Controlling Insects!
Insecticides
Identify common insect pests and select
an effective control method for each.
Describe the six ways in which insects are
killed by insecticides.
List the names and characteristics of the
three major groups of insecticides.
Compare the six ways in which
insecticides are applied.
Explain the relationship between the life
cycle of insects and timing of application.
What is an insect?
Insectsmall animal
with three defined
body regions and
three pairs of legs!
HEAD, THORAX, and
ABDOMEN!
6 Common Orders!
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Orthoptera- includes the grasshopper and
locust
Hemiptera - includes the true bugs such as
leaf hoppers and plant bugs
Lepidoptera – moths and butterflies
Homoptera- aphids
Thysanoptera- thrips
Coleoptera- which is the largest group of the
insect orders, including beetles
Insect grouping!
How are insects grouped?
They are grouped by the way they feed
on plants. So they are grouped by their
mouth parts.
Mouth Parts
There are six different mouth parts
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Sponging
Rasping- sucking
Siphoning
Chewing-lapping
Chewing
Piercing- sucking
How Insecticides Kill
Chemicals must kill insects while doing little or
no damage to the plant.
Stomach poisonsWork against insects that eat
parts of the plant.
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Sprayed or dusted on the plant
As insect eats the plant, it is poisoned through the
stomach.
Insects that chew food (caterpillars, grasshoppers,
beetles) are controlled by stomach poisons.
Example--Rotenone
How Insecticides Kill
Contact Poisonskill insects when they
are hit by or come in contact with the
poison.
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Any type of insect can be controlled this way.
Kill by upsetting the insect’s nervous system
or breathing system.
Example--malathion
How Insecticides Kill
Systemic poisonsenter the plant sap
and move throughout the entire plant.
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When insect eats parts of plants or suck plant
juice, chemical is swallowed.
Effective with insects with chewing or sucking
mouthparts.
Effective with insects that hide under leaves
or underground.
Food crops—allow time for chemical to break
down.
Example--Orthene
How Insecticides Kill
Fumigantscontact poisons applied in
gaseous form.
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Gases or fumes kill the insect after entering
system through breathing pores.
Insect must absorb the poison for this
insecticide to be effective.
Used to control soil-borne insects that
damage roots.
ExampleTAME
How Insecticides Kill
Repellantsdo not kill insects, but drive
them away before they attack the plant.
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Examplealuminum foil (repels flying insects)
How Insecticides Kill
Attractants and Phermoneswork in the
opposite way from repellants.
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They lure insects to their death.
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Chemical Makeup of Insecticides
Three groups!
Inorganic Compounds
Organic Compounds
Synthetic Organic Compounds
Inorganic Compounds
Mineral origina mineral is used as the
basis for the poison
Usually work in the form of a stomach
poison.
Example—Sulfur
Organic Compounds
Derived from plants
Work in form of stomach or contact
poisons
Example—rotenone and pyrethrum
Synthetic Organic Compounds
Recent origin (last 30-35 years)
Produced in the laboratory
Many are also toxic to humans.
Three Groups
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Chlorinated Hydrocarbons
Organophosphates
Carbamates
Synthetic Organic Compounds
Chlorinated HydrocarbonsLong
RESIDUAL Control (continue to kill long
after application)
ExampleDDT (not used in US)
Synthetic Organic Compounds
OrganophosphatesContains chemicals
most toxic to warm-blooded animals
Absorbed rapidly through the skin
Parathionone drop in the eye can kill a
human being.
ExampleMalathion (relatively safe)
Synthetic Organic Compounds
Carbamatessafest insecticides on the
market
Break down rapidly (2-7 days) and leave
no residue to contaminate the environment
Do not build up in the bodies of warmblooded animals
Example—Sevin