Trail pheromones are semiochemicals secreted from the body of an individual to affect the behavior of another individual receiving it. Trail pheromones often serve as a multi purpose chemical secretion that leads members of its own species towards a food source, while representing a territorial mark in the form of an allomone to organisms outside of their species. [1] Specifically, trail pheromones are often incorporated with secretions of more than one exocrine gland to produce a higher degree of specificity. [2] Considered one of the primary chemical signaling methods in which many social insects depend on, trail pheromone deposition can be considered one of the main facets to explain the success of social insect communication today. Many species of ants, including those in the genus Crematogaster use trail pheromones.
In 1962, Harvard professor Edward O. Wilson published one of the first concrete studies constructing the groundwork for the notion of trail pheromones. [2] Claiming an odor trail is deposited by the sting apparatus of the hymenopteran Solenopsis saevissima which results in a pathway from the colony to a food source, this study encouraged further investigation of how this chemical is laid, how it affects communication between species within and outside of its own, the evolution of the semiochemical, etc.
The pheromone is synthesized in the same region as venom, or other primary hormonal departments within the organism. Often, trail pheromone synthesis occurs in the ventral venom gland, poison gland, Dufour's gland, sternal gland, or hindgut. [3] When secreted, the pheromone is dropped in a blotch-like fashion from the foraging organism onto the surface leading to the food source. As the organism proceeds to the food source, the trail pheromone creates a narrow and precise pathway between the food source and the nesting location, which another organism of the same species, and often the same nest, follows precisely. Commonly, an organism, when initially laying down the trail may renew the trail a number of times to demonstrate the value of the food source while running in tandem. [4] Once the trail is laid, other members of the species will recognize the chemical signal and follow the trail, and each individually renew the trail on the way back to the home source. While this pheromone is constantly deposited by its members, the chemicals diffuse up into the environment propagating its message. Once the food source runs out the organisms will simply skip the task of renewing the trail on the way back, thus resulting in the diffusion and weakening of the pheromone. [5] Studies have shown that with quality of food, distance from nest, and amounts of food, the strength of the trail pheromone may vary. [1] Often the foraging individual may synthesize the trail pheromone as a mixture of chemicals produced by different glands which allows such specificity. [3] While members of the same species who discovered the food constantly renew this trail pathway, as the chemical is secreted into the environment as a signal for food in their umwelt, the very same chemical can often be interpreted as a territorial mark for outside species.
Ants typically use trail pheromones to coordinate roles like nest defense and foraging. [6] Ants can produce a trail of defensive secretions that trigger an alarm response within their nestmates. [7] In regards to foraging, an ant can communicate the quality of a food source to its colony; the more rewarding a food source is, the higher the concentration of the trail produced. [8] Additionally, some species, like Lasius niger ants, can "eavesdrop" on the trails produced by another species in order to procure food.
Myrmicine ants produce their trail pheromones through their poison glands. [9] The major component in the trail pheromones secreted by Pristomyrex pungens is 6-n-pentyl-2-pyrone; several monoterpenes were also found in the secretion, but they provided only marginal effects when combined with the former. [10] The major components found in the secretions of Aphaenogaster rudis include anabaseine, anabasine, and 2,3'-bipyridyl, though the third contributes less than the other two. [9] When secreted, this trail pheromone does not recruit ants directly from their nest; instead, worker ants may stumble upon to the trail unintentionally and follow it thereafter to the food source.
Bees can use trail pheromones to mark food sources [11] and the entrance of their hives. [12] Oftentimes, when finding a source, bees will mark that exact location as well as secreting pheromones along the flight back to their hives. Employment of trail pheromones is extensively studied in honey bees and stingless bees, for both are highly social.
The trail pheromone of the stingless bee Trigona recursa is produced by its labial glands. [13] One of its key compounds is hexyl decanoate, and when secreted, the pheromone will recruit other bees towards the source. The stingless bee Scaptotrigona pectoralis, like ants, can utilize another colony's food trail. Specifically, they can learn foreign pheromone trails at a source, broadening their options for foraging. [14] However, in some cases of aggressive bees, like Trigona corvina , encounters between individuals from different colonies at a food source will result in fights and ultimately death amongst both parties. [15]
Termites use trail pheromones primarily as a means of foraging. They can lay pheromones along a trail as their abdomens touch the ground, specifically through their abdominal sternal glands. [16] As the other termites follow, they will continue to add to the trail.
