1

General EntomologyThe Biology of Insects

Arthropod (and insect) dominance(comparisons of numbers of species)

Metazoans(multicellular animals)

only:

2

Metazoa(35 phyla)

GEOLOGIC TIME SCALE

Time Units of the Geologic Time Scale Development ofPlants and AnimalsEon Era Period Epoch

Pha

nero

zoic

Pro

tero

zoic

Arc

hea

n

Hadean

Quaternary

Tertiary

Cen

ozoi

cM

esoz

oic

Pal

aeo

zoic

Cretaceous

Jurassic

Triassic

Permian

Ca

rbo

nife

rous

Pennsylvanian

Mississippian

Devonian

Silurian

Ordovician

Cambrian

Collectively calledPrecambrian

comprisesabout 87% of the

geological time scale

Holocene

Pleistocene

Pliocene

Miocene

Palaeocene

Oligocene

Eocene

“Ageof

Reptiles”

“Ageof

Amphibians”

“Ageof

Fishes

“Ageof

Invertebrates”

Earliest Homo sapiens

“Age of Mammals”

Extinction of trilobites andmany other marine animals

First reptilesLarge coal swamps

Amphibians abundant

First insect fossilsFishes dominant

First land plantsFirst fishes

Trilobites dominant

First multicelled organisms

First one-celled organisms

Age of oldest rocks

Origin of the earth

First flowering plantsFirst birds

Dinosaurs dominant

4600 Ma

3800

2500

505

438

410

360

320

286

248

208

145

65

0.01

1.6

5.3

23.8

33.7

55Extinction of dinosaursand many other species

First organisms with shells

First mammals

First amphibians

Earliest hominids

545

650Abundant Ediacaran faunasVendian “Soft-bodied

faunas”

What sort of animals areinsects?

Ediacaran pre-Cambrian fauna

= Lophotrochozoa= Ecdysozoa,“molting animals”

Deuterostomes

Urmetazoan

Urm

etaz

oan

(proboscis)

(peanut)

(spoon)(horseshoe)

(Siboglinidae)

(moss)

Lophotrochozoa

3

Summary of changes to phylogeny of Metazoa,based on nucleotide sequences of 18S rDNA

(from Aguinaldo et al….& Lake, 1997 – a “paradigm shift”)

Annelida

Pri

ap

uli

da

Pseudocoelomates

Nematoda PriapulidaNematomorphaArthropoda

Non-morphological characters:-- Gene sequences/markers

• nuclear (& RFLPs, AFLPs, SNPs)• mitochondrial

-- Haemocyanin & hexamerin-- Homeobox (HOX) gene expression

• engrailed, distalless, wingless,nubbin, & apterous

-- Histones, ubiquitins, etc.

(a superphylum of molting animals)

Metazoa

PhylumArthropoda

GEOLOGIC TIME SCALE

Time Units of the Geologic Time Scale Development ofPlants and AnimalsEon Era Period Epoch

Pha

nero

zoic

Pro

tero

zoic

Arc

hea

n

Hadean

Quaternary

Tertiary

Cen

ozoi

cM

esoz

oic

Pal

aeo

zoic

Cretaceous

Jurassic

Triassic

Permian

Ca

rbo

nife

rous

Pennsylvanian

Mississippian

Devonian

Silurian

Ordovician

Cambrian

Collectively calledPrecambrian

comprisesabout 87% of the

geological time scale

Holocene

Pleistocene

Pliocene

Miocene

Palaeocene

Oligocene

Eocene

“Ageof

Reptiles”

“Ageof

Amphibians”

“Ageof

Fishes

“Ageof

Invertebrates”

Earliest Homo sapiens

“Age of Mammals”

