Weaver ant 1742892 224717406 2008-07-10T02:45:46Z Tuancao1 7007569 I'm unsure of the species. {{Taxobox | name = '''''Oecophylla''''' | image = O.smaragdina3.jpg | image_width = 250px | image_caption = Weaver ant (''Oecophylla smaragdina'') major worker ([[Viet Nam]]). | regnum = [[Animal]]ia | phylum = [[Arthropod]]a | classis = [[Insect]]a | ordo = [[Hymenoptera]] | familia = [[Ant|Formicidae]] | subfamilia = [[Formicinae]] | tribus = '''Oecophyllini''' | tribus_authority = | genus = '''''Oecophylla''''' | genus_authority = Smith, 1860 | diversity_link = Weaver ant | diversity = 2 species | subdivision_ranks = [[Species]] | subdivision = ''[[Oecophylla longinoda]]'' <br/> ''[[Oecophylla smaragdina]]'' <br/> }} '''Weaver ants''' or '''Green ants''' ([[genus]] ''Oecophylla'') are [[eusocial]] [[insects]] of the family [[Formicidae]] (order [[Hymenoptera]]). Weaver ants are obligately [[arboreal]] and are known for their unique nest building behaviour where workers construct nests by weaving together leaves using larval [[silk]].<ref> Hölldober, B. & Wilson, E.O. 1990. ''The ants''. Cambridge, Massachusetts: Harvard University Press.</ref> Colonies can be extremely large consisting of more than a hundred nests spanning numerous trees and contain more than half a million workers. Like many other ant species, weaver ants prey on small insects and supplement their diet with carbohydrate-rich [[honeydew]] excreted by small insects ([[Hemiptera]]). ''Oecophylla'' workers exhibit a clear [[bimodal]] size distribution, with almost no overlap between the size of the minor and major workers.<ref> Hölldober, B. & Wilson, E.O. 1990. ''The ants''. Cambridge, Massachusetts: Harvard University Press.</ref> The major workers are approximately eight to ten millimeters in length and the minors approximately half the length of the majors. There is a division of labour associated with the size difference between workers. Major workers forage, defend, maintain and expand the colony whereas minor workers tend to stay within the nests where they care for the [[brood]] and 'milk' [[scale insects]] in or close to the nests. ''Oecophylla'' weaver ants vary in color from reddish to yellowish brown dependent on the species. ''Oecophylla smaragdina'' found in Australia often have bright green [[gaster]]s. These ants are highly territorial and workers aggressively defend their territories against intruders. Because of their aggressive behaviour, weaver ants are sometime used by indigenous farmers, particularly in southeast Asia, as natural biocontrol agents against agricultural pests. Although ''Oecophylla'' weaver ants lack a functional sting they can inflict painful bites and often spray [[formic acid]]<ref>J. W. S. BRADSHAW, R. BAKER, P. E. HOWSE (1979) Chemical composition of the poison apparatus secretions of the African weaver ant, Oecophylla longinoda, and their role in behaviour Physiological Entomology 4 (1) , 39–46 doi:10.1111/j.1365-3032.1979.tb00175.x</ref><ref>N. Peerzada, T. Pakkiyaretnam and S. Renaudc. Volatile Constitutents of the Green Ant Oecophylla smaragdina. Agric. Biol. Chem., 54 (12), 3335-3336, 1990 [http://www.journalarchive.jst.go.jp/jnlpdf.php?cdjournal=bbb1961&cdvol=54&noissue=12&startpage=3335&lang=en&from=jnlabstract]</ref> directly at the bite wound resulting in intense discomfort. ==Taxonomy== [[Image:SSL12022p.jpg|thumb|300px|left|Liquid food exchange ([[trophallaxis]]) in ''[[Oecophylla smaragdina|O. smaragdina]]''.]] The weaver ants belong to the ant genus ''Oecophylla'' (subfamily Formicinae) which contains two closely related living species: ''O. longinoda'' found in [[Sub-Saharan Africa]] and ''O. smaragdina'' found in southern [[India]], southeast [[Asia]], and [[Australia]].<ref> Tree of Life Web Project. 2004. Oecophylla. [http://tolweb.org/Oecophylla/22308]</ref><ref> Ant Web. 2008. Search Oecophylla. [http://www.antweb.org]</ref> They are provisionally placed in a [[tribe (biology)|tribe]] of their own, '''Oecophyllini'''. The weaver ant genus ''Oecophylla'' is relatively old, and 11 fossil species have been found from the Oligocene and Miocene deposits.<ref> Azuma, N., Kikuchi, T., Ogata, K. & Higashi, S. 2002. Molecular phylogeny among local populations of weaver ant ''Oecophylla smaragdina''. Zoological Science 19:1321-1328.