1. The Hymenoptera & Sociality
Topic 13

2. Exopterygota Endopterygota Entognatha Insecta Apterygota Pterygota
(Microcoryphia)
(Thysanura)
Apterygota
Pterygota
Palaeoptera
Neoptera
Exopterygota
(Neoptera)
Endopterygota
(Neoptera)

3. The Hymenoptera Ants, wasps, bees, and others
“hymeno” = membrane/married; “ptera” = wing
Third largest order after the Coleoptera + Diptera
>150,000 sp. WW
>18,000 sp. NA
Most mandibulate; some haustellate
Two pairs of linked wings
3 ocelli present; compound eyes
Often with complex social system

4. Hamuli
“hamus” (Latin) = hook; “hamulus” = diminutive form (little hook)

5. Schmidt Pain Index
In the 1980’s Justin Schmidt wanted to test the painfulness and duration of stings of different Hymenoptera. He tested 78 species. Index: measured on a 5-point scale, = insect cannot penetrate skin 4 = most painful

6. Venom LD50s LD50 = Family Species Common Name LD50 (mg/kg) Reference
Apidae
Apis mellifera
honey bee
2.8
Schmidt 1990
Mutillidae
Dasymutilla klugii
velvet ant 71
Schmidt et al. 1980
Vespidae
Polistes canadensis
paper wasp
2.4
Vespula squamosa
yellowjacket
3.5
Formicidae
Pogonomyrmex spp.
harvester ants
0.66
P. maricopa
harvester ant
0.12
Schmidt et al. 1989

7. 1. 0 Sweat bee: Light, ephemeral, almost fruity
1.0 Sweat bee: Light, ephemeral, almost fruity. A tiny spark has singed a single hair on your arm.
1.2 Fire ant: Sharp, sudden, mildly alarming. Like walking across a shag carpet & reaching for the light switch.
1.8 Bullhorn acacia ant: A rare, piercing, elevated sort of pain. Someone has fired a staple into your cheek.
2.0 Bald-faced hornet: Rich, hearty, slightly crunchy. Similar to getting your hand mashed in a revolving door.
2.0 Yellowjacket: Hot and smoky, almost irreverent. Imagine W. C. Fields extinguishing a cigar on your tongue.
2.x Honey bee and European hornet: Like a matchhead that flips off and burns on your skin.
3.0 Red harvester ant: Bold and unrelenting. Somebody is using a drill to excavate your ingrown toenail.
3.0 Paper wasp: Caustic & burning. Distinctly bitter aftertaste. Like spilling a beaker of hydrochloric acid on a paper cut.
4.0 Pepsis wasp: Blinding, fierce, shockingly electric. A running hair drier has been dropped into your bubble bath.
4.0+ Bullet ant: Pure, intense, brilliant pain. Like fire-walking over flaming charcoal with a 3-inch rusty nail in your heel.

8. Chris Starr pain index Rating Insects 1.0 Southern fire ant
(Solenopsis xyloni)
2.0
Honeybee, Africanized bee, bumble-bee, yellow-jacket ("common wasp")
3.0
Velvet ant, paper wasp
4.0
Tarantula hawk (Pepsis wasp) 4+
Bullet ant (Paraponera clavata)
0 – no pain; 1 – pain so slight as to constitute no real deterrent; 2 – painful; 3 – sharply and seriously painful; 4 – traumatically painful

9. Who da man?
The “hormiga veinticuatro”

10. Hormiga veintriquatro

11. Evolution of Hymenoptera
Phytophagy is ancestral

12. Two major subgroups (used to be suborders)
“Symphyta” = sawflies, horntails, wood wasps
Have broad or unconstricted waist between thorax and abdomen
Eruciform larvae with prolegs, stemmata
Apocrita = wasps, bees, ants
Have obvious constriction between thorax and abdomen (called petiolate)
First abdominal segment is fused to thorax
Larvae legless, without prolegs, without ocelli

13. “Symphyta” is paraphyletic

14. The sawflies

15. Horntails

16. Sirex spp., the horntails

17. The Apocrita – bees, wasps, ants
The Apocrita have a greater degree of constriction between thorax and abdomen

18. The two types of Apocrita
Aculeates = the stinging Apocrita
Bees, many wasps, ants
Ovipositor modified as a sting
“Parasitica” = the parasitic Apocrita
Many wasps, including Ichneumonidae

19. Apocritan immatures - honeybee

20. Families usually collected
Symphyta – Tenthredinidae or other
Apidae
Bumblebees
Carpenter bees
Other
Halictidae (sweat bees)
Andrenidae (mason or mining bees)
Pompillidae (spider wasps/hakws)
Sphecidae (digger wasps)
Vespidae (yellow jackets, bald-faced hornets, etc.)
Mutillidae (velvet ants)
Formicidae (ants)
Ichneumonidae (ichneumon wasps)
Braconidae

21. Branched hairs in the bees

22. Wasps vs. bees
Wasps generally lack corbiculae, have unbranched setae over their body surface, and have a much more constricted thorax-abdomen division

23. Mouthparts
Bees tend to be haustellate (suck up fluids), while wasps are more mandibulate

24. To bee or not to be…
Most bees have a corbicula or “pollen basket” to gather pollen

25. Apidae - bumbles, carpenters, honeys

26. Apidae vs. Andrenidae

27. Halictidae – sweat bees
Halictids are often metallic and are attracted to perspiration

28. Vespidae & Sphecidae
Vespids and sphecids are common wasps; sphecids usually have a thin waist, but not always

29. Sphecidae – digger wasps/mud daubers
Sphecids have an obvious rounded lobe on the pronotum

30. Pompilidae – spider wasps
Spider wasps often have curly antennae and are iridescent; also have a transverse/slanted suture on the thorax

31. Spider wasp

32. Ichneumonidae

33. Mutillidae – velvet ants

34. Mimicry rings

35. Formicidae - ants
Ants are named for the secretion of formic acid, used for defense

37. Working collectively…

38. Polymorphism in ants

39. Ant “alates”

40. Eusociality

41. Eusociality Cooperative brood care, even of those unrelated
Overlapping generations within a colony
Division of labor (different castes)
Reproductives
Non-reproductives/workers (sterile caste)

43. Determination of caste

44. Sex determination in Hymenoptera
Females are diploid (2N) and develop from fertilized eggs
Males are haploid (1N) and develop from unfertilized eggs

45. Haplodiploidy to explain evolution of eusociality
Female offspring of a male will have 100% of his genes, but only 50% of their mother’s Sisters thus share 75% of their genes with each other Why does this matter if the sisters cannot reproduce? (only the queen or reproductives can reproduce) If sisters are helping each other in a colonial, eusocial system, they are ensuring that their collective genes are being passed on **note that many hymenopterans are eusocial but not haplodiploid

46. What about termites?
Termites are also eusocial, but do not have haplodiploidy! Sisters thus share only ~50% of their genes in common and 50% with either parent, so why are termites eusocial?

47. Hymies vs. Isoptera Hymenoptera Isoptera 0, 1, or >1 queen No kings
No real “soldier” caste
Queen can mate only once, or many times with multiple males
Haplodiploid system
Only 1 queen
1 king
Soldier caste
Queen mates monogamously with one king
No haplodiploid system
Males are diploid