Selecting and Using Pesticides

Pesticides are included as part of the IPM strategy, but they must be used with care and with attention to safety. There are certain considerations to keep in mind when using a pesticide, especially in regard to potential harm to non-target organisms.

Selecting Pesticides

Using Pesticides

Pesticide Information

Dangers of Pesticides

Pesticide Transportation, Storage, and Disposal

Pesticide Poisoning

Selecting Pesticides

Acquire and consult the Material Safety Data Sheets before deciding on a specific pesticide. These important documents give data on the potential hazards and safety precautions of various pesticides. Pesticide suppliers have MSDS available, and more detailed information about MSDS, how to read them, and where to get them online can be obtained at http://www.ilpi.com/msds/index.html.

Criteria for choosing a pesticide include:

  1. Safety is top priority
    • Questions to ask include what is the toxicity level of the pesticide (measured by LD50--the higher the LD50 number, the less toxic); how mobile is the pesticide and in what fashion can it be distributed (through air, soil, water, etc.); what is the residual life of the pesticide; and what are the environmental hazards listed on the label?
  2. Species specificity
    • This is especially important to look for before using toxic chemicals since certain pesticides only affect the target animals or plants. Try to avoid getting broad spectrum pesticides that have potential to kill or harm many beneficial species along with the pest. If such a pesticide is the only option, try doing spot treatments to reduce the likelihood of affecting non-target organisms.
  3. Effectiveness
    • For pesticides, it is a bit difficult to measure effectiveness because it can vary depending on where the chemicals are being applied. In a lab, for instance, a chemical may kill a large percentage of the target pest because it is a controlled environment, but in a real life situation, the number may be much smaller due to other factors such as killing off natural enemies, temperature changes, etc. Evaluating uses of a considered pesticide in similar situations as that of your school may help in estimating the kind of effect it will have.
  4. Endurance
    • An animal or plant's endurance to the effects of a pesticide may vary. Watch for success in pest control:if it at first seems to work well but then later populations grow despite continued use, there may be some built up resistance.
  5. Pesticides vary in their speeds of interaction
    • Choosing a pesticide should be determined based on circumstances. If it is an emergency, a shorter lived, fast acting and more acutely toxic material (such as organophosphate for cockroaches) may be necessary. But a longer lasting, slow acting and less toxic material (such as boric acid) may be better for chronic pest problems.
  6. Cost
    • This is always a consideration when deciding what chemicals to use. Determination of cost often is done by measuring dollars per volume-some new materials that are effective in lower doses may be more expensive than older pesticides that need larger amounts to do the job. A small container of more concentrated material may seem more expensive, but may be as effective as three times that much in another kind of pesticide.
  7. Once a pesticide is selected, notify
    • Give notification to personnel, students, and parents about what pesticide will be (or has been) used and where it is going to be (or has been) applied so they are aware of any possible exposure. Ideally applications should be done when buildings are unoccupied, but regardless, it is best to give advanced notice that an application is scheduled so that everyone can take appropriate steps to ensure the safety of those involved.

Using Pesticides

  1. Registration bug with a line through it
  2. Read the Pesticide Label
    • Follow its directions for use, registrations, storage, and disposal to the letter. Signal words on labels indicate the toxicity levels:
      • DANGER-a taste to a teaspoon taken by mouth could kill an average-sized adult.
      • WARNING-a teaspoonful to an ounce taken by mouth could kill an average-sized adult.
      • CAUTION-an ounce to over a pint taken by mouth could kill an average-sized adult.
  3. Secure (if required) written recommendations
    • Obtain these from a licensed pest control advisor for use of the pesticide.
  4. Personal Protective Equipment
    • Make sure that all safety equipment, such as gloves, goggles, respirator, hat, etc. are available and worn when the pesticide is used.
  5. Pesticide applicators should be licensed
    • Commercial operators must have a license to apply pesticides on school grounds and be able to handle all equipment needed for the application. Consult http://www.kellysolutions.com/NE/Applicators/index.htm to see what individuals are licensed in the state of Nebraska.
  6. Equipment
    • Make sure it is correctly calibrated and appropriate for the job at hand.
  7. Spot treat 
    • This will keep material confined to the area requiring treatment.
  8. MSDS Sheets should be available
  9. Keep records
    • What pesticide was used and for what? How much was used? Be sure to list all pertinent information about the treatment for future reference about what was done.
  10. Monitor for pests after the application
    • Post-treatment monitoring can help determine the method's success.
  11. Compile Emergency Contact list
  12. Disposal
    • Do not put pesticides down toilets, sinks, or other drains or gutters. Follow the manufacturer's directions for proper disposal.

