Download Mouth parts

Basic Entomology
By: Bob Gara
Overall Goal
The Insect Orders: You
Should Know Them
When You See ‘Em
Hi, Bob, it’s
a beetle!
Remember the Phylum Arthropoda: even spiders are
arthropods
1. Jointed appendages
2. Body composed of somites
3. Exoskeleton
4. Dorsal heart
5. Ventral nervous system
Classes
All are arthropod classes
Pycnogonida
Sea-spiders
Merostomata
Horseshoe crabs
Arachnida
Mites
Arachnida
Ticks
Diplopoda
Millipedes
Chilopoda
Centipedes
Many other classes too
The insects belong to the Class, Insecta
Insects: The class Insecta
• Three body regions
- head
- thorax
- abdomen
• One pr. antennae
• Adults; winged
• Three pr. legs
Besides these basic insectan
characteristics, I’m going to
discuss: molting, metamorphosis,
the mouth, the wings, the
digestive system, and other stuff.
1st, a new word: “molting” shedding old exoskeleton
2nd, a new word: “instar” the insect between molts.
(1) molting
1st
2nd
Egg
(2) instars of
the Psylla
3rd
4th
Adult
Since all arthropods, including
the insects, have a hard
exoskeleton they have to change
it in order to grow. This process
is called MOLTING.
Cicada
molting
This is molting
Metamorphosis – “change in form”
No metamorphosis
Incomplete
metamorphosis
The silver fish:
order, Thysanura,
has no metamorphosis.
Common
silverfish
Jumping
bristletail
(found in the
forest)
Mayflies (order Ephemeroptera) have
incomplete metamorphosis
Gradual metamorphosis
The Pupa
Complete metamorphosis
The plant hoppers, order
Hemiptera, has gradual
metamorphosis.
Complete Metamorphosis!!
Eggs
Maggot
The pupa!
Adult
Some terms associated with complete metamorphosis
Egg
Function
beginning
Character- inactive
istics
Other
names
nit
Larva
Pupa
Adult
feeding
growing
reconstruction
transformation
reprod.
active
inactive
helpless
active no
growth!
grub
chrysalis
maggot
puparium
caterpillar cocoon
imago
Grasshopper, order: Orthoptera
Chewing mouthparts
Mouth
ocelli
antennae
compound
eyes
clypeus
labrum
mandible
peeking out
palps
Labrum
Palp
Maxilla
Some dentistry
Mandible
Tongue
Palp
Labium
Again, the chewing mouth parts
Maxilla
Mandible
Labrum
Palps
Look at the variations found in the chewing mouth parts
Fierce predators: Tiger beetles
Another fierce predator: Dragon flies
Adult
Nymph
Adult
Calculates: speed and
direction of the prey
The last thing
the prey sees!
Mouth parts: Piercing-sucking
(order Hemiptera – the bugs)
Piercing-sucking mouth parts
of the Hemiptera
Mandible
Maxilla
More detail of
piercing-sucking
mouth parts of the
Hemiptera
More, piercing-sucking
mode of feeding.
Insect legs
What’s so great about having
6 legs?
Legs on ground
Legs off ground
Digestion in
insects
Guts of a larva
• Digestion
• Circulation
• Nervous system
Ok, enough already,
tell ‘em about the insect
Orders!
Within the class Insecta there are about 20 insect orders.
Of these 20 I’ll introduce you to a few of them – of these
few, you will identify 5 of them:
1.
2.
3.
4.
5.
Hemiptera – the bugs
Coleoptera – the beetles
Lepidoptera – the moths and butterflies
Hymenoptera – the wasps, ants and sawflies and horntails
Diptera – the flies
Collembola: the springtails.
• Variable in form, wingless,
no metamorphosis,
chewing mouthparts
• Have a “glue pot” on 1st
abdominal segment
• Have a jumping organ,
furcula
• Furcula held down by a
latch called a tenaculum
• The word “cola” is Latin for
glue
Gluepot
Collembolans are important!
• live in the forest litter
• 1st step in decomposition
• operate:
- chip-up leaf particles
- increases surface area
- greater feeding ground
for fungi and bacteria
- mix organic particles
into mineral soil
- fecal matter adds to
soil fertility
Some studies:
• 7% of ingested litter matter was ingested, 93% egested as fecal pellets;
• fecal pellets: increase surface area, aeration, pH, water holding
capacity;
• in 9 months, 60% of litter processed by earthworms, mites etc.; the rest
by collembolans
Thysanura: the silverfish, fire brats & bristle tails
• no metamorphosis, chewing mouthparts
• no wings, scales on
body, 3-tails, fast movements
• skinny legs – fast!
