Integrated Pest Management
Integrated Pest Management
Integrated pest management (IPM) is a system that incorporates many methods of dealing with pest problems. IPM systems may include pest-resistant crop varieties; modification of habitat to make it less suitable for the pest; pest-specific predators, parasites, herbivores, or diseases; and pesticides when necessary. However, because IMP systems do not rely exclusively on the use of pesticides, they are a key element of any strategy to reduce the overall use of these chemicals, and thereby avoid the toxicological and ecological damages they cause.
Pests can be defined as any animals, plants, or microorganisms that interfere with some human purpose. For example, insects may be considered pests if they eat crop plants or stored foods, or if they are important vectors in the transmission of diseases of humans or domestic animals. Plants are considered pests, or weeds, if they compete excessively with crop plants in agriculture or forestry, or if they have an unwanted aesthetic, as is the case of weeds in grassy lawns. Microorganisms are regarded as pests if they cause disease in humans, domestic animals, or agricultural plants. In eaqch case, humans may attempt to manage their pest problems with pesticides, that is, chemicals toxic to the pest.
The judicious use of pesticides can be beneficial. For example, agricultural yields can be increased, and stored foods can be protected. Human lives can also be saved by decreasing the frequency of diseases spread by arthropods; malaria, for example, is spread through bites of a few species of mosquitoes. However, there are also some important negative consequences of the use of pesticides to achieve these benefits.
Pesticides are toxic chemicals, and they are rarely poisonous only to the pests against which they may be used. The spectrum of pesticide toxicity is usually quite wide, and includes a diverse range of nonpest (or nontarget) species, in addition to the pest. Most insecticides, for example, are poisonous to a wide range of insect species, to other arthropods such as spiders and crustaceans, and often to fish, amphibians, birds, and mammals, including humans.
Moreover, the operational use of pesticides does not usually achieve a specific exposure of only the pest target—many nonpest species are also exposed through offsite drift or other movements of the sprayed pesticide, both on the actual spray site as well as elsewhere. Nontarget exposures are especially important when pesticides are applied as a broadcast spray over a large treatment area, for example, by an aircraft or tractor-drawn apparatus.
Some important ecological effects are caused by the typically broad spectrum of toxicity of pesticides, and the extensive exposures to nonpest species whenever broadcast sprays are used. For example, the extensive spraying of synthetic insecticides to manage epidemic populations of spruce budworm
(Choristoneura fumiferana ), an important defoliator of coniferforests in northeastern North America, results in huge nontarget kills of diverse arthropod species, and deaths of birds and other vertebrate animals. Similarly, the use of herbicides kills large numbers of plants, in addition to the few species that are sufficiently abundant to be considered weeds.
In addition, some pesticides are toxic to humans, and people may be poisoned as a result of exposures occurring through the normal use of these chemicals. The most intense exposures involve accidents; in rare cases people may be killed by pesticide poisoning. Usually, however, the exposure is much smaller, and the toxic response is milder—often not easily measurable. Generally, people who are employed in the manufacture or use of pesticides are subject to relatively intense exposures to these chemicals. However, all people are exposed to some degree, through the food, water, and air in their environments. In fact, there is now a universal contamination of animals, including humans, with certain types of pesticides, most notably the persistent chlorinated hydrocarbons such as DDT.
Other ecological effects of pesticide use occur as a result of habitat changes. These effects are indirect, and they can negatively influence populations of wildlife even if they are not susceptible to direct toxicity from the pesticide. For example, the use of herbicides in forestry causes large changes in the abundance and species composition of the plant community. These changes are highly influential on the wildlife community, even if the herbicide is not very toxic to animals. Alternative methods of pest management would allow reliance on the extensive pesticide use to be diminished.
Compared to reliance on the broadcast pesticide use, integrated pest management is preferable. Through IPM an acceptable degree of pest control can be achieved by using a variety of complementary approaches. These include:
(1) Development and use of varieties of pest- and disease-resistant crop species. If there is genetically based susceptibility to the pest or disease, resistant crop varieties can be developed using standard breeding practices. (2) Attacking the pest biologically by introducing or enhancing the populations of its natural predators, parasites, or diseases. (3) Changing other ecological conditions to make the habitat less suitable for the pest. (4) Undertaking careful monitoring of the abundance of pests, so that specific control strategies can be used efficiently, and only when required. (5) Using pesticides as a last resort, and only when they are a necessary component of an integrated, pest-management system.