Pesticide Information


Route of Entry

How pests encounter the pesticide (type of entry):

Animals:

  • Contact (work by physical contact with the pest)
  • Respiratory (Fumigants) (inhaled)
    • Carbon Dioxide
    • Phosphide Generators
    • Methyl Bromides
  • Stomach (must be ingested by the pest)


Weeds:

  • Contact/Nonsystemic (plant surface is covered with pesticide and disruption of cellular membranes occurs)
  • Translocation/Systemic (pesticide is absorbed through leaves, stems, or root system and it spreads throughout tissues)

 

 

Pesticide Formulations Formulation Examples

spray can

Liquids

  • Aerosols
  • Concentrates
  • Emulsifiable Concentrates
  • Flowables
  • Fogging
  • Fumigant
  • Invert Emulsions
  • Microencapsulated
  • Ready to Use
  • Solutions
  • Ultra-low volume
Dry
  • Baits
  • Dusts
  • Fumigants
  • Granules
  • Microencapsulated
  • Pellets
  • Wettable Powders
  • Soluable Powders
  • Water dispersible granules/dry flowables

   

Other: Adjuvants--substance added to a formulation to make it more effective

Liquids
  • Aerosols--CB Wasp Freeze
  • Concentrates--Demand CS (Lambda-cyhalothrin, various insect pests)
  • Emulsifiable Concentrates--Cynoff EC (Cypermethrin, roaches and ants; some other insect pests)
  • Flowables--Marksman (Dicamba/Atrazine, herbicide)
  • Fogging--Insect Fogger Total Release (pyrethrin, various insect pests)
  • Fumigants--Vapam (Metam-sodium, parasitic nematodes)
  • Invert Emulsions--Habitat herbicide (Imazapyr)
  • Microencapsulated (note: both liquid and dry available)--Suspend SC (Deltamethrin, various insect pests), Penncap-M (Methyl Parathion, aphids and other insect pests)
  • Ready-to-Use--Roundup Grass and Weed Killer Ready-to-Use (Glyphosate)
  • Solutions--Orthene (Acephate, aphids and other insect pests)
  • Ultra-low volume--Ripcord (Cypermethrin, insect pests)

 


Dry

  • Baits--MaxForce Ant Gel (Fipronil)
  • Dusts--Permadust (Boric Acid, roaches and other insect pests)
  • Fumigants--Phostoxin (Aluminum Phosphide, vertebrate pests)
  • Granules--Weed and Feed (contain both herbicides and fertilizers)
  • Pellets--Advance Carpenter Ant Bait (Abamectin)
  • Wettable Powders--Demon (Cypermethrin, various insect pests)
  • Soluable Powders--Sevin (Carbaryl, tent caterpillars and other insect pests)
  • Water dispersible granules/dry flowables--Strike 25 WDG (Chlorophenoxy, fungicide)
Other: Adjuvants--substance added to a formulation to make it more effective --Spreader Sticker (helps pesticide adhere better to surfaces)

 

Dangers of Pesticides

Toxicity and LD50

How poisonous, or toxic, a substance is is based on its chemical structure and how it interacts with living tissues. Because pesticides are designed to kill living organisms, they all have some level of toxicity. However, these chemicals vary in who they may affect--some are toxic only to the target pest and harmless to humans while others are dangerous for humans and non-target animals too. Signal Words (CAUTION, WARNING, and DANGER, mentioned under the "Selecting Pesticides" section) can give a good indication about the level of toxicity of a pesticide, and should be heeded. In addition, to help determine your risk to a certain pesticide, a simple formula can be used:

Risk = Toxicity X Exposure

If a person is exposed to a fairly low toxic substance for a long period of time, their risk of ill effects may be less than exposure to a more highly toxic substance for a shorter period of time. It all depends on the circumstances and the chemical involved.

