Insect Biology

Front 1

"flies"

Back 1

encompasses unrelated orders from mayflies (Ephemeroptera) to true flies (Diptera)

Front 2

phenetics

Back 2

A systematic method relying on estimates of overall SIMILARITY, ususally derived from morphology, but sometimes from behavior and molecular evidence.

Front 3

Cladistics

Back 3

A systematic method that seeks patterns of SPECIAL similarity based only on synapomorphies (shared, evolutionarily novel features).

Front 4

Synapomorphies

Back 4

Shared, evolutionarily novel features

Front 5

Sympleisiomorphies

Back 5

ALSO: pleisiomorphies

Shared ancestral features

Front 6

"beetles"

Back 6

Coleopotera

Front 7

autapomorphies

Back 7

Features unique to a particular group; not shared with another group

Front 8

Monophyletic

Back 8

=clade

Front 9

paraphyletic

Back 9

lack one clade from amongst descendants of a common ancestor

Front 10

polyphyletic

Back 10

fail to include two or more clades amongst descendants of a common ancestor

Front 11

Evolutionary systematics

Back 11

A systematic method that uses estimates of derived similarity AND estimates the amount of evolutionary change included within the tree. Larger gaps=higher taxonomic status

Front 12

Compare # of insect species described to # of vertebrates

Back 12

Vertebrates=virtually all described and studied at some level. Wheeler says 7 spp/taxonomist

Insects=perhaps 5-20% described. Wheeler says 425 spp/taxonomist. GLobal insect diversity may include millions of undescribed species!

Front 13

tagmosis

Back 13

the specialization of successive body segments that more or less unite to form sections, or "tagmata", namely the head, ,thorax, and abdomen.

Front 14

Hexapoda: Segmental composition of head

Back 14

pragnathal region (usu. 3 segments) + three gnathal segements bearing mandibles, maxillae, and labium

Front 15

Hexapoda: Segmental composition of thorax

Back 15

three segments, each with one pair of legs, each with a max. of 6 segments (extant forms; primitive had more)

Front 16

Orders in Insecta proper

Back 16

Archaeognatha, Zygentoma, and Pterygota (huge radiation of primarily winged hexapods)

Front 17

Hexapod

Back 17

6-legged arthropod=Insecta and relatives. Share morphologies with crustacea=ultrastructure of nervous system, visual system, and development. This argues for Pancrustacea.

Front 18

Arthropoda: is it monophyletic?

Back 18

It's controversial, but recent molecular and morphological studies suggest is it monophyletic. Internal relationships are still controversial.

Front 19

homeotic gene

Back 19

developmentally regulatory gene

Front 20

gene Dll

Back 20

a homeotic gene for mandibles that is similar in insects and crustaceans. Supports monophyly (Pancrusteacea); refutes earlier claims that hexapod mandibles dervied independently from those of crustaceans

Front 21

apodemes

Back 21

internal supports and muscle attachments; infoldings of exoskeleton

Front 22

Four characters of arthropods

Back 22

1. paired, jointed appendages
2. hard outer cuticle (exoskeleton)
3. molt during development (not unique)
4. Tagmosis (fusion of segments into specialized regions=head, thorax, abdomen)

Front 23

What are arthropods, taxonomically speaking?

Back 23

A phylum that comprises the classes Trilibita (extinct) and Chelicerata, Crustacea, Myriapoda, Hexapoda

Front 24

What are the four extant arthropod groups?

Back 24

Chelicerata, Crustacea, Myriapoda, Hexapoda

(Trilobites extinct)

Front 25

Chelicerata
1. representative organisms
2. # legs
3. body plan
4. mouthparts
5. appendages
6. breathing
7. pairs antennae

Back 25

1. arachnids, horseshoe crabs, eurypterids, ticks, scorpions, mites
2. 4 pairs legs
3. cephalothorax + abdomen
4. chelicerate mouthparts
5. uniramous appendages
6. book lungs
7. no antennae

Front 26

Crustacea
1. representative organisms
2. # legs
3. body plan
4. mouthparts
5. appendages,
6. breathing
7. pairs antennae

Back 26

1. crabs, isopods, shrimp, amphipods
2. variable; 4-5 legs + claws
3. cephalothorax + abdomen
4. mandibulate
5. biramous appendages,
6. gills
7. 2 pairs antennae

