CrazyAntPresentation2014

CRAZY ANTS —
Impact and Management of Invasive Species
by Graham Churchwell

 Crazy Ants are yellow-brownish body color, and is weakly
sclerotized
 Can have darker striping
 Workers have a long slender gracile body, darker gasters,
head and thorax.
 Usually 5mm in length and has long legs, very long antennae
with a long slender body
 When disturbed, Crazy Ants exhibit an erratic walking style
and may spray formic acid.
 Taxonomic name is Anoplolepis gracilipes from the
Formicidae (sub-family: Formicinae)
Identity and Taxonomy

 Native range of the yellow crazy ant is unclear
 Research suggests it is native to either Africa or
Asia
 The Global Invasive Species Database (GISD2009)
lists the native range of the species as Brunei
Darussalam, Cambodia, China, India, Indonesia,
Malaysia, Myanmar (Burma), Philippines,
Singapore, Sri Lanka, Thailand and Vietnam.
Origin

 Ready invaders of disturbed habitats such as
urban areas, forest edges or agricultural
 Can live in human dwellings or human-
frequented areas
 Serious pest in many households and
buildings
 Present around the world including the
United States
Habitat

Diet
 Broad diet for brood production requiring proteinaceous
foods, those essential nitrogenous components of all organic
bodies
 In the Seychelles of the western Indian Ocean, they are
known to feed on invertebrates and, in culture, attack, kill,
and dismember large arthropods
 In the field, they capture ants of other species as well as a
wide range of other insects, isopods, myriapods, mollusks,
and arachnids
 In Hawaii, where Anoplolepis was introduced in the 1950s,
they are associated with decreased occurrence and density of
endemic spiders at elevations up to1000 m

 The first supercolony on Christmas Island was detected
in 1989
 Supercolonies really became widespread from about
1995 onwards
 At present, Crazy Ants infest more than 2000 ha of
rainforest on the island.
 The supercolonies can be huge; one has been mapped at
over 700 ha.
 The infestation on the island makes it a focal point for
the international control effort
They’re here . . .

 A species or organism that causes ecological
or economic harm in a new environment
where it is not native; precisely what the
Crazy Ant is inflicting upon Christmas
Island.
 Crazy Ants are widely regarded as
environmental pests and are included as one
of the world's 100 worst invasive species
What is an invasive specie?

Biologists studied the high-density of
supercolonies of the Yellow Crazy
Ant across Christmas Island
Purpose of Study

 Figure 1 Arrangement of transects perpendicular to
Anoplolepis gracilipes supercolony boundary, extending into
intact rainforest. The shaded region indicates the high-density
supercolony where A. gracilipes kills red land crabs. The
region extending outward to the right is the ‘transition zone’,
where ant activity decreases from > 50 ants per 30 s in the
supercolony to zero in intact rainforest. The larger asterisk is
the initial marker peg. The 2 × 6 m and 1 m2 observation
quadrats were centred on each 10-m interval point (X) where
A. gracilipes activity was recorded. As boundaries expanded
(toward the right in figure) I extended the transect to reflect
the change in boundary position.
Figure 1

Figure 2
 Figure 2 The extent of Anoplolepis gracilipes
supercolony formation on Christmas Island between
1996 and September 2002. Shaded areas indicate
densities of yellow crazy ants that will kill red crabs and
were defined as supercolonies. Supercolony boundaries
used in this study are numbered (1–13) and correspond
with Table 1.

Figure 3
 Figure 3 Range of supercolony areas (ha) on Christmas
Island. Supercolonies described here are those shaded in
Figure 2.

Ant population on forest floor and trees
before and after exclusion.

Before and After Graphs
 These graphs show the number in the trees before and
after the ant exclusion. The Barringtonia was
inconclusive as the biologist determined in the research.
 The other two trees however, were very evident. The
ants being absent played a huge role in their presence

 Land crabs play an
important role in
Christmas Island’s
forest ecosystem
helping in litter
breakdown and
influencing forest
composition by
eating leaves and
seedlings of
rainforest trees
Red Crabs of Christmas Island

Attack of
Crazy Ants
on an
Island Bird

Attack of
Crazy Ants
on other
natives

 It is estimated that since 1995,
Crazy Ants have killed 10-20
million red crabs, which is 20-
25% of the entire population of
Christmas Island
 This has been a catastrophic loss,
and the deletion of red crabs from
large tracts of forest on the island
is immediately obvious
Impact on Crab Population

 Crazy Ants have the ability to form multi-
queened "supercolonies", where rather than fight
each other; the offspring of different queens
cooperate to form infestations.
 There can be several thousand ants per square
meter of forest floor in these supercolonies, but at
any one time there are just as many ants foraging
in the treetops above.
We are family!

 Crazy Ants have the ability to overwhelm and kill the
red land crabs, robber crabs, endemic reptiles, and a host
of native invertebrates.
 There is also grave concern for the island's native birds -
Crazy Ants forage mostly in the canopies of large forest
trees, so nesting land and sea-birds are at risk.
Supercolony Impact

Introduction of the
Human Element

Eractic Behavior of Crazy Ant Attack

 With the Crazy Ant population somewhat under
control, Christmas Island residents must continue
to manage the ant population.
 Infestations are treated by spraying or baiting.
 Foraging ants collect the bait and carry it back to
the colony, sharing it with the queens.
 As the queens are the only ants able to reproduce,
the death of the queens ensures the colony is
destroyed.
Crazy Ant Management

If you can beat ‘em, join ‘em!

CrazyAntPresentation2014

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