1. SOCIALITY IN
INSECTS

2. Social Insects - Importance
One colony
- 306,000,000 workers
- 1,000,000 queens
- 45,000 interconnected nests
- 2.7 km2
Formica yessensis

3. Social Insects - Importance
Pollinators

4. Sociality
Eusociality
1. Division of labour with caste system
2. Cooperation in tending young
3. Overlap of generations
Subsociality

5. Subsocial Groups
1. Aggregations
- non reproductive
Pentatomid bugs

6. Subsocial Groups
1. Aggregations
- non reproductive
Monarch (Danaus) butterflies

7. Subsociality - parental care
Oviposition preferences - Corixidae
% on each
substrate
Wood
Plexiglas
Elodea
- Aiken ‘81

8. Subsociality - parental care
Male Abedus

9. Subsociality - parental care
a) Without nesting
- remove tending parent
Predation
Parasitism
Diseases

10. Subsociality - parental care
a) Without nesting
Membracidae (treehoppers - Homoptera)
Bugs - secrete honeydew
Attracts ants
Ants deter predators
Female bugs leave early

11. SO FAR:
Subsociality
Aggregations
Parental care
Without nesting
With nesting
Solitary nesting
Communal nesting

12. Parental Care - With Nesting
Nest - parents use or make some structure
- lay eggs
- provision young
Found in - Orthoptera
- Dermaptera
- Coleoptera
- Hymenoptera
Dermaptera
(earwigs)

13. Solitary Nesting in the Hymenoptera
- immoblize arthropod prey and provision young
1. Provision prey in its own burrow
2. Dig burrow after prey capture
3. Dig burrow before prey capture
4. Build a solitary structure
5. Build structures in aggregations

14. Subsociality in other Orders
Homoptera - aphids
Normal nymph
“Soldier” nymph

15. Subsociality in other Orders
Thysanoptera - thrips
Normal female
Soldier nymph

16. Quasi- and Semisociality
- subsocial - all females reproduce
Quasisocial
- communal nest
- members of same generation
- all assist in brood rearing
- all females can lay eggs
Semisocial
- communal nest
- members of same generation
- all assist in brood rearing
- only 1 female can lay eggs
- females are sisters
(not daughters of queen)

17. Quasi- and Semisociality
In Social Hymenoptera
-division of labour
-variability in fecundity
Fully reproductive
Reduced fecundity in groups halictine bees
Quasisocial
Some lay only male eggs (workers of Bombus)
Worker sterility
Super reproductive queen
Semisocial

18. Sociality among groups of Hymenoptera
solitary
subsocial
eusocial
Apinae
Megachilinae
Adreninae
Colletinae
Halictinae
Crabronidae
Sphecidae
Other vespoids
Formicidae
Scoliiidae
Eumeninae
Stenogastrinae
Polistinae
Vespinae
Chrysidoidea
Rest of Apocrita

19. Eusocial Hymenoptera

20. Eusocial Hymenoptera
Fertilized 2N Egg
(Female[worker])
Unfertilized N Egg
(Male[drone])

21. Eusocial Hymenoptera
Wasps
Founding queen
-builds nest
-produces and feeds first brood
Stops foraging
-becomes purely reproductive
Later in season
- produce more males and new queens

22. Eusocial Hymenoptera
Wasps
Jobs of workers
YOUNG
-distribution of protein-rich food to larvae
MIDDLE AGE
-distribution of carbohydrate-rich food to adults
OLD
-clean cells and dispose of dead larvae
-ventilation and air-conditioning of nest
-construction and repair of nest
-foraging - wood pulp, fluids, prey
-nest defence

23. Caste Differentiation in Bees

24. Caste Differentiation in Bees
Royal Jelly

25. Caste Differentiation in Bees
Royal Jelly
Hypopharyngeal glands

26. Caste Differentiation in Bees
Royal Jelly

27. Caste Differentiation in Bees
Royal Jelly
Protein
Carbohydrate
Lipid
N D J F A M J J A

28. Eusociality in Termites
Reproductive castes
Primary reproductives - King + Queen
Supplementary reproductives - Neotenics
Non-reproductive castes
Workers
Soldiers

29. Assumption:
Subsociality is a necessary precursor for (and primitive to) eusociality
Cryptocercus - a wood roach - Blattodea √
- symbionts in hind gut √
colonies - mated pair
+ 15  25 offspring
- transfer symbionts by eating exuviae √
- nymphs help in nest maintenance
Conclusion: These animals represent an evolutionary precursor to
Isoptera (termites)

30. Assumption:
Subsociality is a necessary precursor for (and primitive to) eusociality
BLATTODEA
Polyphagidae
(including Cryptocercus)
ISOPTERA
Other families
MANTODEA

31. Termitidae - Pathways for Caste Development
Large worker 5
Alate
Nymph 5
Large worker 4
Nymph 4
Small soldier
Large soldier
Large worker 3
Nymph 3
Small presoldier
Small worker 2
Large presoldier
Large worker 2
Nymph 2
Small worker 1
Large worker 1
Nymph 1
Small larvae (2nd)
Large larvae (2nd)
Larva (1st)
egg
King + Queen

32. Caste Development in Lower Termites
Hormonal Control of Castes
1. Remove King and Queen
2. Divide colony with membrane
1. Re-introduce King and Queen - into membrane
No change
Pseudergates develop into reproductives

33. Why should a female bee (adult) sacrifice her own reproduction for that of the colony ?

34. Kin Selection and Inclusive Fitness
Fitness comes from
Your own reproduction
Reproduction of relatives
Inclusive Fitness

35.   In Social Hymenoptera Males are haploid - N
Sperm contain 100% of paternal genes
Females are diploid - 2N
Eggs contain 50% of maternal genes 
Offspring (daughters/workers)
-have all of father’s genes
Full sisters share 3/4 of their genes
-have 1/2 of mother’s genes 
Workers are more related to each other than their mother