Ant mimicry or myrmecomorphy is mimicry of ants by other organisms; it has evolved over 70 times. Ants are abundant all over the world, and potential predators that rely on vision to identify their prey, such as birds and wasps, normally avoid them, because they are either unpalatable or aggressive. Some arthropods mimic ants to escape predation (Batesian mimicry), while some predators of ants, especially spiders, mimic them anatomically and behaviourally in aggressive mimicry. Ant mimicry has existed almost as long as ants themselves; the earliest ant mimics in the fossil record appear in the mid-Cretaceous alongside the earliest ants.
In myrmecophily, mimic and model live commensally together; in the case of ants, the mimic is an inquiline in the ants' nest. Such mimics may in addition be Batesian or aggressive mimics. To overcome ants' powerful defences, mimics may imitate ants chemically with ant-like pheromones, visually, or by imitating an ant's surface microstructure to defeat the ants' tactile inspections.
Batesian mimics lack strong defences of their own, and make use of their resemblance to a well-defended model, in this case ants, to avoid being attacked by their predators. A special case is where the predator is itself an ant, so that only two species are involved. [2] [3] The mimicry can be extremely close: for instance, Dipteran flies in the genus Syringogaster "strikingly" resemble Pseudomyrmex and are hard even for experts to distinguish "until they take flight". [4] Insects that do not share the narrow-waisted body plan of ants are sometimes elaborately camouflaged to improve their resemblance. For example, the thick waist of the Mirid ant bug Myrmecoris gracilis has white markings at the front of its abdomen and the back of its thorax, making it look ant-waisted. [1]
Over 300 spider species mimic the social behaviours, morphological features and predatory behaviour of ants. Many genera of jumping spiders (Salticidae) mimic ants. [5] Jumping spiders in the genus Myrmarachne are Batesian mimics which resemble the morphological and behavioural properties of ants to near perfection. These spiders mimic the behavioural features of ants such as adopting their zig-zag locomotion pattern. [6] Further, they create an antennal illusion by waving their first or second pair of legs in the air. The slender bodies of these spiders make them more agile, allowing them to easily escape from predators. Studies on this genus have revealed that the major selection force is the avoidance of ants by predators such as spider wasps and other larger jumping spiders. [7] [8] [9] Ant mimicry has a cost, given the body plan of spiders: the body of spider myrmecomorphs is much narrower than non-mimics, reducing the number of eggs per eggsac, compared to non-mimetic spiders of similar size. They seem to compensate by laying more eggsacs over their lifetimes. [8] A study of three species of mantises suggested that they innately avoided ants as prey, and that this aversion extends to ant-mimicking jumping spiders. [10]
Batesian mimicry of ants appears to have evolved even in certain plants, as a visual anti-herbivory strategy. [11] Passiflora flowers of at least 22 species, such as P. incarnata , have dark dots and stripes on their flowers for this purpose. [12]
Some arthropods are myrmecophiles, mimicking ants by non-visual means, including touch, behaviour, and pheromones. Many groups of myrmecophiles have convergently evolved similar features. They are not necessarily visual mimics of ants. [13] The mimicry allows them to live unharmed within ant nests, some beetles even marching with the aggressive Eciton burchellii army ants. [14] The Jesuit priest Erich Wasmann, who discovered ant mimicry, listed 1,177 myrmecophiles in 1894; many more such species have been discovered since then. [14]
The cricket Myrmecophilus acervorum was one of the earliest myrmecophiles to be studied; its relationship with ants was first described by the Italian naturalist Paolo Savi in 1819. [15] [16] It has many ant species as hosts, and occurs in large and small morphs suited to large hosts like Formica and Myrmica , and the small workers of species such as Lasius . On first arriving in an ants' nest, the crickets are attacked by the workers, and are killed if they do not run fast enough. Within a few days, however, they adjust their movements to match those of their hosts, and are then tolerated. Mimicry appears to be achieved by a combination of social releasers (signals), whether by imitating the ants' solicitation (begging) signals with suitable behaviour or ant pheromones with suitable chemicals; Hölldobler and Wilson propose that Wasmannian mimicry, where the mimic lives alongside the model, be redefined to permit any such combination, making it essentially a synonym for myrmecophily. [16]
