An insecticide is a pesticide A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest. A pesticide may be a chemical substance, biological agent , antimicrobial, disinfectant or device used against any pest. Pests include insects, plant pathogens, weeds, molluscs, birds, mammals, fish, nematodes (roundworms), used against insects Insects are a class within the arthropods that have a chitinous exoskeleton, a three-part body (head, thorax, and abdomen), three pairs of jointed legs, compound eyes, and two antennae. They are among the most diverse group of animals on the planet and include more than a million described species and represent more than half of all known living. They include ovicides and larvicides A larvicide is an insecticide that is specifically targeted against the larval life stage of an insect. Their most common use is against mosquitoes. Larvacides may be contact poisons, stomach poisons, growth regulators, or (increasingly) biological control agents used against the eggs In most birds, reptiles, insects, fish, and two types of mammals an egg (Latin, ovum) is the zygote, resulting from fertilization of the ovum. To enable incubation the egg is usually kept within a favourable temperature range as it nourishes and protects the growing embryo. When the embryo is adequately developed it breaks out of the egg in the and larvae A larva 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 of insects respectively. Insecticides are used in agriculture Agriculture is the production of food and goods through farming. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and stratified societies. The study of agriculture is known as, medicine Medicine is the science and art of healing humans. It includes a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness. Before scientific medicine, healing arts were practiced along with alchemical and ritual practices that developed out of religious and cultural traditions. The term &, industry Industry refers to the production of an economic good within an economy. There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction, and manufacturing; the tertiary sector, which deals with services (such as law and the household The household is "the basic residential unit in which economic production, consumption, inheritance, child rearing, and shelter are organized and carried out"; [the household] "may or may not be synonymous with family". The use of insecticides is believed to be one of the major factors behind the increase in agricultural productivity in the 20th century^[1]. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans; and others are concentrated in the food chain.

Classes of agricultural insecticides

The classification of insecticides is done in several different ways:

• Systemic insecticides are incorporated by treated plants. Insects ingest the insecticide while feeding on the plants.
• Contact insecticides are toxic to insects brought into direct contact. Efficacy is often related to the quality of pesticide application Pesticide application refers to the practical way in which pesticides, are delivered to their biological targets (e.g. pest organism, crop or other plant). Public concern about the use of pesticides has high-lighted the need to make this process as efficient as possible, in order to minimise their release into the environment and human exposure (, with small droplets (such as aerosols Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are smoke, oceanic haze, air pollution, smog and CS gas. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can. The word aerosol derives from the fact that matter "floating" in air is a) often improving performance^[2].
• Natural insecticides, such as nicotine Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves. It functions as an antiherbivore chemical with particular specificity to insects; therefore nicotine was widely used as an, pyrethrum Pyrethrum refers to several Old World plants of the genus Chrysanthemum which are cultivated as ornamentals for their showy flower heads. Pyrethrum is also the name of a natural insecticide made from the dried flower heads of C. cinerariifolium and C. coccineum and neem Neem is a tree in the mahogany family Meliaceae. It is one of two species in the genus Azadirachta, and is native to India, Myanmar, Bangladesh, Sri Lanka, Malaysia and Pakistan, growing in tropical and semi-tropical regions. Other vernacular names include Neem (Hindi, Urdu and Bengali), Nimm (Punjabi), Arya Veppu (Malayalam), Azad Dirakht ( extracts are made by plants as defences against insects. Nicotine based insecticides have been barred in the U.S. since 2001 to prevent residues from contaminating foods.^[3]
• Inorganic insecticides are manufactured with metals and include arsenates Arsenate resembles phosphate in many respects, since arsenic and phosphorus occur in the same group of the periodic table, copper Copper is a chemical element with the symbol Cu (Latin: cuprum) and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable, and a freshly exposed surface has a pinkish or peachy color. It is used as a thermal conductor, an electrical conductor, a building material, and a compounds and fluorine Fluorine is the chemical element with atomic number 9, represented by the symbol F. Fluorine forms a single bond with itself in elemental form, resulting in the diatomic F2 molecule. F2 (fluorine) is a supremely reactive, poisonous, pale, yellowish brown gas. Elemental fluorine is the most chemically reactive and electronegative of all the compounds, which are now seldom used, and sulfur Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant, multivalent non-metal. Sulfur, in its native form, is a bright yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals. It is an essential element for life and is found in, which is commonly used.
• Organic insecticides are synthetic chemicals which comprise the largest numbers of pesticides available for use today.
• Mode of action – how the pesticide kills or inactivates a pest – is another way of classifying insecticides. Mode of action is important in predicting whether an insecticide will be toxic to unrelated species, such as fish, birds and mammals.

