A type of defensive behaviour in which an animal uses its body parts to block its nest entrance. In this, Phragmosis mainly invoved in insects are detailed

1. LI VI NG DOOR
Phragmosis
N.Mugundhan
Sr.M.Sc,
Agricultural Entomology
Id No: PALB 8139
Welcome
SEMINAR -1
Department of Entomology
UAS, GKVK
Bengaluru-65

2. Insect Defence

4. Amphibians
Enemies of Insects
Other arthropodsMammals
Birds
Great Humans

5. All insects are potential prey or host to many
kinds of Predators or Parasitoids”

6. “To make or keep safe from danger, attack or harm “
Sigmund Freud (1894)
SAFETY

7. CONTENT
Phragmosis
Examples of Phragmosis
Ecological Specialization - Ants
Colony stabilization - TermitesHead plug Defense - Aphids
Conclusion
Phragmotic and Trapping - Pachyteles

8. Phragmosis is any method by which an
animal defends itself in its burrow, by using
its own body as a barrier.
What is Phragmosis ?
W.M. Wheeler (1927)

9. Importance?
 Potential predators
 Adverse climatic factors
 To maintain constant conditions
inside the chamber
 Crypsis
 Moulting and metamorphosis

10. PACHYTELES
APHIDS
ANTS
TERMITES
PHRAGMOSIS
SPIDERS

11. Genus Cyclocosmia (Arachnida :
Araneae : Ctenizidae)
Habitat?

12. Phragmotic position

13. Phragmotic and Trapping organ
Discotelic Paussini – Carabidae
GIULIO, A. AND TAGLIANTI, V., 1970

14. Terminal Disk
Defensive
Plug -
Phragmosis
Sensorial
relational
organ
Predatory –
Stick/slow
the prey
Attractive
Secretion of
scent
substances
Cryptic
Concealment

15. Habitat
 Humid sandy banks of streams and
ditches with scattered low vegetation.
 Ecotone

16. Mainly with fruit flies , but also accepted
other insects (aphids, flies, termites, ants,
beetles and moths and their immatures
Methods
Species No of Larva Instar
Pachyteles vignai 20 I & II
P. digiulioi 15 II & III
Prey
GIULIO, A. AND TAGLIANTI, V., 1970

17. Hunting and
feeding
behaviours
GIULIO, A. AND TAGLIANTI, V., 1970

18. Selection of size of the prey
The diameter of the entrance is surely the definitive
filter limiting the maximum size of a prey
GIULIO, A. AND TAGLIANTI, V., 1970

19. Symphily
 True guests in ant colony
 Tended by the ants
 Produce secretion which
attracts ants

20. Head-plug defense in a gall aphid
Gall-forming aphid
Astegopteryx sp.
Benjamin tree- Styrax benzoides
KUROSU et.al., 2006

21. Soldier
Plug the
ostiole of the
subgall
Pierce
enemies like
moth larvae
Push garbage
out of the gall
Disturbed,
soldiers rush
out with
abdomen
upcurved
Entrance-
guarding and
rushing-out
tactics
One or few
ostioles
open,aphid
can go out

22. Experiment 1
• Whether soldiers
that had rushed
out of the subgall
could soon go
back into the
subgall
Experiment 2
• How guarding
soldiers would
behave toward
soldiers
Experiment 3
• Guarding
soldiers would
prevent sexuals
from invading
the subgall
KUROSU et.al., 2006

23. Head-plug defense
Total Galls 15
Total Ostioles 173
Completely Plugged 157 (90.8%)
 Wax-coated globules of honeydew
 Cast-off skins
 Shriveled sexuals
 Live males
 Live (but possibly aged) apterous adults
KUROSU et.al., 2006

24. Colony composition for 10 subgalls
Contained - 120–227 soldiers (mean 178.5)
KUROSU et.al., 2006

25. Experiment No of
Subgalls
examined
Soldiers
came out
Remained
outside
1 10 140 54 (38.6 %)
2 10 89 47 (52.8 % )
Case Numbers
Total Enounters b/w soldier and guarding soldier 75
Soldiers entered without being blocked by GS 22
Soldiers blocked by GS 53
Soldiers managed to enter subgall 20
Soldiers failed to enter 32
Moribunded 1
Interaction
between
outside and
inside soldiers
KUROSU et.al., 2006

26. Interaction
between
guarding
soldiers and
sexuals
 First-instar sexuals - 12 introduced onto a subgall
 Two males came to the ostiole
 Third male joined them.
Many sexuals - Intruding into subgalls guarded by soldiers
Field observations
Lab observations
KUROSU et.al., 2006

27. Interaction
between
guarding
soldiers and
other insects
 Four soldiers attacked the larva.
 After depositing them in alcohol
we confirmed, three soldiers
were piercing the larva with
their stylets.
KUROSU et.al., 2006

28. Why do soldiers
prevent
colonymates and
sexuals from
coming in?Select still
active,
reusable
soldiers.
Most (>95
%) sexuals -
Males.
Select strong
males for
sexual
females.
KUROSU et.al., 2006

29. Phragmosis acts in a stabilization
and as ecological specialization?

30. The morphological specialization seen within the
workforce of some insect societies is the most
striking example of this phenomenon.
Individual
specialization within a
larger group context is
of central importance
to the organization of
animal societies.
(Oster and Wilson, 1978)
Social Insects
Polymorphic worker in Solenopsis invicta
social insects with clear morphological
adaptations to different roles.