Front 27

Myriapoda:
1. representative organisms
2. # legs
3. body plan
4. mouthparts
5. appendages,
6. breathing
7. pairs antennae

Back 27

1. centipedes, millipedes
2. 10-750 pair legs
3. head+trunk body plan
4. mandibulate mouthparts
5. uniramous appendages
6. tracheal system
7. 1 pair antennae

Front 28

Hexapoda
1. representative organisms
2. # legs
3. body plan
4. mouthparts
5. appendages,
6. breathing
7. pairs antennae

Back 28

1. insects and non-insect hexapods
2. 3 pair legs
3. head+thorax+abdomen body plan
4. mandibulate mouthparts
5. uniramous appendages
6. tracheal system
7. 1 pair antennae

Front 29

When did arthropods arise?

Back 29

Precambrian (600 mya). Since Cambrian (540 mya), have been dominant life form.

Front 30

Why are there problems in arthropod classification?

Back 30

1. phylogenetic method is relatively new.
2. Not much known about development of groups.
3. More work on fossil records needed b/c insects have radiated quickly and intermediates are missing
4. Homoplasy

Front 31

Homoplasy

Back 31

convergence in characters

Front 32

Phylogeny

Back 32

Hypothesized relationship b/t taxa of interest.

Front 33

How are arthropod groups related to one another? (New and traditional views)

Back 33

Traditional (based on morphological characters):
Chelicerata--crustacea--myriapoda--Hexapoda
New (based on molecular data, N.S. characters, and vision):
Chelicerata--Myriapoda--Crustacea--Hexapoda (last two becoming Pancrustacea)

Front 34

Characteristics of an Insect

Back 34

Class Insecta (In=latin for "into", secta=Latin "secare" for "cut or divide)

1. Exoskeleton
2. Body part in 3s:
->3 body segments (head, thorax, abdomen)
->3 pairs of legs
->3 mouthparts (mandibles, maxilla, and labium)

Front 35

Importance of insects (to humans)

Back 35

* Diverse=est 3-30 mil
* impt ecologically and economically ($30 billion in US alone)--silk, honey, beeswax, dyes, pollination
* Food source in "eastern" cultures
* Pests (food prices would increase 30-50% without pesticides)
*Disease vectors
* Impt models for biological research (eg., drosophilla, flour beetles)

Front 36

Why do we have collections?

Back 36

--research (primary)
--Teaching collections
--Personal interests
--Inventory of given habitat
--conservation, species distribution, climate changes, pollinator declines, evolutionary research, electronic databases

Deposited in museums by researchers, professional collectors, students, amateurs

Front 37

Lectotype

Back 37

"Copy" of the exemplar specimen of the species.

Front 38

How estimate rate of speciation?

Back 38

Using the molecular clock:

1) we can estimate how long ago a specific speciation event (a specific split in the phylogenetic tree) occurred

2) we can do 1) above for all the different speciation events (the splits in a tree) within a given time period - this gives us the rate at which species were originating during this period

3) we can 2) above for many different time periods, and then ask if the rate of speciation differs across time – and if so, when and why it differs?

Front 39

The clade Ecdysozoa

Back 39

Ecdysis=molting, thus other groups that molt!

Phyla:
-Arthropods
-nematodoa
-onychophra (velvet worms), -tardigrada (water bears) -kinorhyncha and priapulida (not discussed)

Front 40

Nematodes, characters

Back 40

Member of the clade Ecdysozoa

-Parasites of plants/animals
-Predators
-diverse group with more than a million est. species

Front 41

Tardigrada, characters

Back 41

Member of the clade Ecdysozoa

-Water bears
-semi-aquatic (mosses, lichens, ferns)
-arthropod-like nervous system
-legs NOT articulated (like slinky)
-clawed foot (to hold substrate)

Front 42

Onychophora, characters

Back 42

Member of the clade Ecdysozoa

-velvet worms
-terrestrial (In Cambrian, also marine)
-chitin (but lack true exoskeleton)
-paired appendages
-open circ. system

Front 43

Serial homology

Back 43

Structures that repeat and share same developmental origin

Front 44

How did the arthropod body plan evolve? From nematodes to arthropods.

