Insecticides are substances used to kill

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...

s. They include ovicides and larvicides used against insect

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

and

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. Th ...

e, respectively. Insecticides are used in

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peop ...

medicine Medicine is the science and Praxis (process), practice of caring for a patient, managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, and Health promotion ...

industry Industry may refer to: Economics * Industry (economics), a generally categorized branch of economic activity * Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery * The wider industrial sector ...

and by consumers. Insecticides are claimed to be a major factor behind the increase in the 20th-century's agricultural productivity. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans and/or animals; some become concentrated as they spread along the food chain. Insecticides can be classified into two major groups: systemic insecticides, which have residual or long term activity; and contact insecticides, which have no residual activity. The

mode of action A mode of action (MoA) describes a functional or anatomical change, resulting from the exposure of a living organism to a substance. In comparison, a mechanism of action (MOA) describes such changes at the molecular level. A mode of action is impor ...

describes how the pesticide kills or inactivates a pest. It provides another way of classifying insecticides. Mode of action can be important in understanding whether an insecticide will be toxic to unrelated species, such as fish, birds and mammals. Insecticides may be repellent or non-repellent. Social insects such as ants cannot detect non-repellents and readily crawl through them. As they return to the nest they take insecticide with them and transfer it to their nestmates. Over time, this eliminates all of the ants including the queen. This is slower than some other methods, but usually completely eradicates the ant colony. Insecticides are distinct from non-insecticidal repellents, which repel but do not kill.

Type of activity

Systemic insecticides

Systemic insecticides become incorporated and distributed systemically throughout the whole plant. When insects feed on the plant, they ingest the insecticide. Systemic insecticides produced by

transgenic A transgene is a gene that has been transferred naturally, or by any of a number of genetic engineering techniques, from one organism to another. The introduction of a transgene, in a process known as transgenesis, has the potential to change the ...

plants are called plant-incorporated protectants (PIPs). For instance, a gene that codes for a specific ''

Bacillus thuringiensis ''Bacillus thuringiensis'' (or Bt) is a gram-positive, soil-dwelling bacterium, the most commonly used biological pesticide worldwide. ''B. thuringiensis'' also occurs naturally in the gut of caterpillars of various types of moths and butter ...

'' biocidal protein was introduced into corn (

maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn ( North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. ...

) and other species. The plant manufactures the protein, which kills the insect when consumed.

Contact insecticides

Contact insecticides are toxic to insects upon direct contact. These can be inorganic insecticides, which are metals and include the commonly used

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...

, and the less commonly used

arsenate The arsenate ion is . An arsenate (compound) is any compound that contains this ion. Arsenates are salts or esters of arsenic acid. The arsenic atom in arsenate has a valency of 5 and is also known as pentavalent arsenic or As(V). Arsenate r ...

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...

and fluorine compounds. Contact insecticides can also be organic insecticides, i.e. organic chemical compounds, synthetically produced, and comprising the largest numbers of pesticides used today. Or they can be natural compounds like pyrethrum, neem oil, etc. Contact insecticides usually have no residual activity. Efficacy can be related to the quality of

pesticide application Pesticide application refers to the practical way in which pesticides (including herbicides, fungicides, insecticides, or nematode control agents) are delivered to their ''biological targets'' (''e.g.'' pest organism, crop or other plant). ...

, with small droplets, such as

aerosol An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog or mist, dust, forest exudates, and geyser steam. Examples of ant ...

s often improving performance.

Synthetic insecticides

Development

Organochlorides

The best known

organochloride An organochloride, organochlorine compound, chlorocarbon, or chlorinated hydrocarbon is an organic compound containing at least one covalently bonded atom of chlorine. The chloroalkane class (alkanes with one or more hydrogens substituted by chlor ...

DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...

