2: Life histories & the rise of the holometabola

Question 1

Describe the Coleoptera

Answer 1

(beetles)
- 4 suborders, 166 families
- Extremely diverse
Synapomorphies:
- Elytra → hardened front wings to form a shield
- Large, hind wings specialised venation for ‘tucking’ and for powerful flight
- Reduced thorax
- Retracted genitalia

Question 2

Describe the function of the elytra in Coleoptera

Answer 2

• Access to hard habitats and spaces
• Wing protection
• Infection and predation protection
• Homeostasis (desiccation, cold)

Question 3

Describe the ecology of the Coleptera

Answer 3

Huge variation!
- Most herbivorous (roots, stems, leaves)
- Fungivorous
- Predacious
- Peculiar diets (e.g pure cellulose/lignin; dried grain)
- Parasitic - very uncommon
- Repeated evo of aquatic adaptations

Question 4

Describe the suborder Adephaga

Answer 4

Mostly predatory
Dominated by the family Carabidae (ground beetles) and aquatics
E.g Bombardier beetles
Anti-predator chemical weapon
Reservoir of hydrogen peroxide

Question 5

Describe the suborder Polyphaga

Answer 5

Form the bulk of the beetles
Overwhelmingly herbivorous → keys to success
E.g stag beetles, dung beetles

Question 6

Describe the Leopidoptera

Answer 6

Moths (and butterflies)
- Largest lineage of plant feeding organisms
- Structurally and ecologically homogenous
- ‘Recent’ (Cretaceous) radiation

Question 7

Describe the synapomorphies of the Lepidoptera

Answer 7

Median ocellus lost
Vom Rath’s organ
Fore tibial brush
Glossa
Wing setae modified to form scales

Question 8

Describe the suborder Glossata

Answer 8

• Largest group of Lepidoptera (90%)
  Synapomorphies
• Vestigial/absent madibles
• Coiled proboscis
• Larval prolegs

Question 9

Describe the Lepidopteran glossa/proboscis

Answer 9

• Uncoiling operated by hydralics (hemolymph)
• Powerful cibarial head pump (can suck half the insects body weight in a single feeding event!)

Question 10

Describe insect chemoreception

Answer 10

→ Most important sensory modality
→ Olfactory perception can be highly specific → good for species recognition

• Olfactory → gas phase
• Contact → liquid phase
• Sensilla, abundant on antennae, mouthparts, legs
• Variable sensitivity based on ligand-receptor interactions
• Axon leads to brain

Question 11

What does Volatile chemoreception (olfaction) allow?

Answer 11

long distance location of resources and mates

Question 12

Pheromone communicationis between…

Answer 12

within-species (intra)

Question 13

Alleochemical communication is between…

Answer 13

different species (interspecies)

Question 14

Describe Mechanoreception in insects

Answer 14

Any mechanical distortion of the body
Tough, vibration strain and stress
Huge range of sensitivity

Question 15

Describe Visual systems in insects

Answer 15

Ommatidia
Ocelli → a single lens but 2 / more rhabdomes
Stemmata → found mostly in lepidoptera larvae
Laterally on head

Question 16

Describe Thermal and hygroreceoption in insects

Answer 16

Water balance and temp obvs important
V little known about these receptors - no temp receptors identified
Hygro-receptors identified by ablation experiments, but not clear how they work