PESTICIDE

1ST GENERATION

2ND GENERATION

3RD GENERATION

The Food and Agriculture Organization (FAO) has defined pesticide as:

any substance or mixture of substances intended for preventing, destroying, or controlling any pest, including vectors of human or animal disease, unwanted species of plants or animals, causing harm during or otherwise interfering with the production, processing, storage, transport, or marketing of food, agricultural commodities, wood and wood products or animal feedstuffs, or substances that may be administered to animals for the control of insects, arachnids, or other pests in or on their bodies. The term includes substances intended for use as a plant growth regulator, defoliant, desiccant, or agent for thinning fruit or preventing the premature fall of fruit. Also used as substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport

Health effects of pesticides may be acute or delayed in those who are exposed. A 2007 systematic review found that "most studies on non-Hodgkin lymphoma and leukemia showed positive associations with pesticide exposure" and thus concluded that cosmetic use of pesticides should be decreased.Strong evidence also exists for other negative outcomes from pesticide exposure including neurological problems, birth defects, fetal deathand neurodevelopmental disorderAccording to The Stockholm Convention on Persistent Organic Pollutants, 9 of the 12 most dangerous and persistent chemicals are pesticides.

Long term effects

Cancer

Many studies have examined the effects of pesticide exposure on the risk of cancer. Associations have been found with: leukemia, lymphoma, brain, kidney, breast, prostate, pancreas, liver, lung, and skin cancers.This increased risk occurs

with both residential and occupational exposures.[ Increased rates of cancer have been found among farm workers who apply these chemicals

Neurological

Evidence links pesticide exposure to worsened neurological outcomes. The risk of developing Parkinson's disease is 70% greater in those exposed to even low levels of pesticides. People with Parkinson's were 61% more likely to report direct pesticide application than were healthy relatives. Both insecticides and herbicides significantly increased the risk of Parkinson's disease. There are also concerns that long term exposures may increase the risk of dementia.

Reproductive effects

Strong evidence links pesticide exposure to birth defects, fetal death and altered fetal growth.In the United States, increase in birth defects is associated with conceiving in the same period of the year when agrochemicals are in elevated concentrations in surface water. Agent Orange , a 50:50 mixture of 2,4,5-T and 2,4-D, has been associated with bad health and genetic effects in Malaya and Vietnam It was also found that offspring that were at some point exposed to pesticides had a low birth weight and had developmental defects

Fertility

A number of pesticides including dibromochlorophane and 2,4-D has been associated with impaired fertility in males. Pesticide exposure resulted in reduced fertility in males, genetic alterations in sperm, a reduced number of sperm, damage to germinal epithelium and altered hormone function.

Types

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.

Organophosphate pesticides

Organophosphates affect the nervous system by disrupting 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.

Carbamate pesticides

Carbamate pesticides affect the nervous system by disrupting an enzyme that regulates acetylcholine, a neurotransmitter. The enzyme effects are usually reversible. There are several subgroups within the carbamates

Organochlorine insecticides

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 and chlordane).

Pyrethroid pesticides

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

Sulfonylurea herbicides

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.Nicosulfurontriflusulfuron methyl,and chlorsulfuron are broad-spectrum herbicides that kill plants 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.

Biopesticides

Biopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. For example, canola oil and baking soda have pesticidal applications and are considered biopesticides.[

Biopesticides fall into three major classes:

Microbial pesticides consist of a microorganism e.g., a bacterium, fungus, virus, or protozoan as the active ingredient. Microbial pesticides can control many different kinds of pests, although each separate active ingredient is relatively specific for its target pest.For example, there are fungi that control certain weeds, and other fungi that kill specific insects.

Plant-Incorporated-Protectants (PIPs) are pesticidal substances that plants produce from genetic material that has been added to the plant. For example, scientists can take the gene for the Bt pesticidal protein, and introduce the gene into the plant's own genetic material. Then the plant, instead of the Bt bacterium, manufactures the substance that destroys the pest. The protein and its genetic material, but not the plant itself, are regulated by EPA.