If a system of integrated management can be successfully designed and implemented to deal with a pest problem, reliance on pesticides can be greatly reduced, although their use is not necessarily eliminated. For example, a system of integrated pest management has been developed to control boll weevils (Anthonomus grandis ) in Texas cottonfields. The widespread use of this system has allowed large reductions in the use of insecticides for this purpose. About 19 million pounds(8.8 million kg) of insecticides were used against boll weevil in 1964, but only 2.4 million pounds (1.1 million kg) in 1976 after an IPM system became widely used.
A very beneficial aspect of IPM is that its control methods are highly specific to the pest, whenever this is biologically or ecologically possible. This allows non-target damages to be avoided or greatly reduced.
Often, the most useful pest-specific control methods involve some sort of biological-control agent, such as a disease, predator, or herbivore that specifically attacks the pest species. Biological agents have been most successful against invasive pests introduced from another continent that are thriving in the absence of their natural control agents.
In the late-nineteenth century, for example, the cottony-cushion scale insect (Icyera purchasi ) was accidentally introduced from Australia to the United States, where it became a serious threat to the developing California citrus industry. In one of the first triumphs of biological control, this pest was successfully managed by introducing an Australian lady beetle (Vedalia cardinalis ) and parasitic fly (Cryptochetum iceryae ).
Because it is toxic to cattle, the klamath weed (Hypericum perforatum ) became a serious problem in pastures in southwestern North America after it was introduced from Europe. However, this weed was controlled by the introducing two European beetles that eat its foliage. A similar success is the control of European ragwort (Senecio jacobea ) in pastures in western North America through the introduction of three of its insect herbivores.
The common vampire bat (Desmodus rotundus ) from subtropical parts of the Americas bites cattle and other animals to obtain a blood meal, which may weaken the victims or cause them to develop diseases. This serious livestockpest can now be controlled by capturing individual bats, treating them with petroleum jelly that contains a pesticide, and then setting the animals free to return to their communal roosts in caves, where the poison is transferred to other bats during social grooming. This treatment is specific, and other bat species are not affected.
Another serious pest of cattle is the screw-worms (Callitroga ominivorax ), whose larvae feed on open wounds and can prevent them from healing. This pest has been controlled in some areas by releasing large numbers of male flies that have been sterilized by exposure to gamma radiation. Because females of this species will only mate once, any copulation with a sterile male prevents them from reproducing. The sterile-male technique works by overwhelming wild populations with infertile males, resulting in few successful matings, and a decline of the pest to an economically acceptable abundance.
Clearly, it is highly desirable to use IPM systems, especially in comparison with broadcast sprays of conventional, synthetic pesticides. This is particularly true of those relatively few pests for which effective biological controls have been discovered, because these methods have few nontarget effects. IPMs are the key to reducing reliance on pesticides in agriculture, forestry, horticulture, and public health.
It is unfortunate that in spite of ongoing research into their development, effective integrated systems have not yet been discovered for most pest management problems. Because it is important to manage pests, their control must therefore continue to rely heavily on synthetic pesticides. Regrettably, the toxicological and ecological
Agroecosystem —An agricultural ecosystem, comprised of crop species, noncrop plants and animals, and their environment.
Drift —Movement of sprayed pesticide by wind beyond the intended place of treatment.
Nontarget effects —Effects on organisms other than the intended pest target of pesticide spraying.
damages associated with a heavy reliance on pesticides will continue until a broader range of integrated tools is available to pest managers.
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Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1994.
National Sustainable Agriculture Information Service. “Biointensive Integrated Pest Management: Fundamentals of Sustainable Agriculture” <http://attra.ncat.org/attra-pub/ipm.html> (accessed November 29, 2006).
U.S. Environmental Protection Agency—Pesticides: Topical & Chemical Fact Sheets “Integrated Pest Management (IPM)and Food Production” <http://www.epa.gov/pesticides/factsheets/ipm.htm> (accessed November 29, 2006).
"Integrated Pest Management." The Gale Encyclopedia of Science. . Encyclopedia.com. (April 25, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/integrated-pest-management
"Integrated Pest Management." The Gale Encyclopedia of Science. . Retrieved April 25, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/integrated-pest-management