Introduction to Insects

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Introduction to Insects
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Classification
Kingdom Phylum Subphylum
Class Order
Family Genus Species
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• Phylum Arthropoda
• Jointed appendages
• Exoskeleton
• Segmented body

Subphylum Hexapoda
Subphylum Chelicerata
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• Phylum Arthropoda
• Jointed appendages
• Exoskeleton
• Segmented body

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• Phylum Arthropoda
• Jointed appendages
• Exoskeleton
• Segmented body

Millipedes- Mostly detritivores
Centipedes- Mostly predators
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• Phylum Arthropoda
• Jointed appendages
• Exoskeleton
• Segmented body

Subphylum Hexapoda
Subphylum Chelicerata
Class Arachnida Spiders, scorpions, Mites,
ticks
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Important Insect Relatives

• Mites -- some beneficial predators
• Mites some livestock pests
• Mites some plant pests
• Spiders Very important as predators (much
  underrated) in agroecosystems

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Class Arachnida
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Mite Damage on Leaf
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Spider Mites

• Note characteristic webbing

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• Phylum Arthropoda
• Jointed appendages
• Exoskeleton
• Segmented body

Subphylum Hexapoda
Class Entognatha Diplura, Protura, Collembola
(soil)
Class Insecta Most numerous Most diverse
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Class Entognatha
Diplura- predators

• Diplura
• Collembola
• Protura
• All soil organisms

Collembola- fungivores
Protura- detritivores
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• Phylum Arthropoda
• Jointed appendages
• Exoskeleton
• Segmented body

Subphylum Hexapoda
Subphylum Chelicerata
Class Insecta Most numerous Most diverse
Class Arachnida Spiders, scorpions, Mites,
ticks
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Insects vs Arachnids (Mites, Spiders)
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Insect Life Cycles

• Simple metamorphosis

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Simple Metamorphosis
Egg
Nymphs
Adult has full-size wings,
functional reproductive system
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Simple Metamorphosis
Nymphs
Molt
Molt
Instar
Instar
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Simple Metamorphosis
Egg
Nymphs
Adult has full-size wings,
functional reproductive system
Usually 4-6 instars, resemble adults, smaller size
Same food and environment for nymphs and adults
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Insect Life Cycles

• Simple metamorphosis
• Grasshoppers
• Aphids
• Stink bugs

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Insect Life Cycles

• Simple metamorphosis
• Grasshoppers
• Aphids
• Stink bugs
• 2. Complete metamorphosis

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Complete Metamorphosis
Corn Earworm
Pupa
Egg
(Non-feeding)

• Adult
• reproductive phase

• Larva
• several instars
• important feeding stage

Very different food and environment between larva
and adult
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Insect Life Cycles

• Simple metamorphosis
• Grasshoppers
• Aphids
• Stink bugs
• 2. Complete metamorphosis
• Butterflies and moths
• Beetles Flies
• Ants, bees, wasps

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Insect Life Cycles

• Simple metamorphosis
• Grasshoppers
• Aphids
• Stink bugs
• 2. Complete metamorphosis
• Butterflies and moths
• Beetles Flies
• Ants, bees, wasps

Life stages are important because ecology, food
habits, and management of larval and adult stages
can be different.
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Role of different stages

• Example butterflies and moths
• Larva feeding causes damage
• Adult feeding results in
• pollination and is beneficial

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Role in Agriculture

• Pest
• Feeding damages crops
• Feeding vectors diseases (viruses)

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Role in Agriculture

• Pest
• Feeding damages crops
• Feeding vectors diseases (viruses)
• Beneficial
• Controlling pests
• Predators
• Parasitoids

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Role in Agriculture

• Pest
• Feeding damages crops
• Feeding vectors diseases (viruses)
• Beneficial
• Controlling pests
• Predators
• Parasitoids
• Pollinators

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Role in Agriculture

• Pest
• Feeding - damages crops
• Feeding- vectors diseases (viruses)
• Beneficial
• Controlling pests
• Predators
• Parasitoids
• Pollinators
• Recyclers of OM

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Vectors

• Vector organism that does not cause disease,
  but is carrier of pathogen

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Vectors

• Vector organism that does not cause disease,
  but is carrier of pathogen
• Viruses in plants

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Vectors

• Vector organism that does not cause disease,
  but is carrier of pathogen
• Viruses in plants
• Transmitted by insects, etc.