Biochemical pesticides are naturally occurring substances that control pests by non-toxic mechanisms. Conventional pesticides, by contrast, are, in general, synthetic materials that directly kill or inactivate the pest. Biochemical pesticides include substances, such as insect sex pheromones, that interfere with mating, as well as various scented plant extracts that attract insect pests to traps. Because it is sometimes difficult to determine whether a substance meets the criteria for classification as a biochemical pesticide, EPA has established a special committee to make such decisions.

Type of pesticide Target pest groupHerbicides Plant

Algicides or Algaecides AlgaeAvicides Birds

Bactericides BacteriaFungicides Fungi and OomycetesInsecticides Insects

Miticides or Acaricides MitesMolluscicides SnailsNematicides Nematodes

Rodenticides RodentsVirucides Viruses

Classified by type of pest

Pesticides that are related to the type of pests are:

Type Action

AlgicidesControl algae in lakes, canals, swimming pools, water tanks, and other sites

Antifouling agentsKill or repel organisms that attach to underwater surfaces, such as boat bottoms

Antimicrobials Kill microorganisms (such as bacteria and viruses)

AttractantsAttract pests (for example, to lure an insect or rodent to a trap). (However, food is not considered a pesticide when used as an attractant.)

BiopesticidesBiopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals

Biocides Kill microorganisms

Disinfectants and sanitizers

Kill or inactivate disease-producing microorganisms on inanimate objects

Fungicides Kill fungi (including blights, mildews, molds, and rusts)

FumigantsProduce gas or vapor intended to destroy pests in buildings or soil

HerbicidesKill 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

NematicidesKill nematodes (microscopic, worm-like organisms that feed on plant roots)

Ovicides Kill eggs of insects and mites

Pheromones Biochemicals used to disrupt the mating behavior of insects

Repellents Repel pests, including insects (such as mosquitoes) and birds

Rodenticides Control mice and other rodents

Insecticides

Insecticides are chemicals used to control insects. Often the word "insecticide" is confused with the word "pesticide." It is, however, just one of many types of pesticides. An insecticide may kill the insect by touching it or it may have to be swallowed to be effective. Some insecticides kill both by touch and by swallowing. Insecticides called Systemics may be absorbed, injected, or fed into the plant or animal to be protected. When the insect feeds on this plant or animal, it ingests the systemic chemical and is killed.

Broad Spectrum. Insecticides vary in the numbers of different kinds of insects they kill. Some insecticides kill only a few kinds of insects. Sometimes you can choose these insecticides when you wish to kill only one insect pest and not other beneficial insects in the area. Many insecticides are general purpose or wide range killers. These "broad spectrum" pesticides are used when several different kinds of insects are a problem. One chemical can kill them all. No broad spectrum insecticide kills all insects; each varies as to the kinds of insects it controls.

Narrow Spectrum. While many insecticides are broad spectrum, killing a wide variety of animals by attacking a system common to all, such as the nervous

system, a new group of insecticides are much more selective. The chitin inhibitors only affect animals with chitin in their exoskeleton (i.e. insects). Growth regulators are even more specific. They affect certain groups of species that have a particular hormone. Finally, pheromones are the most restrictive because they react with only one species or one sex of a single species.

Chitin synthesis inhibitors interfere with the development and molting of immature insects causing their death. Chitin is the primary structural chemical in an insects body wall. An immature insect treated with a chitin inhibitor dies the next time it attempts to molt.

Insect growth regulators or IGRs mimic the action of an insect's naturally occurring juvenile hormone. They interfere with certain normal processes and prevent immature insects from completing development into normal reproductive adults. The effects of IGRs on insects include abnormal molting, twisted wings, loss of mating behavior, and sometimes death to embryos in eggs. IGRs attack a growth process found only in insects, thus there is a great margin of safety for humans and other vertebrates. However, one disadvantage is that growth regulators act slowly, since they do not kill the insect until it molts into an adult.

Pheromones are naturally produced chemicals used by animals to communicate to each other. There are three basic types of pheromones. Aggregation pheromones attract many individuals together, for example, a site where food may be plentiful. Sex pheromones are used by one sex of a species to attract a mate. Trail pheromones are deposited by walking insects, such as ants, so that others can follow. Synthetic pheromones produced in laboratories mimic these natural chemicals. They are used to attract pest insects into traps, disrupt mating, and monitor populations of insects. Because they do not kill insects, they are often not considered to be pesticides.

