2. PEST MANAGAMENT NC II
CONDUCT FIELD ASSESSMENT
APPLY BIO-CONTROL MEASURES
APPLY CULTURAL MANAGEMENT STRATEGIES
APPLY PHYSICAL-CONTROL MEASURES
APPLY CHEMICAL CONTROL MEASURES
MONITOR RESULTS OF PEST-MANAGEMENT ACTIVITIES AND PROVIDE FEEDBACK

3. UC 4: Applying Chemical
Control Measures
PREPARED BY: SIR RICHIE D. LEGANDIN

4. WHAT IS CHEMICAL CONTROL?
 Chemical pesticides are often used to control diseases, pests or
weeds.
 Chemical control is based on substances that are toxic
(poisonous) to the pests involved.
 When chemical pesticides are applied to protect plants from
pests, diseases or overgrowth by weeds, we speak of plant
protection products.
 It is of course important that the plant that needs protection
does not itself suffer from the toxic effects of the protection
products.

5. CHEMICAL CONTROL
 The most common method of pest control is the use of pesticides—
chemicals that either kill pests or inhibit their development.
 Pesticides are often classified according to the pest they are intended to
control.
 For example, insecticides are used to control insects; herbicides to control
plants; fungicides, fungi; rodenticides, rodents; avicides, birds; and
bactericides to control bacteria.
 Pesticides also include chemosterilants and growth regulators, which are used
to interfere with the normal reproduction or development of the pest.

6.  Chemical control of pests probably began with poisonous plant
compounds.
 In the 18th and 19th centuries, farmers ground up certain plants that
were toxic to insects or rodents—plants such as chrysanthemums or
tobacco.
 The plant “soup” was then applied directly to either the crops or the
pests.
 Chemists later discovered that they could extract the toxic compounds
from these poisonous plants and apply the compounds as liquid
sprays.

7. Use of Chemical Pesticides
There are four main ways of classifying insecticides:
CONTACT INSECTICIDES
SYSTEMIC INSECTICIDES
STOMACH INGESTION INSECTICIDES
FUMIGANT INSECTICIDES

8. CONTACT INSECTICIDES
These chemicals are applied in such a way that an
insect cannot avoid contact.
The insect is either sprayed directly or walk-through
deposited spray.

9. Many contact insecticides which
include
 acephate (Orthene®),
 carbaryl (Sevin®),
 fipronil (Over ‘N Out®),
 pyrethrins, pyrethroids (bifethrin,
 cyfluthrin, cypermethrin, deltamethrin,
 lambda-cyhalothin, permethrin, es-fenvalerate,
 tefluthrin or tralomethrin), and liquid fipronil or
spinosad

16. SYSTEMIC INSECTICIDE-
 Sap feeding insect are particular for the target of these chemical.
 Sprayed chemicals are absorbed by the plant.
 Entering the circulatory system.
 When the insect pierces the leaf cuticle and penetrates the sap
stream.
 It withdraws poisoned fluid.
 Thus an aphids feeding on protected crops will inevitably suck
up some insecticide

18. Question:
What is the relationship between water
solubility and systemic insecticides?

19. Answer: Excellent question.
 First of all, what is water solubility?
 Water solubility is a measure of the amount of chemical
substance (insecticide) that will dissolve in water at a
specific temperature (e.g., 68º F) or pH (e.g., less than 7,
7 or more than 7).
 Water solubility is expressed as ppm (parts per million)
or mg/L (milligrams per liter), and is classified as low
(less than 10 ppm or 10 mg/L), moderate (10 to 1,000
ppm or 10 to 1,000 mg/L), or high (more than 1,000
ppm or 1,000 mg/L).

20. In general,
 systemic insecticides must be water-soluble to some degree,
 which allows the dissolved active ingredient to move into the
root zone when applied to the growing medium,
 and then be absorbed by plant roots, and consequently
translocated throughout the plant.
 The water solubility of commercially available systemic
insecticides used in greenhouse production systems are
presented in Table 1.

21. Table 1. Active ingredient (and common trade name), and water solubility (ppm and mg/L) of
commercially available systemic insecticides registered for use in greenhouse production
systems.

22. Water solubility determines how rapidly the
active ingredient is absorbed by roots and
translocated within the plant and deposited
into plant parts such as leaves and stems.
 In general, a high water-soluble systemic
insecticide will kill insect pests (e.g., aphids and
whiteflies) more rapidly but may not provide
long-term or sufficient residual activity
(persistence) compared to a low water-soluble
systemic insecticide.