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Vectors

• Vector organism that does not cause disease,
  but is carrier of pathogen
• Viruses in plants
• Transmitted by insects, etc.
• Vector feeds on infected plant acquires
  virus feeds and passes virus to other plants

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Survey of Insects- Classification
Kingdom Phylum Subphylum
Class Order
Family Genus Species
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Major orders of ag pests or beneficials

• Odonata (dragonflies)
• Orthoptera (hoppers, mantids, roaches)
• Thysanoptera (thrips)
• Hemiptera (true bugs)
• Homoptera (piercing-sucking insects)
• Coleoptera (beetles)
• Neuroptera (nerve-winged insects)
• Lepidoptera (butterflies and moths)
• Hymenoptera (bees, wasps, and ants)
• Diptera (flies)

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• Odonata
• Dragonflies and damselflies
• Beneficial, predators of flying insects
• Minor pest to beekeepers, eat honeybees
• Vector of parasite to chickens in Europe
• Simple metamorphosis

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• Orthoptera
• Grasshoppers, crickets, locusts, katydids
• major ag pests
• Mantidsbeneficial predators, minor role
• Roaches.minor OM recyclers in ag systems
• Simple metamorphosis

Tawny mole cricket Pest of turf, pasture
grasses, vegetable seedlings.
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Locusts can cause severe loss of rangeland cereal
crops.
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• Thysanoptera (Thrips)
• very small
• fringed wings
• Predators
• pollinators
• Simple metamorphosis
• Most are herbivores,
• crop pests vectors

Thrips palmi
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Hemiptera

• True bugs
• Predators (beneficial)
• Plant feeders (pests)
• Piercing and sucking mouthparts
• Note typical appearance
• Simple metamorphosis

Squash bug (pest)
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Hemiptera
Predatory stink bug
Wheel bug- predator
Marmorated stink bug damage on apple
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Homoptera (piercing-sucking insects)

• Formerly an order- Homoptera, often placed within
  Hemiptera, true bugs
• Like other Hemiptera, piercing-sucking mouthparts
  to feed on plants
• All sap feeders, no beneficials
• Many important plant pests, vectors
• Aphids, cicadas, whiteflies, scale insects,
  leafhoppers, etc
• Simple metamorphosis

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Green Peach Aphid (Homoptera)

• Very abundant pest of crops and ornamentals
• Vector of viruses

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Whitefly (Homoptera)

• Common underneath leaves
• Squash, peppers, broccoli, okra, roses, lantana,
  etc.
• Simple metamorphosis

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Sooty Mold - Silverleaf

• Important sign of whiteflies, aphids, etc

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Coleoptera (Beetles)

• Very many species
• Many pests typically larval form. Weevils,
  wireworms, pine beetles, etc.
• Many beneficials lady beetles, ground beetles,
  tiger beetles
• Complete metamorphosis

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Coleoptera (Beetles)

• Pepper Weevil, pest

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Neuroptera (Nerve-Winged Insects)

• Brown Lacewing
• Larva are beneficial predators
• Complete metamorphosis

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Lepidoptera (Butterflies and Moths)

• Pests many kinds of caterpillars
• Beneficial as pollinators (not in ag. systems)
• Complete metamorphosis

Cornborer
Cotton bollworm
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Hymenoptera (Bees, Wasps, Ants)

• Beneficial as pollinators (bees)
• Important as predators and parasites
• Complete metamorphosis
• Parasitoids microscopic wasps, lay eggs in eggs
  or body of pest (e.g., caterpillar)

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Diptera (Flies)

• Complete metamorphosis
• Diverse, difficult to distinguish
• Important pests of livestock (bot, biting flies)
• Beneficial as pollinators (hover flies)
• Beneficial as predators (robber flies)
• Some are parasitoids (tachinid flies)
• Some are plant pests (leaf miners)

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• Diptera (flies)

