A detailed introduction to entomology.ppt

Introduction to Entomology

1. Introduction to the Study
of Insects
for Master Gardeners
Richard Sprenkel
University of Florida/IFAS
North Florida Research and Education Center

2. Phylum Arthropoda
An arthropod is an animal that is
distinguished from other animals in
having an external skeleton and jointed
appendages.

3. Arthropods
Examples of arthropods include insects,
ticks, spiders, horseshoe crabs,
millipedes, chiggers, centipedes,
shrimp, sowbugs and scorpions.

4. Class Insecta
An insect is an arthropodhaving three body
regions (head, thorax and abdomen), three
pair of legs, one pair of antennae and
generallyone or two pair of wings in the adult
stage.
Headwith antennae, eyes and mouth.
Three segmented thoraxwith legs and wings (if
present).
Abdomencomposed of varying number of
segments depending on the species. Internally
contains most of the digestive system and the
reproductive system.

5. Insects
•Old Group
–Oldest fossils are 400 million years old.
•Diverse
–80% of all described animal species are insects.
One-half of the described species of insects are
beetles.
•Numerous
–It has been estimated that the total weight of all
insects on the planet exceed the combined weight
of all people on earth by a factor of 200 times.

6. Old Group
Homo sapiens 0.3 Mil Yr
Dinosaurs 135 (65 -250) Mil Yr
Flowering Plant 135 Mil Yr
Birds 180 Mil Yr
Mammals 225 Mil Yr
Modern Insect Orders270 Mil Yr
Winged Insects 350 Mil Yr
First “Insect” 400 Mil Yr

7. Insect as Pests
Usually an insect is considered to be a pest if
it transmits diseases (mosquitoes), feeds on
food (flour moth), crops (corn earworm) or
structures (termite) or is a nuisance
(cockroaches and lovebugs).
World-wide only 8% of insects are considered
pests. In the U.S., only 600 of the100,000
described species (0.6%) are pests.

8. Beneficial Insects
•Pollinators (apples, watermelons,
squash)
•Products (honey, silk, dyes)
•Scavengers
•Predators/parasites
•Food for fish and birds
•Scientific study
•Art, religion, relaxation

9. Some of the ‘Systems’
Which make Insects Unique
•Digestive System
•Circulatory System
•Nervous System
•Respiratory System

10. Digestive System
The digestive system is basically a tube
that runs through the middle of the
body. It consists of a foregut, midgut
(stomach) and hindgut.
The excretory system is made up of
malpighian tubules (which function
similar to our kidneys) which remove
wastes from the insect body through the
hindgut.

11. Circulatory System
The circulatory system is an open
system that is not confined to arteries
and veins. Haemolymph (insect blood)
is circulated through the body cavity by
a dorsal “heart” and a short aorta. The
blood is picked up in the abdomen and
carried forward to the head where to
flows back into the body cavity.

12. Nervous System
The nervous system consists of a small
brain in the head that is connected by a
double nerve cord to a series of ventral
ganglia or nerve centers located in
several segments of the body.

13. Respiratory System
Insects do not have lungs. They breathe
passively (diffusion of oxygen in and
carbon dioxide out) through a system of
tubes called tracheae. The tracheae
open to the outside through spiracles.
Inside the body, the tracheae branch
into finer tubes called tracheoles which
provide oxygen to cells.

14. The Class Insecta (Hexapoda)
is divided into Orders

15. The 30-35 Orders of Insects
are Separated on the Basis of:
•Wings
–Structure, number, etc.
•Mouthparts
–Chewing
–Piercing-sucking (mosquitoes, bugs, etc.)
–Siphoning (butterflies, moths)
•Metamorphosis
–Simple (or Incomplete)
–Complete

16. Simple Metamorphosis
•Also called incomplete metamorphosis.
•Egg > nymph > adult
•Aphids, grasshoppers, cockroaches,
true bugs

17. Complete Metamorphosis
•Egg > larva > pupa > adult
•Moths, butterflies, beetles and flies

18. Insect Orders Containing
Plant Pests of
Economic Importance
•Orthoptera (grasshoppers and crickets)
•Hemiptera (true bugs, aphids and
leafhoppers)
•Thysanoptera (thrips)
•Coleoptera (beetles)
•Diptera (flies and mosquitoes)
•Lepidoptera (butterflies and moths)

19. Orthoptera (grasshoppers)
•ortho,straight; ptera,wings
•Characteristics
–Front wings are elongated with many
veins. Hind wings have many veins and
are folded fanwise beneath the front wings.
–Chewing mouthparts
–Simple metamorphosis

