PESTICIDES are substances that are meant to control pests or weeds. The term pesticide includes all of the following: herbicide , insecticide , insect growth regulator , nematicide , termiticide, molluscicide , piscicide , avicide , rodenticide , predacide, bactericide , insect repellent , animal repellent , antimicrobial , fungicide , disinfectant (antimicrobial), and sanitizer . The most common of these are herbicides which account for approximately 80% of all pesticide use. Most pesticides are intended to serve as plant protection products (also known as crop protection products), which in general, protect plants from weeds , fungi, or insects .
In general, a pesticide is a chemical or biological agent (such as a virus , bacterium , antimicrobial, or disinfectant) that deters, incapacitates, kills, or otherwise discourages pests. Target pests can include insects, plant pathogens , weeds, molluscs , birds , mammals , fish , nematodes (roundworms ), and microbes that destroy property, cause nuisance, or spread disease, or are disease vectors . Although pesticides have benefits, some also have drawbacks, such as potential toxicity to humans and other species. According to the Stockholm Convention on Persistent Organic Pollutants , 9 of the 12 most dangerous and persistent organic chemicals are organochlorine pesticides.
* 1 Definition * 2 Uses * 3 Amount used
* 4 Benefits
* 4.1 Primary benefits * 4.2 Monetary
* 5 Costs
* 5.1 Health effects * 5.2 Environmental effect * 5.3 Economics
* 6 Alternatives
* 6.1 Push pull strategy * 6.2 Effectiveness
* 7 Types
* 7.1 Neonicotinoid pesticides
* 8 Regulation
* 8.1 International
* 9 History * 10 See also * 11 References * 12 Further reading * 13 External links
TYPE OF PESTICIDE TARGET PEST GROUP
Algicides or algaecides
Fungicides Fungi and oomycetes
Miticides or acaricides Mites
Food and Agriculture Organization
Pesticides can be classified by target organism (e.g., herbicides , insecticides , fungicides , rodenticides , and pediculicides – see table), chemical structure (e.g., organic, inorganic, synthetic, or biological (biopesticide) , although the distinction can sometimes blur), and physical state (e.g. gaseous (fumigant) ). Biopesticides include microbial pesticides and biochemical pesticides. Plant-derived pesticides, or "botanicals", have been developing quickly. These include the pyrethroids , rotenoids , nicotinoids , and a fourth group that includes strychnine and scilliroside . :15
Many pesticides can be grouped into chemical families. Prominent
insecticide families include organochlorines , organophosphates , and
Organochlorine hydrocarbons (e.g.,
Pesticides can be classified based upon their biological mechanism function or application method. Most pesticides work by poisoning pests. A systemic pesticide moves inside a plant following absorption by the plant. With insecticides and most fungicides, this movement is usually upward (through the xylem ) and outward. Increased efficiency may be a result. Systemic insecticides, which poison pollen and nectar in the flowers , may kill bees and other needed pollinators .
In 2009, the development of a new class of fungicides called paldoxins was announced. These work by taking advantage of natural defense chemicals released by plants called phytoalexins, which fungi then detoxify using enzymes. The paldoxins inhibit the fungi's detoxification enzymes. They are believed to be safer and greener.
Pesticides are used to control organisms that are considered to be
harmful. For example, they are used to kill mosquitoes that can
transmit potentially deadly diseases like
West Nile virus , yellow
fever , and malaria . They can also kill bees , wasps or ants that can
cause allergic reactions.
Insecticides can protect animals from
illnesses that can be caused by parasites such as fleas . Pesticides
can prevent sickness in humans that could be caused by moldy food or
Herbicides can be used to clear roadside weeds,
trees and brush. They can also kill invasive weeds that may cause
Herbicides are commonly applied in ponds and
lakes to control algae and plants such as water grasses that can
interfere with activities like swimming and fishing and cause the
water to look or smell unpleasant. Uncontrolled pests such as
termites and mold can damage structures such as houses. Pesticides
are used in grocery stores and food storage facilities to manage
rodents and insects that infest food such as grain. Each use of a
pesticide carries some associated risk. Proper pesticide use decreases
these associated risks to a level deemed acceptable by pesticide
regulatory agencies such as the
In 2006 and 2007, the world used approximately 2.4 megatonnes (5.3×109 lb) of pesticides, with herbicides constituting the biggest part of the world pesticide use at 40%, followed by insecticides (17%) and fungicides (10%). In 2006 and 2007 the U.S. used approximately 0.5 megatonnes (1.1×109 lb) of pesticides, accounting for 22% of the world total, including 857 million pounds (389 kt) of conventional pesticides, which are used in the agricultural sector (80% of conventional pesticide use) as well as the industrial, commercial, governmental and home in the U.S., farmers get an estimated fourfold return on money they spend on pesticides. One study found that not using pesticides reduced crop yields by about 10%. Another study, conducted in 1999, found that a ban on pesticides in the United States may result in a rise of food prices, loss of jobs, and an increase in world hunger.
