Entomology Exam 1

Ecological importance of insects

-Widespread

-fill many niches

-food resource for other animals

Economic importance of insects

-compete for food

-human parasites

-disease vectors

-valuable services (pollinators, parasitoids, useful products)

Reasons for success

-evolved >450 MYA

-early terrestrial species

-small

-segmented body/specialized body regions and appendages

-exoskeleton/further reduce water loss

-wings

-different types of development

-social biology

Why does being small help success in insects?

-require little food

-high birthrate

-fast development

-many possible habitats

-high muscle:body mass ratio (less force to move body around. proportionally small)

Why does a segmented body and specialized body regions and appendages help with insect success?

-modified appendages on each section for different functions

-specialization leads to efficiency

-appendages for feeding

How do exoskeletons help with the success of insects?

-lightweight but strong

-impermeable waxy coating to reduce water loss (good for stressful environments)

What helps insects reduce water loss?

-hindgut

-malpighian tubules

-trachea with spiracles

How does a hindgut reduce water loss?

-they help resorb water

-they dont lose liquid when they poop

How do malpighian tubules help reduce water loss?

-uric acid

-kidney like

How do trachea with spiracles help with water loss?

-internal respiratory structure

-helps respiration in dry environments

How have wings allowed insects to have success?

-rapid/low energy transport

-escape unfavorable conditions/seek favorable

-modified to cover and protect body

-only flying invertebrate

Why do all these traits make insects so successful?`

-combination of traits make them successful

-fill many niches

Hemimetabolous vs Holometabolous metamorphosis

-Hemi: gradual development, more primitive

-Holo: complete development, more advanced

Hemimetabolous development characteristics

-they change gradually into adult form through molting

-new molts gradually change

-adult forms have functional wings and gentalia

Holometabolous development characteristics

-complete development=look completely different

-adults and larvae different body form

-don’t compete for food (caterpillar and butterfly dont eat same things)

-division of labor: nymphs eat/grow; adults mate/lay eggs

-85% of all insects

How does social biology allow insects to be successful?

-division of labor

-survive harsh environmental conditions

-allows for more energy=more babies

-specialization=more efficiency

Why are insects valuable to humans?

They have economic importance. Pollinators help with our food and give other useful products (honey, silk).

Why are insects so successful?

The combination of the traits they have make them more successful. They are able to fill many niches.

Goals of insect classification

-show relatedness among species

-show overall similarity among species

Problems with insect classification

-Convergent evolution (six-legged body plan)

-problems with molecular methods

-lack of data (few insect fossils)

-this results in “best guess” about relationships among species

Characteristics that define Kingdom Animalia

-multicellular

-mobile

-heterotrophic

-lack cell wall

-lack photosynthesis

Phylum Arthropoda characteristics

-segmented bodies w/ exoskeleton

-paired jointed appendages, muscles attached to inside of exoskeleton

-specialized segments with modified jointed appendages

-advanced cephalization, dorsal brain, ventral nerve cord, compound eyes

-open circulatory system with dorsal heart

-respiration with internal trachea or modified jointed appendages

Subphylum Mandibulata characteristics

-head → 6 segments, 2 pairs antennae, 3 pairs mouthparts

-trunk with many segments

Why is the subphylum Chelicerata (spiders) not related to Mandibulata?

-Cephalothorax with 8 segments

-no antennae

-2 pairs of mouthparts

-4 pairs of legs

Superclass Hexapoda characteristics

-three body regions: head, thorax, abdomen

-single pair antennae, mandibles lack palp, 1 maxillae, 1 labium

-3 segments in thorax, uniramous appendages

-12 (or less) abdomincal segments, appendages lost or modified

Class Protura and Class Collembola characteristics

-retracted mouthparts, bladelike mandibles and maxillae

-all antennal segments w/ muscles (centipedes, crustaceans)

-juveniles add segments as they molt

-wingless

Class Diplura characterisitcs

-retracted mouthparts, chewing mandibles and maxillae

-all antennal segments w/ muscles

-juveniles w/ fixed number of segments

-wingless

Class Insecta characteristics (~34 orders of “true insects”)

-external mouthparts, chewing mandibles and maxillae modified in advanced orders

-antennae with muscles only in Scape and Pedicel

-juveniles fixed number of segments

-some with wings

-some with complete development

Insect fossils

-oldest fossil is ~410 MYA

-don’t fossilize well (lack “missing link” fossil)

-lack DNA

Evolution of Mandibles

-primitive-single hinge, not as much strength (crustacean)

-advanced- 2 hinges (all winged insects)

When did Hexapods evolve?

475 MYA

When did Class Insecta evolve?

440 MYA

When did winged insects evolve?

320 MYA

Hexapod fossil

Order Monura

What is Rhyniognatha hirsti a fossil of?

-winged insect

-fragmented head/mouthparts

What did Pterygota (winged insects) evolve from?

