2: Hemimetabola & Holometabola

Question 1

Define viviparous

Answer 1

Give birth to live young

Question 1

Define Ametabolous development + example

Answer 1

→ slight/no metamorphosis
Only apterygota insects (Silverfish, springtails)
Gradual change

Question 2

Define Hemimetabolous development + example

Answer 2

→ incomplete metamorphosis
E.g Orthoptera
Immature stage somewhat similar
If found in same habitat as adults = nymphs
If aquatic = naiads

Question 3

Define Holometabolous development + example

Answer 3

→ complete metamorphosis
E.g Lepidoptera
Non-feeding stage (pupa) between immature larva and adult stages
Adults structures develop as imaginal discs inside larva

Question 4

Describe the Plectoera (Stoneflies)

Answer 4

• Reduced ovipositor (eggs dropped into water in flight)
• Pulsatile organ (accessory heart) associated with the cerci
• 3 segmented tarsi
• High 02 requirement

Question 5

Describe the Phasmatodea

Answer 5

(stick insects)All herbivores
- Pair of defensive glands inside the prothorax
- Fusion of thorax and 1st abdominal segment
- Claspers (vomer) present on males
- Amazing crypsis associated with host plant speciation

Question 6

Define crypsis

Answer 6

The ability of an organism to conceal itself especially from a predator by having a colour, pattern, and shape that allows it to blend into the surrounding environment

Question 7

Generally decribe the Orthoptera

Answer 7

(Grasshoppers and crickets)
- Cryptoleuron (lateral extension of the (pronotum)
- Saltatorial hindlegs
- Wings included over abdomen at rest

Question 8

Describe the Ensifera (Crickets)

Answer 8

Fine antennae >30 segments
Biting/shearing mandibles
Auditory organs on legs (protibia)

Question 9

Describe the Caelifera (grasshoppers)

Answer 9

Short, robust antennae <30 segments
Chewing mandibles
Abdominal auditory organs

Question 10

Describe the synapomorphies of the Mantodea

Answer 10

(mantises)
Enlarged, raptorial forelegs
Femoral brush on front leg
Extraordinary head mobility
Ootheca (egg mass) embedded in protective froth

Question 11

Desrcibe the synapomorphies of the Blattodea

Answer 11

(Cockroaches)
Wrap around eyes
Dorsoventral flattening
Slightly hardened, leathery (coreacious) front wings

Question 12

Describe some features of Blattodea development and parental care

Answer 12

• Oviparous
• Some produce live young
• Maternal and biparental care:
• Adults protect nymphs
  (Retention of the Ootheca by the basal blattodea may be first step to parental care)

Question 13

Describe the Isoptera

Answer 13

(Termites)
- Eusocial
- Thought to be own order, but actually eusocial cockroaches!

Question 14

Describe termite mounds

Answer 14

• Air comes into base and out through the top = thermoregulation and improves air circulation
• 100s years old
• Mounds alter soil → plant growth → tree distribution → levels of N fixation

Question 15

Describe the Thysanoptera

Answer 15

(Thrips)
- Wings strap-like with fringe of long setae
- Right mandible reduced, left mandible inflexible
- Pre-adult instar inactive, non-feeding - pupa like?
- Haplodiploid

• Most feed on plants/ fungi
• Some species in galls are eusocial (division of labour)
• Important pests of plants

Question 16

Describe the Hemiptera

Answer 16

(‘true bugs’ e.g aphids, shield bugs)
- Mouthparts fused = piercing, sucking beak or rostrum
- Mostly herbivores → feed on plant vascular tissue
- Major plant pests
- Lots of repro diversity: Viviparity and parthenogenesis in some groups

Question 17

Describe phloem sap

Answer 17

Sugary sap flowing from leaves to roots
Positive pressure

Question 18

Describe xylem fluid

Answer 18

• Dilute, nutrient poor flow to leaves
• Negative pressure - leaf transpiration
  = Feeding insect must counteract the evapotranspirative pressure (difficult)

Question 19

Describe the Sternorrhyncha
(Psyllids, aphids, whiteflies, scale insects)

Answer 19

• Fine, hairlike stylets
• Parthenogenetic viviparity
• Reduced or lost ovipositor
• Phloem feeding
• Honeydew secretion

Question 20

Describe the Auchenorrhyncha
(cicadas, ceropids, membracids, flugoroids)

Answer 20

• Elaborate acoustic organs on legs
• Enlarged clypeus (forehead)
• Cibarial pump
• Xylem feeding

Question 21

Describe the synapomorphies of the Heteroptera

Answer 21

• Beak attached front of head
• Hemelytrous forewings
• Flat folded wings, overlap abdomen
• Scent glands on nymphs (anti-predator)
• Some predators