Insects Living With Ants! (Myrmeciphilous Insects)

Ants are social insects found in various habitats, with over 20,000 species. They live in colonies and construct complex nests. Ants undergo complete metamorphosis and have queens, males, and workers. Workers perform various tasks, and ants communicate using chemical signals. Some insects form associations with ants, called myrmecophilous insects, adapting to avoid predation. Myrmecophilous insects can be obligate or facultative. Mutualistic relationships exist between ants and insects like aphids and lycaenid butterfly larvae. Ants also associate with other ant species, displaying cooperative or parasitic behaviours. Habitat destruction affects myrmecophilous species, like Maculinea arion. Studying these associations is valuable in entomology.

if its chemical signal does not match the one that is characteristic of the colony.

Myrmecophilous Insects
Many insect species have managed to forge varying degrees of associations with ants thereby gaining protection. Such insects are known as myrmecophilous insects and include Lycaenid butterflies, aphids, termites, beetles and a number of other insects. Some docile species of ants are also known to be associated with more pugnaceous ones. It goes without saying that a myrmecophilous insect must necessarily be able to overcome the predatory instinct of the host ants. A very large number of insects have managed to do so.

Adaptations of Myrmecophilous insects
Myrmecophilous insects have evolved one or more of the following mechanisms to avoid predation by their hosts.
1. Myrmecophilous aphids and Lycaenid larvae have secretory organs that secrete honeydew. It is a liquid rich in sugars and amino acids and is relished by ants. 2. Some Lycaenid larvae possess perforated cupola organs like minute pits scattered over the epidermis that are supposed to secrete appeasement substances. 3. Many myrmecophilous insects produce chemical signals that modify behaviour of ants. In addition to above measures a large number of adaptations are found in different species. In a certain group of Lycaenid species the larvae have vibratory papillae that produce sounds that appear to attract * 23 Budhwar Peth, Pune 411002 10.54081/JES.014/03 JOURNAL OF ECOLOGICAL SOCIETY ants. Some butterfly larvae have evolved very thick skins which ensure protections from ants. The best Indian example of this type is the Moth Butterfly (Lyphira brassolis) from Sikkim whose carnivorous larva is a most unwelcome guest in the nests of the fierce Red Tree Ants. Its skin is very tough and also conceals head and legs. It retains this tough skin even after pupation unlike other butterflies and moths. The imago that emerges from the pupa is covered with easily detachable but adhesive scales. They keep the ants occupied while the butterfly escapes from the nest.

Obligative and faculative Myrmecophiles
Schonrogge and Thomas estimate that more than 10,000 species of insects worldwide are obligative social parasites of ants and a further 80,000 to 90,000 species form closely coupled mutualistic reactions with ants. Obligative myrmecophiles require presence of ants to complete their life cycle whereas facultative myrmecophiles can complete their life cycle without ants. In general facultative myrmecophiles tend to associate with a broad range of ant species while obligative myrmecophiles exhibit a high degree of specificity for ant species.

Relationship between myrmecophilous insects and their hosts
Honey-dew secreting Lycaenid larvae and aphids share a mutualistic relationship with ants. Ants are seen to actively solicit honeydew secretion by caressing the bodies of these insects by their antennae. This behaviour is aptly called as milking. In return ants protect these insects from enemies.

Myrmecophilous Lycaenids
Butterflies belonging to family Lycaenidae are small to medium in size. They are popularly known as Blues and Coppers, these being their predominant colours. Like all butterflies they have 4 stages in their life cycle viz. egg, larva or caterpillar, pupa or chrysalis and adult. The eggs hatch into larvae which feed and grow. They moult five times before pupation. The stage between two successive moults is known as an instar.
Members of several genera in this family have evolved associations with ants. Myrmecophilous Lycaenid larvae have a pair of mouthlike openings on the 11th segment of body for secreting honey-dew. Depending upon the species they enjoy varying degrees of protection from ants. Some caterpillars are only intermittently attended by ants, whereas obligative myrmecophiles receive their constant attendence. In fact adult females of obligative myrmecophilous Lycaenids lay their eggs only in the vicinity of ants. Ants may carry Lycaenid eggs or larvae to their nests where they complete their life cycle. Ants are also known to construct shelters for their wards. Once inside the ants nest the Lycaenid caterpillars receive regurgitated foof from ants and/or feed upon the brood of their hosts. Thus myrmecophilous Lycaenid larvae can be divided into following groups : 1. Phytophagous : They feed exclusively on their respective food plants. Ants protect them but do not have any major role in their feeding. 2. Phytopredaceous : The first two instars feed on plants after which they are transported by ants to their nests. The larval epidermal glands produce a chemical which mimics the pheromone of the ants brood. Hence ants treat these larvae as their own brood. In the safety of the nest, the caterpillars become predaceous and feed on the brood of host ants.

Myrmecophilous Aphids
Aphids are fairly common insects and at least a few species of them can be found in most localities. They have sucking mouth parts and feed on sap of plants. Many of them are pests of agriculture. Out of the 4,500 odd species of aphids nearly half are protected by ants in return for their honeydew. Lady Bird Beetles and wasps are among the chief enemies of aphids. Ants are known to fight off predators just as farmers protect their cattle. They also herd the aphids to different regions of the plant that will provide more sap. Some species of ants even build shelters for aphids. However, if ants find that some aphids are not producing adequate quantities of honeydew they may be carried to the colony as food.

Myrmecophious Termite
Though termites and ants belong to two different orders, they are similar in certain respects. Like ants termites are social insects living in colonies, each colony has a chemical signature and they have three castes viz. queens, males and workers.
Associations between termites and ants are well documented. They are mainly in the form of few ants living in a termite colony or few termites living in an ants nest. The former type is more common. It is likely that a few stray individuals enter the host colony and if they manage to stay long enough to achieve chemical harmonization they can continue to live there. However, it must be remembered that what is true of one colony is not necessarily reproducible in another colony of the same species.
In many cases the relationship is mutualistic and both species participate in day-to-day activities of the colony. However parasitic relationships are also found where the intruders only share the resources of the colony but contribute nothing.

Myrmecophilous Beetles
Several species of beetles have evolved myrmecophilous habits. They imitate the chemical profile of their host ants allowing integration into the host nest. Ants treat them as one of their own brood and feed them regurgitated food after tactile communication.

Ant-Ant Associations
When two species of ants have their nests close to each other and share the same foraging trails, they may form a close association where individuals of one species live in the colony of the other one. In such cases both species work together. Some species of ants are known as slave-maker ants. They steal brood from other colonies and house it in their own colony where it develops and serves as slave labour. In some ant-ant associations individuals of one species are completely dependent on the other. They contribute nothing to the hosts who tolerate and feed them.

The Case of Maculinea arion
Maculinea arion is an obligative myrmecophilous Lycaenid found in Britain and other parts of Europe. Researchers had noticed that its population in Britain was steadily declining for more than 150 years before it finally became extinct from Britain in 1979. Habitat destruction resulting in shortage of food plants was thought to be the main cause. However, researchers later discovered that what really sealed its fate in Britain was the fact that changes in agricultural practice had rendered the ranges of its foodplant Thyme and its ant host Myrmica sabuleti disjunct. This knowledge was eventually used for the planned reintroduction of Maculinea arion in Britain.
Apart from ants several other insects, especially termites, form associations with other insects. The study of such associations is a fascinating and useful branch of Entomology. q