</ref> ''[[Polyrhachis]]'' and ''[[Dendromyrmex]]'' are two other genera of weaving ants that also use larval silk in nest construction, but the construction and architecture of their nests are simpler than those of ''Oecophylla''.<ref> Hölldober, B. & Wilson, E.O. 1990. ''The ants''. Cambridge, Massachusetts: Harvard University Press.</ref> In Australia, ''Oecophylla smaragdina'' is found in the tropical coastal areas as far south as Rockhampton and across the coastal tropics of the Northern Territory down to Broome in West Australia. The common features of the genus include an elongated first funicular segment, presence of propodeal lobes, helcium at midheight of abdominal segment 3 and gaster capable of reflexion over the mesosoma. Males have [[vestigial]] pretarsal claws.<ref> Bolton, B. 2003. Synopsis and Classification of Formicidae. 370 pp. Memoirs of the American Entomological Institute, Vol. 71. Gainesville, FL.</ref> ==Colony ontogeny and social organization== [[Image:OecophyllaQueen.jpg|thumb|left|A [[dealate]] [[Queen (insect)|queen]] of ''[[Oecophylla smaragdina|O. smaragdina]]'' having shed her wings after a mating flight]] [[Image:SSL12037p.jpg|thumb|right|''[[Oecophylla smaragdina|O. smaragdina]]'' major workers inspecting and cleaning ([[social grooming|allogrooming]]) another worker on its return to the nest, Thailand]] [[Image:SSL12023p.jpg|thumb|120px|right|Social carrying in ''[[Oecophylla smaragdina|O. smaragdina]]''. A major worker transports a minor worker.]] Weaver ant colonies are founded by one or more mated females ([[Queen (insect)|queens]]).<ref>RK Peng, K Christian, K Gibb (1998) How many queens are there in mature colonies of the green ant, Oecophylla smaragdina (Fabricius)? Australian Journal of Entomology 37 (3) , 249–253 doi:10.1111/j.1440-6055.1998.tb01579.x </ref> A queen lays her first clutch of [[egg (biology)|eggs]] on a leaf and protects and feeds the larvae until they develop into mature workers. The workers then construct leaf nests and help rear new brood laid by the queen. As the number of workers increases, more nests are constructed and colony productivity and growth increase significantly. Workers perform tasks that are essential to colony survival, including foraging, nest construction, and colony defense. Because the tasks performed by workers are spatially and temporarily isolated, the integration and coordination of worker activities are important in colony organization. The emergence of an organized, complex social colony results from nonrandom repeated interactions between individuals that follow simple behavioral rules.<ref> Anderson, C. & McShea, D.W. 2001. Individual versus social complexity, with particular reference to ant colonies. Biol. Rev. 76:211-237.</ref><ref> Detrain, C. & Deneubourg J. 2006. Self-organized structures in superorganisms: do ants "behave" like molecules? Physics of Life Reviews 3:162-187.</ref> The exchange of information and modulation of worker behaviour that occur during worker-worker interactions are facilitated by the use of chemical and tactile communication signals. These signals are used primarily in the contexts of foraging and colony defense. Successful foragers lay down pheromone trails that help recruit other workers to new food sources. Pheromone trails are also used by patrollers to recruit workers against territorial intruders. Along with chemical signals, workers also use tactile communication signals such as attenation and body shaking to stimulate activity in signal recipients. Multimodal communication in ''Oecophylla'' weaver ants importantly contribute to colony [[self-organization]].<ref> Hölldobler, B. 1999. Multimodal signals in ant communication. J Comp Physiol A 184:129-141.</ref><ref> Hölldobler, B. 1983. Territorial behavior in the green tree ant (''Oecophylla smaragdina''). Biotropica 15:241-250.