, was created by Swiss scientist Paul Müller. For this discovery, he was awarded the 1948

Nobel Prize for Physiology or Medicine The Nobel Prize in Physiology or Medicine ( sv, Nobelpriset i fysiologi eller medicin) is awarded yearly by the Nobel Assembly at the Karolinska Institute, Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or ...

. DDT was introduced in 1944. It functions by opening

sodium channel Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell's membrane. They belong to the superfamily of cation channels and can be classified according to the trigger that opens the channel ...

s in the insect's

nerve cell A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. ...

s. The contemporaneous rise of the chemical industry facilitated large-scale production of DDT and related

chlorinated hydrocarbon An organochloride, organochlorine compound, chlorocarbon, or chlorinated hydrocarbon is an organic compound containing at least one covalently bonded atom of chlorine. The chloroalkane class (alkanes with one or more hydrogens substituted by chlo ...

Organophosphates

Organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...

s are another large class of contact insecticides. These also target the insect's nervous system. Organophosphates interfere with the

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

acetylcholinesterase Acetylcholinesterase (HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme that catalyzes the breakdown of acety ...

and other

cholinesterase The enzyme cholinesterase (EC 3.1.1.8, choline esterase; systematic name acylcholine acylhydrolase) catalyses the hydrolysis of choline-based esters: : an acylcholine + H2O = choline + a carboxylate Several of these serve as neurotransmitters ...

s, disrupting nerve impulses and killing or disabling the insect. Organophosphate insecticides and

chemical warfare Chemical warfare (CW) involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from nuclear warfare, biological warfare and radiological warfare, which together make up CBRN, the military a ...

nerve agents (such as

sarin Sarin (NATO designation GB G-series, "B"">Nerve_agent#G-series.html" ;"title="hort for Nerve agent#G-series">G-series, "B" is an extremely toxic synthetic organophosphorus compound.tabun,

soman Soman (or GD, EA 1210, Zoman, PFMP, A-255, systematic name: ''O''-pinacolyl methylphosphonofluoridate) is an extremely toxic chemical substance. It is a nerve agent, interfering with normal functioning of the mammalian nervous system by inhibiti ...

, and VX) work in the same way. Organophosphates have a cumulative toxic effect to wildlife, so multiple exposures to the chemicals amplifies the toxicity. In the US, organophosphate use declined with the rise of substitutes.

Carbamates

Carbamate In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formall ...

insecticides have similar mechanisms to organophosphates, but have a much shorter duration of action and are somewhat less toxic.

Pyrethroids

Pyrethroid A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and '' C. coccineum''). Pyrethroids are used as commercial and household insecticides. In ...

pesticides mimic the insecticidal activity of the natural compound

pyrethrin The pyrethrins are a class of organic compounds normally derived from ''Chrysanthemum cinerariifolium'' that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin naturally occurs in chrysanthemum flowers and is ...

, the

biopesticide A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships. They are obtained from organisms inclu ...

found in ''

Pyrethrum ''Pyrethrum'' was a genus of several Old World plants now classified as ''Chrysanthemum'' or '' Tanacetum'' which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants formerly incl ...

'' (Now ''

Chrysanthemum Chrysanthemums (), sometimes called mums or chrysanths, are flowering plants of the genus ''Chrysanthemum'' in the family Asteraceae. They are native to East Asia and northeastern Europe. Most species originate from East Asia and the center ...

'' and ''

Tanacetum ''Tanacetum'' is a genus of about 160 species of flowering plants in the aster family, Asteraceae, native to many regions of the Northern Hemisphere.

'') species. These compounds are nonpersistent sodium channel modulators and are less toxic than organophosphates and carbamates. Compounds in this group are often applied against household pests.

Neonicotinoids

Neonicotinoid Neonicotinoids (sometimes shortened to neonics ) are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s. The neonicotinoid family includes acetamiprid, clothianidin, din ...

s are synthetic analogues of the natural insecticide nicotine (with much lower acute mammalian toxicity and greater field persistence). These chemicals are

acetylcholine Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Par ...

receptor

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

s. They are broad-spectrum systemic insecticides, with rapid action (minutes-hours). They are applied as sprays, drenches, seed and

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...

treatments. Treated insects exhibit leg tremors, rapid wing motion, stylet withdrawal (

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A ...

s), disoriented movement, paralysis and death.

