CRAZY ANTS —

Impact and Management of Invasive Species

by Graham Churchwell

Location of Christmas Island

Identity and

Taxonomy

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

Origin

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

Habitat

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

Diet

http://www.youtube.com/watch?v=0Vyg8qs8S48

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

Arrival on Christmas Island

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?

Research

Studies

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

Impact on

Biodiversity

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

Supercolonies

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

Crab Migration Efforts

Introduction of the

Human Element

Impact of Venom on Human

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

Crazy Ant Aerial Management

Environmental Impact

Other Options?

If you can beat ‘em, join ‘em!

Questions about ?