Mites are among the most speciose mimics of ants, and can occur in large numbers in an ant colony. A single colony of Eciton burchellii army ants may contain some 20,000 inquiline mites. [14] The phoretic mite Planodiscus (Uropodidae) attaches itself to the tibia of its host ant, Eciton hamatum . The cuticular sculpturing of the mite's body as seen under the electron microscope strongly resembles the sculpturing of the ant's leg, as do the arrangements and number of the bristles (setae). Presumably, the effect is that when the ant grooms its leg, the tactile sensation is as it would be in mite-free grooming. [16]
The snail Allopeas myrmekophilos lives in colonies of the army ant Leptogenys distinguenda . The snails live in bivouacs of the ants except when the colony migrates, during which the ants carry along the snails. A. myrmekophilos feeds on the meat of animals killed by the ants. [17]
Some 75% of lycaenid butterfly species are myrmecophiles, their larvae and pupae living as social parasites in ant nests. [18] [19] [20] [21] These lycaenids mimic the brood pheromone and the alarm call of ants so they can integrate themselves into the nest. In Aloeides dentatis the tubercles release the mimicking pheromone which deceives its host, the ant Acantholepis caprensis, into caring for the mimics as they would their own brood. In these relationships, worker ants give the same preference to the lycaenids as they do to their own brood, demonstrating that chemical signals produced by the mimic are indistinguishable to the ant. Larvae of the mountain Alcon blue, Phengaris rebeli , similarly mimic Myrmica ants and feed on their brood. [21]
The parasitoid wasp Gelis agilis (Ichneumonidae) shares many similarities with the ant Lasius niger . G. agilis is a wingless wasp which exhibits multi-trait mimicry of garden ants, imitating the ant's morphology, behaviour, and surface chemicals that serve as pheromones, cuticular hydrocarbons. [22] [23] When threatened it releases a toxic chemical similar to the ant's alarm pheromone. This multi-trait mimicry serves to protect G. agilis both from ants and (in Batesian mimicry) from ground predators such as wolf spiders. [24] [22]
Aggressive mimics are predators which resemble ants sufficiently to be able to approach their prey successfully. Some spiders, such as the Zodariidae and those in the genus Myrmarachne, [3] use their disguise to hunt ants. These ant hunters often do not visually resemble ants very closely. [25] Among the many spiders which are aggressive mimics of ants, Aphantochilus rogersi mimics its sole prey, Cephalotini ants. Like many other ant-mimicking spiders, it is also a Batesian mimic, gaining protection from predators such as spider-hunting wasps. [26]
Multiple groups of insects have evolved ant mimicry for their young, while their adults are protected in different ways, either being camouflaged or have conspicuous warning coloration. [2] [27]
The young instars of some mantids, such as Odontomantis pulchra [28] and Tarachodes afzelii are Batesian mimics of ants. Bigger instars and adults of these mantids are not ant mimics, but are well-camouflaged predators, and in the case of Tarachodes, that eat ants. [29]
Young instars of some bush crickets in the genus Macroxiphus , have an "uncanny resemblance" to ants, extending to their black coloration, remarkably perfect antlike shape, and convincingly antlike behaviour. [2] Their long antennae are camouflaged to appear short, being black only at the base, and they are vibrated like ant antennae. Larger instars suddenly change into typical-looking katydids, and are entirely nocturnal, while the adult has bright warning coloration. [2]
The phasmid Extatosoma tiaratum , resembling dried thorny leaves as an adult, hatches from the egg as a replica of a Leptomyrmex ant, with a red head and black body. The long end is curled to make the body shape appear ant-like, and the movement is erratic, while the adults move differently, if at all. In some species the eggs resemble ant-dispersed (myrmecochoric) plant seeds, complete with a mimic oil body (a "capitulum"). These eggs are collected by the ants, deceived in a different way, and taken to their nests. The capitulum is removed and eaten, leaving the eggs viable. [27]