There are two levels of benefits for pesticide use, primary and secondary. Primary benefits are direct gains from the use of pesticides and secondary benefits are effects that are more long-term.
* Controlling pests and plant disease vectors
* Improved crop /livestock yields
* Improved crop/livestock quality
* Controlling human/livestock disease vectors and nuisance organisms
* Human lives saved and suffering reduced * Animal lives saved and suffering reduced * Diseases contained geographically
* Controlling organisms that harm other human activities and structures
* Drivers view unobstructed * Tree/brush/leaf hazards prevented * Wooden structures protected
Every dollar ($1) that is spent on pesticides for crops yields four dollars ($4) in crops saved. This means based that, on the amount of money spent per year on pesticides, $10 billion, there is an additional $40 billion savings in crop that would be lost due to damage by insects and weeds. In general, farmers benefit from having an increase in crop yield and from being able to grow a variety of crops throughout the year. Consumers of agricultural products also benefit from being able to afford the vast quantities of produce available year-round. The general public also benefits from the use of pesticides for the control of insect-borne diseases and illnesses, such as malaria. The use of pesticides creates a large job market within the agrichemical sector.
On the cost side of pesticide use there can be costs to the environment , costs to human health, as well as costs of the development and research of new pesticides.
A sign warning about potential pesticide exposure. Main
Health effects of pesticides
Pesticides may cause acute and delayed health effects in people who
The American Academy of Pediatrics recommends limiting exposure of children to pesticides and using safer alternatives:
World Health Organization
One study found pesticide self-poisoning the method of choice in one third of suicides worldwide, and recommended, among other things, more restrictions on the types of pesticides that are most harmful to humans.
A 2014 epidemiological review found associations between autism and exposure to certain pesticides, but noted that the available evidence was insufficient to conclude that the relationship was causal.
Main article: Environmental effects of pesticides
In addition, pesticide use reduces biodiversity , contributes to pollinator decline , destroys habitat (especially for birds), and threatens endangered species . Pests can develop a resistance to the pesticide (pesticide resistance ), necessitating a new pesticide. Alternatively a greater dose of the pesticide can be used to counteract the resistance, although this will cause a worsening of the ambient pollution problem.
Since chlorinated hydrocarbon pesticides dissolve in fats and are not excreted, organisms tend to retain them almost indefinitely. Biological magnification is the process whereby these chlorinated hydrocarbons (pesticides) are more concentrated at each level of the food chain. Among marine animals, pesticide concentrations are higher in carnivorous fishes, and even more so in the fish-eating birds and mammals at the top of the ecological pyramid . Global distillation is the process whereby pesticides are transported from warmer to colder regions of the Earth, in particular the Poles and mountain tops. Pesticides that evaporate into the atmosphere at relatively high temperature can be carried considerable distances (thousands of kilometers) by the wind to an area of lower temperature, where they condense and are carried back to the ground in rain or snow.
In order to reduce negative impacts, it is desirable that pesticides be degradable or at least quickly deactivated in the environment. Such loss of activity or toxicity of pesticides is due to both innate chemical properties of the compounds and environmental processes or conditions. For example, the presence of halogens within a chemical structure often slows down degradation in an aerobic environment. Adsorption to soil may retard pesticide movement, but also may reduce bioavailability to microbial degraders.
HARM ANNUAL US COST
Public health $1.1 billion
Pesticide resistance in pest $1.5 billion
Groundwater contamination $2.0 billion
Other costs $1.4 billion
TOTAL COSTS $9.6 BILLION
Human health and environmental cost from pesticides in the United States is estimated at $9.6 billion offset by about $40 billion in increased agricultural production:
Additional costs include the registration process and the cost of purchasing pesticides. The registration process can take several years to complete (there are 70 different types of field test) and can cost $50–70 million for a single pesticide. Annually the United States spends $10 billion on pesticides.