Short Term vs. Residual. Insecticides also vary in how long they last as a killing agent. Some break down almost immediately into nontoxic by -products. These "short term" chemicals are very good in situations where the insects do not return or where long-term exposure could injure non-target plants or animals. For example, short-term insecticides are often used in homes and dwellings where people and domestic animals might be exposed. Other insecticides remain active killers for a fairly long period of time. These "residual" pesticides are very useful when the insects are a constant problem and where they will not be an environmental and/or health hazard. For example, residuals are often used for fly control in livestock buildings or for termite control in wooden structures.

Miticides (or Acaricides) are chemicals used to control mites (tiny Insecticides spider-like animals) and ticks. The chemicals usually must contact the mites or ticks to be effective. These animals are so numerous and small, that great care must be used to completely cover the area on which the mites live. Miticides are very similar in action to insecticides and often the same pesticide kills both insects and mites. The terms "broad spectrum," "short term," and "residual" are also used

Fungicides

Fungicides are chemicals used to control the fungi which cause molds, rots, and plant diseases. All fungicides work by coming in contact with the fungus, because fungi do not "swallow" in the normal sense. Therefore, most fungicides are applied over a large surface area to try to directly hit every fungus. Some fungicides may be systemic in that the plant to be protected may be fed or injected with the chemical. The chemical then moves throughout the plant, killing the fungi. to describe miticides.

Protectant vs. Eradicant. There are two basic approaches in the use of fungicides. One is designed to prevent the plant from getting the disease. These fungicides are used as "protectants" and are similar in purpose to polio and smallpox vaccinations for humans. They are applied before the disease gets a start. This type of fungicide is very useful when a particular disease or group of diseases are likely to attack a plant or crop, year after year. Protectants, for example, have often been used as a routine precaution on fruit and vegetable crops.

Most protectant fungicides are fungistatic. This means they prevent or inhibit fungal growth. Once the fungistatic action ceases, the controlled fungus may grow again or produce spores. Thus, a protectant fungicide may have to be applied at regular intervals to continue the protection from infection.

The other type of fungicide kills the disease after it appears on (or in) the plant. These fungicides, called "eradicants," are like penicillin or other antibiotics which cure diseases in humans after the sickness appears. Eradicants are less common than protectants because once the fungus is established in a plant, it is often difficult to destroy. Eradicants are often used when protectants aren't available, aren't applied in time, or are too expensive. Eradicants are also applied when the disease appears unexpectedly on a plant or in an area. For example, a common use is on fruit and vegetables when the protectant spray wasn't applied on time to prevent infection. Eradicants are also used by orchardists in combatting diseases of fruit trees, such as apple scab.

Herbicides

Herbicides are chemicals used to control unwanted plants. These chemicals are a bit different from other pesticides because they are used to kill or slow the growth of some plants, rather than to protect them. Some herbicides kill every plant they contact, while others kill only certain plants.

Nonselective herbicides are toxic to all plants. These are often used when no plants are wanted in an area. For example, nonselective herbicides could be used for clearing under guardrails or for total control of weeds in industrial areas.

Selective herbicides kill some plants with little or no injury to other plants. Usually selective types will kill either broadleaved plants or grassy plants. These are useful for lawns, golf courses or in areas with desirable trees. Some very selective herbicides may kill only certain plants in a group; for example, crabgrass killers on lawns.

Preplanting vs. Preemergence vs. Postemergence. The timing of an herbicide application is important. Care must be used to get the job done effectively without injuring desirable plants. The directions on the label tell you when to apply the herbicide for best results. Preplanting treatments are made before the crop is planted. These chemicals may be used in seed beds or incorporated into the soil before planting.

Any treatment made before the crop and weed appears is called preemergence. The application may be made before both the crop and weeds appear, or after the crop appears but before the weeds appear. The label or directions will state "preemergence to the crop," "preemergence to the weeds," or "preemergence to both crop and weeds."

When the herbicide treatment is made after the crop or weeds appear, it is called postemergence. Postemergence applications must be very selective. They must control the weeds but leave the crop unharmed. Often, the chemical will be applied postemergent to the crop but preemergent to the weeds.