Ant mimicry has a wide taxonomic range, including some 2000 species of terrestrial arthropods in more than 200 genera. It has evolved over 70 times, including some 15 clades of spiders, 10 clades of plant-sucking bugs, and 7 clades of staphylinid rove beetles. Outside the arthropods, ant mimics include snails, snakes, and flowering plants. [14] [13]
In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. In the simplest case, as in Batesian mimicry, a mimic resembles a model, so as to deceive a dupe, all three being of different species. A Batesian mimic, such as a hoverfly, is harmless, while its model, such as a wasp, is harmful, and is avoided by the dupe, such as an insect-eating bird. Birds hunt by sight, so the mimicry in that case is visual, but in other cases mimicry may make use of any of the senses. Most types of mimicry, including Batesian, are deceptive, as the mimics are not harmful, but Müllerian mimicry, where different harmful species resemble each other, is honest, as when species of wasps and of bees all have genuinely aposematic warning coloration. More complex types may be bipolar, involving only two species, such as when the model and the dupe are the same; this occurs for example in aggressive mimicry, where a predator in wolf-in-sheep's-clothing style resembles its prey, allowing it to hunt undetected. Mimicry is not limited to animals; in Pouyannian mimicry, an orchid flower is the mimic, resembling a female bee, its model; the dupe is the male bee of the same species, which tries to copulate with the flower, enabling it to transfer pollen, so the mimicry is again bipolar. In automimicry, another bipolar system, model and mimic are the same, as when blue lycaenid butterflies have 'tails' or eyespots on their wings that mimic their own heads, misdirecting predator dupes to strike harmlessly. Many other types of mimicry exist.
Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both. It is named after the English naturalist Henry Walter Bates, who worked on butterflies in the rainforests of Brazil.
Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avoiding detection, warding off attack, fighting back, or escaping when caught.
Müllerian mimicry is a natural phenomenon in which two or more well-defended species, often foul-tasting and sharing common predators, have come to mimic each other's honest warning signals, to their mutual benefit. The benefit to Müllerian mimics is that predators only need one unpleasant encounter with one member of a set of Müllerian mimics, and thereafter avoid all similar coloration, whether or not it belongs to the same species as the initial encounter. It is named after the German naturalist Fritz Müller, who first proposed the concept in 1878, supporting his theory with the first mathematical model of frequency-dependent selection, one of the first such models anywhere in biology.
In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and mimicry. Crypsis can involve visual, olfactory or auditory concealment. When it is visual, the term cryptic coloration, effectively a synonym for animal camouflage, is sometimes used, but many different methods of camouflage are employed by animals or plants.
Myrmaplata plataleoides, also called the red weaver-ant mimicking jumper, is a jumping spider that mimics the Asian weaver ant in morphology and behaviour. This species is found in India, Sri Lanka, China and many parts of Southeast Asia.
Myrmecophily is the term applied to positive interspecies associations between ants and a variety of other organisms, such as plants, other arthropods, and fungi. Myrmecophily refers to mutualistic associations with ants, though in its more general use, the term may also refer to commensal or even parasitic interactions.
Aggressive mimicry is a form of mimicry in which predators, parasites, or parasitoids share similar signals, using a harmless model, allowing them to avoid being correctly identified by their prey or host. Zoologists have repeatedly compared this strategy to a wolf in sheep's clothing. In its broadest sense, aggressive mimicry could include various types of exploitation, as when an orchid exploits a male insect by mimicking a sexually receptive female, but will here be restricted to forms of exploitation involving feeding. For example, indigenous Australians who dress up as and imitate kangaroos when hunting would not be considered aggressive mimics, nor would a human angler, though they are undoubtedly practising self-decoration camouflage. Treated separately is molecular mimicry, which shares some similarity; for instance a virus may mimic the molecular properties of its host, allowing it access to its cells. An alternative term, Peckhamian mimicry, has been suggested, but it is seldom used.