20. Hemiptera (true bugs, aphids and
leafhoppers)
•hemi,half; ptera,wings
•Characteristics
–In many species in this Order, the basal
portion of front wing is thickened and
leathery while apical portion is
membranous. At rest, wings are held flat
over body with membranous tips
overlapping (e.g. stink bug).
–Piercing-sucking mouthparts
–Simple metamorphosis

21. Thysanoptera (thrips)
•thysano,fringe; ptera,wings
•Characteristics
–The two pair of wings are stout and fringed
with long hairs.
–Sucking mouthparts
–Complete metamorphosis

22. Coleoptera (beetles)
•coleo,sheath; ptera,wings
•Characteristics
–In most species the front pair of wings is
thickened and hard. The hind wings are
membranous.
–Chewing mouthparts; mandibles are
usually well developed
–Complete metamorphosis

23. Diptera (flies)
•di,two; ptera,wings
•Characteristics
–One pair of wing; hind wings are reduced to small
knobbed structures called halteres.
–Sucking type of mouthparts in adults but with
considerable variation; mouthparts in larvae of the
primitive families are of the chewing type and the
mandibles move laterally, in the larvae in the
higher families mouthparts are reduced and move
in a vertical plane.
–Complete metamorphosis

24. Lepidoptera (butterflies)
•lepido,scale; ptera,wings
•Characteristics
–Most readily recognized by scales on
wings, body and legs.
–Sucking mouthparts -adult; chewing
mouthparts-immature stage
–Complete metamorphosis

25. Insect Management
•Genetic
–Resistant varieties
•Biological
–Conservation and augmentation
•Cultural, Mechanical
–Crop rotation, destruction of residue, hand
picking, etc.
•Chemical

26. Chemical Control
•Should be used as a last resort
–Treatment based on scouting and/or anticipated
loss or damage.
•A few of the classes of insecticide chemistry
–Cholinesterase inhibitors (Diazinon, Dursban,
Malathion, Orthene, Sevin)
–GABA blockers (pyrethrins, pyrethroids)
–Neonictinoid disrupter (imidacloprid)
–Biological (Bacillus thuringiensis)
–Insect growth regulators (Amdro)
–Soaps and oils

27. Some Active Ingredients Labeled
for Homeowner Use
•Acephate
•Bacillus
thuringiensis
•Bifenthrin + fertilizer
•Carbaryl
•Cyfluthrin
•Esfenvalerate
•Horticultural oils
•Imidacloprid
•Malathion
•Permethrin
•Soaps
•Trichlorfon

28. Richard Sprenkel
University of Florida/IFAS
North Florida Research and Education Center, Quincy
Copyright 2004, University of Florida

29. Pre-Test/Post-Test
A.Taxonomically, insects are separated from the other arthropods
by the fact that the insects have
1.Fewer legs
2.Three pair of legs, three body regions and wings
3.Segmented appendages and an exoskeleton
4.More complex life cycles
5.Don’t know
B.According to the fossil record, insects are
1.Approximately 265 million years old
2.Nearly as old as the oldest known dinosaur
3.Slightly older than the oldest dinosaur
4.More than 100 million years older than the oldest known dinosaur
5.Don’t know

30. Pre-Test/Post-Test
C.Taxonomists have
1.Divided the insects into 12 Orders
2.Separated the Orders based on type of mouthparts, type of wings and
coloration in the adult stage
3.Separated the Orders based on type of legs, type of wings and type of
development
4.Separated the Orders based on type of wings, type of mouthparts and type
of development
5.Don’t know
D.In the United States
1.Approximately one-half of the described species of insects are considered
to be pests
2.Slightly less than 25% of the described species of insects are considered to
be pests
3.Less than 1% of the described species of insects are considered to be
pests
4.There are about equal numbers of pest and beneficial species of insects
5.Don’t know

31. Pre-Test/Post-Test
E.Tracheoles are
1.Part of the insect digestive system
2.Part of the insect respiratory system
3.Part of the insect nervous system
4.The ‘foot pad’ of the insect
5.Don’t know
F.Insects with complete metamorphosis have
1.Two developmental stages
2.Three developmental stages
3.Four Developmental stages
4.Five developmental stages
5.Don’t know

32. Pre-Test/Post-Test
G.In the insect circulatory system
1.Haemolymph is pumped from the rear of the insect toward the
head
2.Haemolymph is pumped from the head toward the rear of the
insect
3.Haemolymph is pumped from the heart both toward the head and
rear of the insect in a closed system
4.There is no means for pumping the haemolymph
5.Don’t know
H.In insect management, augmentation and conservation are
components of
1.Cultural control
2.Genetic control
3.Biological control
4.Chemical control
5.Don’t know