• Importance:
- domesticated
- live under baseboards,
stoves, sinks, cabinets,
books etc.
• huge pest in libraries
• family Machilidae live in litter
with collembolans and
important in mineral cycling
Here’s some trivia that only entomologists could love:
• fossil insect
• flight
• all insects have these muscles
• contraction of
these muscles
allows for
wing movement
& flight
The Ephemeroptera (mayflies) and the Odonata
(dragonflies & damselflies) are ancient remnants of the
earliest flying insects.
When not flying mayflies and dragonflies can’t fold their
wings. They either hold them “tent-like” over their
thorax or out horizontally. The wing-folding
mechanisms wasn’t invented yet: the axillary sclerites.
These are axillary sclerites that allow
for wing folding – most insects have
these mechanisms.
Ephemeroptera*: the mayflies
• ± 2,000 spp.
• 2-pr. membranous
wings held tent-like
over body;
• adults have no
mouths, incomplete
metamorphosis;
• aquatic immatures;
• 1° consumer role in
the aquatic
ecosystem.
*ptera-
Gr. for wing
ephemera- Gr. prefix for temporary
gills
Ecological role of mayflies:
• shredders – headwaters of streams;
•scrapers – scrape off 1° production
on stones and boulders
•collectors – collect fine particles as
they drift down stream;
• filter feeders – strain microscopic
particles from the water column;
• predators – few immatures are
predators
Odonata: dragon flies and damsel flies:
• adults and nymphs exquisite predators!
• two pr. wings held horizontal by dragonflies
and tent-like by damsel flies (but can’t fold
them);
• chewing mouthparts, incomplete
metamorphosis;
• adults are territorial and capture prey in
flight;
• ecological pts.
- prey for birds
- movement of energy from aquatic to
terrestrial ecosystem
- increase energy flux within aquatic
ecosystem ( role as general
predators)
All the rest of the insect orders have wing folding and let’s
first talk about the Orthoptera.
Orthoptera: grasshoppers, roaches, mantids, crickets,
katydids, etc.
• have chewing mouthparts, and 2pr. of wings either held straight back,
like the grasshoppers, or flat along the top of their bodies;
• gradual metamorphosis
• most phytophagous, but some are predacious like the mantids
Dermaptera: earwigs
• Chewing mouth parts;
• 2pr. wings, 1st pair truncate and
hardened;
• gradual metamorphosis
• posterior – a pincher
• can be pests of nurseries
Isoptera: termites:
• have a caste system, live in colonies;
• typically have, sterile workers,
soldiers and reproductives;
• have yearly swarms of males and
females to establish new colonies;
• in the PNW establish colonies in
wood, paper piles – houses;
• order characteristics:
- 2pr. wings of equal length
- chewing mouthparts
- gradual metamorphosis
queen
steriles
reproductives
Queen regulates and
controls the castes
through a process of
tropholaxis
Termites continued:
• ecological benefits:
- increase surface
area of large woody
material;
- great amount of
fecal matter enriches
the soil;
- main agent of soil
turnover in tropics:
earthworms in the
temperate parts of the
world.
The Hemiptera: bugs, leaf hoppers, aphids, scales,
toe-nippers, assassin bugs, white flies, tree hoppers etc.
When I was a student of entomology: two discrete orders
Hemiptera = gr. half wing
wings the same
Homoptera = wings all
membranous
Then it all changed: China went to
Chile.
• Now, the “old Hemiptera and
Homoptera” are lumped into the
new order, Hemiptera.
• What used to be the Hemiptera is
now called the suborder,
Heteroptera.
• What used to be the Homoptera is
now called the suborder,
Homoptera.
So, the order Hemiptera has these two suborders.
(1) Heteroptera: the bugs:
• gradual metamorphosis, piercing-sucking mouthparts;
• two pr. wings – upper part hardened, lower part membranous;
• bugs are phytophagous and predacious
• bugs are terrestrial, many aquatic
hemelytra
Some Heteroptera
(2) Homoptera: aphids, scales, plant hoppers, cicadas etc.
• two pr. homogenously membranous wings (when winged);
• gradual metamorphosis (sometimes real weird) and piercing-sucking
mouthparts.
plant hoppers
tree hoppers
cicada
Aphids are bad
homopterans.
Aphids are major
pests in forestry;
especially in
nursery
management.
Many aphids cause
galls.
The scale insects are
terrible homopterans,
especially in urban forestry
Coleoptera, the beetles:
• > 550,000 species
• complete metamorphosis
• chewing mouthparts
• 2pr. wings; front pair hardened
and called an elytra.
Hind wings are membranous.
Even in the
early beginnings
of the profession
of Economic Entomology,
the beetles played a
major role.