31. Advantage ?
Ecological specialization and the evolution of a
specialized caste in Cephalotes ants
POWELL, S., 2008

32. Morphological Specialization
No soldier (ancestral)
Simple domed head
Soldiers - Elaborate and complete head-disc
Cephalotes pusillus
Cephalotes depressus
Cephalotes atratus
Cephalotes persimilis
Incomplete head-disc (retains domed head)
Specialized use of
cavities with entrances
close to the area of one
ant head has driven the
evolution of a
morphologically and
behaviourally
specialized soldier in
Cephalotes ants.
POWELL, S., 2008

33. Ecological
specialization
Evolved use of a distinct subset of
available resource
Can be a powerful selective force
in phenotypic evolution and
diversification
It can drive associated increases
in functional (e.g. morphological)
and behavioural specialization
Could
evolutionary
shifts in ecology
explain soldier
evolution?
(Irschick et al., 2005)

34. FIELD SITE AND FOCAL SPECIES
Methods
Cerrado reserve of Clube Caçae Pesca Itororó, Ublerlândia, Brazil.4 – different
Character States
POWELL, S., 2008

35. NEST DEFENCE AND BEHAVIOURAL
SPECIALIZATION OF SOLDIERS
Azteca a nt s
 To elicit defensive response (Forceps – 45s)
 Attacks on the Azteca worker & number and caste of
individuals that blocked the nest entrance
 10 trails – 9 nest tested for each species
 Soldiers in foraging (3 species)
 Baits - 1 m (Caste of the ant that discovered the bait )

36. NESTING ECOLOGY
 Abandoned cavities of wood-boring insects
 Some cavities ( ≤ 5) Newly inhabited (Workers
removing frass from the original occupant)
 No evidence : Excavate the hard wood of the
cavities they occupied (Small plier like
mandibles)
POWELL, S., 2008

37. ECOLOGICAL SPECIALIZATION
(a) Outlier boxplots of nest entrance area
(b) Outlier boxplots of the standardized nest entrance
area (entrance area/max. head area)
POWELL, S., 2008

38. C. atratus C. pusillus C. depressus C. persimilis
Soldier morphology No soldier Domed head Incomplete head-
disc
Complete head-
disc
Defensive strategy Attack and block
(all trials)
Attack and block
(all trials)
Block only (all
trials)
Block only (all
trials)
Caste of blockers Workers only Soldiers and
workers
Soldiers and
workers
Soldiers only
Mean number of ants blocking small
entrances
(3 nests per species, 10 trials per nest)
2·0 (SD ± 0·0; Pred. = 1·0) 1·7 (SD ± 0·5; Pred. = 0·7) 1·0 (SD ± 0·0; Pred. = 0·6) 1·0 (SD ± 0·0; Pred. = 0·9)
2·4 (SD ± 0·5; Pred. = 1·3) 2·3 (SD ± 0·5; Pred. = 1·0) 1·0 (SD ± 0·0; Pred. = 0·8) 1·0 (SD ± 0·0; Pred. = 1·0)
2·5 (SD ± 0·5; Pred. = 1·4) 2·4 (SD ± 0·5; Pred. = 1·1) 1·0 (SD ± 0·0; Pred. = 0·6) 1·0 (SD ± 0·0; Pred. = 1·0)
Mean number of ants blocking mean
entrances
(3 nests per species, 10 trials per nest)
4·6 (SD ± 0·8; Pred. = 3·4) 3·8 (SD ± 0·8; Pred. = 2·4) 1·0 (SD ± 0·0; Pred. = 1·2) 1·1 (SD ± 0·3; Pred. = 1·3)
5·5 (SD ± 0·5; Pred. = 3·8) 3·9 (SD ± 1·0; Pred. = 2·6) 2·2 (SD ± 0·4; Pred. = 1·3) 1·3 (SD ± 0·5; Pred. = 1·3)
8·8 (SD ± 0·6; Pred. = 5·5) 4·2 (SD ± 0·8; Pred. = 2·6) 2·4 (SD ± 0·5; Pred. = 1·2) 1·3 (SD ± 0·5; Pred. = 1·3)
Mean number of ants blocking large
entrances
(3 nests per species, 10 trials per nest)
8·8 (SD ± 0·6; Pred. = 5·5) 6·6 (SD ± 0·9; Pred. = 5·6) 2·0 (SD ± 0·0; Pred. = 1·8) 3·2 (SD ± 0·4; Pred. = 2·1)
13·6 (SD ± 1·2; Pred. = 8·3) 8·2 (SD ± 1·3; Pred. = 6·8) 3·2 (SD ± 0·4; Pred. = 2·2) 3·4 (SD ± 0·5; Pred. = 2·2)
13·7 (SD ± 1·6; Pred. = 10·8) 7·5 (SD ± 0·9; Pred. = 6·3) 4·5 (SD ± 0·7; Pred. = 2·7) 3·3 (SD ± 0·5; Pred. = 2·0)
Soldiers discovering baits N/A 3/20 trials 0/20 trials 0/20 trials
Mean proportion of soldiers recruited
to baits
N/A 16·8% (SD ± 11·6) 3·0% (SD ± 4·4) 1·0% (SD ± 2·2)
POWELL, S., 2008

