THE BUGYMAN EXTERMINATORS
Pesticides; Background, How They Work & Examples Of.
| 1. Botanicals | 2. Synthetic Pyrithroids |
| 3. Inorganics | 4. Chlorinated Hydrocarbons |
| 5. Organophosphates | 6. Carbamates |
| 7. InsectGrowthRegulators | 8. Pesticides: Formulation |
Botanicals
Background :
Discovered many centuries ago
when certain dried and crushed flowers were found to have insecticidal properties. They
are referred to as the "natural insecticides".
How they work :
Botanicals interfere with the
function of the insect's nervous system, yet have very low toxic effects to dogs, cats and
humans. However, they are quite toxic to most fish, birds, reptiles and amphibians.
Examples of botanical insecticides:
* pyrethrum: extracted from the flower, chrysanthemum. Pyrethrum is most used today. It is most usually combined with other materials in order to assist in its effectiveness. It is used primarily as a flushing agent (to get the bugs out).
* rotenone
* ryania
* nicotine
Synthetic Pyrethroids
Background :
Examples of synthetic pyrethroids:
* Allethrin: principle use is a "knockdown agent."* Syfluthrin (Barthroid, Tempo): fair flushing action, good roach knockdown, and effective residual action.
* Cypermethrin (Demon, Cynoff): exceptional flushing action and knockdown and modest residual action.
* Deltamethrin (Suspend): some flushing and knockdown action, but Is outstanding for its long residual and toxicity to roaches.
* Resmethrin (SBP-1382): slower knockdown and less flushing action.
Inorganics
Background :
Examples of inorganics :
* Boric Acid: a stomach poison.
* Diatomaceous Earth: made from plants which exist in the ocean. They kill by disrupting the outer layer of the insect, causing it to die by dehydration.
* Silica Aerogel: a fine powder made of silicic acid. They kill by disrupting the outer
layer of the insect, causing it to die by dehydration
Chlorinated Hydrocarbons
Background :
How they work :
They are effective due to there ability to kill by interfering with the pest's nervous system.
Examples of CH's :
* DDT: banned in 1971
* Chlordane(Cyanogas, A-Dust): when contacted with moist air causes a gas to be released.
* Lindane: has a vapor action. Is only allowed for control of wood burrowing beetles
Background :
These types of pesticides
were the first to replace CH's. The first OP's were developed in the early 1950's and were
highly toxic to mammals and some such as dichlorvos and parathion remain so. Others such
as diazinon, dursban, orthene and safrotin which has a much safer toxic level have allowed
these materials to still be used today.
How they work :
The primary toxic action
of OP's involves inhibition of an important enzyme in the nervous system, called
cholinesterase. This enzyme is important in the process where nerve impulses bridge the
gap between two nerve cells, and when inhibited, the communication of nerve impulses are
disrupted, which eventually causes death. Mammals such as cats, dogs and humans also have
cholinesterase and could be harmed by these chemicals. Most OP's deteriorate rapidly in
the environment.
Examples of OP's :
* Chlorpyrifos(Dursban):moderately toxic, good residual action, and a fast knockdown and flushing action. It is not effective on porous surfaces such as wood and concrete
* Acephate(Orthene): moderate toxicity to mammals. It is generally effective against German roaches which may be resistant to other Ops such as diazinon and chlorpyrifos
* Endrin(Rid-A-Bird): highly toxic and is used for control of pigeons.
* Naled (Dibrom): moderate toxicity which is primarily used for outdoor spraying for mosquito and flying insect control.
* Trichlorfon(Dipterex):moderately toxic &is readily soluble in water. Because
there is no solvent odor, it has been used in sugar baits for fly control.
Background :
The first carbamates were
developed in the late-1950's, and through the early 1960's.
How they work :
The primary toxic action
of carbamates involves inhibition of an important enzyme in the nervous system, called
cholinesterase. This enzyme is important in the process where nerve impulses bridge the
gap between two nerve cells, and when inhibited, the communication of nerve impulses are
disrupted, which eventually causes death. Generally, most carbamates have a much lower
toxicity to mammals than most Organophosphates.
Examples of carbamates :
* Carbaryl(Sevin): low toxicity to mammals. Useful against fleas on pets and Highly toxic to honeybees and wasps.
* Propoxur(Baygon): fair flushing action against roaches, fast knockdown and moderate residual action on many surfaces.