Alternatives to pesticides are available and include methods of cultivation, use of biological pest controls (such as pheromones and microbial pesticides), genetic engineering , and methods of interfering with insect breeding. Application of composted yard waste has also been used as a way of controlling pests. These methods are becoming increasingly popular and often are safer than traditional chemical pesticides. In addition, EPA is registering reduced-risk conventional pesticides in increasing numbers.
Cultivation practices include polyculture (growing multiple types of plants), crop rotation , planting crops in areas where the pests that damage them do not live, timing planting according to when pests will be least problematic, and use of trap crops that attract pests away from the real crop. Trap crops have successfully controlled pests in some commercial agricultural systems while reducing pesticide usage; however, in many other systems, trap crops can fail to reduce pest densities at a commercial scale, even when the trap crop works in controlled experiments. In the U.S., farmers have had success controlling insects by spraying with hot water at a cost that is about the same as pesticide spraying.
Release of other organisms that fight the pest is another example of an alternative to pesticide use. These organisms can include natural predators or parasites of the pests. Biological pesticides based on entomopathogenic fungi , bacteria and viruses cause disease in the pest species can also be used.
Interfering with insects' reproduction can be accomplished by sterilizing males of the target species and releasing them, so that they mate with females but do not produce offspring. This technique was first used on the screwworm fly in 1958 and has since been used with the medfly , the tsetse fly , and the gypsy moth . However, this can be a costly, time consuming approach that only works on some types of insects.
Agroecology emphasize nutrient recycling, use of locally available and renewable resources , adaptation to local conditions, utilization of microenvironments, reliance on indigenous knowledge and yield maximization while maintaining soil productivity. Agroecology also emphasizes empowering people and local communities to contribute to development, and encouraging “multi-directional” communications rather than the conventional “top-down” method.
PUSH PULL STRATEGY
Main article: Push–pull technology
The term "push-pull" was established in 1987 as an approach for integrated pest management (IPM). This strategy uses a mixture of behavior-modifying stimuli to manipulate the distribution and abundance of insects. "Push" means the insects are repelled or deterred away from whatever resource that is being protected. "Pull" means that certain stimuli (semiochemical stimuli, pheromones, food additives, visual stimuli, genetically altered plants, etc.) are used to attract pests to trap crops where they will be killed. There are numerous different components involved in order to implement a Push-Pull Strategy in IPM.
Many case studies testing the effectiveness of the push-pull approach have been done across the world. The most successful push-pull strategy was developed in Africa for subsistence farming. Another successful case study was performed on the control of Helicoverpa in cotton crops in Australia. In Europe, the Middle East, and the United States, push-pull strategies were successfully used in the controlling of Sitona lineatus in bean fields.
Some advantages of using the push-pull method are less use of chemical or biological materials and better protection against insect habituation to this control method. Some disadvantages of the push-pull strategy is that if there is a lack of appropriate knowledge of behavioral and chemical ecology of the host-pest interactions then this method becomes unreliable. Furthermore, because the push-pull method is not a very popular method of IPM operational and registration costs are higher.
Some evidence shows that alternatives to pesticides can be equally
effective as the use of chemicals. For example,
However, pesticide resistance is increasing. In the 1940s, U.S. farmers lost only 7% of their crops to pests. Since the 1980s, loss has increased to 13%, even though more pesticides are being used. Between 500 and 1,000 insect and weed species have developed pesticide resistance since 1945.
Pesticides are often referred to according to the type of pest they control. Pesticides can also be considered as either biodegradable pesticides, which will be broken down by microbes and other living beings into harmless compounds, or persistent pesticides, which may take months or years before they are broken down: it was the persistence of DDT, for example, which led to its accumulation in the food chain and its killing of birds of prey at the top of the food chain. Another way to think about pesticides is to consider those that are chemical pesticides or are derived from a common source or production method.