Back 44

--presence of cuticle and molting -> NEMATODA

--Segmentation, chitin in culticle, presence of lateral appendages ->.ONYCHOPHORA and TARDIGRADA

--jointed apprendages, hard cuticle, fusion of body into specialized sections ->ARTHROPODA

Front 45

Describe the proto-arthropod

Back 45

--May have had 20 segments w/appendages
--tagma become: 1-6 -> head, 7-9 -> thorax, 10-20 -> abdomen, including ovipositors (segs 8-9) and cerci (seg. 11)
--biramous
--6 segs fused w/head=Myriapoda, Crutacea and INSECTA
--3 segs. fused with head=Chelicerata

Front 46

Evidence for homology of proto-arthropod segments and contemporary tagma

Back 46

1. Dev/ comparative/ gene expression
2. creation of mutants that express appendages
3. Fossil intermediates/modern remnants (like Monura and bristletails)

Front 47

Segments in the insect head

Back 47

1. Labrum (keeps food in)
2. Antennae
3. Lost appendage
4. Mandibles
5. Maxillae (move food, taste receptors)
6. Labium

Front 48

Fossil Monura

Back 48

Controversial as basal insect b/c person "etched out" areas to make them clearer

Front 49

How many species of insects are described?

Back 49

~1 million described (estimated because of redundancies)

Front 50

How many insect species are predicted?

Back 50

--in 1980's, people believed ~2-5 million
--Terry Erwin (smithsonian, 1982) increased est. by 10-fold. Used beetles in canopy of tropical forests as starting point
--Current conservative estimates are 5-10 million (range 2-80 million)
--55-65% of species are insects

Front 51

Why are there discrepancies between estimates of insect species?

Back 51

1. number descovered unknown (described more than once)
2. effort not similar across groups/areas (popularity)
3. little known about tropics and other areas (80% of taxonimists in N Am or Europe)
4. Methods of extrapolation are controversial

Front 52

Why are insects so diverse?

Back 52

Like arthropods:
1. small
2. exoskeleton
3. High birth rate and short generation time
4. very old group

Unique to insects
5. Flight (allows dispersal)
6. complete metamorphosis (parent/offspring difdfer in form and habitat)
7. Phytophagy (assoc with diversity)

Front 53

Parts of the integument

Back 53

(surface)
-Waxy layer
-cement layer
-epicuticle
-exocuticle
-endocuticle
-epidermis (only living layer)
-basement membrane
(hemocoel)

Front 54

procuticle

Back 54

--undifferentiated cuticle layers equivalent to endocuticle + exocuticle
--20-50-% of dry weight is chitin
--more than 50% protein
--reactive amine group allows binding

Front 55

Functions of the epidermal layer

Back 55

--microvilli increase surface area
--produces chitin and proteins to bind it
--produces cuticle
--some exocrine glands that produce pheromones, waxes, cements, and defensive compounds
--pore canals

Front 56

Functions of the basement membrane

Back 56

protects adn supports the epidermal cells. Buffers against physical damage, pH shifts.

Front 57

Functions of exocuticle

Back 57

--hardness= "Sclerotized"
--chitin molecules form sheets laid down in anti-clockwise fashion
--proteins used to connect chitin chains and sheets (Some color from this)

Front 58

Functions of endocuticle

Back 58

--cushiony layer
--keeps growing, can be resorbed/eaten (esp during ecdysis) and regenerated
--support and storage
--chitin chains with no protein binding (proteins "floating")

Front 59

Functions of epicuticle

Back 59

--prevents dessication
--dictates outer shape of integument (shiny, bumpy, etc)
--metallic, irridescence

Front 60

Functions of cement layer

Back 60

--may be contiguous, an outer mesh, or absent
--limits cuticle expansion (holds shape)
--protects wax

Front 61

Functions of waxy layer

Back 61

--prevents dessication
--composed of 15-17 C alkanes (if too warm, they separate and insect dries up rapidly)

Front 62

Importance of waxes (4)

Back 62

1. nestmate recognition /communication (CHCs)
2. sexual selection
3. Bee homes
4. Protection (shellac)

Front 63

Which two areas *don't* have integument?`

Back 63

1. midgut
2. reproductive structures

Front 64

How modify the integument to increase external hardness/rigidity?

