:Pyrethrum

Some members of the genus Chrysanthemum, such as the following two, are placed in the genus Tanacetum instead by some botanists. Both genera are members of the daisy (or aster) family, Asteraceae. They are all perennial plants with a daisy-like appearance and white petals.

{{anchor|Tanacetum cinerariifolium}}

• Image:Tanacetum cinerariifolium1.jpg Tanacetum cinerariifolium is called the Dalmatian chrysanthemum, denoting its origin in that region of the Balkans (Dalmatia). It looks more like the common daisy than other pyrethrums do. Its flowers, typically white with yellow centers, grow from numerous fairly rigid stems. Plants have blue-green leaves and grow to {{convert|45|to|100|cm|abbr=on}} in height. The plant is economically important as a natural source of pyrethrin insecticides.
• Image:Tanacetum coccineum2.jpgC. coccineum, the Persian chrysanthemum, is a perennial plant native to Caucasus and looks somewhat like a daisy. It produces large white, pink or red flowers. The leaves resemble those of ferns, and the plant grows to between {{convert|30|and|60|cm|abbr=on}} in height. The flowering period is June to July in temperate climates (Northern Hemisphere). C. coccineum also contains insecticidal pyrethrins, but it is a poor source compared to C. cinerariifolium.
• Other species, such as C. balsamita and C. marshalli, also contain insecticidal substances, but are less effective than the two species mentioned above.

File:Tanacetum cinerariifolium MHNT.BOT. 2012.10.14.JPG

The flowers are pulverized and the active components, called pyrethrins, contained in the seed cases, are extracted and sold in the form of an oleoresin. This is applied as a suspension in water or oil, or as a powder. Pyrethrins attack the nervous systems of all insects, and inhibit female mosquitoes from biting. When present in amounts less than those fatal to insects, they still appear to have an insect repellent effect. They are harmful to fish, but are far less toxic to mammals and birds than many synthetic insecticides and are not persistent, being biodegradable and also decompose easily on exposure to light. They are considered to be amongst the safest insecticides for use around food. In 1998 Kenya was producing 90% (over 6,000 tonnes) of the world's pyrethrum, called py for short. Production in Tanzania and Ecuador is also significant. Currently the world's major producer is Tasmania, Australia.

Pyrethrum has been used for centuries as an insecticide,Bioaromatica [https://web.archive.org/web/20100324061424/http://www.aromatica.hr/eng/page.asp?id=buhac&sub=buhac3 The history of pyrethrum] and as a lice remedy in the Middle East (Persian powder, also known as "Persian pellitory"). It was sold worldwide under the brand Zacherlin by Austrian industrialist J. Zacherl.{{US patent reference| number = 308172|issue-date=November 18, 1884| inventor = Johann Zacherl| title =Pyrethrum Soap}} It is one of the most commonly used non-synthetic insecticides allowed in certified organic agriculture.[http://www.colostate.edu/Depts/CoopExt/4DMG/VegFruit/organic.htm Some Pesticides Permitted in Organic Gardening], by Laura Pickett Pottorff, Colorado State University Cooperative Extension, January 5, 2010.

The flowers should be dried and then crushed and mixed with water.

• Pyrethroids are synthetic insecticides based on natural pyrethrum (pyrethrins); one common example is permethrin. Pyrethrins are often sold in preparations that also contain the synthetic chemical piperonyl butoxide, which enhances the toxicity to insects and is faster acting compared with pyrethrins used alone. These formulations are known as synergized pyrethrins.

A pheromone produced by these plants attracts ladybug beetles, and at the same time acts as an alarm signal to aphids.{{cite journal |last1=Li |first1=Jinjin |last2=Hu |first2=Hao |last3=Mao |first3=Jing |last4=Yu |first4=Lu |last5=Stoopen |first5=Geert |last6=Wang |first6=Manqun |last7=Mumm |first7=Roland |last8=Ruijter |first8=Norbert C. A. |last9=Dicke |first9=Marcel |last10=Jongsma |first10=Maarten A. |last11=Wang |first11=Caiyun |title=Defense of pyrethrum flowers: repelling herbivores and recruiting carnivores by producing aphid alarm pheromone |journal=New Phytologist |date=August 2019 |volume=223 |issue=3 |pages=1607–1620 |doi=10.1111/nph.15869|pmid=31087371 |pmc=6772172 |bibcode=2019NewPh.223.1607L }}