Myrmecophagy is a feeding behavior defined by the consumption of termites or ants, particularly as pertaining to those animal species whose diets are largely or exclusively composed of said insect types. Literally, myrmecophagy means "ant-eating" rather than "termite eating". The two habits often overlap, as both of these eusocial insect types often live in large, densely populated nests requiring similar adaptations in the animal species that exploit them.
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The wasps do not constitute a clade, a complete natural group with a single ancestor, as bees and ants are deeply nested within the wasps, having evolved from wasp ancestors. Wasps that are members of the clade Aculeata can sting their prey.
Myrmarachne melanotarsa, the dark-footed ant-spider, is an African jumping spider found around Lake Victoria in Africa. Like other spiders in the genus Myrmarachne, these spiders mimic ants, in this case, ants of the genus Crematogaster. However, they are unusual in that they exhibit some form of social behavior, forming clusters of silk nests on fig and other trees. Hundreds of these spiders, of both sexes and of all ages, can be found in such communal nests, but most nests have between 10 and 50 spiders. The Crematogaster ants which they mimic are often found in the nests with the spiders, along with other species of jumping spider.
Chemical mimicry is a type of biological mimicry involving the use of chemicals to dupe an operator.
Insects have a wide variety of predators, including birds, reptiles, amphibians, mammals, carnivorous plants, and other arthropods. The great majority (80–99.99%) of individuals born do not survive to reproductive age, with perhaps 50% of this mortality rate attributed to predation. In order to deal with this ongoing escapist battle, insects have evolved a wide range of defense mechanisms. The only restraint on these adaptations is that their cost, in terms of time and energy, does not exceed the benefit that they provide to the organism. The further that a feature tips the balance towards beneficial, the more likely that selection will act upon the trait, passing it down to further generations. The opposite also holds true; defenses that are too costly will have a little chance of being passed down. Examples of defenses that have withstood the test of time include hiding, escape by flight or running, and firmly holding ground to fight as well as producing chemicals and social structures that help prevent predation.
In evolutionary biology, mimicry in plants is where a plant evolves to resemble another organism physically or chemically. Mimicry in plants has been studied far less than mimicry in animals. It may provide protection against herbivory, or may deceptively encourage mutualists, like pollinators, to provide a service without offering a reward in return.
Symphiles are insects or other organisms which live as welcome guests in the nest of a social insect by which they are fed and guarded. The relationship between the symphile and host may be symbiotic, inquiline or parasitic.
Locomotor mimicry is a subtype of Batesian mimicry in which animals avoid predation by mimicking the movements of another species phylogenetically separated. This can be in the form of mimicking a less desirable species or by mimicking the predator itself. Animals can show similarity in swimming, walking, or flying of their model animals.
Mallophora bomboides, also known as the Florida bee killer, is a predaceous species of robber fly of the family Asilidae that feeds primarily on bumblebees. M. bomboides is a noteworthy instance of Batesian mimicry given its close resemblance to its prey, the bumblebee. These bees are typically found in the Eastern and Southern regions of the United States like South Carolina and Florida.
In evolutionary biology, mimicry in vertebrates is mimicry by a vertebrate of some model, deceiving some other animal, the dupe. Mimicry differs from camouflage as it is meant to be seen, while animals use camouflage to remain hidden. Visual, olfactory, auditory, biochemical, and behavioral modalities of mimicry have been documented in vertebrates.
Chemical communication in insects is social signalling between insects of the same or different species, using chemicals. These chemicals may be volatile, to be detected at a distance by other insects' sense of smell, or non-volatile, to be detected on an insect's cuticle by other insects' sense of taste. Many of these chemicals are pheromones, acting like hormones outside the body.
Phrurolithus festivus is a spider in the family Phrurolithidae. It was originally distributed only in the Palaearctic and was introduced into Canada. The highly adaptable species inhabits a variety of both dry and wet habitats and can also be found in man-made habitats, but generally prefers open areas.
As noted by Papavero (1964), syringogastrids walking on leaves are strikingly similar to ants (especially Pseudomyrmex Lund) that often occur on the same leaf surfaces. They resemble ants in movement, size and shape (with the latter similarity enhanced by wing pigmentation), and can be difficult to distinguish from ants until they take flight.