Growth Regulators and Harvest Aids

A plant growth regulator (or plant regulator) increases, decreases or changes normal growth or reproduction in a plant. Fertilizers and other nutrients are not included. Some growth regulators are used to move up or move back the normal harvest date for the crop. Others are used to obtain better quality and/or yield of the

crop. Electric power utilities could use growth regulators to slow the growth of a tree threatening power lines, thus saving the tree from being cut.

Defoliants and desiccants are pesticide materials generally referred to as harvest aids. A defoliant causes the leaves of a plant to drop off early, but does not kill the plant. A desiccant draws moisture from a plant, killing the plant foliage.

Rodenticides

Rodenticides are chemicals used to control rats, mice, bats and other rodents. Chemicals which control other mammals, birds, and fish are also grouped in this category by regulatory agencies. Most rodenticides are stomach poisons and are often applied as baits. Even rodenticides which act by contacting the pest are usually not applied over large surfaces because of the hazard to domestic animals or desirable wildlife. They are usually applied in limited areas such as runways, known feeding places, or as baits.

Nematicides Molluscicides Repellents

Nematicides are chemicals used to control nematodes. Nematodes are tiny hir-like worms, many of which live in the soil and feed on plant roots. Very few of these worms live above ground. Usually, soil fumigants are used to control nematodes in the soil. (See section on fumigants in Module XV.) However, a few contact insecticides and fungicides are also effective against these tiny worms.

Molluscicides are chemicals used to control snails and slugs. Usually the chemicals must be eaten by the pest to work. Baits are often used to attract and kill snails or slugs in an area.

A repellent is a pesticide that makes a site or food unattractive to a target pest. They are registered in the same way other pesticides are and must be used according to the label. Insect repellents are available as aerosols and lotions and can be applied to skin, clothing, or plants to repel biting and nuisance insects. Vertebrate repellents are available as concentrates to be mixed with water, powders, and granules. They can be sprayed or painted on nursery crops, ornamental plantings, orchards, vineyards, vegetables, and seeds. Repelling deer, dogs, birds, raccoons, and others can protect sites from damage.

Pesticides: Chemical & Physical Characteristics

Understanding the chemical and physical characteristics of a pesticide allows the applicator to make better decisions about which pesticide active ingredient and/or formulation to use for a particular situation. Two chemical characteristics of interest are water solubility and volatility. The more water soluble a pesticide is, the greater the potential for runoff and leaching. The more volatile a pesticide is, the greater the potential for drift.

When a pesticide is highly water soluble the pesticide remains dissolved in the water as it moves around in the environment. Less water soluble pesticides deposit in the soil or on plants more quickly and are less likely to move around in the environment. Because highly water soluble pesticides tend to move around in the environment, they are more likely to contaminate nearby rivers, lakes, streams, wells, and storm sewers, especially following heavy rainfall or excessive irrigation. If soils are sandy or if ground water tables are close to the surface, highly water soluble pesticides are not a good choice for use in these areas. This is because the dissolved pesticide has a greater chance of moving into groundwater.

The physical form of a pesticide or pesticide formulation can also travel throughout the environment. Pesticides formulated as granules, for instance, can be easily carried by wind or water into undesirable areas.

EFFECTS OF PESTICIDE

Air

Pesticides can contribute to air pollution. Pesticide drift occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them. Pesticides that are applied to crops can volatilize and may be blown by winds into nearby areas, potentially posing a threat to wildlife. Weather conditions at the time of application as well as temperature and relative humidity change the spread of the pesticide in the air. As wind velocity increases so does the spray drift and exposure. Low relative humidity and high temperature result in more spray evaporating. The amount of inhalable pesticides in the outdoor environment is therefore often dependent on the season. Also, droplets of sprayed pesticides or particles from pesticides applied as dusts may travel on the wind to other areas,] or pesticides may adhere to particles that blow in the

wind, such as dust particles.Ground spraying produces less pesticide drift than aerial spraying does.