Imidacloprid Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system ...

may be the most common. It has recently come under scrutiny for allegedly pernicious effects on

honeybee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the current cos ...

s and its potential to increase the susceptibility of rice to

planthopper A planthopper is any insect in the infraorder Fulgoromorpha, in the suborder Auchenorrhyncha, a group exceeding 12,500 described species worldwide. The name comes from their remarkable resemblance to leaves and other plants of their environment ...

attacks.

Phenylpyrazoles

Phenylpyrazole insecticides Phenylpyrazole insecticides are a class of chemically-related broad-spectrum insecticides. The chemical structures of these insecticides are characterized by a central pyrazole ring with a phenyl group attached to one of the nitrogen atoms of the ...

, such as

fipronil Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole chemical family. Fipronil disrupts the insect central nervous system by blocking the ligand-gated ion channel of the GABAA receptor and glutamate-gated chloride (GluCl ...

are a class of synthetic insecticides that operate by interfering with GABA receptors.

Butenolides

Butenolide pesticides are a novel group of chemicals, similar to neonicotinoids in their mode of action, that have so far only one representative:

flupyradifurone } Flupyradifurone is a systemic butenolide insecticide developed by Bayer CropScience under the name Sivanto. Flupyradifurone protects crops from sap-feeding pests such as aphids and is safer for non-target organisms compared to other insecticides. ...

. They are

receptor

s, like

neonicotinoid Neonicotinoids (sometimes shortened to neonics ) are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s. The neonicotinoid family includes acetamiprid, clothianidin, din ...

s, but with a different pharmacophore. They are broad-spectrum systemic insecticides, applied as sprays, drenches, seed and

treatments. Although the classic

risk assessment Broadly speaking, a risk assessment is the combined effort of: # identifying and analyzing potential (future) events that may negatively impact individuals, assets, and/or the environment (i.e. hazard analysis); and # making judgments "on the ...

considered this insecticide group (and flupyradifurone specifically) safe for

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamil ...

s, novel research has raised concern on their

lethal Lethality (also called deadliness or perniciousness) is how capable something is of causing death. Most often it is used when referring to diseases, chemical weapons, biological weapons, or their toxic chemical components. The use of this ter ...

and sublethal effects, alone or in combination with other chemicals or environmental factors.

Ryanoids/diamides

Diamides are synthetic

ryanoid Ryanoids are a class of insecticides which share the same mechanism of action as the alkaloid ryanodine. Ryanodine is a naturally occurring insecticide isolated from '' Ryania speciosa''. Ryanoids include natural chemicals which are closely relat ...

analogues with the same mode of action as

ryanodine Ryanodine is a poisonous diterpenoid found in the South American plant '' Ryania speciosa'' (Salicaceae). It was originally used as an insecticide. The compound has extremely high affinity to the open-form ryanodine receptor, a group of calcium c ...

, a naturally occurring insecticide extracted from ''Ryania speciosa'' (

Salicaceae The Salicaceae is the willow family of flowering plants. The traditional family (Salicaceae ''sensu stricto'') included the willows, poplar, aspen, and cottonwoods. Genetic studies summarized by the Angiosperm Phylogeny Group (APG) have greatly ...

). They bind to

calcium channel A calcium channel is an ion channel which shows selective permeability to calcium ions. It is sometimes synonymous with voltage-gated calcium channel, although there are also ligand-gated calcium channels. Comparison tables The following tables ...

s in cardiac and skeletal muscle, blocking nerve transmission. The first insecticide from this class to be registered was Rynaxypyr, generic name

chlorantraniliprole Chlorantraniliprole (Rynaxypyr) is an insecticide of the ryanoid classes. Chlorantraniliprole was developed world-wide by DuPont and belongs to a class of selective insecticides featuring a novel mode of action to control a range of pests belong ...