Rat and rabbit {{LD50}} levels for pyrethrum are high, with doses in some cases of about 1% of the animal's body weight required to cause significant mortality. This is similar to fatal levels in synthetic pyrethroids.[http://edis.ifas.ufl.edu/pi091 Pesticide Toxicity Profile: Synthetic Pyrethroid Pesticides] {{Webarchive|url=https://web.archive.org/web/20210422160831/https://edis.ifas.ufl.edu/pi091 |date=2021-04-22 }}, by Frederick M. Fisher, University of Florida IFAS Extension Service, 2013 Nevertheless, pyrethrum should be handled with the same caution as synthetic insecticides:[http://edis.ifas.ufl.edu/in197#TABLE_1 insecticide (botanical, mineral, synthetic) toxicity to mammals] Electronic Data Information Source of University of Florida safety equipment should be worn, and mixing with other chemicals should be avoided.{{cite web |title=Using Pyrethrum |url=https://www.abc.net.au/gardening/factsheets/using-pyrethrum/9434612 |website=Gardening Australia |publisher=Australian Broadcasting Corporation |access-date=3 November 2018 |date=25 May 2013 |quote="I've also marked my pyrethrum bottle 'for pesticides only'. I have another one for herbicides. It doesn't matter whether you're organic or not, accidents can happen. It's best to keep these chemicals apart." As a precaution, safety gear should be worn when using pyrethrum.}}

People can be exposed to pyrethrum as a mixture of cinerin, jasmolin, and pyrethrin in the workplace by breathing it in, getting it in the eyes or on the skin, or swallowing it. The Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for pyrethrum exposure in the workplace as 5 mg/m³ over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 5 mg/m³ over an 8-hour workday. At levels of 5000 mg/m³, pyrethrum is immediately dangerous to life and health. People exposed to pyrethrum may experience symptoms including pruritus (itching), dermatitis, papules, erythema (red skin), rhinorrhea (runny nose), sneezing, and asthma.{{Cite web|title = CDC - NIOSH Pocket Guide to Chemical Hazards - Pyrethrum |url = https://www.cdc.gov/niosh/npg/npgd0685.html|website = www.cdc.gov|access-date=October 23, 2015}}

Pyrethrum, specifically the pyrethrin within, is highly toxic to insects including useful pollinators like bees. The risk of killing bees and other beneficial insects is partially reduced by the compound's rapid breakdown (a half-life of approximately 12 hours on plants and on the surface of the soil, with about 3% remaining after five days, but persisting several weeks or more if it enters a body of water or is dug into the soil) and its slight insect-repellant activity.{{cite web |title=Pyrethrins general fact sheet |url=http://npic.orst.edu/factsheets/pyrethrins.pdf |website=national pesticide information center}}

Common names for Chrysanthemum cinerariifolium include:

• Pyrethrum
• Pyrethrum daisy
• Dalmatian pyrethrum
• Dalmatian chrysanthemum
• Dalmatian insect flower
• Dalmatian pellitory
• Big daisy

Common names for Chrysanthemum coccineum include:

• Pyrethrum
• Pyrethrum daisy
• Painted daisy
• Persian chrysanthemum
• Persian insect flower
• Persian pellitory
• Caucasian insect powder plant

• Chrysanthemum
• List of companion plants
• Category: Plant toxin insecticides
• Permethrin
• Pyrethrin

{{Reflist}}

• [http://npic.orst.edu/factsheets/pyrethrins.pdf National Pesticide Information Center: Pyrethrins and Pyrethroids Fact Sheet]
• [https://www.cdc.gov/niosh/npg/npgd0685.html CDC - NIOSH Pocket Guide to Chemical Hazards]
• [https://web.archive.org/web/20070927005503/http://www.andover.edu/news/documents/B-ChemicalFactSheet.pdf EXTOXNET: Pyrethrins and Pyrethroids]
• [http://www.pyrethrum.com "What is Pyrethrum?"] {{Webarchive|url=https://web.archive.org/web/20110124192128/http://www.pyrethrum.com/ |date=2011-01-24 }}
• [http://nph.onlinelibrary.wiley.com/doi/10.1111/nph.15869 Role of aphid alarm pheromone produced by the flowers in repelling aphids and attracting ladybug beetles]

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Category:Pyrethroids

Category:Flora of Europe

Category:Plant toxin insecticides

Category:Biological pest control

Category:Garden plants of Europe

Category:Household chemicals

Category:Anthemideae

Category:Plant common names

Category:Historically recognized angiosperm genera