The basal termite Mastotermes darwiniensis produces trail pheromones from at least two sternal glands despite every other species producing theirs from only one. [17] This pheromone, composed soley of a norsesquiterpene alcohol, elicits trail-following from other termites. As aforementioned, these successive termites can add to the trail, depending if it is used for foraging or recruiting workers to complete tasks. In the case of Reticulitermes santonensis , foraging trails have spotted markings throughout the path, whereas recruitment trails are more continuous from the termites dragging their bodies along the path. [18]
Trail pheromone deposition from an organism is correlated with its environment. In the event where a food source is identified and a trail pheromone is deposited, certain wildlife may flock towards or away from the trail causing temporary or dispersal of the population or individual. With relocation of wildlife, surrounding plant life may change as well; for example, pollen attached to the migrating organism is also relocating, thus may potentially regenerate in different patches.
Termites are a group of detritophagous eusocial insects which consume a wide variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the soft-bodied and typically unpigmented worker caste for which they have been commonly termed "white ants"; however, they are not ants, to which they are distantly related. About 2,972 extant species are currently described, 2,105 of which are members of the family Termitidae.
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavior of the receiving individuals. There are alarm pheromones, food trail pheromones, sex pheromones, and many others that affect behavior or physiology. Pheromones are used by many organisms, from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones. The ecological functions and evolution of pheromones are a major topic of research in the field of chemical ecology.
Trophallaxis is the transfer of food or other fluids among members of a community through mouth-to-mouth (stomodeal) or anus-to-mouth (proctodeal) feeding. Along with nutrients, trophallaxis can involve the transfer of molecules such as pheromones, organisms such as symbionts, and information to serve as a form of communication. Trophallaxis is used by some birds, gray wolves, vampire bats, and is most highly developed in eusocial insects such as ants, wasps, bees, and termites.
Pogonomyrmex barbatus is a species of harvester ant from the genus Pogonomyrmex. Its common names include red ant and red harvester ant. These large ants prefer arid chaparral habitats and are native to the Southwestern United States. Nests are made underground in exposed areas. Their diets consist primarily of seeds, and they consequently participate in myrmecochory, an ant-plant interaction through which the ants gain nutrients and the plants benefit through seed dispersal. Red harvester ants are often mistaken for fire ants, but are not closely related to any fire ant species, native or introduced.
An allomone is a type of semiochemical produced and released by an individual of one species that affects the behaviour of a member of another species to the benefit of the originator but not the receiver. Production of allomones is a common form of defense against predators, particularly by plant species against insect herbivores. In addition to defense, allomones are also used by organisms to obtain their prey or to hinder any surrounding competitors.
Acromyrmex is a genus of New World ants of the subfamily Myrmicinae. This genus is found in South America and parts of Central America and the Caribbean Islands, and contains 33 known species. Commonly known as "leafcutter ants" they comprise one of the two genera of advanced attines within the tribe Attini, along with Atta.
Eusociality, the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care, overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. The division of labor creates specialized behavioral groups within an animal society which are sometimes referred to as 'castes'. Eusociality is distinguished from all other social systems because individuals of at least one caste usually lose the ability to perform at least one behavior characteristic of individuals in another caste. Eusocial colonies can be viewed as superorganisms.
Tetragonula carbonaria is a stingless bee, endemic to the north-east coast of Australia. Its common name is sugarbag bee. They are also occasionally referred to as bush bees. The bee is known to pollinate orchid species, such as Dendrobium lichenastrum, D. toressae, and D. speciosum. It has been identified as an insect that collects pollen from the cycad Cycas media. They are also known for their small body size, reduced wing venation, and highly developed social structure comparable to honey bees.