Heavy metals A heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight, and some on chemical properties or toxicity, e.g. arsenic Arsenic is the chemical element that has the symbol As, atomic number 33 and atomic mass 74.92. Arsenic was first documented by Albertus Magnus in 1250. Arsenic is a notoriously poisonous metalloid with many allotropic forms, including a yellow (molecular non-metallic) and several black and grey forms (metalloids). Three metalloidal forms of have been used as insecticides; they are poisonous and very rarely used now by farmers.

Organochlorine compounds

The insecticidal properties of the best known representative of this class of insecticides, DDT DDT is one of the most well-known synthetic pesticides. It is a chemical with a long, unique, and controversial history, was made by the Swiss Scientist Paul Müller. For this discovery, he was awarded the Nobel Prize for Physiology and Medicine in 1948. DDT was introduced on the market in 1944. With the rise of the modern chemical industry, it was possible to make chlorinated hydrocarbons An organochloride, organochlorine, chlorocarbon, chlorinated hydrocarbon, or chlorinated solvent is an organic compound containing at least one covalently bonded chlorine atom. Their wide structural variety and divergent chemical properties lead to a broad range of applications. Many derivatives are controversial because of the effects of these. DDT works by opening the sodium Sodium is a metallic element with a symbol Na (from Latin natrium or Arabic ناترون natrun; perhaps ultimately from Egyptian netjerj) and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals within "group 1" (formerly known as ‘group IA’). It has only one stable isotope, 23Na channels in the nerve cells of the insect.

Organophosphates

The next large class developed was the organophosphates An organophosphate is the general name for esters of phosphoric acid. Phosphates are probably the most pervasive organophosphorus compounds. Many of the most important biochemicals are organophosphates, including DNA and RNA as well as many cofactors that are essential for life. Organophosphates are also the basis of many insecticides, herbicides,, which bind to acetylcholinesterase and other cholinesterases. This results in disruption of nerve impulses, killing the insect or interfering with its ability to carry on normal functions. Organophosphate insecticides and chemical warfare nerve agents (such as sarin Sarin is an organophosphorus compound with the formula [2CHO]CH3P(O)F. It is a colorless, odorless liquid, which is used as a chemical weapon. It has been classified as a weapon of mass destruction in UN Resolution 687. Production and stockpiling of sarin was outlawed by the Chemical Weapons Convention of 1993, tabun Tabun or GA is an extremely toxic chemical substance. It is a clear, colorless, and tasteless liquid with a faint fruity odor. It is classified as a nerve agent because it fatally interferes with normal functioning of the mammalian nervous system. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations, soman Soman, also known by its NATO designation GD , is an extremely toxic chemical substance. It is a nerve agent, interfering with normal functioning of the mammalian nervous system by inhibiting the cholinesterase enzyme. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations according to UN Resolution 687. Its and VX VX, IUPAC name O-ethyl S-[2-ethyl] methylphosphonothioate, is an extremely toxic substance whose only application is in chemical warfare as a nerve agent. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations in UN Resolution 687. The production and stockpiling of VX was outlawed by the Chemical Weapons) work in the same way. Organophosphates have an additive toxic effect to wildlife, so multiple exposures to the chemicals amplifies the toxicity.^[4]

Carbamates

Carbamate Carbamates are organic compounds derived from carbamic acid . A carbamate group, carbamate ester, and carbamic acids are functional groups that are inter-related structurally and often are interconverted chemically. Carbamate esters are also called urethanes insecticides have similar toxic mechanisms to organophosphates, but have a much shorter duration of action and are thus somewhat less toxic.