</ref> Like many other ant species, ''Oecophylla'' workers exhibit social carrying behavior as part of the recruitment process, in which one worker will carry another worker in its mandibles and transport it to a location requiring attention. ==Nest building behaviour== [[Image:SSL11903p.jpg|thumb|left|Nest construction by ''[[Oecophylla smaragdina|O. smaragdina]]'' major workers, Thailand]] [[Image:AntsStitchingLeave.jpg|thumb|Weaver ants collaborating to pull nest leaves together.]] Oecophylla weaver ants are known for their remarkable cooperative behaviour used in nest construction. Possibly the first description of weaver ant's nest building behaviour was made by the English naturalist [[Joseph Banks]], who took part in [[Captain James Cook]]'s voyage to [[Australia]] in 1768. An excerpt from Joseph Banks' ''Journal'' (cited in Hölldobler and Wilson 1990) is included below: <blockquote> The ants...one green as a leaf, and living upon trees, where it built a nest, in size between that of a man's head and his fist, by bending the leaves together, and glueing them with whitish paperish substances which held them firmly together. In doing this their management was most curious: they bend down four leaves broader than a man's hand, and place them in such a direction as they choose. This requires a much larger force than these animals seem capable of; many thousands indeed are employed in the joint work. I have seen as many as could stand by one another, holding down such a leaf, each drawing down with all his might, while others within were employed to fasten the glue. How they had bent it down I had not the opportunity of seeing, but it was held down by main strength, I easily proved by disturbing a part of them, on which the leaf bursting from the rest, returned to its natural situation, and I had an opportunity of trying with my finger the strenth of these little animals must have used to get it down.<ref> Hölldober, B. & Wilson, E.O. 1990. ''The ants''. Cambridge, Massachusetts: Harvard University Press.</ref> </blockquote> The weaver ant's ability to build capacious nests from living leaves has undeniably contributed to their ecological success. The first phase in nest construction involves workers surveying potential nesting leaves by pulling on the edges with their mandibles. When a few ants have successfully bend a leaf onto itself or draw its edge toward another, other workers nearby join the effort. The [[probability]] of a worker joining the concerted effort is dependent on the size of the group, with workers showing a higher probability of joining when group size is large.<ref> Deneubourg, J.L., Lioni, A. & Detrain, C. 2002. Dynamics of aggregation and emergence of cooperation. Biological Bulletin 202:262-267.</ref> When the span between two leaves is beyond the reach of a single ant, workers form chains with their bodies by grasping one another's [[petiole]] (waist). Multiple intricate chains working in unison are often used to ratchet together large leaves during nest construction. Once the edges of the leaves are drawn together, other workers retrieve [[larva]]e from existing nests using their mandibles. These workers hold and manipulate the [[larva]]e in such a way that causes them to excrete [[silk]]. The workers then maneuver between the leaves in a highly coordinated fashion to bind them together.<ref> Hölldober, B. & Wilson, E.O. 1990. ''The ants''. Cambridge, Massachusetts: Harvard University Press.</ref> Weaver ant's nests are usually [[elliptical]] in shape and range in size from a single small leaf folded and bound onto itself to large nests consisting of many leaves and measure over half a meter in length. The time required to construct a nest varies depending on leaf type and eventual size, but often a large nest can be built in significantly less than 24 hours. Although weaver ant's nests are strong and impermeable to water, new nests are continually being built by workers in large colonies to replace old dying nests and those damaged by storms. ==Use as natural biocontrol agents== Large colonies of ''Oecophylla'' weaver ants consume significant amounts of food, and workers continuously kill and retrieve all kinds of [[arthropods]] (primarily [[insects]]) to their nests. Insects are not only consumed by workers, but this [[protein]] source is necessary for brood development. Because weaver ant workers hunt and kill insects that are potentially harmful plant pests, trees harboring weaver ants benefit from having decreased levels of [[herbivory]]. Many studies have shown the efficacy of using weaver ants as natural [[biocontrol]] agents against agricultural pests.