Pseudomyrmex ferruginea
Encyclopedia
The acacia ant is a species of ant
of the genus Pseudomyrmex
. These arboreal, wasp-like ants have a orange-brown body around 3 cm in length and very large eyes. The acacia ant is best known and named for living in symbiosis
with the Bull's-horn Acacia (Acacia cornigera
) throughout Central America
.
The ant and the acacia exemplifies a coevolution of a mutualistic system, as described by evolutionary ecologist
Daniel Janzen
.
, A. collinsii
, A. cornigera
, A. hindsii and A. sphaerocephalia). Its life cycle conforms to the claustral
pattern of ants in general.
chemicals, and like in the case of the bull's horn acacia by developing a mutualism with the Acacia ant.
The symbiotic relationship begins when a newly mated queen gets attracted by the odour from the tree and starts nesting inside the large hollow acacia thorns. The queen nibbles into the thorn to lay 15-20 eggs to produce the first generation of workers. As the colony grows, more of the bulbous thorns gets inhabited, and when the colony reaches some 400 individuals the ants start to act as gardeners.
As gardeners, the ants aggressively attack creatures of all sizes attracted by the acacia leaves, killing insects such as crickets
and stinging the heads of mammals such as goat
s. Even other plants such as epiphytic vines are repelled and as little as an unfamiliar odour can cause the ants to swarm toward the potential threat. Additionally, the ants scout the ground around the tree for seedlings and destroy any competitors they find. In compensation, special glands at the base of the tree's leaves produce a nectar rich in sugar and amino acids, and the tips of the leaves sprout Beltian bodies
, small nutritious packets of oils and proteins. However, not all is mutually beneficial: the ants relish the sweet honeydew produced by scale insect
s which suck the sap of the acacia and therefore protect them as well, effectively providing entry to diseases.
The development of myrmecophytism
("ant symbiosis") and spininess in African and New World acacia species was an adaptation to the presence of large faunas of effective browsing mammals. The ants' sting is very painful, causing a lasting burning and throbbing effect. The ants provide vital protection to the bull's-horn acacias day and night, and it has been shown that without the ants, Acacia cornigera suffer greater damage from attacking insects and tend to be overgrown by competing plant species.
occurs in warm weather any month of the year. If an acacia thorn has not been opened by a previous occupant, the queen gnaws a circular hole to enter the thorn cavity. She lays 15 to 20 eggs, rears her first brood while remaining secluded inside the thorn. The population of the colony then increases to 150 workers within seven months, to 300 three months later, to 1,100 in two years, and to over 4,000 in three years.
In young colonies workers leave the protective thorns to collect nectar and Beltian bodies, but only as long as necessary. At rare intervals they leave their thorns to occupy new ones. Males and virgin queens are produced during the second year. As the number of ants reach 50-100, workers start patrolling the open plant surface next to their home thorn, and as the population reaches 200-400 workers become more aggressive and attack other smaller nearby colonies, ward off phytophagous
insects that make landing attempts near the thorn more effectively.
In old colonies the queen is physogastric (i.e. a swollen, membranous abdomen), heavily attended by workers, and accompanied by hundreds of eggs and young larvae.
Fragments that protrude from the pouch are removed by a worker and redistributed. Regularly, workers force open the pouch to regurgitate
droplets of fluid into it. The nature of this fluid is uncertain. It is possible captured insects constitute a secondary source of nutrition to the larvae.
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
of the genus Pseudomyrmex
Pseudomyrmex
Pseudomyrmex is a genus of stinging, wasp-like ants in the family Formicidae . They are large eyed, slender ants with an arboreal habitat. They are found exclusively in the New World in tropical and subtropical regions...
. These arboreal, wasp-like ants have a orange-brown body around 3 cm in length and very large eyes. The acacia ant is best known and named for living in symbiosis
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
with the Bull's-horn Acacia (Acacia cornigera
Acacia cornigera
Acacia cornigera, commonly known as Bullhorn Acacia , is a swollen-thorn acacia native to Mexico and Central America. The common name of "bullhorn" refers to the enlarged, hollowed-out, swollen thorns that occur in pairs at the base of leaves, and resemble the horns of a steer...
) throughout Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
.
The ant and the acacia exemplifies a coevolution of a mutualistic system, as described by evolutionary ecologist
Evolutionary ecology
Evolutionary ecology lies at the intersection of ecology and evolutionary biology. It approaches the study of ecology in a way that explicitly considers the evolutionary histories of species and the interactions between them. Conversely, it can be seen as an approach to the study of evolution that...
Daniel Janzen
Daniel Janzen
Daniel Hunt Janzen is an evolutionary ecologist, naturalist, and conservationist and the son of a previous Director of the US Fish and Wildlife Service...
.
Description
P. ferruginea is an obligate plant ant that occupies at least five species of acacia (A. chiapensisAcacia chiapensis
Acacia chiapensis is a species of legume in the Fabaceae family.It is found only in Mexico.-References:* González-Espinosa, M. 1998. . Downloaded on 18 July 2007....
, A. collinsii
Acacia collinsii
Acacia collinsii is a species of flowering plant. It grows in secondary succession in seasonally dry ecosystems in southern Central America, where it exhibits a symbiotic relationship with several species of ant...
, A. cornigera
Acacia cornigera
Acacia cornigera, commonly known as Bullhorn Acacia , is a swollen-thorn acacia native to Mexico and Central America. The common name of "bullhorn" refers to the enlarged, hollowed-out, swollen thorns that occur in pairs at the base of leaves, and resemble the horns of a steer...