Insect growth regulators

Insect growth regulator An insect growth regulator (IGR) is a substance (chemical) that inhibits the life cycle of an insect. IGRs are typically used as insecticides to control populations of harmful insect pests such as cockroaches and fleas. Advantages Many IGRs are l ...

(IGR) is a term coined to include insect

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

mimics and an earlier class of chemicals, the benzoylphenyl ureas, which inhibit

chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...

(exoskeleton) biosynthesis in insects

Diflubenzuron Diflubenzuron is an insecticide of the benzoylurea class. It is used in forest management and on field crops to selectively control insect pests, particularly forest tent caterpillar moths, boll weevils, gypsy moths, and other types of moths. ...

is a member of the latter class, used primarily to control

caterpillar Caterpillars ( ) are the larva, larval stage of members of the order Lepidoptera (the insect order comprising butterfly, butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawfly ...

s that are pests. The most successful insecticides in this class are the juvenoids (

juvenile hormone Juvenile hormones (JHs) are a group of acyclic sesquiterpenoids that regulate many aspects of insect physiology. The first discovery of a JH was by Vincent Wigglesworth. JHs regulate development, reproduction, diapause, and polyphenisms.The che ...

analogues). Of these,

methoprene Methoprene is a juvenile hormone (JH) analog which acts as a growth regulator when used as an insecticide. It is an amber-colored liquid with a faint fruity odor. Methoprene does not kill insects. Instead, it interferes with an insect’s lif ...

is most widely used. It has no observable acute toxicity in rats and is approved by

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...

(WHO) for use in drinking water

cistern A cistern (Middle English ', from Latin ', from ', "box", from Greek ', "basket") is a waterproof receptacle for holding liquids, usually water. Cisterns are often built to catch and store rainwater. Cisterns are distinguished from wells by ...

s to combat

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or deat ...

. Most of its uses are to combat insects where the adult is the pest, including

mosquito Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning "gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "lit ...

es, several

fly Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced m ...

species, and

flea Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, a ...

s. Two very similar products,

hydroprene Hydroprene is an insect growth regulator used as an insecticide. It is used against cockroaches, beetles, and moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with m ...

and kinoprene, are used for controlling species such as

cockroach Cockroaches (or roaches) are a Paraphyly, paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are we ...

es and

white flies Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described. Description and taxonomy The ...

. Methoprene was registered with the EPA in 1975. Virtually no reports of resistance have been filed. A more recent type of IGR is the

ecdysone Ecdysone is a prohormone of the major insect molting hormone 20-hydroxyecdysone, which is secreted from the prothoracic glands. It is of steroidal structure. Insect molting hormones (ecdysone and its homologues) are generally called ecdysteroid ...

agonist

tebufenozide Tebufenozide is an insecticide that acts as a molting hormone. It is an agonist of the ecdysone receptor that causes premature molting in larvae. It is primarily used against caterpillar pests. Because it has high selectivity for the targeted ...

(MIMIC), which is used in

forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. ...

and other applications for control of caterpillars, which are far more sensitive to its hormonal effects than other insect orders.

Biological pesticides

More natural insecticides have been interesting targets of research for two main reasons, firstly because the most common chemicals are losing effectiveness, and secondly due to their toxic effects upon the environment. Many organic compounds are already produced by plants for the purpose of defending the host plant from predation, and can be turned toward human ends. Four extracts of plants are in commercial use:

pyrethrum ''Pyrethrum'' was a genus of several Old World plants now classified as ''Chrysanthemum'' or '' Tanacetum'' which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants formerly incl ...

rotenone Rotenone is an odorless, colorless, crystalline isoflavone used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the seeds and stems of several plants, such as the jicama vine plant, and the roots of several member ...

neem oil Neem oil, also known as margosa oil, is a vegetable oil pressed from the fruits and seeds of the neem ('' Azadirachta indica''), a tree which is indigenous to the Indian subcontinent and has been introduced to many other areas in the tropics. It ...