Apterygota

-evolved within the class Insecta after hexapods

Exaptation

-structures evolve through incremental changes of pre-existing feature on ancestral species

-intermediate stages must be useful

-unclear what pre-existing feature gave rise to wings

Paranotal extensions theory

-evolved as extensions on meso and metathorax

Function of intermediate steps for paranotal extension theory?

-initial stage-courtship, thermoregulation

-intermediate stages-gliding with fixed lobes

-later stages- hinge, muscles evolve to steer glide

Evidence of paranotal theory

-fossil insects with large thoracic lobes

-thernoregulate/signal mates with wings and pronotum

-no extant gliding species besides a type of ant

Gill theory

-evolved from modified thorax gills

-early stages-swimming

-intermediate stages-skate on surface

-later stages- hop/glides on surface

Evidence for gill theory

-abdominal gill create water current

-fossils with thoracic gills

-gills and wings move with similar muscles

-crustacean gill genes ~insect wing genes

Ametabolous

-primitive insect groups

-looks the same whole time

-hatched at size

-molting

Hemimetabolous

-”incomplete” (still develop completely)

-functional wings only in adults

Holometabolous

-”Complete” (completely different looking from their baby)

Parainsecta classes

-Protura

-Collembola (springtails)

-Diplura

Class Protura

-Primitive features

-no antennae, no compound eyes, no tail appendages

Class Collembola

-very primitive

-modified jumping tail

Class Diplura

-internalized mouthparts

-epomorphic growth

-trachea, antennae, cercie

Class Insecta subclasses

Apterygota (wingless insects)

Paleoptera (winged insects)

Apterygota orders

-Archeognatha

-Thysanura (silverfish)

Order Archeognatha characteristics

-primitive

-abdominal appendages

-cercus

-adults continue to molt

-wingless

Order Thysanura characteristics

-very primitive

-no wings

-2 attachment points (mandibles)

-not very strong mandible

-3 cerci same length

Pterygota subclass/orders

Subclass: Paleoptera

Orders:

-Emphemeroptera (mayflies)

-Odonata (dragonflies and damselflies)

• Suborders: Zygoptera (damselfly) and Anisoptera (dragonflies)

Characteristics of Pterygota/Paleoptera

-Ancient winged

-Paleoptera refers to insects that cannot fold their wings over their abdomens → DISTINGUISING FEATURE

Order Ephemeroptera

-mayflies

-most primitive insects of winged insects

-most of life is as aquatic nymph

-molt one time when adults → ONLY winged insect that does, very unusual

-2 pairs of wings with many veins

Order Odonata characteristics

-Dragonflies and damselflies

-cross veins in wings still present

-short, bristle-like antennae

-bristly hair legs-grab prey out of air

-2 sets of wings

-aquatic habitats

-predatory in nymph stage too

Suborder Zygoptera

Damselflies

-more primitive of the 2

-wings above back

-fragile, slender body

-nymph have gills for respiration that LOOK like cerci

Suborder Anisoptera

Dragonflies

-beefy and more viscious

-hold wings out when resting

-Nymph gills in abdomen

-nymphs expand abdomen and squirt water out to create waterflow over gills. also use for propulsion

Superorder Polyneoptera

Contains the classes Neoptera and Exopterygota

Neoptera/Exopterygota characteristics

-more advanced wing

-incomplete development

-juvenile has outside wings

-fold wings down

-more primitive chewing mouthparts

-cerci

-leathery forewings

-most flight with hindwings

Orders in Neoptera/Exopterygota

-Order Blattodea (cockroaches/termites)

-Order Orthoptera (grasshopper)

-Order Mantodea (mantids)

-Order Phasmatodea (walking sticks)

-Order Mantophasmatodea

-Order Dermaptera

Order Blattodea

-cockroaches and termites

Cockroach characterstics

-some cockroaches subsocial

-350 million years old

-chewing mouthparts

-cerci

-2 pairs of wings

-extended pronotum over head

-some species only found in houses now “domesticated”