Trigona spinipes is a species of stingless bee. It occurs in Brazil, where it is called arapuá, aripuá, irapuá, japurá or abelha-cachorro ("dog-bee"). The species name means "spiny feet" in Latin. Trigona spinipes builds its nest on trees, out of mud, resin, wax, and assorted debris, including dung. Therefore, its honey is not fit for consumption, even though it is reputed to be of good quality by itself, and is used in folk medicine. Colonies may have from 5,000 to over 100,000 workers.
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.
Tetragonisca angustula is a small eusocial stingless bee found in México, Central and South America. It is known by a variety of names in different regions. A subspecies, Tetragonisca angustula fiebrigi, occupies different areas in South America and has a slightly different coloration.
Novomessor cockerelli is a species of ant in the subfamily Myrmicinae. It is native to the deserts of the Southwestern United States and Mexico. It lives in large underground colonies in which there is a single queen. The worker ants leave the nest daily to forage for seeds, plant material and dead insects.
Dufour's gland is an abdominal gland of certain insects, part of the anatomy of the ovipositor or sting apparatus in female members of Apocrita. The diversification of Hymenoptera took place in the Cretaceous and the gland may have developed at about this time as it is present in all three groups of Apocrita, the wasps, bees and ants.
Trigona corvina is a species of stingless bee that lives primarily in Central and South America. In Panama, they are sometimes known as zagañas. They live in protective nests high in the trees, but they can be extremely aggressive and territorial over their resources. They use their pheromones to protect their food sources and to signal their location to nest mates. This black stingless bees of the tribe Meliponini can be parasitic toward citrus trees but also helpful for crop pollination.
Scaptotrigona postica is a species of stingless bee that lives mainly in Brazil. It is a eusocial bee in the tribe Meliponini. S. postica is one of 25 species in the genus Scaptotrigona and is a critical pollinator of the tropical rain forests of Brazil. They construct their nests in hollowed sections of tree trunks, allowing for effective guarding at the nest entrance. This species shows colony structure similar to most members of the Meliponini tribe with three roles within the colony: queen, worker, and male. S. postica individuals have different forms of communication from cuticular hydrocarbons to pheromones and scent trails. Communication is especially useful during worker foraging for nectar and pollen through the Brazilian tropical rain forests. S. postica is a very important pollinator of the Brazilian tropical rain forests and is widely appreciated for its honey. Stingless bees account for approximately 30% of all pollination of the Brazilian Caatinga and Pantanal ecosystems and up to 90% of the pollination for many species of the Brazilian Atlantic Forest and the Amazon.
Paratrigona subnuda, commonly known as the jataí-da-terra, is a species of eusocial stingless bee in the family Apidae and tribe Meliponini. These social bees are prevalent in Neotropical moist forests, including Brazilian Atlantic and other South American forests. They inhabit spherical nests in moist underground environments with their forest habitats. Within their Neotropical habitats the P. subnuda is considered to be a very successful and common species of bee. P. subnuda’s main source of food is pollen and nectar from a large variety of native Mesoamerican tropical plants. They have been extensively studied due to social conflicts arising from single mate behaviors and particular virgin behaviors. P. subnuda also exhibits the particular daily behavior in which they open the nest entrance at dawn and close the entrance at dusk when all their activities are done.
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.
Messor capitatus is an ant species part of the genus Messor. This genus includes about 40 specialized species that are found in dry areas of Mediterranean countries such as Africa, Southern Europe, and Asia.Messor capitatus are known as an Old World species because they release trail pheromones from the Dufour gland instead of from poison glands. Messor capitatus are known as individual foragers that collect food independently of one another but sometimes will also use group foraging to form irregular, broad columns. Messor capitatus main food source is seeds but they also will eat remains of plants and animals.
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.
Insect pheromones are neurotransmitters that serve the chemical communication between individuals of an insect species. They thus differ from kairomones, in other words, neurotransmitters that transmit information to non-species organisms. Insects produce pheromones in special glands and release them into the environment. In the pheromone receptors of the sensory cells of the recipient, they produce a nerve stimulus even in very low concentrations, which ultimately leads to a behavioral response. Intraspecific communication of insects via these substances takes place in a variety of ways and serves, among other things, to find sexual partner, to maintain harmony in a colony of socially living insects, to mark territories or to find nest sites and food sources.