, and various essential oils A trivial case is tree

rosin Rosin (), also called colophony or Greek pitch ( la, links=no, pix graeca), is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene com ...

, which is a natural insecticide. Specifically, the production of

oleoresin Oleoresins are semi-solid extracts composed of resin and essential or fatty oil, obtained by evaporation of the solvents used for their production. The oleoresin of conifers is known as crude turpentine or gum turpentine, which consists of oil of ...

by conifer species is a component of the defense response against insect attack and fungal

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a ger ...

infection. Many fragrances, e.g.

oil of wintergreen Methyl salicylate (oil of wintergreen or wintergreen oil) is an organic compound with the formula C8H8O3. It is the methyl ester of salicylic acid. It is a colorless, viscous liquid with a sweet, fruity odor reminiscent of root beer, but often a ...

, are in fact antifeedants.

Other biological approaches

Plant-incorporated protectants

= ''Bacillus thuringiensis''

= Transgenic crops that act as insecticides began in 1996 with a

genetically modified potato A genetically modified potato is a potato that has had its genes modified, using genetic engineering. Goals of modification include introducing pest resistance, tweaking the amounts of certain chemicals produced by the plant, and to prevent b ...

that produced

Cry protein Delta endotoxins (δ-endotoxins) are pore-forming toxins produced by ''Bacillus thuringiensis'' species of bacteria. They are useful for their insecticidal action and are the primary toxin produced by Bt maize/corn. During spore formation th ...

s, derived from the bacterium ''

'', which is toxic to beetle

larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. T ...

such as the

Colorado potato beetle The Colorado potato beetle (''Leptinotarsa decemlineata''), also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, or the potato bug, is a major pest of potato crops. It is about long, with a bright yellow/or ...

= RNA interference

= The technique has been expanded to include the use of RNAi insecticides which fatally

silence Silence is the absence of ambient audible sound, the emission of sounds of such low intensity that they do not draw attention to themselves, or the state of having ceased to produce sounds; this latter sense can be extended to apply to the c ...

crucial insect genes. (RNAi likely originally evolved as a defense against

virus A virus is a wikt:submicroscopic, submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and ...

es.) This was first demonstrated by Baum et al 2007, who incorporated a

V-APTase Vacuolar-type ATPase (V-ATPase) is a highly conserved evolutionarily ancient enzyme with remarkably diverse functions in eukaryotic organisms. V-ATPases acidify a wide array of intracellular organelles and pumps protons across the plasma ...

as a protectant into transgenic ''Zea mays'' and demonstrated effectiveness against ''

Diabrotica virgifera virgifera The Western corn rootworm, ''Diabrotica virgifera virgifera'', is one of the most devastating corn rootworm species in North America, especially in the midwestern corn-growing areas such as Iowa. A related species, the Northern corn rootworm, ''D ...

''. This suggests oral delivery against

Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

as a whole will probably be effective. Similar studies have followed Baum's technique to protect with

dsRNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

s targeting detox, especially insect

P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compo ...

s. Bolognesi et al 2012 is one of these following studies, however they found dsRNA to be processed into

siRNA Small interfering RNA (siRNA), sometimes known as short interfering RNA or silencing RNA, is a class of double-stranded RNA at first non-coding RNA molecules, typically 20-24 (normally 21) base pairs in length, similar to miRNA, and operating ...

s by the plants (in this case ''

Solanum tuberosum The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern United ...