Extinction of trilobites andmany other marine animals

First reptilesLarge coal swamps

Amphibians abundant

First insect fossilsFishes dominant

First land plantsFirst fishes

Trilobites dominant

First multicelled organisms

First one-celled organisms

Age of oldest rocks

Origin of the earth

First flowering plantsFirst birds

Dinosaurs dominant

4600 Ma

3800

2500

505

438

410

360

320

286

248

208

145

65

0.01

1.6

5.3

23.8

33.7

55Extinction of dinosaursand many other species

First organisms with shells

First mammals

First amphibians

Earliest hominids

545

650Abundant Ediacaran faunasVendian “Soft-bodied

faunas”

Anomalocaris (Burgess Shale)mid-Cambrian, 510 my

4

“Panarthropoda”

Regular arthropods, plus:

Onychophora (“velvet worms”)Cambrian; ~200 species

Tardigrada (“water bears”)Cambrian? ~1150 species

Aysheaia sp.Burgess Shale: 510 my

Peripatus sp.

• α-chitinous exoskeleton• open circulatory system• pericardial & perineural

sinuses• embryological

development• molecular markers

Arthropoda – “jointed foot” (leg)

sclerotized chitinous cuticle + epidermis

exoskeleton(better at small body sizes)

endoskeleton(better at larger body sizes)

..

..

5

Arthropoda – major groups

hypothetical insect ancestor

Arthropoda: Trilobitomorpha †~4000 species (Cambrian-Permian)

antennae

uniramouslimbs

trilobed body

tiny to huge:1 mm to 90 cm (3 ft)

6

Arthropoda: Chelicerata

Pycnogonida (Sea Spiders) – Devonian-Present; ~1300 species

like trilobites, tiny to huge: 1 mm to 90 cm

Chelicerates are defined by their front-most pincer-like chelicerae and their pedipalps. Devonian fossil (400 mya)

Arthropoda: Chelicerata, continued:Euchelicerata: Merostomata

Eurypterida † (Ordivician-Permian)200 fossil species, some huge (>8 feet)

Xiphosura (Cambrian-Present)4 extant but many fossil species

carapace

compound eye (!)

480 mya 250 mya

7

Arthropoda: Chelicerata, continued:Euchelicerata: Arachnida 1, the Scorpion clade

Opiliones (harvestmen, daddy longlegs)6500 species

Scorpiones (scorpions)1750 species; Silurian (430 mya)

Pseudoscorpiones (pseudoscorpions)3300 species

Solpugida (Solfugae) (sun spiders)1000 species

pedipalp

Arthropoda: Chelicerata, continued:Euchelicerata: Arachnida 2, the Tick clade

Acari or Acarina (ticks and mites)Devonian;50,000 species

Ricinulei (ricinulids)Carboniferous; 60 species

350 mya

leaf galls

8

Arthropoda: Chelicerata, continued:Euchelicerata: Arachnida 3, the Spider clade

Palpigradi (microwhip scorpions)80 species

Araneae (spiders) - U. Carboniferous; 40,000 species

Amblypygi (tailless whip scorpions) 140 species

300 mya

Arthropoda: Crustacea (67,000 species)(mid Cambrian; relationships are very poorly understood)

Branchiopoda (brine shrimp)

Ostracoda (ostracodes)

Maxillopoda (barnacles & copepods)

Mallocostracacrabs & shrimp) Pentastomida

(???)

Daphnia

Isopoda

Decapoda

520 mya

Remipedia

9

Arthropoda: Myriapoda (Silurian, 430 mya)

Chilopoda (centipedes) 3000 species Diplopoda (millipedes) 12,000 species

Symphyla (symphylans) 200 species Pauropoda (pauropods) 500 species

uniramouslimbs

Phylogeny of myriapod classes/subclassesGai et al. 2006: nearly complete 28S & 18S rDNA

Myriapoda

“Uniramia”

10

epicoxa

subcoxa

prefemur

patella

wing exite

exites

tergum

femur

tibia

tarsus

trochanter

pretarsus

coxa

3rd leg of Machilis

(Archaeognatha)

A “not souniramous” limb

(after Kukalová-Peck 1987)

hypothetical ancestral insect leg

Chelicerata

Myriapoda

Crustacea

HexapodaPancrustacea

RELATIONSHIPS OF ARTHROPOD TAXA: CURRENT HYPOTHESES

Snodgrass, Weygoldt, Wägele, Wheeler et al.

