week 7 - insect social structures

Question 1

social structures
solitary?

Answer 1

Most insects are entirely solitary in lifestyle

Question 2

social structures
solitary?
Exopterygote insects

Answer 2

In Exopterygote insects (Hemimetabola)- partial metamorphasis, only strongly social insects are the Order Blattodea (formerly Isoptera) - TERMITES

Question 3

social structures
solitary?
Endopterygote insects

Answer 3

In Endopterygote insects (Holometabola) - full metamorphosis), social insects are in the Order Hymenoptera – BEES, WASPS ANTS

Question 4

social structures
Order Blattodea – TERMITES

Answer 4

Very important pests in tropical regions
No species in the UK?
Only two species common in Europe

Highly social insects
Large colonies in mounds – TERMITARIUM
Up to 4-5m high (several million individuals)

Question 5

social structures
Order Blattodea – TERMITES
dawkins

Answer 5

They are a prime example of decentralised, self-organised systems using swarm intelligence and use this cooperation to exploit food sources and environments that could not be available to any single insect acting alone.
SELFISH GENES (argument that you dont have to pas on genes directly – INDIRECT)
Richard Dawkins (1976) The Selfish Gene

Question 6

social structures
Order Blattodea – TERMITES
termite castles

Answer 6

Colony consists of 4 main types:
Primary reproductives (eventually become King and Queen)
winged adults (♂ and ♀) (swarmers)
Roles: establish colony

Secondary
(supplementary reproductives if either primary dies)
wingless adults (♂ and ♀) or reduced wings

Workers
wingless and sterile
Roles: foraging, food storage, brood/nest maintenance

Soldiers
wingless and sterile
FUNCTIONAL MORPHOLOGY: mandibulate and nasute
Roles: defense

different morphology for all of them

Question 7

social structures
Order Blattodea – TERMITES
nasute

Answer 7

soliders
armoured head
chemicals out of head
large antenna

Question 8

social structures
Order Blattodea – TERMITES
mandibulate

Answer 8

soliders
very armoured head
bulldozer thing

Question 9

social structures
Order Blattodea – TERMITES
feeding

Answer 9

Two main feeding habits
Wood (rotten or sound), grass, fungi
Normal diet of workers

Prepared diet
stomodaeal – salivary secretion and regurgitated intestinal contents
proctodaeal – droplets from the rectal pouch taken from anus after tactile stimulation

PREPARED DIETS ARE SOLE DIET OF SOLDIERS

Question 10

social structures
biology of termites

Answer 10

New colonies founded by primary reproductives – leave in a swarm from an existing colony.

Fly short distance, shed wings, excavate small chamber, mate.
Reproduction – in year 1 primary Queen may produce 15-50 eggs. Mature queens produce several thousand eggs per day.

Reproductive forms live for ~50 years; strerile castes for 2-4 years, supplementary reproductives develop if primary Queen dies.

Question 11

social structures
ANTS – Familae Formicidae

Answer 11

All ants are social
Two female castes: Queen and workers
Workers can exist in different size classes
New queens and males have wings, lost after mating – male dies.
Complex genetics depending on species: workers may be sterile or egg laying, produce only males from unfertilised eggs.
Queen exerts strong influence over workers

Question 12

social structures
BEES – Family Apidae

Answer 12

Honey bees
New colony established when old one becomes too crowded.
Founder Queen departs with a swarm of workers.
Workers build nest cells from wax – malleable at nest temperature 35°C – produced from wax glands.
Cells in honey bee hive vary in size: small workers; larger drones
Later in life of nest, elongate cells are produced containing new queens.
Collected pollen and honey are stored separately in nest.
Honey bees feed exclusively on plant fluids, and larvae are fed on honey and pollen.
No animal prey = key difference with wasps.
Honey bees do not hibernate – reduce activity and feed on stored honey

Question 13

social structures
bumble bees

Answer 13

queen establsihes nest (spring)
colony developent
males produced

large colony in summer
new queens
leave colony
mate

queens store sperm
males die
queen survives winter in diapause (shallow burrow in soil)
(climate change is affecting this –> establishing colony in autumn because warmer even though day length changes–> can see evidence of this is field data)

Question 14

social structures
summary

Answer 14

Sociality bestows selective advantage over living as an individual (selfish gene theory)
Sociality has evolved more than once:
Exopterygotes: Termites
Endopterygotes: Antes, Bees, Wasps

Castes are another very good example of functional morphology

Some are so specialised cannot feed themselves

Great diversity in biology of colony including very specific behaviours for different castes.