It is a term used to define positive interactions between ants and other organisms like plants, fungi, or other insects.
Symbiosis may be defined as the close interactions between two or more different organisms, such that all the organisms in the association are benefited from each other. Such a relationship is called a symbiotic relationship and is demonstrated by a number of organisms.
Ants are one of the most common insects, and there are more than ten thousand species of ants present worldwide. These are ground dwelling, social insects that show several unique capabilities. They are usually found underground and sometimes under logs. They feed upon small insects, dead insects, nectar, or honeydew.
Aphids are sometimes called plant lice. There are more than four thousand known species of aphids. These are tiny little insects that are found on the stems and the underside of leaves; they are usually hard to detect. These insects cause maximum damage to plants and bore into their stem in order to feed on plant sap.
Relationship Between Aphids and Ants
The relationship between aphids and ants is said to be analogous to humans rearing cattle. In which both individuals derive some benefit from each other. Here, the aphids provide a source of nutrition to the ants, and the ants provide protection in return.
The excess sugar and amino acids is given off by the aphids as secretions from their alimentary canal in the form of honeydew. Ants can stimulate the production of honeydew by simply stroking the abdomen of the aphids with their antennae.
❖ Aphids are capable of reproducing through parthenogenesis. Parthenogenesis is a type of asexual reproduction in which an individual develops from an unfertilized egg.
The female aphid is capable of laying a large number of unfertilized eggs and a large number of wingless female aphids arise from it. Old and other aphids that do not produce enough honeydew are eaten by ants and form a source protein for ants.
This pheromone may be taken up by the ants, and they may attack the predator. In addition to this, they carry the eggs of aphids to their nest during winters, and provide a warm and moist environment that help to keep the eggs viable.
❖ Ants eat excess of honeydew that may be generated, and therefore, provide protection to the aphids from infestation by fungi.
❖ When predator larvae are placed near aphid colonies, ants protect the aphids by attacking the larvae. Another interesting fact about the aphid-ant relationship is that when lycaenid butterflies lay eggs near a colony of aphids tended by Myrmica ants, the ants carry the caterpillars to their nest.
These caterpillar are fed so that they too produce honeydew (yet another symbiotic relationship!) These caterpillars later morph into adult butterflies and leave the nest.
❖ Infestation by aphids may cause the crops to wilt, mottle, or die (due to the plant virus that they may carry or the toxin present in their saliva). In such cases, the ants carry the aphids to a new host plant and thus, help in preserving them.
Sometimes, ants clip the wings of the aphids so that they do not scatter easily. They may also produce certain chemicals that can prevent the proper development of wings in aphids.
❖ Despite this, the interaction between them seems to be favorable as the population of aphids increases with the increase in the number of ants. It is also seen that the content of trisaccharide, melezitose is increased in the honeydew produced by aphids that are tended by ants. This indicates that there is a positive interaction between the two organisms.
Aphids may be specific for their host plants, this may lead to the production of only a particular type of honeydew. As a result, only a few ants may tend to such aphids, giving rise to a highly specific symbiotic relationship.