Water

In the United States, pesticides were found to pollute every stream and over 90% of wells sampled in a study by the US Geological Survey.Pesticide residues have also been found in rain and groundwaterStudies by the UK government showed that pesticide concentrations exceeded those allowable for drinking water in some samples of river water and groundwater.[Pesticide impacts on aquatic systems are often studied using a hydrology transport model to study movement and fate of chemicals in rivers and streams. As early as the 1970s quantitative analysis of pesticide runoff was conducted in order to predict amounts of pesticide that would reach surface waters.There are four major routes through which pesticides reach the water: it may drift outside of the intended area when it is sprayed, it may percolate, or leach, through the soil, it may be carried to the water as runoff, or it may be spilled, for example accidentally or through neglect.

Soil

The use of pesticides decreases the general biodiversity in the soil. Not using the chemicals results in higher soil quality with the additional effect that more organic matter in the soil allows for higher water retention. This helps increase yields for farms in drought years, when organic farms have had yields 20-40% higher than their conventional counterparts A smaller content of organic matter in the soil increases the amount of pesticide that will leave the area of application, because organic matter binds to and helps break down pesticides.

Degradation and sorption are both factors which influence the persistence of pesticides in soil.

Effect on plants

Nitrogen fixation, which is required for the growth of higher plants, is hindered by pesticides in soilThe insecticides DDT, methyl parathion, and especially pentachlorophenol have been shown to interfere with legume-rhizobium chemical signaling.Pesticides can kill bees and are strongly implicated in pollinator

decline, the loss of species that pollinate plants, including through the mechanism of Colony Collapse Disorder,On the other side, pesticides have some direct harmful effect on plant including poor root hair development, shoot yellowing and reduced plant growth

Effect on animals

Pesticides can eliminate some animals' essential food sources, causing the animals to relocate, change their diet or starve. Residues can travel up the food chain; for example, birds can be harmed when they eat insects and worms that have consumed pesticides. Earthworms digest organic matter and increase nutrient content in the top layer of soil. They protect human health by ingesting decomposing litter and serving as bio-indicators of soil activity. Pesticides have had harmful effects on growth and reproduction on earthworms. Some pesticides can bio-accumulate, or build up to toxic levels in the bodies of organisms that consume them over time, a phenomenon that impacts species high on the food chain especially hard.

Laws regulating the manufacture and the use of pesticides

The Food Quality Protection Act (FQPA), or H.R.1627The FQPA standardized the way the Environmental Protection Agency (EPA) would manage the use of pesticides and amended the Federal Insecticide, Fungicide, and Rodenticide Act and the Federal Food Drug and Cosmetic Act. It mandated a health-based standard for pesticides used in foods, provided special protections for babies and infants, streamlined the approval of safe pesticides, established incentives for the creation of safer pesticides, and required that pesticide registrations remain current. The FQPA required the re-testing of all existing pesticide tolerance levels within 10 years. When assessing this risk the EPA is required to take into account the “aggregate risk” (the exposure to a pesticide from multiple sources) and the “cumulative exposure” to pesticides with similar mechanisms of toxicity. To do this the EPA is required to establish new science polices to assess the risks. The FQPA requires the EPA to set tolerances for pesticide uses that fall under section 18 of the Federal Insecticide, Fungicide and Rodenticide Act (emergency exemptions). The FQPA mandates that the EPA expedite the approval of reduced risk pesticides. To be considered reduced risk pesticides must have a proven low-impact on human health, have low toxicity to non-target organisms and have a low

potential to contaminate groundwater. The FQPA requires the EPA to give special consideration to pesticides used on products that have less than 300,000 acres of total U.S. production or products that do not have enough economic incentive to either support an initial registration or a continuing registration. The FQPA requires the EPA to establish a list of pests that are considered significant to public health and to give special consideration to pesticides with public health uses. The EPA is also required to provide maintenance fee waivers to and encourage the safe and necessary use of methods/pesticides that either combat or control pests that have been deemed of public health importance. The EPA also provides waiver fees for the pesticides used on pests that are deemed of public health importance.

The United States Environmental Protection Agency (EPA or sometimes USEPA) is an agency of the U.S. federal government which was created for the purpose of protecting human health and the environment by writing and enforcing regulations based on laws passed by Congress. EPA administers the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (which is much older than the agency) and registers all pesticides legally sold in the United States.