Pyrethroids

To mimic the insecticidal activity of the natural compound pyrethrum Pyrethrum refers to several Old World plants of the genus Chrysanthemum which are cultivated as ornamentals for their showy flower heads. Pyrethrum is also the name of a natural insecticide made from the dried flower heads of C. cinerariifolium and C. coccineum another class of pesticides, pyrethroid A pyrethroid is a synthetic chemical compound similar to the natural chemical pyrethrins produced by the flowers of pyrethrums . Pyrethroids now constitute a major proportion of the synthetic insecticide market and are common in commercial products such as household insecticides. In the concentrations used in such products, they may also have pesticides, has been developed. These are nonpersistent, which is a sodium channel modulators, and are much less acutely toxic than organophosphates and carbamates. Compounds in this group are often applied against household pests Pesticide application refers to the practical way in which pesticides, are delivered to their biological targets (e.g. pest organism, crop or other plant). Public concern about the use of pesticides has high-lighted the need to make this process as efficient as possible, in order to minimise their release into the environment and human exposure (.

Neonicotinoids

Neonicotinoids Neonicotinoids are a class of insecticides which act on the central nervous system of insects with lower toxicity to mammals. Neonicotinoids are among the most widely used insecticides worldwide, but recently the uses of some members of this class have been restricted in some countries due to a possible connection to honey-bee Colony Collapse are synthetic analogues of the natural insecticide nicotine Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves. It functions as an antiherbivore chemical with particular specificity to insects; therefore nicotine was widely used as an (with a much lower acute mammalian toxicity and greater field persistence). These chemicals are nicotinic acetylcholine receptor agonists. Broad-spectrum – systemic insecticides, they have a rapid action (minutes-hours). They are applied as sprays, drenches, seed and soil Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and environmental processes that include weathering and treatments – often as substitutes for organophosphates and carbamates. Treated insects exhibit leg tremors, rapid wing motion, stylet withdrawal (aphids), disoriented movement, paralysis and death.

Biological insecticides

Recent efforts to reduce broad spectrum toxins added to the environment have brought biological insecticides The term biopesticide is used for microbial biological pest control agents that are applied in a similar manner to chemical pesticides. Commonly these are bacterial, but there are also examples of fungal control agents, including Trichoderma spp. and Ampelomyces quisqualis . Bacillus subtilis are used to control plant pathogens. Weeds and rodents back into vogue. An example is the development and increase in use of Bacillus thuringiensis Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a biological alternative to a pesticide; alternatively, the Cry toxin may be extracted and used as a pesticide. Additionally , B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterflies, as well as on the dark, a bacterial disease of Lepidopterans Lepidoptera is a large order of insects that includes moths and butterflies (called lepidopterans). It is one of the most speciose orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies and found virtually everywhere. Lepidoptera contains more than 180,000 species in 128 and some other insects. It is used as a larvicide A larvicide is an insecticide that is specifically targeted against the larval life stage of an insect. Their most common use is against mosquitoes. Larvacides may be contact poisons, stomach poisons, growth regulators, or (increasingly) biological control agents against a wide variety of caterpillars Caterpillars are the larval form of a member of the order Lepidoptera . They are mostly herbivorous in food habit, with some species being insectivorous. Caterpillars are voracious feeders and many of them are considered pests in agriculture. Many moth species are better known in their caterpillar stages because of the damage they cause to fruits. Because it has little effect on other organisms In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole. An organism may either be unicellular (single-celled) or be composed of, as in humans, many trillions of cells grouped into, it is considered more environmentally friendly Environmentally friendly are synonyms used to refer to goods and services, laws, guidelines and policies considered to inflict minimal or no harm on the environment. To make consumers aware, environmentally friendly goods and services often are marked with eco-labels. But because there is no single international standard for this concept, the than synthetic pesticides. The toxin from B. thuringiensis (Bt toxin Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a pesticide. Additionally, B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterflies, as well as on the dark surface of plants) has been incorporated directly into plants through the use of genetic engineering Genetic engineering, recombinant DNA technology, genetic modification/manipulation , and gene splicing are terms that apply to the direct manipulation of an organism's genes. Genetic engineering is different from traditional breeding, where the organism's genes are manipulated indirectly. Genetic engineering uses the techniques of molecular. Other biological insecticides include products based on entomopathogenic fungi (e.g. Metarhizium anisopliae), nematodes (e.g. Steinernema feltiae) and viruses (e.g. Cydia pomonella granulovirus).