Some examples of chemically-related pesticides are:
Neonicotinoids are a class of neuro-active insecticides chemically
similar to nicotine . Imidacloprid, of the neonicotanoid family, is
the most widely used insecticide in the world. In the late 1990s
neonicotinoids came under increasing scrutiny over their environmental
impact and were linked in a range of studies to adverse ecological
effects, including honey-bee colony collapse disorder (CCD) and loss
of birds due to a reduction in insect populations. In 2013, the
Organophosphates affect the nervous system by disrupting acetylcholinesterase activity, the enzyme that regulates acetylcholine , a neurotransmitter . Most organophosphates are insecticides. They were developed during the early 19th century, but their effects on insects, which are similar to their effects on humans, were discovered in 1932. Some are very poisonous. However, they usually are not persistent in the environment.
They were commonly used in the past, but many have been removed from the market due to their health and environmental effects and their persistence (e.g., DDT, chlordane, and toxaphene ).
They were developed as a synthetic version of the naturally occurring pesticide pyrethrin, which is found in chrysanthemums. They have been modified to increase their stability in the environment. Some synthetic pyrethroids are toxic to the nervous system.
The following sulfonylureas have been commercialized for weed control: amidosulfuron, azimsulfuron, bensulfuron-methyl, chlorimuron-ethyl, ethoxysulfuron, flazasulfuron, flupyrsulfuron-methyl-sodium, halosulfuron-methyl, imazosulfuron, nicosulfuron, oxasulfuron, primisulfuron-methyl, pyrazosulfuron-ethyl, rimsulfuron, sulfometuron-methyl Sulfosulfuron, terbacil, bispyribac-sodium, cyclosulfamuron, and pyrithiobac-sodium. Nicosulfuron, triflusulfuron methyl, and chlorsulfuron are broad-spectrum herbicides that kill plants weeds or pests by inhibiting the enzyme acetolactate synthase . In the 1960s, more than 1 kg/ha (0.89 lb/acre) crop protection chemical was typically applied, while sulfonylureates allow as little as 1% as much material to achieve the same effect.
Main article: Biopesticide
* Microbial pesticides which consist of bacteria, entomopathogenic fungi or viruses (and sometimes includes the metabolites that bacteria or fungi produce). Entomopathogenic nematodes are also often classed as microbial pesticides, even though they are multi-cellular. * Biochemical pesticides or herbal pesticides are naturally occurring substances that control (or monitor in the case of pheromones ) pests and microbial diseases. * Plant-incorporated protectants (PIPs) have genetic material from other species incorporated into their genetic material (i.e. GM crops ). Their use is controversial, especially in many European countries.
CLASSIFIED BY TYPE OF PEST
Pesticides that are related to the type of pests are:
Algicides Control algae in lakes, canals, swimming pools, water tanks, and other sites
Antifouling agents Kill or repel organisms that attach to underwater surfaces, such as boat bottoms
Antimicrobials Kill microorganisms (such as bacteria and viruses)
Attractants Attract pests (for example, to lure an insect or rodent to a trap). (However, food is not considered a pesticide when used as an attractant.)
Biocides Kill microorganisms
Disinfectants and sanitizers Kill or inactivate disease-producing microorganisms on inanimate objects
Fungicides Kill fungi (including blights, mildews, molds, and rusts)
Fumigants Produce gas or vapor intended to destroy pests in buildings or soil
Herbicides Kill weeds and other plants that grow where they are not wanted
Insecticides Kill insects and other arthropods
Miticides Kill mites that feed on plants and animals
Microbial pesticides Microorganisms that kill, inhibit, or out compete pests, including insects or other microorganisms
Molluscicides Kill snails and slugs
Nematicides Kill nematodes (microscopic, worm-like organisms that feed on plant roots)
Ovicides Kill eggs of insects and mites
Repellents Repel pests, including insects (such as mosquitoes) and birds
Rodenticides Control mice and other rodents
FURTHER TYPES OF PESTICIDES
The term pesticide also include these substances:
DEFOLIANTS : Cause leaves or other foliage to drop from a plant, usually to facilitate harvest. DESICCANTS : Promote drying of living tissues, such as unwanted plant tops. INSECT GROWTH REGULATORS : Disrupt the molting, maturity from pupal stage to adult, or other life processes of insects. PLANT GROWTH REGULATORS : Substances (excluding fertilizers or other plant nutrients) that alter the expected growth, flowering, or reproduction rate of plants.
