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Types of Pesticides
Pesticides are often referred to according to the type
of pest they control. Another way to think about pesticides is to
consider those that are chemical pesticides
or are derived from a common source or production method. Other categories
include biopesticides, antimicrobials,
and pest control devices.
Some examples of chemically-related pesticides follow. Other examples
are available in sources such as Recognition
and Management of Pesticide Poisonings.
Organophosphate Pesticides
- These pesticides 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. Some are very poisonous (they were used in World
War II as nerve agents). However, they usually are not persistent in the
environment.
Carbamate Pesticides affect the nervous system by disupting
an enzyme that regulates acetylcholine, a neurotransmitter. The enzyme
effects are usually reversible. There are several subgroups within the
carbamates.
Organochlorine Insecticides 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 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.
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.
At the end of 2001, there were approximately 195 registered biopesticide
active ingredients and 780 products. Biopesticides fall into three major
classes:
(1) 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[s]. For example, there are fungi that control certain weeds, and
other fungi that kill specific insects.
The most widely used microbial pesticides are subspecies and strains
of Bacillus thuringiensis, or Bt. Each strain of this bacterium produces
a different mix of proteins, and specifically kills one or a few related
species of insect larvae. While some Bt's control moth larvae found
on plants, other Bt's are specific for larvae of flies and mosquitoes.
The target insect species are determined by whether the particular Bt
produces a protein that can bind to a larval gut receptor, thereby causing
the insect larvae to starve
(2) 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.
(3) Biochemical pesticides are naturally occurring
substances that control pests by non-toxic mechanisms. Conventional
pesticides, by contrast, are generally 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.
Pest Types
Pesticides that are related because they address the same type of pests
include:
- 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
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.)
- Biopesticides
- Biopesticides 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).
- 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 (also called acaricides)
- 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.
- 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.
The term pesticide also includes 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.
-
Pest Control Devices
What about pest control devices? EPA also has a role in regulating devices
used to control pests. More specifically, a "device" is any instrument
or contrivance (other than a firearm) intended for trapping, destroying,
repelling, or mitigating any pest. A mousetrap is an example of a device.
Unlike pesticides, EPA does not require devices to be registered with
the Agency. Devices are subject to certain labeling, packaging, record
keeping, and import/export requirements, however.
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