The Toxic Substances Control Act (TSCA) is a United States law, passed by the United States Congress in 1976 and administered by the United States Environmental Protection Agency, that regulates the introduction of new or already existing chemicals. Its three main objectives are to assess and regulate new commercial chemicals before their entrance into the market, to regulate chemicals (which were already existing in 1976) that posed an "unreasonable risk to health or to the environment", and to regulate these chemicals' distribution and use. However, as explained below, the TSCA specifically regulates polychlorinated biphenyl (PCB) products. The Toxic Substances Control Act of 1976 mandated the EPA to protect the public from "unreasonable risk of injury to health or the environment" by regulating the manufacture and sale of chemicals. This act does not address wastes produced as by product of manufacturing, as did the Clean Water and Air Acts of the era. Instead, this act attempted to exert direct government control over which types of chemicals could and could not be used in actual use and production

Integrated pest management and other alternatives to insecticide dependence

Integrated pest management (IPM), also known as Integrated Pest Control (IPC) is a broad-based approach that integrates practices for economic control of pests. IPM aims to suppress pest populations below the economic injury level (EIL). The UN's Food and Agriculture Organisation defines IPM as "the careful consideration of all available pest control techniques and subsequent integration of appropriate measures that discourage the development of pest populations and keep pesticides and other interventions to levels that are economically justified and reduce or minimize risks to human health and the environment. IPM emphasizes the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms. Entomologists and ecologists have urged the adoption of IPM pest control since the 1970s. IPM allows for safer pest control. This includes managing insects, plant pathogens and weeds. IPM extended the concept of integrated control to all classes of pests and was expanded to include all tactics. Controls such as pesticides were to be applied as in integrated control, but these now had to be compatible with tactics for all classes of pests. Other tactics, such as host-plant resistance and cultural manipulations, became part of the IPM framework. IPM combined entomologists, plant pathologists, nematologists and weed scientists. IPM is used in agriculture, horticulture, human habitations, preventive conservation and general pest control, including structural pest management, turf pest management and ornamental pest management.

Principles

An American IPM system is designed around six basic components:

Acceptable pest levels—The emphasis is on control, not eradication. IPM holds that wiping out an entire pest population is often impossible, and the attempt can be expensive and unsafe. IPM programmes first work to establish acceptable pest levels, called action thresholds, and apply controls if those thresholds are crossed. These thresholds are pest and site specific, meaning that it may be acceptable at one site to have a weed such as white clover, but not at another site. Allowing a pest population to survive at a reasonable threshold reduces selection pressure. This lowers the rate at which a pest develops resistance to a control, because if almost all pests are killed then those that have resistance will provide the genetic basis of the future population. Retaining a significant number unresistant specimens dilutes the prevalence of any resistant genes that appear. Similarly, the repeated use of a single class of controls will create pest populations that are more resistant to that class, whereas alternating among classes helps prevent this.

Preventive cultural practices—Selecting varieties best for local growing conditions and maintaining healthy crops is the first line of defense. Plant quarantine and 'cultural techniques' such as crop sanitation are next, e.g., removal of diseased plants, and cleaning pruning shears to prevent spread of infections. Beneficial fungi and bacteria are added to the potting media of horticultural crops vulnerable to root diseases, greatly reducing the need for fungicides. Monitoring—Regular observation is critically important. Observation is broken into inspection and identification. Visual inspection, insect and spore traps, and other methods are used to monitor pest levels. Record-keeping is essential, as is a thorough knowledge target pest behaviour and reproductive cycles. Since insects are cold-blooded, their physical development is dependent on area temperatures. Many insects have had their development cycles modeled in terms of degree-days. The degree days of an environment determines the optimal time for a specific insect outbreak. Plant pathogens follow similar patterns of response to weather and season. Mechanical controls—Should a pest reach an unacceptable level, mechanical methods are the first options. They include simple hand-picking, barriers, traps, vacuuming and tillage to disrupt breeding. Biological controls—Natural biological processes and materials can provide control, with acceptable environmental impact, and often at lower cost. The main approach is to promote beneficial insects that eat or parasitize target pests. Biological insecticides, derived from naturally occurring microorganisms (e.g.—Bt, entomopathogenic fungi and entomopathogenic nematodes), also fall in this category. Further 'biology-based' or 'ecological' techniques are under evaluation.