'') themselves, and siRNAs to be less effectively taken up by insect cells. Bolognesi therefore produced additional transgenic ''S. tuberosum'' plants which instead produced ''longer'' dsRNAs ''in the chloroplasts'', which naturally accumulate dsRNAs but do not have the machinery to convert them to siRNAs. Midgut cells in many larvae take up the molecules and help spread the signal. The technology can target only insects that have the silenced sequence, as was demonstrated when a particular RNAi affected only one of four Drosophila, fruit fly species. The technique is expected to replace many other insecticides, which are losing effectiveness due to the spread of insecticide resistance.

= Venom

= Spider venom peptide fraction (chemistry), fractions are another class of potential transgenic traits which could expand the

repertoire and help to answer the insecticide resistance, resistance question.

Enzymes

Many plants exude substances to repel insects. Premier examples are substances activated by the

myrosinase. This enzyme converts glucosinolates to various compounds that are toxic to herbivorous insects. One product of this enzyme is allyl isothiocyanate, the pungent ingredient in horseradish sauces. Myrosinase general mechanism

The myrosinase is released only upon crushing the flesh of horseradish. Since allyl isothiocyanate is harmful to the plant as well as the insect, it is stored in the harmless form of the glucosinolate, separate from the myrosinase enzyme.

Bacterial

'' is a bacterial disease that affects Lepidopterans and some other insects. Toxins produced by strains of this bacterium are used as a larvicide against

s, beetles, and mosquitoes. Toxins from ''Saccharopolyspora spinosa'' are isolated from fermentations and sold as Spinosad. Because these toxins have little effect on other organisms, they are considered more environmentally friendly than synthetic pesticides. The toxin from ''B. thuringiensis'' (Bt toxin) has been incorporated directly into plants through the use of genetic engineering.

Other

Other biological insecticides include products based on entomopathogenic fungus, entomopathogenic fungi (e.g., ''Beauveria bassiana'', ''Metarhizium anisopliae''), nematodes (e.g., ''Steinernema feltiae'') and

es (e.g., ''Cydia pomonella'' granulovirus).

Synthetic insecticide and natural insecticides

A major emphasis of organic chemistry is the development of chemical tools to enhance agricultural productivity. Insecticides represent a major area of emphasis. Many of the major insecticides are inspired by biological analogues. Many others are not found in nature.

Environmental harm

Effects on nontarget species

Some insecticides kill or harm other creatures in addition to those they are intended to kill. For example, birds may be poisoned when they eat food that was recently sprayed with insecticides or when they mistake an insecticide granule on the ground for food and eat it.Palmer, WE, Bromley, PT, and Brandenburg, RL
Wildlife & pesticides - Peanuts
North Carolina Cooperative Extension Service. Retrieved on 14 October 2007. Sprayed insecticide may drift from the area to which it is applied and into wildlife areas, especially when it is sprayed aerially.

DDT

The development of DDT was motivated by desire to replace more dangerous or less effective alternatives. DDT was introduced to replace lead and arsenic-based compounds, which were in widespread use in the early 1940s. DDT was brought to public attention by Rachel Carson's book ''Silent Spring''. One side-effect of DDT is to reduce the thickness of shells on the eggs of predatory birds. The shells sometimes become too thin to be viable, reducing bird populations. This occurs with DDT and related compounds due to the process of bioaccumulation, wherein the chemical, due to its stability and fat solubility, accumulates in organisms' fatty tissues. Also, DDT may biomagnification, biomagnify, which causes progressively higher concentrations in the body fat of animals farther up the food chain. The near-worldwide ban on agricultural use of DDT and related chemicals has allowed some of these birds, such as the peregrine falcon, to recover in recent years. A number of organochlorine pesticides have been banned from most uses worldwide. Globally they are controlled via the Stockholm Convention on persistent organic pollutants. These include: aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex and toxaphene.