Wood preservatives : They are used to make wood resistant to insects, fungus, and other pests.
In most countries, pesticides must be approved for sale and use by a government agency.
In Europe, recent EU legislation has been approved banning the use of highly toxic pesticides including those that are carcinogenic , mutagenic or toxic to reproduction, those that are endocrine-disrupting, and those that are persistent, bioaccumulative and toxic (PBT) or very persistent and very bioaccumulative (vPvB). Measures were approved to improve the general safety of pesticides across all EU member states.
Though pesticide regulations differ from country to country,
pesticides, and products on which they were used are traded across
international borders. To deal with inconsistencies in regulations
among countries, delegates to a conference of the United Nations Food
Three other efforts to improve regulation of international pesticide trade are the United Nations London Guidelines for the Exchange of Information on Chemicals in International Trade and the United Nations Codex Alimentarius Commission . The former seeks to implement procedures for ensuring that prior informed consent exists between countries buying and selling pesticides, while the latter seeks to create uniform standards for maximum levels of pesticide residues among participating countries. Both initiatives operate on a voluntary basis.
Pesticides safety education and pesticide applicator regulation are
designed to protect the public from pesticide misuse , but do not
eliminate all misuse. Reducing the use of pesticides and choosing less
toxic pesticides may reduce risks placed on society and the
environment from pesticide use.
Integrated pest management , the use
of multiple approaches to control pests, is becoming widespread and
has been used with success in countries such as
Pesticides can be created that are targeted to a specific pest's lifecycle, which can be environmentally more friendly. For example, potato cyst nematodes emerge from their protective cysts in response to a chemical excreted by potatoes; they feed on the potatoes and damage the crop. A similar chemical can be applied to fields early, before the potatoes are planted, causing the nematodes to emerge early and starve in the absence of potatoes.
Main article: Pesticide regulation in the United States Preparation for an application of hazardous herbicide in USA.
Some pesticides are considered too hazardous for sale to the general public and are designated restricted use pesticides . Only certified applicators, who have passed an exam, may purchase or supervise the application of restricted use pesticides. Records of sales and use are required to be maintained and may be audited by government agencies charged with the enforcement of pesticide regulations. These records must be made available to employees and state or territorial environmental regulatory agencies.
The EPA regulates pesticides under two main acts, both of which
amended by the
Food Quality Protection Act of 1996. In addition to the
In addition, the U.S. EPA uses the National Research Council's four-step process for human health risk assessment: (1) Hazard Identification, (2) Dose-Response Assessment, (3) Exposure Assessment, and (4) Risk Characterization.
Recently Kaua'i County (Hawai'i) passed Bill No. 2491 to add an article to Chapter 22 of the county's code relating to pesticides and GMOs. The bill strengthens protections of local communities in Kaua'i where many large pesticide companies test their products.
Since before 2000 BC, humans have utilized pesticides to protect
their crops. The first known pesticide was elemental sulfur dusting
used in ancient Sumer about 4,500 years ago in ancient Mesopotamia.
Rig Veda , which is about 4,000 years old, mentions the use of
poisonous plants for pest control. By the 15th century, toxic
chemicals such as arsenic , mercury , and lead were being applied to
crops to kill pests. In the 17th century, nicotine sulfate was
extracted from tobacco leaves for use as an insecticide. The 19th
century saw the introduction of two more natural pesticides, pyrethrum
, which is derived from chrysanthemums , and rotenone , which is
derived from the roots of tropical vegetables . Until the 1950s,
arsenic-based pesticides were dominant. Paul Müller discovered that
The first legislation providing federal authority for regulating pesticides was enacted in 1910; however, decades later during the 1940s manufacturers began to produce large amounts of synthetic pesticides and their use became widespread. Some sources consider the 1940s and 1950s to have been the start of the "pesticide era." Although the U.S. Environmental Protection Agency was established in 1970 and amendments to the pesticide law in 1972, pesticide use has increased 50-fold since 1950 and 2.3 million tonnes (2.5 million short tons) of industrial pesticides are now used each year. Seventy-five percent of all pesticides in the world are used in developed countries, but use in developing countries is increasing. A study of USA pesticide use trends through 1997 was published in 2003 by the National Science Foundation's Center for Integrated Pest Management.
In the 1960s, it was discovered that
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