I.
Course: Horticulture
Unit: Plant Pests
Lesson: Insects and Nematodes
Benchmark: IAG6
II.
Situation: mixed grade levels introductory horticulture course. Students have varied
backgrounds in horticulture.
III.
Teacher Objectives: After this lesson student will be able to:
1) Describe the biology of insects
2) Classify insects
3) Classify nematodes and describe their biology
4) Explain scouting and threshold in insect management
5) Describe methods of insect and nematode management
1) Insect Biology- helps explain why insects damage plants or perform beneficial services,
and allows proper selection of control method.
3 major body segments:
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Head- eyes, antennae, and mouthparts
Thorax- wings and 3 pairs of legs
Abdomen- contains organs for digestion, reproduction, and excretion
Mouthparts:
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Chewing- bites off, chews, and swallows plant parts
Sucking- pierces outer layer of plants parts and draws sap from it
Reproduction:
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Metamorphosis- stages of development where insects go from egg to adult, there
are 2 types:
 Incomplete- 3 stages: egg, nymph, adult
 Complete- 4 stages: egg, larvae, pupa, adult
2) Insect Classification- Insects are in the arthropoda phylum, Nematodes are in the
Nematoda phylum
Scientific classification- phyla are further divide into classes; classes are further divided
into orders and then families, genus, and species
Benefit Classification of insects:
 Beneficial insect- one that is of value for the role it fills in the environment
 Harmful insect- one that causes damage to plants, animals or property
Mouthparts Classification- control measures must be selected based upon the way an
insect feeds
Reproduction classification- determined by the type of metamorphosis they go through
which also determines control method
Feeding location classification- one of the 3 types must be identified in order to
effectively choose a control method
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External feeders- chew or suck form the exterior of the plant
Internal feeders- chewing type that bore into the plant and go inside to feed
Subterranean- species in the soil that attack plant roots.
3) Nematode Classification and Biology:
 Nematodes- damage plants by piercing and sucking juice or tunneling inside plant
roots and secreting a substance that injures the roots. The injury allows fungi and
bacteria to enter the roots which can cause disease.
 2 types root knot (attacks the roots) and foliar (attacks the leaves or stem)
4) Methods of Insect and Nematode Management:
Scouting- visually inspecting for the presence of insect pests and damage
Threshold- density of the pest population that will justify using pest management
measures, there are 2 types of thresholds:
 Economic- the balance of cost with returns
 Aesthetic- deals with the appearance of plants such as turf
5) Selecting Management Methods:
Quarantine- isolation or exclusion of a pest problem
Cultural management- preventing insect and nematode problems by the practices used
in growing the plants such as:
 Crop rotation
 Residue management
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Trap crops
Using resistant varieties
Sanitation
Biological Management:
 Releasing beneficial insects
 Disrupting reproduction
 Using bacteria and fungi
Chemical Use:

Pesticides:
 Insecticides- used to kill insects, classified by entry
 Contact- absorbed through skin or exterior
 Stomach- must be ingested
 Respiratory- must be inhaled
 Systemic- taken up by the plant and passed on to pest through
ingestion of plant
 Formulation- the way pesticide is prepared
 Active Ingredient- percent poison material in an insecticide
 Nematocides- used to kill nematodes
Genetic Engineering:
Used to genetically modify or alter an organism by adding or subtracting qualities
through the changing of the genetic code
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Transgenic- plants altered by genetic engineering
A. Summary:
Plants can be damaged by nematodes and insect pests, the control of these pests
improves the quality and amount of plant production. All known factors should be
considered when planning a method of control.
Some insects are beneficial others are harmful. Knowing the biology of insects
affects the control method choice. Insects have 3 parts head, thorax, and abdomen.
Insects feed in two primary ways, chewing and sucking. Some feed on the
exterior of plants, some feed on the inside, while others feed below the soil.
Damage by insects often occurs at different stages of their development. Insects
have either complete or incomplete metamorphosis. The larvae stage often causes
the most damage to plants.
Nematodes live in the soil and attack plant roots like the cyst nematode or live
above the soil and attack plant leaves and stems.
There are various control methods used to combat insects and nematodes.
Scouting helps determine the threshold of insect impact thus establishing grounds
for the application of a control method such as: quarantine, cultural control,
biological control, chemical control, and genetic engineering.
B. Evaluation:
Students will define chapter terms on a sheet of paper as they are discussed in
class. The term sheets will be turned in at the end of the period for daily points. At
the end of the lesson a short power point quiz will be given to the group as a
whole. This lesson will be covered on the Plant Pests unit test.