. 

To Muller, just starting out on his search for an effective insecticide, the situation looked desperate indeed. A flood of patents had already been issued, and he realized that the chances were worse than poor only a particularly cheap or remarkably effective insecticide had any prospects of being used in agriculture. Yet there was hope. After experimenting with products described in the patent literature, he realized that practically none of the new compounds was being sold the existing arsenates, pyrethrum, and rotenone insecticides were more effective. Reassured about the competition, Muller had the courage to press on. 

For four years, Muller synthesized his own compounds and almost single-handedly screened them for their effect on houseflies. They were known to be transmitters of intestinal diseases like dysentery, and it was speculated at the time that they might spread polio. Muller built a cubic-meter glass chamber for insects and sprayed compound after compound at them. As soon as one compound seemed promising, he searched more carefully among its close relatives, using the natural insecticides, rotenone and pyrethrum, as controls. 

At first, Geigy s biologists were puzzled because the insects sprayed with DDT did not die immediately. Accustomed to the quick action of pyrethrum and rotenone, they dismissed Muller s discovery as unimportant. They did not realize that DDT s long period of activity could be far more important than sheer speed. In the parlance of insecticides, DDT had slow knockdown but sure kill. Surfaces sprayed with DDT in 1941 and stored under dust-free laboratory conditions were still toxic to insects seven years later. 

Botanical Pyrethrum Pyganic, Safer Whitefly, aphid, leafhopper Tomato, cucumber, apple, potato Insecticide... 

Chrysanthemum cinerariaefolium (1) is a species of white flower and contains more insecticidal ingredients than other species. This pyrethrum species originated from Dalmatia and has been used for cultivation. On the other hand, the origin of Roseum (2) is Persia and the Caucasus. It has beautiful red flowers but its pyrethrin content is extremely low compared to (1). Known as red-flowered pyrethrum, it is used merely as an ornamental plant. Marshalli (3) originated from Persia and contains pyrethrins in negligible amounts therefore, the pyrethrum referred to in this text is from C. cinerariaefolium (1). 

As mentioned above, the origin of pyrethrum is the Dalmatian region of the former Yugoslavia on the Mediterranean coast of the Adriatic Sea, east of Italy. It is said that pyrethrum was discovered in 1694. While inhabitants of the pyrethrumgrowing region seem to have already known about the properties of this plant and to have utilized it in powder form for insecticide applications, its insecticidal activity was verified in around 1840. 

Pyrethrum became the main source of household insecticides in sprays in the USA (1919) and mosquito coils (1895) as well as oil-based preparations (1924) in Japan. Thereafter, the insecticidal ingredients shifted from pyrethrins to various synthetic pyrethroids, but mosquito coils have been used worldwide for more than 110 years without changing in shape. 

Pyrethrin II was also detected in young leaves 2 months after seeding, similarly to pyrethrin I, but the content remained at about 0.05 wt% without seasonal change for 2 years. The insecticidal potency of pyrethrins obtained from pyrethrum leaves was confirmed with Musca domestica. 

Fujitani [6] separated the insecticidally active syrupy ester from pyrethrum flowers in 1909 and named the ester pyrethron. Yamamoto [7, 8] subjected the hydrolysis product of this pyrethron to ozone oxidation, and isolated Iram-caronic acid and aldehyde (1 and 2, respectively, Fig. 3). Although Yamamoto did not determine the structure of this acid, he presumed it to be pyrethron acid (Fig. 3). Eventually, the presence of a cyclopropane ring in the molecule of natural pyrethrins became clear for the first time in 1923. 

Natural pyrethrins, derived from pyrethrum, contain six insecticidal components. Due to their excellent insecticidal potency against insects in small amounts and their high safety for mammals, they are the only natural insecticidal components used for more than 100 years to date throughout the world as a household insecticide. 

Sanitary insects coming into houses are largely divided into two types - flying insects and crawling insects. The use of pyrethrum powders as an insecticide for crawling insects was started around 1855 in the USA and in 1886 in Japan. Mosquito coils were developed in 1890 in Japan and oil formulations containing pyrethrum extract were available in 1919 in the USA. 

Natural pyrethrins are a neurotoxin and repel, knock down, and kill by contact with insects at a low concentration. On the other hand, they have ideal features for household insecticides because of their quite low dermal and oral toxicides to warm-blooded animals. Neither plants other than pyrethrum nor synthetic insecticides have been reported to have such properties. Numerous synthetic pyrethroids have been developed by chemists since the complicated chemical structure of natural pyrethrins was elucidated in the middle of the twentieth century. Allethrin was the first synthetic pyrethroid put into practical use. 

Pyrethroids are a class of synthetic insecticides designed and optimized based on the structure of the pyrethrins found in natural pyrethrum extracted from chrysanthemum flowers [1, 2], Pyrethroids are widely used to control insect pests in agriculture and public health because of their relative safety for humans and high insecticidal potency [3]. 

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