Runoff and Percolation

Solid bait and liquid insecticides, especially if improperly applied in a location, get moved by water flow. Often, this happens through nonpoint sources where runoff carries insecticides in to larger bodies of water. As snow melts and rainfall moves over and through the ground, the water picks applied insecticides and deposits them in to larger bodies of water, rivers, wetlands, underground sources of previously potable water, and percolates in to watersheds. This runoff and percolation of insecticides can effect the quality of water sources, harming the natural ecology and thus, indirectly effect human populations through biomagnification and bioaccumulation.

Pollinator decline

Pesticide toxicity to bees, Insecticides can kill bees and may be a cause of pollinator decline, the loss of bees that pollination, pollinate plants, and colony collapse disorder (CCD), in which worker bees from a Beehive (beekeeping), beehive or Western honey bee colony abruptly disappear. Loss of pollinators means a reduction in crop yields. Sublethal doses of insecticides (i.e. imidacloprid and other neonicotinoids) affect bee foraging behavior. However, research into the causes of CCD was inconclusive as of June 2007.

Bird decline

Besides the effects of direct consumption of insecticides, populations of insectivorous birds decline due to the collapse of their prey populations. Spraying of especially wheat and corn in Europe is believed to have caused an 80 per cent decline in flying insects, which in turn has reduced local bird populations by one to two thirds.

Alternatives

Instead of using chemical insecticides to avoid crop damage caused by insects, there are many alternative options available now that can protect farmers from major economic losses. Some of them are: # Plant breeding, Breeding crops resistant, or at least less susceptible, to pest attacks. # Releasing Predation, predators, parasitoids, or

s to control pest populations as a form of Biological pest control, biological control. # Chemical control like releasing pheromones into the field to confuse the insects into not being able to find mates and reproduce. # Integrated pest management, Integrated Pest Management: using multiple techniques in tandem to achieve optimal results. # Push–pull agricultural pest management, Push-pull technique: intercropping with a "push" crop that repels the pest, and planting a "pull" crop on the boundary that attracts and traps it.

Examples

Organochlorides

* Aldrin * Chlordane * Chlordecone *

* Dieldrin * Endosulfan * Endrin * Heptachlor * Hexachlorobenzene * Lindane (gamma-hexachlorocyclohexane) * Methoxychlor * Mirex * Pentachlorophenol * Dichlorodiphenyldichloroethane, TDE

Organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...
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* Acephate * Azinphos-methyl * Bensulide * Chlorethoxyfos * Chlorpyrifos * Chlorpyriphos-methyl * Diazinon * Dichlorvos (DDVP) * Dicrotophos * Dimethoate * Disulfoton * Ethoprop * Fenamiphos * Fenitrothion * Fenthion * Fosthiazate * Malathion * Methamidophos * Methidathion * Mevinphos * Monocrotophos * Naled * Omethoate * Oxydemeton-methyl * Parathion * Parathion-methyl * Phorate * Phosalone * Phosmet * Phostebupirim * Phoxim * Pirimiphos-methyl * Profenofos * Terbufos * Tetrachlorvinphos * Tribufos * Trichlorfon

Carbamate In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formall ...
s

* Aldicarb * Bendiocarb * Carbofuran * Carbaryl * Dioxacarb * Fenobucarb * Fenoxycarb * Isoprocarb * Methomyl * Oxamyl * Propoxur * 2-(1-Methylpropyl)phenyl methylcarbamate

Pyrethroid A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and '' C. coccineum''). Pyrethroids are used as commercial and household insecticides. In ...
s

* Allethrin * Bifenthrin * Cyhalothrin, Lambda-cyhalothrin * Cypermethrin * Cyfluthrin * Deltamethrin * Etofenprox * Fenvalerate * Permethrin * Phenothrin * Prallethrin * Resmethrin * Tetramethrin * Tralomethrin * Transfluthrin

Neonicotinoid Neonicotinoids (sometimes shortened to neonics ) are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s. The neonicotinoid family includes acetamiprid, clothianidin, din ...
s