Back 64

1. add more proteins and/or specialized proteins
2. add metals (Zn, Mg, Cu)--often black. Mandibles, ovipositors, tarsal calws, etc.

Front 65

How modify the integument to provide internal support/muscle attachments?

Back 65

1. Apodemes=hollow, straight ingrowths of exoskeleton

2. Apophyses=arm-shaped apodemes, usually a hollow, pitlike inflection

Both withstand pressure from flight, eating, etc.

Front 66

How modify the integument to increase flexibility?

Back 66

1. leave procuticle undifferentiated (caterpillars, maggots)
2. Produce more unsclerotized cuticle than needed for expansion/telescoping

Front 67

How modify the integument to increase elasticity?

Back 67

--Add resilin (colorless polymer of protein added to exo-and endoculticle)
--Adds ability to RETURN to position by absorbing and releasing energy
--only 30% on energy lost as heat (very effic.)

Front 68

Ecdysial line

Back 68

Thin, central line that gives way during molting

Front 69

White light

Back 69

all wavelengths visible to a given organism

Front 70

Black

Back 70

A lack of all wavelengths

Front 71

Structural colors

Back 71

--result of interference, diffraction, or scattering of light
--tend to be SHORT WAVE LENGTHS=blue, green, UV
--mostly epicuticle, sometimes exocuticle, rarely epidermis

Front 72

Interference

Back 72

the addition (or superposition) of two or more waves that result in a new wave pattern
ex. Blue Morpho=little ribs on scales that scatter all but bluek, which has *constructive* interference

Front 73

Diffraction

Back 73

When light passes sharp edges or through slits, which deflects and separates the rays
--analogous to a prism
--changes with position

Front 74

Pigment-based colors

Back 74

--absorb all wavelengths but those reflected (some may pass through as well)
--white pigments=STRUCTURAL molecule
--produced by metabolism, from food, from symbionts (rare, eg. aphids)

Front 75

Which pigments are produced from which metabolic process?

Back 75

* Yellow/white=uric acid (byproducts of purine synthesis)

* Yellow/red/brown/black= Ommochromes (product of tryptophan synthesis)

* Black/brown/yellow/red= Melanins (product of tyrosine synthesis)

* Red= Pteridines (byproducts of pyramidine (DNA/RNA) synthesis)

Front 76

How are pigments made from food?

Back 76

yellow/red=carotenoids, flavonoids
Ex. Sphinx moth metabolizes bilin (blue) and yellow pigment from plant to make green

Front 77

Where are pigments stored?

Back 77

--cuticle (most)
--epidermal (when cuticle transparent)
--hemolymph and fat body (aphids)

Front 78

Three (3) sources of color change between and within individuals

Back 78

1. genes (w/in pops, b/t sexes)
2. influenced by developmental stage, temperature/daylength, plants eaten
3. A few can actively change color (walking sticks, crab spiders)

Front 79

Functions and characteristics of insect circulatory system

Back 79

--circulates hemolymph through body
--open or closed
--dorsal longitudinal vessel=heart (w/ ostia, alary muscles), segmental vessels, aorta
-dorsal and ventral diaphragms
--hemocoel

Front 80

Hemocoel

Back 80

body cavity containing hemolymph

Front 81

How is hemolymph circulated?

Back 81

--Heart pulsates (peristalsis)
--hemocoel--->in through ostia--->heart--->aorta or segmental vessels (valves counter tidal effect)
--accessory pulsatile organs for appendages

Front 82

parts of accessory pulsatile organ

Back 82

Help move hemolymph into appendages with:
--constricting muscle
-septum
--valve(s)

Front 83

What is hemolymph?