Responsible use—Synthetic pesticides are used as required and often only at specific times in a pest's life cycle. Many newer pesticides are derived from plants or naturally occurring substances (e.g.—nicotine, pyrethrum and insect juvenile hormone analogues), but the toxophore or active component may be altered to provide increased biological activity or stability. Applications of pesticides must reach their intended targets. Matching the application technique to the crop, the pest, and the pesticide is critical. The use of low-volume spray equipment reduces overall pesticide use and labor cost.

Some elements of integrated pest management

Sterile-male technique

A direct method aimed at decreasing the reproduction of pest species. One of the early uses of this was during the 1950s against the screwworm fly which attacks

cattle. The release of Radiation-sterilized male to mate with a female fly results in infertile eggs. This plan works as the female fly mates just once, whether or not they are fertilized.

Pheromones and juvenile hormones

Sex attractant pheromones can be used to draw insects into trap, disorient insect or otherwise decrease their reproduction. Pheromones are most effective in low-density population. They are also useful in monitoring infected areas: the extent of infestation can be determined on the basis of the number of insects trapped over a specific period of time. Juvenile Hormones are substances produced by insects that maintain them in an immature state. Chemicals that have the similar effects can prevent insects from reaching sexual maturity and reproducing. The chief advantage of hormone approach is its species specificity.

Biological and natural enemies

Both bacteria and viruses have also been successfully used to control specific pests, Bacteria have been used to control the Japanese beetles.

Resistance management

>Because it is multifaceted approach to the control of pests, IPM should diminish the resistance in pest species. Resistance Management refers to any attempts to prevents, delay or reverse the evolution of resistance through various ecological and chemical techniques. The development of resistance is costly in terms of crop loss, increasing volumes of pesticide applied, and the use of new, more expensive pesticides to replace those no longer usable. Biotechnology is expected to play a significant role in resistance management, since genes for resistance or susceptibility can be altered. The use of nonchemical control methods should certainly be considered as promising alternative in pesticide resistance management.

Low input sustainable agriculture

This approach to farming minimizes the use of synthetic chemical fertilizers and pesticides and focuses on practices that will maintain the ability of the land to

grow crops for an unlimited period of time. Thus erosion control and good irrigation practices are part of the said program. The actual methods used depend on the characteristics of the specific farm and the crops to be grown but includes such practices.

(KEY CONCEPTS) ENVIRONMENTAL CONTROL: Is a term used to designate a number of techniques that alter the biotic and abiotic conditions in crops making

them inhospitable to pests.

Increasing crop diversity: heteroculture and crop rotating Altering plants and soil nutrients Controlling adjacent crops and weeds Altering the time of planting Biological controls: Introducing predators, parasites and disease

organisms.

CHEMICAL CONTROL:

Reducing the use of Second generation pesticides

PESTICIDE BANS AND RESTRICTIONS

AGENT ORANGE MIREX AND FIRE ANTS EDB –ETHYLENE DIBROMIDE WOOD PRESERVATIVES

Pesticide Characteristics

Solubility

Solubility is a measure of the ability of a pesticide to dissolve in a solvent, which is usually water. Pesticides that are highly soluble in water dissolve easily. Such pesticides are more likely to move with water in surface runoff or to move through the soil in water than less-soluble pesticides.

Adsorption

Adsorption is the process whereby a pesticide binds to soil colloids, which are microscopic inorganic and organic particles in the soil. Colloid is derived from the Greek term meaning glue-like. These particles have an extremely large surface area in proportion to a given volume. It has been calculated that 1 cubic inch of colloidal clay may have 200–500 square feet of particle surface area.

Adsorption occurs because of an attraction between the chemical and soil particles. Typically, oil-soluble pesticides are more attracted to clay particles and to organic matter in soil than water-soluble pesticides. Pesticide molecules with positive charges are more tightly adsorbed to negatively charged soil particles. A pesticide that adsorbs to soil particles is less likely to move from the application site than a chemical that does not adsorb tightly to the soil.

Persistence

Persistence is the ability of a pesticide to remain present and active in its original form during an extended period before degrading. A chemical's persistence is described in terms of its half-life, which is a comparative measure of the time needed for the chemical to degrade. The longer a pesticide's half-life, the more persistent the pesticide. Persistent pesticide residues are sometimes desirable because they provide long-term pest control and reduce the need for repeated applications. However, some persistent pesticides applied to soil, plants, lumber, and other surfaces or spilled into water or on soil can later harm sensitive plants or animals, including humans. It is especially important to prevent persistent pesticides from moving off-site through improper handling, application, drift, leaching, or runoff.