<ref>Van Mele, P. 2008. A historical review of research on the weaver ant ''Oecophylla'' in biological control. Agricultural and Forest Entomology 10:13-22.</ref> The use of weaver ants as biocontrol agents has especially been effective for fruit agriculture, particularly in [[Australia]] and [[southeast Asia]].<ref>Van Mele, P., Cuc, N.T.T. & Van Huis, A. Direct and indirect influences of the weaver ant ''Oecophylla smaragdina'' on citrus farmers' pest perceptions and management practices in the Mekong Delta, Vietnam. International Journal of Pest Management 48:225-232.</ref><ref>Peng, R. & Christian, K. 2007. The effect of the weaver ant, ''Oecophylla smaragdina'' (Hymenoptera: Formicidae), on the mango seed weevil, ''Sternochetus mangiferae'' (Coleoptera: Curculionidae), in mango orchards in the Northern Territory of Australia. International Journal of Pest Management 53:15-24.</ref> Fruit trees harboring weaver ants produce higher quality [[fruits]], show less leaf damage by [[herbivores]], and require fewer applications of synthetic [[pesticides]].<ref> Peng, R.K & Christian, K. 2008. The dimpling bug, ''Campylomma austrina'' Malipatil (Hemiptera : Miridae): the damage and its relationship with ants in mango orchards in the Northern Territory of Australia. International Journal of Pest Management 54:173-179.</ref><ref>Peng, R. & Christian, K. 2007. The effect of the weaver ant, ''Oecophylla smaragdina'' (Hymenoptera: Formicidae), on the mango seed weevil, ''Sternochetus mangiferae'' (Coleoptera: Curculionidae), in mango orchards in the Northern Territory of Australia. International Journal of Pest Management 53:15-24.</ref> Farmers in [[southeast Asia]] often build rope bridges between trees and [[orchards]] to actively recruit ants to unoccupied trees. Established colonies are often supplemented with food to promote faster growth and to deter emigration. ''Oecophylla'' colonies may not be entirely beneficial to the host plants. Studies indicate that the presence of ''Oecophylla'' colonies may also have negative effects on the performance of host plants by reducing fruit removal by mammals and birds and therefore reducing seed dispersal <ref>The Influence of Aggressive Ants on Fruit Removal in the Tropical Tree, Ficus capensis (Moraceae) Donald W. Thomas Biotropica, Vol. 20, No. 1 (Mar., 1988), pp. 49-53</ref> and by lowering the flower-visiting rate of flying insects including pollinators. <ref>Asian weaver ants, Oecophylla smaragdina, and their repelling of pollinators Kazuki TSUJI, Ahsol HASYIM, Harlion and Koji NAKAMURA Ecological Research (2004) 19: 669–673</ref> ==From ant intelligence to artificial intelligence== Weaver ants, like other ants, live in large colonies consisting of thousands of individuals. Each individual has limited cognitive capacity and reacts to its environment using simple behavioural rules, yet at the colony level, the individual decisions and actions [[self-organize]] into collective order and behaviour. Hundreds of ants can quickly find the shortest route from the nest to food, cooperatively carry large prey items, quickly respond to and attack intruders, and form intricate bridges to pull together large leaves during nest construction. The self-organizing properties and emergent behaviour of ants have inspired new approaches in scientific fields such as [[robotics]], [[engineering]], and [[computer science]]. Ant-based [[algorithms]] have been used to create [[robot]]s that demonstrate behavioural integration and collective problem solving,<ref>Ijspeert, A.J., Martinoli, A., Billard, A. & Gambardella, L.M. 2001. Collaboration through the exploitation of local interactions in autonomous collective robotics: the stick pulling experiment. Autonomous Robots 11:149-171.</ref> develop multi-agent simulation environments to solve complex mathematical problems such as the [[traveling salesman problem]], <ref>Huang, L., Zhou, C.G. & Wang K.P. 2003. Hybrid ant colony algorithm for traveling salesman problem. Progress in Natural Science 13:295-299.</ref> and to model and engineer solutions to [[complex systems]] such as [[internet protocol]] and [[telecommunication]] networks.<ref>Nahas, N., Nourelfath, M. & Ait-Kadi, D. 2007. Coupling ant colony and the degraded ceiling algorithm for the redundancy allocation problem of series-parallel systems. Reliability Engineering & System Safety 92:211-222.