LD50 is a measurement of toxicity of chemicals based on the amount of the material it takes to kill 50% of lab animals tested. The lower the LD50 number, the higher the toxicity level (i.e. perhaps 1 mg of a substance kills 20 animals and it takes 10 mg of another chemical to kill that same number). Chemicals placed in the "Low-toxic" category are usually those that have higher LD50 ratings, and chemicals that have lower LD50's have "High-toxic" ratings. Least-toxic pesticides are effective against pests, but have low toxicity (acute or chronic) to mammals, rapid biodegradability, little effect on non-target species, and a small range of target pests. For especially difficult situations, however, sometimes use of more toxic substances is necessary.

To give you a better idea of how various LD50's compare, please consult the chart below. It demonstrates the LD50's of various common pesticides with LD50's of well known everyday products (in italics). The chart gives examples from highest LD50's (lowest toxicity) to lowest LD50's (highest toxicity). Keep in mind, however, that concentration, formulation, amount, and exposure are all factors in how lethal a substance can be.

Substances and their LD50's (mg/kg of rat? body weight)--examples taken from Cockroach Control Manual, Ogg et.al and online MSDS
diatomaceous earth (insect growth regulator) non-toxic

methoprene (insect growth regulator) 34,000

absolute alcohol (beverage/preservative) 10,600

aspartame (artificial sweetener) 10,000

ethylene glycol (antifreeze) 8540

vitamin A 7910

salt 3750

borax (mineral) 3000

pyrethrins (botanical) 1500

aspirin 1000

malathion (organophosphate) 885

ibuprofen (pain reliever) 626

cyfluthrin (pyrethroid) 500

caffeine 355

warfarin 323

bendiocarb (carbamate) 34

acetone (nail polish remover) 10.7

nicotine 0.3

 

 cockroach

Types of Chemical Controls

Chemicals listed here vary in toxicity, but view all materials as potentially hazardous and use with caution and according to the label. It is important to keep in mind the idea of using the least toxic approach possible for your circumstances, and design a plan around methods that have the most chance of success.