40. PHYLOGENETIC CONSIDERATIONS
AND ANALYSES
Ancestral character state reconstructions
of nesting ecology and nest defence
behaviours in the ant genus Cephalotes
using four terminal taxa
Numbers
Ancestral
node
Reconstructed mean and standard
deviation for standardized nest
entrance area
Terminal
taxon
Observed mean and standard
deviation for standardized nest
entrance area
Bar
(Reconstructed
point )
Dark grey
Loss of an attack strategy during
nest
Light grey
Loss of worker involvement in
nest entrance blocking
POWELL, S., 2008

41. Termite Soldiers
The colony is the adaptive unit, and selection for
colony defence can drive the morphology and
behaviour of soldiers to such extremes that they
can no longer feed themselves
(Hölldobler & Wilson 1990)
Termites plays – Essential role
At the cost of reproduction and self
maintnence.

42. Role of soldiers - Reticulitermes
Examined the relative effectiveness of soldier
defenses, and concluded that Reticulitermes
soldiers were incompetent compared with
Coptotermes soldiers.
Soldiers are so few and do not use their
cephalic sesquiterpenes against ants.
Waller and LaFage (1986)
(Zalkow et al.,1981)
Colony-level stabilization of soldier head
width for head-plug defense in
Reticulitermes speratus

43. The nests are divided into chambers
connected by small openings that allow
only one termite at a time to pass through.
Chamber-by-chamber nest defense
Deligne et al., (1981)

44. Soldier defense
Combination
of mandibular and
head-plug
(phragmotic) defenses
that were
complementary to the
structure of the nest.
MATSUURA, K., 2002

45. Soldier defense against ant predation
Brachyponera chinensis
MATSUURA, K., 2002

46. Phragmotic defense - Requires soldiers to have heads
wide enough to block the small openings between each
nest chamber.
Too narrow : Allow enemies to pass through
Too large : Would clog the openings
How
Stabilizing
selection is
acting upon?

47. Soldier head width was more stable than the size of other
body parts, they compared the coefficients of variation
(CVs) of head width and other body parts.
(Phragmotic defense requires a uniform head width)
How to determine Stabilization ?
Non-phragmotic soldiers
 Coptotermes formosanus Shiraki
 Nasutitermes takasagoensis Shiraki
 Rush out and assault intruders
Free from head-width stabilization
Phenotypic Variation

48. Size measurements and biometric analysis
1. Maximum head width (HW)
2. Head length (HL) - Base of the mandibles to the
posterior margin of the head
3. Head volume (HV) - (HW/2)2π x HL
4. Maximum Pronotum width (PW)

49. Head width
Almost unimodal pattern
Frequency distributions
Pronotum width & Head length
Bimodal patterns
MATSUURA, K., 2002

50. Comparison of CVs b/w HW and other body parts
Bars - CVs of pooled data of males and females.
Closed bars - Significant difference from HW
R. speratus soldiers
MATSUURA, K., 2002

51. C. formosanus N. takasagoensis
MATSUURA, K., 2002

52. Evidences for Phragmosis
 The small openings in a Reticulitermes nest were
of relatively uniform size in the colony.
 The mean diameter of small openings in colony C
was 1.23±0.03 (SD) mm (n=20).
 The CV of the diameter of small openings was
2.61, which was as small as the CV of soldier
head width in R. speratus.
MATSUURA, K., 2002

53. Termite genus Percenatge of
Soldiers
Mode of Defence
Reticulitermes 3.59±2.50 (n=108 ) Phragmosis
Coptotermes 40 Rush out and assault
intruders
Evidences for Phragmosis
MATSUURA, K., 2002

54. CONCLUSION
 Specialized defence traits can be the key
feature of adaptive evolution
 They play a crucial role in surviving
enemy attacks and in securing resources.
 Because it improves functional specialization (i.e.,
performance of a particular task) and ultimately
yielding the fitness gains to the colony
 Selection is thought to favour the
evolution of novel phenotypes.

55. T H A N K S