</ref> <gallery> Image:Oecophylla.jpg|Weaver ants ([[Oecophylla longinoda]]) collaborating in attacking a larger insect Image:WeaverAntsNest.JPG|Weaver ants nest Image:Weaverantnest05268.jpg|Weaver ants nest on a Mango tree Image:Weaver_ants.jpg|Weaver ants ([[Oecophylla smaragdina]]) foraging on lime sap, Rayong, Thailand Image:P0001166_Green_Ant_Picture.JPG|Green Tree Ant ([[Oecophylla smaragdina]]), North Queensland, Australia Image:O.smaragdina1.jpg|Weaver ants ([[Oecophylla smaragdina]]) capturing a caterpillar ([[Viet Nam]]) Image:O.smaragdina2.jpg|Weaver ant ([[Oecophylla smaragdina]]) major worker ([[Viet Nam]]) Image:O.smaragdina4.jpg|Weaver ants ([[Oecophylla smaragdina]]) on a leaf nest ([[Viet Nam]]) Image:O.smaragdina7.jpg|Weaver ants ([[Oecophylla smaragdina]]) ([[Viet Nam]]) Image:O.smaragdina6.jpg|Weaver ants ([[Oecophylla smaragdina]]) hunting a [[termite]] ([[Viet Nam]]) Image:Coreid bug (weaver ant mimic).jpg|A weaver ant [[mimic]]! It's really a [[coreid bug]]! ([[Viet Nam]]) Image:Myrmarachne plataleoides.jpg|Another weaver ant mimic! It's a [[jumping spider]]: [[Myrmarachne sp.]] ([[Viet Nam]]) </gallery> ==References== {{reflist}} ==Selected bibliography== * Azuma, N., Ogata, K., Kikuchi, T. & Higashi, S. 2006. Phylogeography of Asian weaver ants, ''Oecophylla smaragdina''. Ecological Research 21:126-136. * Bonabeau, E., Dorigo, M. & Theraulaz, G. 1999. ''Swarm Intelligence: From Natural to Artificial Systems''. NY, Oxford: Oxford University Press. * Chapuisat, M. & Keller, L. 2002. Division of labour influences the rate of ageing in weaver ant workers. Proc of the Royal Society B 269:909-913. * Federle, W., Baumgartner, W. & Hölldober, B. 2004. Biomechanics of ant adhesive pads: frictional forces are rate- and temperature-dependent. Journal of Experimental Biology 207:67-74. * Hölldober, B. & Wilson, E.O. 1977. Weaver ants. Scientific American 237:146. * Hölldober, B. & Wilson, E.O. 1977. Weaver ants - social establishment and maintenance of territory. Science 195:900-902. * Hölldober, B. & Wilson, E.O. 1990. ''The Ants''. Cambridge, Massachusetts: Harvard University Press. * Hölldober, B. & Wilson, E.O. 1994. ''Journey to the Ants''. Cambridge, Massachusetts: Harvard University Press. * Huang, H.T. & Yang, P. 1987. Ancient cultured citrus ant used as biological control agent. BioScience 37:665-671. * Kube, C.R. & Bonabeau, E. 2000. Cooperative transport by ants and robots. Robotics and Autonomous Systems 30:85-101. * Kube, C.R. & Zhang, H. 1993. Collective robotics: from social insects to robots. Adaptive Behavior 2:189-219. * Lioni, A., Sauwens, C., Theraulaz, G. & Deneubourg, J.L. 2001. Chain formation in ''Oecophylla longinoda''. Journal of Insect Behavior 14:679-696. * Peng, R.K., Christian, K. & Gibb, K. 1998. Locating queen ant nests in the green ant, ''Oecophylla smaragdina'' (Hymenoptera, Formicidae). Insectes Sociaux 45:477-480. * Sharkey, A.J.C. 2006. Robots, insects and swarm intelligence. Artificial Intelligence Review 26:255-268. * Van Mele, P., Cuc, N.T.T. & Van Huis, A. 2001, Farmer's knowledge, perceptions and practices in mago pest management in the Mekong Delta, Vietnam. International Journal of Pest Management 47:7-16. ==See also== *[[Ant]] *[[Social insects]] *[[Self-organization]] *[[Emergence]] *[[Ant colony optimization]] *[[Swarm intelligence]] *[[Artificial intelligence]] *[[E.O. Wilson]] *[[Bert Hölldobler]] ==External links== {{commons|Oecophylla}} * [http://www.antweb.org/description.do?name=oecophylla&project=worldants&rank=genus AntWeb - Ants of the world] * [http://tolweb.org/Oecophylla/22308 Tree Of Life - Oecophylla] * [http://www.myrmecos.net/formicinae/oecophylla.html Weaver ant photographs by Alex Wild] * [http://www.meethil.com/features/ants/weaverants1.htm Colonised for Life! - A peek into a colony of weaver ants] * [http://www.soe-townsville.org/greentreeants/index.html Green tree ants] * [http://www.eco-innovation.net/system/files/LEISA+weaver+ants.pdf A farmer and his ants] * [http://www.eowilson.org/ E.O. Wilson Biodiversity Foundation] [[Category:Formicinae]] [[de:Weberameisen]] [[eo:Tekso-formiko]] [[fr:Oecophylla]] [[ms:Kerengga]] [[no:Vevermaur]]