|
|
Weaver
Ants
Oecophylla smaragdina
Kerengga, Green Ant, Red Ants
Weaver
Ants eat any small creatures that they can find, but they are particularly
attracted to nectar. The weaver ants do not have a stinger, but inflict
a painful bite which is aggravated by irritating chemicals secreted
from their abdomen.
|
|
Mangrove
and wetland wildlife at
Sungei Buloh Nature Park
|
Main
features: Large
reddish ants with a fierce bite.
Status in Singapore: Common. |
 |
World distribution: Tropical
Old World from India to Taiwan, across Southeast Asia
to Australia.
Classification: Family Formicidae. |
|
|
Nest-building:
Weaver Ants' nests are among the most complex ants' nests. The
ants choose living leaves to build nests. These provide well camouflaged
protection from predators and the elements. To create their neat nest, chains
of worker ants form along the edge and pull the edges together by shortening
the chain by one ant at a time. Once the edges are in place, an ant holds
one of their larvae in its mandibles and gently squeezes it so the larvae
produces silk. The silk is used to glue the leaf edges together. The larvae
have special glands to produce lots of strong silk. The adults do not produce
silk.
A
colony may be dispersed over several nests which may be placed in various
locations in a tree, or even span several trees. The queen is located in
one nest and her eggs are distributed to the other nests.
The ability of simple-minded ants to co-ordinate on such complex tasks is
being studied for applications in robotics. If the ants' behaviour could
be better understood, simple cheap robots could be built that could achieve
complex tasks.
Role
in the habitat: Weaver Ants are exploited by plants and animals.
Some plants such as the Sea Hibiscus
(Hibiscus tiliceaus) secrete nectar in their leaves to attract these
ants, which in turn protect the plant from insect leaf eaters. The nasty
bite of the ants also discourages larger herbivores. Another plant that
does the same is the Great Morinda (Morinda
citrifolia). Weaver Ants' nests are often found in these two plants
at Sungei Buloh Nature Park.
Some other creatures also exploit the Weaver Ant's sweet tooth. Some caterpillars
of the Lycaenidae and Noctuidae butterfly families secrete a honey dew that
attracts these ants to protect them. Some of these caterpillars are more
sinister and use their bribe to gain entry into the ant's nest and devour
their larvae! Some jumping spiders look and more importantly, smell like
ants, and in their disguise, enter the ant's nest to devour them and their
larvae.
Status and threats: Weaver Ant eggs
(i.e., pupae) are harvested and sold in markets in Thailand and the Philippines.
The taste of the pupae has been described as creamy. The adults are also
eaten, their taste has been described as lemony or creamy and sour. The
Dayaks in Borneo mix adult ants with their rice for flavouring. Needless
to say, harvesting these fiercely biting ants requires good technique!
The ancient Chinese as early as in 300 AD, exploited the voracious appetite
of these ants by using them to control insect pests in their citrus orchards.
A Weaver Ants' nest is introduced into the orchard, and the ants encouraged
to colonise all the trees by placing bamboo strips among the trees as "ant
bridges". This practice is now being revived as a cheaper means of
growing fruit (which can then be sold as higher value organic fruit), and
dealing with insects that have developed resistance to chemical insecticides.
LINKS
- The
Social Hymenoptera (Insecta) of Lakekamu by Roy R. Snelling Natural
History Museum of Los Angeles County: habits, habitats.
- Birds
and other wildlife around Chiang Dao: details on how Weaver Ants
build their nest, caterpillars and spiders associated with them, and
how their eggs are eaten in Thailand.
- Myrmecology:
The Science about Ants: how Weaver Ants build their nest.
- Why
use weaver ants, Oecophylla spp, to manage the main insect pests in
cashew orchards? R.K. Peng, K. Christian and K. Gibb School of Biological,
Environmental and Chemical Sciences, Northern Territory University,
Darwin:
- Piotr
Naskrecki's photo album on The Orthopterists' Society webpage: with
large close-up photo of Weaver Ants building a nest.
- The
Food Insects Newsletter Volume VII, No. 2 JULY 1994: Ants Used as
Food and Medicine in China by Yi Chen (Charlie) Roger D. Alue Department
of Entomology Washington State University Pullman: about the use of
Weaver Ants as pest control.
- Insectes
Sociaux article by R.K. Peng, K. Christian, K. Gibb: about modern
uses for Weaver Ants as natural pest control in cashew orchards.
- Eat
the ants that bite you by Frank Cimatu from the Philippines Inquirer:
details about how ants and their larvae are harvested for food.
- Ancient
Cultured Citrus Ant Used as Biological Control Agent : details on
how the ancient Chinese use Weaver Ants as pest controllers.
- Collective
Robotics: From Social Insects to Robots by C. Ronald Kube and Hong
Zhang: developing robots by observing ant behaviour.
|