Chelicerata

Myriapoda

Crustacea

HexapodaPancrustacea

Mandibulata

Chelicerata

Crustacea

Myriapoda

Hexapoda

Schizoramia

Atelocerata(Uniramia)

Chelicerata

Crustacea

‘Myriapoda’

HexapodaAtelocerata (Uniramia)

NoteSecond note

: Atelocerata = Tracheata = Uniramia (more or less):: Pancrustacea (Mallatt) = Tetraconata (Richter 2002)

Zrzavý, Giribet et al.

Cisne, Briggs et al., BuddTurbeville et al., Friedrich & Tautz, Mallatt et al.

Paradoxopoda

Mandibulata

two traditional views

A.

B.

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Von Reumont et al. 2012.Insects-from-Remipedia hypothesis

Autapomorphies:• Lateral eye ultrastructure• CNS ontogeny and function• EF1-α and EF2 (nuclear) sequences• SSU rRNA (small subunit) sequence• LSU rRNA (large subunit) sequence• Mitochondrial genome sequence• Shared mitochondrial rearrangement

Hexapod sister group within Pancrustacea:• Branchiopoda (Artemia, Daphnia) – some molecular studies• Remipedia (blind) – recent molecular studies• Malacostraca (crabs, shrimp) – brain anatomy• Ostracoda (ostracods) – body plan

Included subphyla/classes:• Crustacea• Collembola• Diplura• Protura• Insecta

SUMMARY of PANCRUSTACEA (TETRACONOTA)

Hexapoda

12

MetazoaArthropoda

GEOLOGIC TIME SCALE

Time Units of the Geologic Time Scale Development ofPlants and AnimalsEon Era Period Epoch

Pha

nero

zoic

Pro

tero

zoic

Arc

hea

n

Hadean

Quaternary

Tertiary

Cen

ozoi

cM

esoz

oic

Pal

aeo

zoic

Cretaceous

Jurassic

Triassic

Permian

Car

boni

fero

us

Pennsylvanian

Mississippian

Devonian

Silurian

Ordovician

Cambrian

Collectively calledPrecambrian

comprisesabout 87% of the

geological time scale

Holocene

Pleistocene

Pliocene

Miocene

Palaeocene

Oligocene

Eocene

“Ageof

Reptiles”

“Ageof

Amphibians”

“Ageof

Fishes

“Ageof

Invertebrates”

Earliest Homo sapiens

“Age of Mammals”

Extinction of trilobites andmany other marine animals

First reptilesLarge coal swamps

Amphibians abundant

First insect fossilsFishes dominant

First land plantsFirst fishes

Trilobites dominant

First multicelled organisms

First one-celled organisms

Age of oldest rocks

Origin of the earth

First flowering plantsFirst birds

Dinosaurs dominant

4600 Ma

3800

2500

505

438

410

360

320

286

248

208

145

65

0.01

1.6

5.3

23.8

33.7

55Extinction of dinosaursand many other species

First organisms with shells

First mammals

First amphibians

Earliest hominids

545

650Abundant Ediacaran faunasVendian “Soft-bodied

faunas”

Insecta

1. Tripartite Tagmosis

Six shared specializations of true Insecta

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2. Trignathous, ectognathous mouthparts

1.

2.

3.

3. Antennae withno intrinsic muscles

past the pedicel

4. Non glandular cerci:(singular = cercus)

5. No anamorphosis:(i.e., epimorphic development

flagellumpedicel

scape

muscles

9

10

11

tip of insect abdomen

terminal segmentadded at each molt

14

6. “Amniotic” Egg

Genduara punctigeraLepidoptera: Lasiocampidae)

Amnion

amniotic cavity Yolkamniotic fold

Blastoderm Serosa

Germband

Yolk