pyrethroids
TRANSCRIPT
• Pyrethroids is an organic compound similar to the natural pyrethrins.
• Obtained from dried and powdered flowers, daisy-like plant Chrysanthemum
cinerariaefolium.
• Name given to the active insecticidal component of dried flower “Pyrethrins”.
Combination of two carboxylic acid and three keto alcohols.
• Grown in Kenya, Tanzania, Ecuador, Japan, Uganda, Rwanda and other
countries.
• Recently Australia has become the world’s second largest producer after
Kenya.
Introduction
French soldiers used crushed flowers to control fleas and body
lice during the Napoleonic Wars (1803-1815).
In 1860, pyrethrum powder was introduced to the United States.
In 1881, pyrethrum cultivation was introduced to Japan from
England about 82%.
In 1914, Japan became the principle supplier of pyrethrum flowers to the
United States.
In 1917, the US Navy made the first pyrethrum extracts against houseflies
and mosquitoes.
History
In 1949, first synthetic pyrethroids, allethrin and bioallethrin developed in
America by Milton S. Schechter and colleagues.
Twenty times more effective than DDT.
More active than the natural pyrethrum but are unstable in sunlight.
In 1974, the Rothamsted team had discovered more persistent compounds:
permethrin, cypermethrin and deltamethrin.
More resistant to degradation by light and air.
Suitable for use in agriculture.
Significantly low mammalian toxicities
Rapid action: Contact insecticide that attack on nervous system of insects
almost immediately.
Broad spectrum of insecticides: because it consist of group of complex
compounds.
Lack of persistence: Degraded by sunlight and air, so they have less
environmental hazards.
Repellency: Powerful insect repellent and have Knockdown effect.
Low mammalian toxicity: One of least toxic domestic insecticide
Properties
Some other properties
Pale yellow viscous oils or tan dusts.
Insoluble in water.
Soluble in organic solvent
In light and air, oxidation and loss of insecticidal
activity occur.
Hydrolyzed in the presence of alkalies.
Not readily washed off from plants by rain due to
lipophilic character.
Natural InsecticidesChemicals that are obtained from natural sources and used to
control insect pests.
Pyrethrum also called natural pyrethrum, natural pyrethroid or simply pyrethrins.
• Highly effective botanical insecticide used for centuries against all manner of
insect pests.
• Occur in the daisy, Tanacetum cinerariaefolium.
• Found in tiny oil containing glands on the surface of seed case in tightly packed
flower head.
• Insecticidal activity was discovered in iran around 1800.
Made up of six complex organic esters formed by combination of carboxylic acid
and keto alcohols
Pyrethrins I or Chrysanthemates Pyrethrins I or Pyrethrates
Pyrethrin I 35% Pyrethrin II 32%Cinerin I 10% Cinerin II 14%Jasmolin I 5% Jasmolin II 4%
Total 50% Total 50%
CH3R1
CH3 CH3
O
O
O
CH3
R2KetoneCarboxylicacid
• Flowers are harvested after blooming.
• Either dried and powdered or the oils are extracted with solvents.
• Resulting pyrethrin usually have an active ingredient content of about 30%.
• Active insecticidal components are collectively known as pyrethrins.
Extraction of Pyrethrum
• Non-systemic insecticides act as contact poison.
• Affect the nervous system of insects by causing multiple action potentials.
• Delaying the closing of ion channels.
• The sequence of poisoning symptoms are
Excitation Convulsions Paralysis Death
• Sometime mixed with another chemical known as a synergist Piperonyl butoxide or sulphoxide used
Increase their effect
Inhibit detoxification
Mode of Action
Human lice, mosquitoes, cockroaches, beetles, flies and mites.
Control chewing and sucking insects pest.
Some "pyrethrin dusts" used to control insects in horticultural crops.
Some compounds may be used in grain storage, poultry pens and
on dogs and cats to control lice and fleas.
Over 2,000 registered pesticide products.