  1. Pheromones
    • Pheromones act as chemical signals, fooling an insect into thinking a mate is nearby. Sticky traps flooded with pheromones usually confuse males looking for females in the vicinity, and they unwittingly take the bait.
  2. Baits
    • These can be "stations," filled with sticky substances, dusts, or granules containing pesticide, they can be free standing baits (solids or powders) left in a pest's path, or gels placed in and around pest harborages. When animals come in contact with baits, they may eat the materials or gather them on their feet and carry them back to nests or to others of their kind.  Toxicity levels found in baits vary, but because of how they are used, they are considered safer than other forms of application.
  3. Cleaning Solutions
    • Using household cleansers is a simple way to keep areas disinfected and deter pests. These would include Lysol and bleach and are very effective in killing microorganisms and insects. Use for surface cleaning of counters, appliances, and floors, but take care not to spray on plants. Also be aware that although these chemicals are found in our everyday lives, they can pose dangers and should be handled with care, especially around children and pets.
  4. Insect Growth Regulators (IGRs)
    • IGRs stop the maturity process in insects. They are species-specific and have no impact on mammals. The biggest advantage to this is that immature insects become sterile if their growth is stunted, thus resulting in them not being able to mate and contribute to population growth. Some IGRs include hydrophene for roaches, methoprene for fleas, and diflubenzuron for termites.
  5. Repellents
    • These are used to deter animals from certain areas or from feeding on certain plants. Many of these are fairly low-toxic to mammals. Some, such as DEET, can be used in close proximity to humans (such as on clothes and even limited skin exposure) without serious effects. There are two main types of repellants: animal (such as Ropel, capsaicin extract, and moth crystals) and insect (limonene, DEET).
  6. Desiccating Dusts
    • Desiccating dusts attack the waxy outer layer of an insect's body and causes the insect to lose water and dry out. Common forms of these low-toxic pesticides include boric acid, diatomaceous earth, and silica aerogel.
  7. Pesticidal Soaps/Insecticidal Oils
    • Pesticidal Soaps are made from refined coconut oil and have low toxicity to mammals but should not be used around bodies of water as they have been shown to harm fish. These substances are toxic to insects and decompose rapidly in the environment, not leaving residues. There are some issues with some soft bodied beneficial insects being harmed by these soaps, so take care when using them around areas that may harbor helpful species. Insecticidal oils are often highly refined yet gentle on the environment. Applied to trees and other plants, these oils successfully kill insects without harming the plant.
  8. Botanical Pesticides
    • Botanical Pesticide substances are derived from plants, are easily degraded in the environment, and have powerful effects on insects. They are not necessarily better or less dangerous than synthetics, and should still be used with caution. Pyrethrins, which come from crushed petals of the pyrethrum chrysanthemum flower, are a common part of this group. Other examples include antibiotics (avermectins), rotenone, neem (azadirachtin), pyrethrum, sabadilla, and ryania.
  9. Concentrated Liquid, Wettable Powders and Solutions of Herbicides, Insecticides, and Fungicides
    • Organophosphates and Carbamates--extensively used over the last 20-30 years, mostly not available now. Examples of Carbamates include Sevin, Baygon, and Ficam. Examples of Organophosphates include Dursban, Diazinon, Malathion.
    • Synthetic Pyrethroids--these insecticides, which are man-made representations of the natural botanicals, replaced Organophosphates and Carbamates. Some examples: Permethrin, Resmethrin, Bifenthrin, Cypermethrin, and Cyhalothrin.
    • Nicotinoids--taking after the natural nicotine substances, these insecticides include Imidacloprid and Thiamethoxam.
    • Fipronil--the only chemical in the Fiprole class, Fipronil is being used where pyrethroids, organophosphates, or carbamates have been ineffective.
    • Chlorfenapyr--the only substance found in the Pyrroles chemical group. Used as an insecticide/miticide.
    • Inorganics--include pesticides such as Disodium Octaborate for control of termites and other wood boring pests.
    • Phenoxy--includes 2, 4-D for weed control
    • Phosphono Amino Acids--includes glyphosate (Roundup) for weed control, more effective with grasses than broadleaf plants.
  10. Rodenticide Baits
    •  Anticoagulants, including Coumarins (multi feeding, products such as Warfarin, Talon, Maki) and Indandiones (multi feeding, products such as Diphacin and Rozol). Non Anticoagulants include Benzenamines (single feeding, products such as Vengeance)
    • Zinc phosphide--vertebrate pesticide

Pesticide Transportation, Storage, and Disposal

Proper handling and storage of pesticides is important in a school environment. Transportation of pesticide containers to and from school property should be conducted with caution. Keep an emergency spill kit (with chemical resistant gloves, cat litter or other absorbent material, goggles, and coveralls) with you when carrying pesticides in a vehicle as well as at the storage site. A truck or pickup is probably the best vehicle for pesticide transportation, and you will want to load the pesticides into the back of the truck, never in passenger areas. Inspect containers very carefully when loading and unloading.

Pesticides should be kept in dry, well ventilated locked rooms or closets and be accessible only to people authorized to use them. They should not be stored with food, pet food, plants, or fertilizer. Storage areas should be away from food areas, classrooms, and other sensitive environments. Keep pesticides in original containers with their labels. Watch for expiration dates or leaks and dispose of pesticides properly according to the directions on the label. States have developed regulations for how to discard of many pesticide containers, including instructions for rinsing, destruction, and location for recycling or disposal.

For more details about pesticide transportation, storage, and disposal, please consult the University of Nebraska Extension publication, Safe Transport, Storage and Disposal of Pesticides.

Pesticide Poisoning

Pesticides, if not used properly, can have harmful effects on the human body. If you suspect pesticide poisoning of any kind--be it via inhalation, oral, or dermal--contact the Nebraska Poison Center : 1-800-222-1222 or in the Omaha area 955-5555. First aid varies depending on the pesticide and the area affected. Read the label; there may be instructions for how to administer first aid to a victim of accidental exposure to that product. For more detailed information, please read: Signs and Symptoms of Pesticide Poisoning and Recognition and Management of Pesticide Poisoning

Interested in applying Integrated Pest Management principles to your school? If so, please review and electronically "sign" the form below to express your desire to begin IPM, and let's get started! In addition, you may wish to develop a formal policy outlining a customized IPM program in your school/school district.