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Leaf-mining insects

• Feed within leaf, characteristic damage
• Larvae of certain flies, moths, beetles
• Not very damaging to plant (except spinach)

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Many Important Pests of Livestock

• Flies, Lice, Fleas, etc

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Management of Insect Pests
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Insecticides and Acaricides

• effective, detailed knowledge of pest
  biology not needed
• reliable, fast-acting
• quick response to emergency situations
• - - - non target effects
• - - - and energy costs
• - - - high expectations

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Biological Control

• Control by living organism or natural product of
  living organism
• Hyperparasitism
• Caterpillar Tachinid fly Parasitoid Wasp

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Biological Control -- Two Approaches

• Introduced add control agents to ecosystem
  (many good examples with introduced pests)
• Introduced classical (new agent) vs augmentation
  (agent already present)
• Natural favor increase of naturally occurring
  control agents (manipulate environment, cropping
  systems)

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Biological Control Many possible organisms

• Predators (often not specific)
• Parasites
• Diseases (parasites)

Parasitoids (often highly specific) Entomopathogen
ic nematodes
Fungi Bacteria Viruses
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Host Plant Resistance

• Interfere with host finding, feeding, pest
  nutrition, timing of life cycles, etc
• Hairs on leaves, sticky, etc.
• Alkaloids in plants deter insects
• Crop cultivars/genotypes selected for resistance
  to pests

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What is Biological Control and What Is Not ???
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What is Biological Control?

• Predators
• Parasites
• Diseases

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What is Biological Control?

• Predators
• Parasites
• Diseases
• Bacterial disease of insects caused by Bacillus
  thuringiensis (BT)

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What is Biological Control?

• Bacterial disease of insects caused by Bacillus
  thuringiensis (BT)
• Allow bacteria to produce spores with toxin in
  lab, isolate BT toxin, and spray it on pests

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What is Biological Control?

• Bacterial disease of insects caused by Bacillus
  thuringiensis (BT)
• Allow bacteria to produce spores with toxin in
  lab, isolate BT toxin, and spray it on pests
• Transgenic plants that produce BT toxin (Bt corn,
  Bt cotton)

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What is Biological Control?

• Resistant plants as biological control agents
• Plants with alkaloids
• Pyrethrum natural plant alkaloid

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What is Biological Control?

• Resistant plants as biological control agents
• Plants with alkaloids
• Pyrethrum natural plant alkaloid
• Isolate pyrethrum from plants and use it

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What is Biological Control?

• Resistant plants as biological control agents
• Plants with alkaloids
• Pyrethrum natural plant alkaloid
• Isolate pyrethrum from plants and use it
• Make synthetic pyrethrum
• Pyrethroid pyrethrum analog, similar chem
  structure

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Environmental Heterogeneity

• Crop genetics (uniform genotypes vs mix)
• Vegetation diversity vs pest dispersal
• Vegetation diversity as reservoir for natural
  enemies

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Plant Health

• Healthy plant can withstand some insect
  damage
• - - - High N can increase insect growth and
  reproduction

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Attractants and Repellents

• Attractant, e.g., pheromone (sex or aggregation)
  useful for
• Sampling and monitoring (important use for
  quarantine detection, regional monitoring)
• Attracting insects to traps
• Confusing normal life processes and patterns

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Cultural Practices

• Crop Rotation
• Weed control of virus hosts
• Sanitation and cleanup of crop residues (affected
  overwintering of boll weevil)
• Timing of planting dates (winter wheat, Hessian
  fly)
• Others (sterile males, etc.)

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For most effective insect management, usually
need to know biology and habits of individual
insect pests
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References

• Text Ch. 10, pp. 201-208 Ch. 11, pp. 219-222.
• Metcalf, C.L., W.P. Flint, and R.L. Metcalf.
  1962. Destructive and Useful Insects.
  McGraw-Hill, NY.
• Metcalf, R.L., and W.H. Luckmann. 1994.
  Introduction to Insect Pest Management. John
  Wiley Sons, NY.
• Images from UF Dept. Entomology Nematology
  Featured Creatures
• http//creatures.ifas.ufl.edu