Available in foggers, sprays, dusts and pet shampoos.
Highly toxic to cats
Applications
Environmental Effects
• Low in toxicity to people and other mammals.
• Toxic to beneficial insects such as bees, dragonflies, mayflies and gadflies.
• Very highly toxic to fish, lobster, shrimp and oysters.
• Eaten or inhaled, rapidly broken down into inactive products
and are removed from the body.
Irritation of the respiratory passages, runny nose,
coughing, difficulty breathing, vomiting and diarrhea.
• On skin contact, it can be irritating.
• Presence of sunlight, pyrethrins, breaks down rapidly in water and on
soil and plant surfaces.
• More than 85% left the body in feces or urine within two days.
• Very small amounts in the milk and eggs of exposed animals.
• On potato and tomato leaves, less than 3% remained after 5 days.
Hydrolysis
of Ester bondCH3R1
H3C CH3
O
OH
O
CH3
R2
HO
CH3R1
CH3 CH3
O
O
O
CH3
R2
+
Brand Name
Evergreen®
Pyganic®
Pyrenone®
Pyronyl Crop Spray® Tersus®
Pyrethrum TR®
Synthetic Insecticides
Originally pyrethroids were made to synthetically mimic pyrethrins.
Derived from naturally occurring pyrethrins, taken from pyrethrum of dried
Chrysanthemum flowers.
Chemically more complicated molecules making more toxic
10 times mores effective than natural Pyrethrins
Today's pyrethroids have very low or no odor at all
Last longer, can be used in lower concentrations
Pyrethroids are formulated with compounds like piperonyl butoxide,
piperonyl sulfoxide and sesamex called synergists.
Pyrethroids are grouped into two classes
• Type I pyrethroids are derivatives of pyrethrin.
Do not have a cyano group
• Type II pyrethroids have cyano group.Type I Pyrethroids Type I Pyrethroids
Allethrin Cyfluthrin Bifenthrin Cyhalothrin Permethrin Cypermethrin Phenothrin Deltamethrin Resmethrin Fenvalerate Tefluthrin Fenpropathrin Tetramethrin Flucythrinate
Flumethrin Fluvalinate
Allethrin • First synthetic pyrethroid
• Pale yellow liquid
• Contact insecticide
• Effective against mosquito, flies and ants
• Available as coils, mats, oil formulations, and as an aerosol spray.Brand Name• Alleviate ®
• Bioallethrin ®
• Pyrocide®
• Raid ®
• Thermacell®
Resmethrin• Colorless waxy solid
• Contact insecticide
• Resmethrin is not toxic to plants.
• Used to cntrol agricultural, horticultural and public health insect pests.
55 to 82% broken down within 2 hours
Brand Name
• Chrysron ®
• Crossfire ®
• Vectrin ®
• Discovered in 1973
• Used as a medication to treat fleas, termites and lice.
• Applied to the skin as a cream or lotion.
• More effective at low temperature
• White, odourless, crystalline solid and contact insecticide.
Permethrin
Brand Name• Nix ®
• Ambush ®
• Pounce ®
• Coopex ®
Phenothrin•Also called sumithrin and d-phenothrin
•Kills adult fleas, ticks, beg bugs and human lice
•It is extremely toxic to bees and aquatic life.
•Affects the insect's central and peripheral nervous system.
•It is pale yellow liquid.
Brand Name
• Raid ®
Bifenthrin•Primarily against the red imported fire ant
•Affective against cockroach, ants, moths, earwigs, mites,
flies, grasshoppers, fleas, Yellow jackets, flies, fleas, and termites.
•Poorly soluble in water and often remains in soil.
•White, waxy solid with a faint sweet smell.
•Not naturally occurringBrand Name• Capture ®
• Maxtor ®
• Transport ®
Tefluthrin•Introduced in 1986.