Application of persistent pesticides presents a hazard to persons and non-target animals entering a treated area and may lead to the presence of illegal residues on rotational food or feed crops. Check the label for statements about the persistence of the pesticide and for replanting restrictions. The rate of pesticide degradation relates to the persistence of the pesticide.

Volatility

Volatility is the tendency of a pesticide to turn into a gas or vapor. Some pesticides are more volatile than others. The likelihood of pesticide volatilization increases as temperatures and wind increase. Volatility is also more likely under conditions of low relative humidity.

The potential for a pesticide to volatilize is measured by its vapor pressure. This measurement may be described in units of Pa (Pascals) or mmHg (millimeters of mercury). Pesticides that have high vapor-pressure values are more volatile. Vapors from such pesticides can move off-site and cause injury to susceptible plants. Some volatile pesticide products carry label statements that warn handlers of the product's potential for vapor movement

Pesticide Safety

Since pesticides are poisons designed to destroy pest species, there are many hazards associated with their use. Pesticides can harm humans in different ways. Exposure to pesticides can be through the skin, mouth, eyes or lungs. Hazards to nontarget organisms and environmental contamination also are important concerns.

All pesticides should be handled with care to avoid unnecessary exposure. The label is designed to ensure safe use, so be sure to always read

understand and follow all label instructions. Use pesticides only when they are necessary. Use the protective equipment indicated on the label and make sure that this

equipment is clean and in proper working order. Make sure that application equipment is properly calibrated and in good

working order. Take precautions to avoid unnecessary drift during application. Use pesticides that have low volatility. Use formulations that resist drift and volatility. Use low pressures during spraying. Use nozzles which reduce formation of small spray particles. Use high water volumes during application. Apply pesticides close to the crop or soil surface. Avoid applying pesticides when the temperature is high. Avoid applying pesticides during windy conditions. Use drift-reducing adjuvants. Take precautions to avoid contamination of surface and groundwater. Store pesticides properly, in accordance with federal, state and local

pesticide laws and regulations. Dispose of empty pesticide containers promptly, safely, and according to the

label. Know the proper procedures for controlling, containing, and cleaning up

accidental pesticide spills. Know the symptoms of pesticide poisoning.

Seek medical attention immediately if poisoning is suspected. Take the pesticide label to the physician.

Know first aid procedures for pesticide poisoning and keep a first aid kit available.

Managing Pesticide Resistance

By: Frank B. Peairs

Resistance is a naturally existing characteristic that can be inherited, that increases a pest’s ability to withstand the effects of the pesticide. Pesticide resistance is a growing problem. Nearly 450 species of insects and mites have developed resistance to one or more insecticides, including carbamates and organophosphates. More than 55 resistant weed species have been reported in the United States. Many systemic and some contact fungicides are prone to resistance because they attack fungi with a specific mode of action. Among the fungicides considered candidates for resistance are: bensimidaoles (Benlate, Tersan, Topsin M), phenylamides (Ridomil), dicarboximides (Rovral, Ronilan), and sterol inhibitors (Rubigan Bayleton, Tilt).

Rotate the mode of action of pesticides used in the field. Use pesticides only when necessary. Scout for resistance. Utilize integrated pest management.

Eliminating pesticides

Many alternatives are available to reduce the effects pesticides have on the environment. Alternatives include manual removal, applying heat, covering weeds with plastic, placing traps and lures, removing pest breeding sites, maintaining healthy soils that breed healthy, more resistant plants, cropping native species that are naturally more resistant to native pests and supporting biocontrol agents such as birds and other pest predators. Biological controls such as resistant plant varieties and the use of pheromones, have been successful and at times permanently resolve a pest problem. Integrated Pest Management (IPM) employs chemical use only when other alternatives are ineffective. IPM causes less harm to humans and the environment. The focus is broader than on a specific pest, considering a range of pest control alternatives. Biotechnology can also be an innovative way to control pests. Strains can be genetically modified (GM) to increase their resistance to pests.