23. STOMACH INGESTION INSECTICIDES-
 These compound are sprayed over crop foliage so that
those pests with biting mouth parts, like flea beetles,
caterpillars and weevils, eats a poisoned meal.
 These pest may also be affected by other insecticides if
they consume sprayed plant material.

27. FUMIGANT INSECTICIDES-
Vapor given off by the insecticide is inhaled by
the insect.
Once the chemicals has gained entrance it may
exert its lethal action in a variety of ways, where
the chemical vapour can give optimum
penetration.

28. Fumigant
 any volatile, poisonous substance used to kill insects, nematodes, and
other animals or plants that damage stored foods or seeds, human
dwellings, clothing, and nursery stock.
 Soil fumigants are sprayed or spread over an area to be cultivated and
are worked into the soil to control disease-causing fungi, nematodes,
and weeds.
 Fumigants with a high vapour pressure, such as methyl bromide,
ethylene oxide, hydrogen cyanide, and hydrogen phosphide, penetrate
quickly and are used to treat sealed storage areas or materials enclosed
in gas proof sheets.
 Low-pressure compounds such as ethylene dibromide and ethylene
dichloride diffuse more slowly; they are used to treat more open storage
areas and as soil fumigants.

29.  Common fumigants used to treat stored products or nursery stock
include hydrogen cyanide, naphthalene, nicotine, and methyl
bromide.
 Soil fumigants commonly used as nematocides are methyl bromide,
dichloropropane, propylene oxide, dibromochloropropane,
organophosphate insecticides, and chloropicrin.
 Because these substances may kill other soil organisms that
ordinarily control nematodes by predation or infection, serious
nematode infestations may follow fumigation.

34. Problems with chemical pesticides.
 Some pesticides are persistent, they do not break down in the
environment or within the tissues of living organism.
 This give rise to two potential problem.
 Bioaccumulation-is the accumulation of a substance in a biological
tissue.
 Organism at any trophic level may be capable of bioaccumulation

35. Bio magnification
is the increasing concentration of a
substance up a food chain. i.e. from one
trophic level to the next.
Animals at the higher trophic levels will be
most affected.

36. Examples of chemical control include.
 Using an herbicide to wipe out dandelions in your lawn
 Using an insecticide to control scale insects, or
 Using a fungicide to control powdery mildew on dogwoods.
 Some pesticide referred to as restricted use, can be
purchased and applied only by applicators who have taken
to become certified.

37.  Chemical tactics to manage pests can include many types
of compound.
 Some merely repel or confuse pests.
 Some interfere with weeds photosynthesis, insect molting
processes or development in some ways.
 Other, including some botanical and most conventional
insecticides, are broadly toxic to living system.
 The term pesticides literally means “pest killer”
insecticides kill insects,

38. Various characteristic of pesticides
Generally speaking, when using pesticides, we
are trying to garner the advantages of using
pesticides while minimizing risk to human
and other non-target organisms.
Risk to human of pesticide use often
described as.

39. RISK= TOXICITY X EXPOSURE
 The simplest way to safely use pesticides is read the label, be use you
understand the label and follow.
 All instruction exposure can be minimized by simply following the direction
about precaution.
 Both toxicity and exposure are eliminated if you choose not to use a pesticide
as one of your IPM tactics.
 A number of characteristic of pesticide should be understood in order to
consider whether or not to use and how it might be safely used.
 You and your students might investigate the following question when
considering a pest management scenario involving the need for a pesticide.

40. TOXICITY QUESTION

41.  If a chemical is ‘broad spectrum’” that means kills a lot of different organism
within its category.
 In contrast, “narrow spectrum’” chemicals affect more narrow range organism,
 So, for example, if you IPM approach was going to include limited use of an
insecticide to kill caterpillars but you wanted to leave their predators and
parasites unharmed, you would choose a narrow spectrum product targeted at
caterpillars only, others “non-target”, or unintentional, victims of an insecticide
use might include bees, fish, birds, pigs, or aquatic organism.
 These risk are usually listed on the pesticide label.
 There are also list that show relative toxicity of specific compounds towards
these organism
1. How widely toxic is the pesticide?

42. 2. How is toxicity to mammals
(including humans) measured?

43. a) ACUTE TOXICITY: toxicity that cause harm
or death from a single exposure.
 Each pesticide contains small percentage of chemical component
responsible for killing activity.
 This component is called “Active ingredient” or a.i. for short.
 Before release for sale, pesticide are required to undergo testing to
determine how much the active ingredient will kill a mammal.
 Laboratory rats of known weights are feed specific quantities of the
pesticide active ingredients, measured in milligrams of a.i. per
kilogram of body weights (mg/kg.).