Antifeedants

Many plants have evolved substances, like polygodial Polygodial is an active constituent of Dorrigo Pepper, Mountain Pepper, Horopito, Canelo, Paracress and Water-pepper, which prevent insects from eating, but do not kill them directly. The insect often remains nearby, where it dies of starvation. Since antifeedants are nontoxic, they would be ideal as insecticides in agriculture. Much agrochemical research is devoted to make them cheap enough for commercial use.

Environmental effects

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 insecticide granules on the ground for food and eat it.^[4]

Sprayed insecticides may drift from the area to which it is applied and into wildlife areas, especially when it is sprayed aerially.^[4]

DDT

One of the bigger drivers in the development of new insecticides has been the desire to replace toxic Toxicity is the degree to which a substance is able to damage an exposed organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ (organotoxicity), such as the liver (hepatotoxicity). By extension, the word may be and irksome insecticides. DDT DDT is one of the most well-known synthetic pesticides. It is a chemical with a long, unique, and controversial history was introduced as a safer alternative to the lead Lead is a main-group element with symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a and arsenic Arsenic is the chemical element that has the symbol As, atomic number 33 and atomic mass 74.92. Arsenic was first documented by Albertus Magnus in 1250. Arsenic is a notoriously poisonous metalloid with many allotropic forms, including a yellow (molecular non-metallic) and several black and grey forms (metalloids). Three metalloidal forms of compounds.

Some insecticides have been banned due to the fact that they are persistent toxins which have adverse effects on animals and/or humans. An oft-quoted case is that of DDT, an example of a widely used (and maybe misused) pesticide, which was brought to public attention by Rachel Carson's book, Silent Spring. One of the better known impacts of DDT is to reduce the thickness of the egg shells on predatory birds. The shells sometimes become too thin to be viable, causing reductions in bird populations. This occurs with DDT and a number of 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 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 the organochlorine pesticides have been banned from most uses worldwide, and globally they are controlled via the Stockholm Convention on persistent organic pollutants. These include: aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex and toxaphene.

Pollinator decline

Insecticides can kill bees and may be a cause of pollinator decline, the loss of bees that pollinate plants, and colony collapse disorder (CCD)^[5], in which worker bees from a beehive or Western honey bee colony abruptly disappear. Loss of pollinators will mean a reduction in crop yields.^[5] Sublethal doses of insecticides (i.e. imidacloprid and other neonicotinoids) affect foraging behavior of bees.^[6]. However, research into the causes of CCD was inconclusive as of June 2007.^[7]

Individual insecticides

Chlorinated hydrocarbons

• Aldrin
• Chlordane
• Chlordecone
• DDT
• Dieldrin
• Endosulfan
• Endrin
• Heptachlor
• Hexachlorobenzene
• Lindane (gamma-hexachlorocyclohexane)
• Methoxychlor
• Mirex
• Pentachlorophenol
• TDE

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