* Acetamiprid * Clothianidin * Dinotefuran *

* Nithiazine * Thiacloprid * Thiamethoxam

Ryanoids

* Chlorantraniliprole * Cyantraniliprole * Flubendiamide

Insect growth regulators

* Benzoylureas **

** Flufenoxuron * Cyromazine * Methoprene * Hydroprene * Tebufenozide

Derived from plants or microbes

* Anabasine * Anethole (mosquito larvae) * Annonin * Asimina (pawpaw tree seeds) for lice * Azadirachtin * Caffeine * Carapa * Cinnamaldehyde (very effective for killing mosquito larvae) * Cinnamon leaf oil (very effective for killing mosquito larvae) * Cinnamyl acetate (kills mosquito larvae) * Citral * Citronellol * Deguelin * Derris (active ingredient is

) * ''Desmodium caudatum'' (leaves and roots) * Eucalyptol * Eugenol (mosquito larvae) * Hinokitiol * Ivermectin * Limonene * Linalool * Menthol * Myristicin * Neem (Azadirachtin) * Nicotine * Nootkatone * ''Peganum harmala'', seeds (smoke from), root * Oregano oil kills ''Rhyzopertha dominica'' (bug found in stored cereal) *

* ''Quassia'' (South American plant genus) * Ryanodine * Spinosad AKA Spinosyn A * Spinosyn D * Tetranortriterpenoid * Thymol (controls varroa mites in bees, bee colonies)

Biologicals

* Bacillus sphaericus *

Bacillus thuringiensis aizawi
* Bacillus thuringiensis israelensis * Bacillus thuringiensis kurstakihttp://www.biocontrol.entomology.cornell.edu/pathogens/bacteria.html * Bacillus thuringiensis tenebrionis * Nuclear Polyhedrosis Virus, Nuclear Polyhedrosis virus * Cydia pomonella granulovirus, Granulovirus * Lecanicillium lecanii

Inorganic/mineral derived insecticides

* Diatomaceous earth * Borax * Boric Acid

References

External links

InsectBuzz.com
- Daily updated news on insects and their relatives, including information on insecticides and their alternatives
International Pesticide Application Research Centre (IPARC)

Pestworld.org
– Official site of the National Pest Management Association * Streaming online video about efforts to reduce insecticide use in rice in Bangladesh
on Windows Media Playeron RealPlayer

– Has a thorough explanation on how insecticides work.

Michigan State University Extension * Example of Insecticide application in th

(Japanese dry rock garden) in Lelystad, The Netherlands. * {{Authority control Insecticides, Biocides

Type of activity

Systemic insecticides

Contact insecticides

Synthetic insecticides

Development

Organochlorides

Organophosphates

Carbamates

Pyrethroids

Neonicotinoids

Phenylpyrazoles

Butenolides

Ryanoids/diamides

Insect growth regulators

Biological pesticides

Other biological approaches

Plant-incorporated protectants

= ''Bacillus thuringiensis''

= RNA interference

= Venom

Enzymes

Bacterial

Other

Synthetic insecticide and natural insecticides

Environmental harm

Effects on nontarget species

DDT

Runoff and Percolation

Pollinator decline

Bird decline

Alternatives

Examples

Organochlorides

Organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...s

Carbamate In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formall ...s

Pyrethroid A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and '' C. coccineum''). Pyrethroids are used as commercial and household insecticides. In ...s

Neonicotinoid Neonicotinoids (sometimes shortened to neonics ) are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s. The neonicotinoid family includes acetamiprid, clothianidin, din ...s

Ryanoids

Insect growth regulators

Derived from plants or microbes

Biologicals

Inorganic/mineral derived insecticides

See also

References

Further reading

External links

Organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...
s

Carbamate In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formall ...
s

Pyrethroid A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and '' C. coccineum''). Pyrethroids are used as commercial and household insecticides. In ...
s

Neonicotinoid Neonicotinoids (sometimes shortened to neonics ) are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s. The neonicotinoid family includes acetamiprid, clothianidin, din ...
s