Termite charactersitics

-termites evolved within cockroach lineage

-termites social

-equal sized wings

-short cerci

-true social insects

-subdivide labor in colony

-the mom of the colony mates continuosly for years

-wings break off when they start colony

-queen reproduction parts swell

-soldier and workers do not mate

Order Orthoptera characteristics

Grasshoppers and crickets

-chewing mouthparts

-cerci

-leathery forewings

-auditory organs near their legs

Order Mantodea characteristics

Mantids

-triangular, down pointed head

-cerci

-long antennae

-all predators

-elongate pro thorax

-grab stuff with forelegs

-leathery forewings

-chinese, european, carolina

Order Phasmatodea characteristics

Walking sticks

-head forward pointing

-herbivious

-mesa and meta thorax elongated

-leathery forewings

Order Mantophasmatodea characteristics

-only found in africa

-look/act similar to mantids and walking sticks bc convergent evolution

-entirely carnivirous

-downward pointing head

-thorax and abdomen elongated

-prolonged mating

-no wings

-chewing mouthparts

Order Dermaptera characteristics

Earwigs

-soil, leaf litter, moist environment

-chewing mouthparts

-cerci modified into pinchers-used for mating display

-hindwings modified to be highly foldable

-forewing modified for protection

-mom stays with eggs/babies for a period of time

Superorder Hemoipteroidea/Paraneoptera characteristics

True bugs, lice

-some have chewing mandibles, but most have piercing, sucking structure

-fluid feeding

-less veins in wings

-no cerci

Orders in Hemipteroidea/Paraneoptera

-Psocoptera

-Hemiptera

-Pthiraptera

Order Psocoptera characteristics

barklice

-more ancestral

-chewing mouthparts

-big snout

-occur in colonies

Order Hemiptera characteristics

-true bugs

-sucking mouthparts

Suborder Heteroptera characteristics

Seedbug, stinkbug

-wings are leathery and membranous

-wings laid on back and cross over (X pattern on back)

-mouth part in front of head

-multi segmented antennae

Suborder Homoptera characteristics

Cicada, leafhopper, lanternfly

-not advanced antennae

-entire forewing is one texture

-wings roof like on back

-mouth parts attached to back of head

Order Pthiraptera suborders

Lice

-Mallophaga

-Anoplura

Suborder Mallophaga characteristics

Head lice

-entirely parasitic

-chewing lice, sucking lice

-head is same width or wider than thorax

-single small like claws

Suborder Anoplura characteristics

-sucking louse

-head is smaller than thorax

-big claws, hold onto hair really well bc of the shape of them

-pube lice

Neoptera/Endopterygota Orders/characteristics

-developing wings internally

-most advanced insect lineages

-most species rich

-Neuroptera

-Coleoptera

-Diptera

-Siphonaptera

-Lepidoptera

-Hymenoptera

Order Neuroptera characteristics

Lacewings

-more primitive wing structure

-predators

-chewing mouthparts

Order Coleoptera characteristics

Beetles

-chewing mouthparts

-wings have been highly modified for body protection (predators, abrasion, moisture loss)

-considered the most successful group

-predatory, parasitic, plants

Order Diptera suborders

True flies

Liquid feeding

-Nematocera

-Brachycera

Nematocera characteristics

Mosquitos

-more primitive suborder

-thread like antennae

-body long and slender

-spindly legs

-long wings

Suborder Brachyera characteristics

Flies

-short horned

-robust body

-advantages in manuevbarility in flight

Order Siphonaptera

Fleas

-parasites in adult stage

-modified mouthparts for sucking

-laterally compressed

-leathery exoskeleton

-antennae held down

-dark/light sense structure not actual seeing

-mouthparts sense host walking near

-great jumping legs

Order Lepidoptera characteristics

Butterflies and moths

-200-300,000 species

-wing venation slimmed down to only needed ones

-wings and bodies have scales

-scales with colors-for mates, camoflauge

-juveniles have chewing mouthparts

-maxialle modified in tube (for nectar in plants)

Order Hymenoptera suborders

-Symphyta

-Apocrita

Hymenoptera characteristics

Wasps, bees, ants

-2 pairs of membranous wings

-reduced venation

-forewings > hindwings

-ovipasitor : egg laying appendage/stinger

Symphyta characteristics

Broad waisted wasps

-more primitive

-broad connection btwn abdomen and thorax

-most herbivious

Apocrita characteristics

Narrow waisted wasp

-Herbivious, predators, parasatoid

-young cared for by parents

-more species rich group

-many have solitary lifestyle, but also social insects

Characteristics of exoskeleton

-Up to 0.1-1mm thick

-Connected to foregut, hindgut, trachea, genital and dermal glands

-rigid plates (sclerites)

-up to 25-50% dryweight

-molted during growth

Functions of exoskelton

-protect against abrasion, punctures

-block pathogens and toxins

-coloration- pigmented, irridescence

-muscle attachment- movement by “lever action”

-reduce water loss

Properties of exoskeleton

-rigid (muscle attachment, protection) but flexible (movement)

-impermeable (pathogens, water loss) but permeable (uptake of respiratory gasses)

-discarded during growth but recycled to reduce energy loss

Structure of exoskeleton

5 layers all performing different functions

-Basement layer

-Epidermis

• Procuticle

-Endocuticle

-Exocuticle

-Epicuticle

Basement layer

connective tissue

muscle attachment

Epidermis

-gland cells

-secretory cells → makes materials of rest of structure

Endocuticle

-more flexible

-recyclable

-layers of chitin and protein

Exocuticle

-more rigid

-layers of chitin and protein

Epicuticle

-waterproofing

-Inner wax layer (most of it made up by this)

-outer cement later (protects the wax)