44.  The number of milligrams /kilograms required to kill a half of the
experimental population is referred to as the “Lethal dose at which 50% of
the animals die” abbreviated as LD 50.
 The assumption is that as mammals, both humans and rats share common
physiological characteristic.
 Thus, LD50 data are used to estimate toxicity of pesticides to humans.
 Also, the pesticide can be administered by mouth (oral LD50), on the skin
(dermal LD50) and by breathing (inhalation LD50) .
 So for example, some active ingredients are more dangerous than breath
rather than when ingested.
 High LD50 values are better than low ones from an acute toxicity point of
view, it means it would take more of it to kill you!

45. LD50 values are reflected on the pesticides
labels by the “signal words” which
represent levels of toxicity:
CAUTION ----WARNING ----DANGER
(See “Lessons from labels” for how to use this information in a classroom activity

46. CHRONIC TOXICITY:
 harmful effects of exposure over long periods of time.
 Long-term effects of pesticide exposure, or of exposure to multiple
pesticides are poorly understood.
 Laboratory tests with rats measures various factors over time such as
whether the chemical is carcinogenic (causes cancer) or is teratogenic
(causes mutation).
 Other tests whether the chemical is mutagenic (causes mutations).
 You can find information on these factors (see websites below) but it is not
clear how to interpret these result with regards to pesticides use and human
exposure.

47. 3. Which types of pesticides are most
and least toxic to humans?
 Generally speaking, from least of the most toxic common pesticides are:
 FUNGICIDES-- HERBICIDES ---RODENTICIDES--- INSECTICIDES

48. 4. Within the insecticides, which chemical
categories are most toxic?
 (You could ask this question within each type of pesticides. Here we are using insecticides as
an example since they are the most dangerous.)
 Generally speaking, from least to most toxic common insecticides are:
 Soap - microbial products - insect growth regulators -
botanicals pyrethrins -Chlorinated hydrocarbons –
carbamates- organophosphates

49.  These toxicities are generally related to the “mode of action” of
the insecticides; how does it kill?
 For example, all nervous system use the same chemicals to
transmit (and stop) nerve impulses.
 If the pesticides “mode of action” is to interfere with nerve
transmissions, it is potentially more toxic to all organism than
pesticides that is more specific to just insect’ waxy outer covering,
the cuticle, having a little or no effect on mammals.
 So would you choose a soap or an organophosphate to control
aphids on your houseplants?
 Lists of common household chemical and their chemical
categories are included in background materials.

50. 5. What is the formulation of the insecticides?
 Insecticides and other pesticides come in various kind
of mixes.
 These can affect both the toxicity per se and how likely
you are to be exposed. Generally least to most toxic
formulation of insecticides.
 ENCLOSED BAIT---- GRANULAR----- DUST WATER
SOLUTION ----WATER EMULSION OIL SOLUTION-----
AEROSOL---- EMULISIFIABLE CONCENTRATE ------
LIQUID CONCENTRATE

51.  Toxicity of a formulation is related to how easily a dangerous
amount might be able to get into your system.
 Liquid concentrates, if swallowed on contacting skin, are more
toxic than dilute or premixed version of the same chemical.
 Oil “soak” into the skin more. Fine particles of aerosol
formulation can pass through the lungs into bloodstream.
 Dust can be breathed if you are not careful but they usually
carry relatively little active ingredient.
 There are, of course, exceptions!

52. 6. How does the insecticide get into
the insect?
 Insecticides work on insect ways. Once you knows the pest and have
identified your management goals, this knowledge is important in
your choice of insecticide.
 There are 4 basic "routes of entry” of the poison into the insect:
 Stomach poison (insect must eat it)
 Contact poison (just has to hit them)
 Systemic poison (absorbed by the plant and then eaten by insect)
 Fumigant (kills by breathing or vapors absorbed across
membranes)

53.  Each mechanism has relative advantages and
disadvantages, and different efficacy on particular
groups of stages of insects.
 For example, a stomach poison will not work on
sucking insects. It works on caterpillar but not their
adult moths.
 A contact poison will kill individual worker ants in
your kitchen but they will keep coming back.
 Why?
 Fumigants can also be quite toxic when breathed by
mammals (us) and should be used with extreme
caution.

54. QUESTIONS…

55. THANK YOU,
FOR
LISTENING….