•Colorless solid at room temperature
•Low solubility in water
•Low flammability
•Effective against soil pests in crops such as maize, sugar beet, corn and grains
Brand Name
• Technical ®
• Force ®
Tetramethrin•Potent synthetic insecticide
•It is a white crystalline solid
•Degrade rapidly after it applied.
•It is metabolized quickly
•Effective against wasps, hornets, roaches, ants, fleas, and mosquitoes.
Brand Name
• Hot Shot ®
• Deep ®
Cyfluthrin
•Both contact and stomach poison action
•Available in the form of emulsifiable concentrates,
Wettable powder, aerosol, granules, liquid.
•Affective against cutworms, ants, silverfish, cockroaches, termites, weevils,
mosquitoes, fleas, flies, corn earworms, codling moth, loopers, etc.
Brand Name• Laser ®
• Contur ®
• Responsar ®
• Solfac ®
Cyhalothrin• Effective for longer periods of time
• Colorless solid with a mild odor
• Low water solubility and is nonvolatile
• Forms strong bonds with soil so cause water contamination
• Affective against aphids, colorado beetles and butterfly larvae.
• Mainly used as tickicide.Brand Name• Danger ®
• Demand ®
• Karate ®
Cypermethrin•Popular and widely used insecticides
•Stomach and contact insecticide
•Behaves as a fast-acting neurotoxin in insects
•Easily degraded on soil and plants but effective for weeks when applied to
indoor inert surfaces.
•Effective against cockroachs, flies, mosquitoes and mothsBrand Name• Viper ®
• Raid ®
• Ripcord ®
• Cymbush ®
Deltamethrin•Most popular and widely used insecticides
•Colorless crystalline powder
•Potent insecticide, contact and stomach poison
•Against wide range of pests of fruits, vegetables, cotton and stored products.
•Control spiders, bed bugs, ants, carpenter ants, fleas, ticks and clothes moths
•Plays key role in controlling malaria vectors particularly anopheles
gambiae.Brand Name• Blast ®
• Dose ®
• Deltahit ®
Fenvalerate •Contact and stomach poison.
•Yellow brown viscous liquid practically soluble in water
•Commonly used to control insects in food, feed, cotton products,
flies, beetles and ticks in barns.
•Does not affect plants.
Brand Name• Fenrus-4 ®
Fenpropathrin
• Insecticides as well as acaricide
• Contact and stomach poison
• Used to control aphid, red spider, armworm, and noctuids
• Risk for parkinson's disease
Brand Name• Danitol ®
• Tame ®
• Meothrin ®
Flucythrinate
•Insecticide and acaricide.
•Highly toxic pesticide
•Currently not approved for use in the United States.
•Affective against phytophagous mites and insects of cotton and vegetables.
Brand Name
• Cybolt ®
•Pay-Off ®
Flumethrin
• Externally used in veterinary medicine against parasitic insects
Such as flea and tick
• Treatment of parasitic mites in honeybee colonies
Brand Name• Bayer ®
• Bayticol ®
Fluvalinate• Viscous yellow oil
• Stable, non-volatile, fat-soluble compound
• Acaricide commonly used to control Varroa Mites
• Against moths, beetles and other insect pests on cotton,
cereal, grape, potato, fruit tree, vegetable and ornamental plants.
Brand Name
• Apistan ®
• Yardex ®
• Mavrik ®
• Extremely high insecticidal activity at extremely low doses
• Biodegradable in nature
• Effective against lepidopterous pests and beetles, leaf miners and bugs.
• Effective against eggs, larval and adult stages of insects
• Powerful antifeedant and repellent properties
• Not readily washed off from the plant by rain
•Movement from site of application is limited in air due to low volatility
Merits
• Not systemic and do not have translaminar action
• Constant use of synthetic pyrethroids increase resistance in insects pest
• Harmful for beneficial organisms (honey bees, beetles, spiders, centipedes
and predatory mites)
• Highly toxic to fish
• On prolonged storage, pyrethrum looses its insecticidal action
Hence; antioxidants like hydroquinolene are added
Demerits