* Bendiocarb(Ficam): has no odor and good residual action when applied as a wettable
powder spray of dust. It has low toxicity to mammals. Not to effective against German
roaches. In a dust formula, it gives quick kill against bees, wasps, and hornets.
Insect Growth
Regulators (I G R's)
Background :
do not cause the targeted pest to die when
coming in contact with the chemical.
How they work :
1) "Juvenoids" sterilize the young insects so they are unable to reproduce once they reach adulthood. This sterilization occurs because the adult insects fail to
develop necessary sexual organs and they retain other immature, or juvenile, characteristics
2) "Chitin inhibitors" disrupt an enzyme called chitin synthetase. This
enzyme is important in the formation of new outer shells (cuticles) after the old cuticle
is shed, or molted. Effected insects typically die when they are unable to shed their old
cuticle or when the new cuticle cannot provide the strength to allow the insects muscles
to work.
Examples of I G R's :
* Hydroprene(Gentrol): a juvenoid. Very effective against German roaches.* Fenoxycarb: a juvenoid. Very effective against Berman roaches.
* Methoprene: a chitin inhibitor.
1. Liquid Formulations
A. Concentrates
1. Emulsifiable Concentrates (EC or E): Many pesticide concentrates in their pure form will not dissolve and mix with water. Emulsifiable concentrates are concentrated oil solutions of insecticides with emulsifiers added to them. Emulsifiers are detergent-like materials that make it possible for the millions of insecticide oil droplets to be suspended (or mixed) in water to form an emulsion.
Some insecticides can be emulsified very well and will remain "mixed" in water for a considerable period of time. Others will settle out relatively quickly. EC's will penetrate porous materials. They are non-flammable, but water emulsions are good conductors of electricity and must not be used close to electrical installations.
2. Flowable Microencapsulated (FM): FM's are formed when the insecticide particle is enclosed, or "encapsulated," inside tiny spheres of nylon or some other polymer material. FM's are very effective on porous Surfaces, but may leave a visible residue when used indoors. The polymer coating protects the insecticide from the degrading effects of environmental factors which break down other types of spray residues. The toxicity of FM's to mammals is usually much lower than for other formulations of the same active ingredient.
B. Ready-to-use Sprays (may be oil solutions, emulsion, "aerosols," etc.)
C. Fumigants (Gaseous Liquids)
2. Dry Formulations
A. Dusts (D) Most dusts are dry mixtures of insecticide with some type of inactive powders such as clay, talc, or ash. Some dusts such as boric acid are used as insecticides without other ingredients. Dust can be used on almost any surface without harming it. It is not necessary to leave a visible residue to effectively control insects. Dusts generally leave an effective residual deposit as long as the deposit remains dry.
B. Wettable Powders (WP or W) Wettable powders are essentially concentrated dusts impregnated with an insecticide concentrate. While the water from a WP mixture will penetrate porous materials, the powder usually does not. Most of the insecticide is left on the surface where it can be picked up by a passing insect. WP's may leave a visible off-white deposit on some dark, smooth surfaces. For this reason, WP's are usually applied outdoors, which aside from any visible deposits, is safe to apply to most surfaces, including lawns or ornamental plants. WP's can be used indoors in areas where the presence of a visible powder is not objectionable.
C. Baits (B) Like granules, the pesticide is impregnated on or in a bait material which acts as a food substance attractive to the pest. Ant baits are effective in dry formulas, but paste baits mixed with food such as peanut butter or some type of jelly, will generally be taken more readily. Most rodent baits are combined with grain materials to make them attractive as food to rodents. Baits for bird control generally use seed or grain as the attractant.
D. Granules (G) Pesticides are formulated into such materials as ground corn cobs, crushed walnut or pecan shells. After applied, it is usually necessary to wet the granules with water to release the active ingredient.
Which type of formulation to choose ?
To choose the best insecticide formulation for any particular job, we must first consider the surface which it will be applied to, the structural and environmental factors as well as determine how the insecticide is to be applied. In making your recommendation, consider the following:
* The surface type to be treated (metal, wood, concrete, dirt, etc.)
* Application equipment available and best suited for the job.
* Hazard of drift and runoff (nearness to sensitive areas, likelihood of wind or rain).
* Safety to applicator, helpers, and other humans and pets likely to be exposed.
* habits or growth patterns of the pest ( bait vs. Spray, granular vs. foliar spray).
* Cost.
* Type of environment in which the application must be made ( outdoors, damp areas, dusty areas, dry rooms, etc.)
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Last modified: November 24, 1997