Back 83

15-75% insects volume

--PLASMA(90%)--H2Ok amino acids, carbs, fats, salts, proteins, waste--NO OXYGEN

--HEMOCYTES (10%) for metabolism, defense, waste, removal of foreign materials, encapsulation

--defense compounds

Front 84

Functions of hemolymph

Back 84

1. lube organs
2. distribute hormones and nutrients
3.dissipate metabolic waste
4. dissipate heat
5. hydrostatic pressure
6. water/nutrient storage
7. defense (sequestration), eg. arachne checkerspot and monarch

Front 85

Kreb's cycle formula (respiration)

Back 85

o2 + c6h12o6 --> co2 + h2o +Energy

Front 86

Tracheal system

Back 86

A series of structures (spiracles, trachea, tracheoles, etc) that allow ijnsect cells to exchange gases w/ surroundings
--5-50% of body volume

Front 87

taenidia

Back 87

--extensions of epicuticle within trachea
--ringlike, support

Front 88

Difference between open and closed respiratory system

Back 88

OPEN: open to outside via spiracles

CLOSED: tracheal system lacks spiracles (diffusion through cuticle, or gills)

Can change from larvae to adult!

Front 89

How does gas exchange happen in insects?

Back 89

DIffusion

Ventilation (for larger, more active insects)

Front 90

How can the tracheal systems of insects change as they develop?

Back 90

Closed-->open: aquatic insects w/ gills, parasitoids

Passive-->active: in many holometabolous insects (complete metamorphosis

Number of spiracles

Front 91

holometabolous

Back 91

experiencing complete metamorphosis

Front 92

What are the aquatic adaptations for respiration?

Back 92

OPEN SYSTEM
--renewal of air supply
--compressible gills
--plastron

CLOSED SYSTEM
--cuticular respiration
--tracheal gills
--brachial chamber
(read in book)

Front 93

Developmental origin of the alimentary canal?

Back 93

foregut and hindgut=ectoderm

midgut and Malpighian tubules=mesoderm

Front 94

Functions of foregut, midgut, and hindgut

Back 94

FOREGUT: mech. breakdown, food processing, storage (crop)
MIDGUT: digestions, absorption (enzymes)
HINDGUT: excretion, sybiont storage, reabsorption, H2O regulation

Front 95

Parts and functions of the preoral cavity

Back 95

--salivary glands (lube, enzymes, anticoagulants, antibiotics)

--preoral muscles (hemipterans) pump fluids into mouth

Front 96

Function of the proventriculus

Back 96

Gizzard, maceration plates

Front 97

Parts of the foregut

Back 97

Pharynx, Esophagus, Crop

Front 98

Parts of the Midgut

Back 98

Gastric caecum=^ surface area, expels H2O into hemocoel, movement of nutrients, enzymes

Ventriculus=tubular portion (epidermal)

Epithelial cells=produce/secrete enzymes, absorb nutrients

Peritrophic membrane= separates epithelial cells from food (lines ventriculus); perforated, contains embedded enzymes, etc

Front 99

Functions of peritrophic membrane

Back 99

--separates epithelial cells from food (lines ventriculus);
--compartmentalizes digestion
--perforated: helps filter toxins
--contains embedded enzymes
--grabs tannins (from plants; bind to proteins)
--protects against infection

Front 100

Which insects produce a peritropic membrane?

Back 100

Most, but not:
--insects with liquid diets (unless includes feces, mud, or rotting flesh)

Front 101

Five (5) steps of digestion in insects

Back 101

1. Food enters peritrophic membrane space
2. Enzymes breakdown food
3. SMall nutrients penetrate PM and are absorbed by epithelial cells
4. Larger materials (and recycled enzymes) may penetrate PM, or are moved to anterior midgut by fluids on the "conveyor belt"
5. Partially digested food (and enzymes) passes through caecum and back into PM

Front 102

Parts and function of the hindgut

Back 102

--Malpighian tubules: elim. waste, pump for salts-->nitrogenous waste follows (reduce in evolutionary time)

--Ileum: sugar absorption and water retention. Stored symbionts (anoxic). Large in roaches, termites, beetles, flies.

--Colon: connects

--Rectum: reabsorbs impt. nutrients and water (via rectal pads); heavy pumps to reuptake H2O.

--Rectum

Front 103

How can insect digestive systems vary?

Back 103

--PREDATORS: large storage and well-developed gizzards for infrequent, nutrient-rich food

PLANT-FEEDERS: short gut, no storage, well-developed gizzards for low-quality food requiring a lot of processing

BLOOD, SAP, AND NECTAR FEEDERS: long convoluted gut to increase absorption; flexible gut, little protection, some storage capacity (water stider, cicada, moth, house fly)