, A. hindsii and A. sphaerocephalia). Its life cycle conforms to the claustral
Cloister
A cloister is a rectangular open space surrounded by covered walks or open galleries, with open arcades on the inner side, running along the walls of buildings and forming a quadrangle or garth...
pattern of ants in general.
Symbiosis
To repel herbivorous animals, various acacias protect their succulent leaves with one of several methods, including vicious-looking spines, repellent, noxiousPoison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
chemicals, and like in the case of the bull's horn acacia by developing a mutualism with the Acacia ant.
The symbiotic relationship begins when a newly mated queen gets attracted by the odour from the tree and starts nesting inside the large hollow acacia thorns. The queen nibbles into the thorn to lay 15-20 eggs to produce the first generation of workers. As the colony grows, more of the bulbous thorns gets inhabited, and when the colony reaches some 400 individuals the ants start to act as gardeners.
As gardeners, the ants aggressively attack creatures of all sizes attracted by the acacia leaves, killing insects such as crickets
Cricket (insect)
Crickets, family Gryllidae , are insects somewhat related to grasshoppers, and more closely related to katydids or bush crickets . They have somewhat flattened bodies and long antennae. There are about 900 species of crickets...
and stinging the heads of mammals such as goat
Goat
The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s. Even other plants such as epiphytic vines are repelled and as little as an unfamiliar odour can cause the ants to swarm toward the potential threat. Additionally, the ants scout the ground around the tree for seedlings and destroy any competitors they find. In compensation, special glands at the base of the tree's leaves produce a nectar rich in sugar and amino acids, and the tips of the leaves sprout Beltian bodies
Beltian body
A Beltian body is a structure found on the leaves of some species of Acacia. Beltian bodies, named after Thomas Belt, are found on the tips of each leaflet and are rich in lipids and proteins and often red in colour. They are believed to have evolved in a symbiotic relationship with ants...
, small nutritious packets of oils and proteins. However, not all is mutually beneficial: the ants relish the sweet honeydew produced by scale insect
Scale insect
The scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale insects.-Ecology:...
s which suck the sap of the acacia and therefore protect them as well, effectively providing entry to diseases.
The development of myrmecophytism
Myrmecophyte
Myrmecophyte is a plant that lives in a mutualistic association with a colony of ants. There are over 100 different genera of myrmecophytes. These plants possess structural adaptations that provide ants with food and/or shelter. These specialized structures include domatia, food bodies, and...
("ant symbiosis") and spininess in African and New World acacia species was an adaptation to the presence of large faunas of effective browsing mammals. The ants' sting is very painful, causing a lasting burning and throbbing effect. The ants provide vital protection to the bull's-horn acacias day and night, and it has been shown that without the ants, Acacia cornigera suffer greater damage from attacking insects and tend to be overgrown by competing plant species.
Life cycle
Nuptial flightNuptial flight
Nuptial flight is an important phase in the reproduction of most ant, termite and some bee species. During the flight, virgin queens mate with males and then land to start a new colony, or, in the case of honey bees, continue the planned succession of an existing hived colony.- Before the flight :A...
occurs in warm weather any month of the year. If an acacia thorn has not been opened by a previous occupant, the queen gnaws a circular hole to enter the thorn cavity. She lays 15 to 20 eggs, rears her first brood while remaining secluded inside the thorn. The population of the colony then increases to 150 workers within seven months, to 300 three months later, to 1,100 in two years, and to over 4,000 in three years.
In young colonies workers leave the protective thorns to collect nectar and Beltian bodies, but only as long as necessary. At rare intervals they leave their thorns to occupy new ones. Males and virgin queens are produced during the second year. As the number of ants reach 50-100, workers start patrolling the open plant surface next to their home thorn, and as the population reaches 200-400 workers become more aggressive and attack other smaller nearby colonies, ward off phytophagous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
insects that make landing attempts near the thorn more effectively.
In old colonies the queen is physogastric (i.e. a swollen, membranous abdomen), heavily attended by workers, and accompanied by hundreds of eggs and young larvae.
Larvae
The larvae are fed on unaltered fragments of Beltian bodies that are pushed deep into the larva's food pouch (the trophothylax, a pocket just behind the mouth). The larva then starts to rotate its head in and out of the pouch to chew the contents, while ejecting droplets of clear fluid possibly containing digestive enzyme into the pouch.Fragments that protrude from the pouch are removed by a worker and redistributed. Regularly, workers force open the pouch to regurgitate
Regurgitation (digestion)
Regurgitation is the expulsion of material from the mouth, pharynx, or esophagus, usually characterized by the presence of undigested food or blood.Regurgitation is used by a number of species to feed their young...
droplets of fluid into it. The nature of this fluid is uncertain. It is possible captured insects constitute a secondary source of nutrition to the larvae.
See also
- List of symbiotic relationships
- Acacia collinsiiAcacia collinsiiAcacia collinsii is a species of flowering plant. It grows in secondary succession in seasonally dry ecosystems in southern Central America, where it exhibits a symbiotic relationship with several species of ant...
- Myrmelachista schumanniMyrmelachista schumanniMyrmelachista schumanni, also known as the lemon ant, is a species of ant that is notable for the creation of Devil's garden. Using its own herbicide, it is able to shape its surroundings....
- MyrmecodiaMyrmecodiaMyrmecodia is a genus of epiphytic myrmecophytes native to Southeast Asia and large islands extending south to Queensland in Australia. Myrmecodia plants grow in tree branches and on trunks. In nature, Myrmecodia tubers often grow hanging downward on bare branches without significant amounts of...