Ropalidia marginata is an Old World

Old World

The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of paper wasp

Paper wasp

Paper wasps are -long wasps that gather fibers from dead wood and plant stems, which they mix with saliva, and use to construct water-resistant nests made of gray or brown papery material...

 found in Pakistan

Pakistan

Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

, peninsular India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Sri Lanka

Sri Lanka

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

, South-east Asia

Southeast Asia

Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

 and Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. It was originally described by Fabricius

Fabricius

Fabricius may refer to:*people from the Ancient Roman gens Fabricia:*Gaius Fabricius Luscinus, the first of the Fabricii to move to Rome* Carel Fabricius , painter...

 in 1793 under the name Vespa

Hornet

Hornets are the largest eusocial wasps; some species can reach up to in length. The true hornets make up the genus Vespa and are distinguished from other vespines by the width of the vertex , which is proportionally larger in Vespa and by the anteriorly rounded gasters .- Life cycle :In...

 ferruginea, but that name was preoccupied, so the oldest available name for the species is that given to it later by Lepeletier in 1836. One of its subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

, R. marginata jucunda, occurring in New Guinea

New Guinea

New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

 and Australia, was described in 1898, and two others (R. marginata rufitarsis from Myanmar

Myanmar

Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....

 and R. marginata sundaica from Indonesia

Indonesia

Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 and the Malay Peninsula

Malay Peninsula

The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...

) were described in 1941.

Biology

The nominate subspecies (R. m. marginata) has been studied extensively in India, though little is known of its biology elsewhere within its range, or the biology of any of the other subspecies. In India, it has an aseasonal, indeterminate and perennial colony

Colony (biology)

In biology, a colony reference to several individual organisms of the same species living closely together, usually for mutual benefit, such as stronger defense or the ability to attack bigger prey. Some insects live only in colonies...

 cycle, which means that nest initiation occurs round the year, and nests are active throughout the year.

These wasps make gymnodomous nests (open, not covered by an envelope) with one or more petioles

Petiole (insect)

In entomology, the term petiole is most commonly used to refer to the constricted first metasomal segment of members of the Hymenopteran suborder Apocrita; it may be used to refer to other insects with similar body shapes, where the metasomal base is constricted...

, which they coat with ant-repellant chemicals. The nests are usually found in closed spaces with small openings, inside bushes

Shrub

A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

 and within various man-made structures like electric poles

Utility pole

A utility pole is a pole used to support overhead power lines and various other public utilities, such as cable, fibre optic cable, and related equipment such as transformers and street lights. It can be referred to as a telephone pole, power pole, hydro pole, telegraph pole, or telegraph post,...

, broken pillars, crevices of buildings, electric cable boxes, switch boards

Electric switchboard

An electric switchboard is a device that directs electricity from one source to another. It is an assembly of panels, each of which contains switches that allow electricity to be redirected. The U.S...

, tube light

Fluorescent lamp

A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful...

 holders, the bottom of park benches

Bench (furniture)

A bench is a piece of furniture, on which several people may sit at the same time. Benches are typically made of wood, but may also be made of metal, stone, or synthetic materials. Many benches have arm and back rests; some have no back rest and can be sat on from either side. In public areas,...

, and even from within dustbins

Waste container

A waste container is a container for temporarily storing refuse and waste. Different terms are in use, depending on the language area, the design and material and the respective site .The most general terms are waste receptacle and container bin.Common terms include dustbin ,...

 and letter box

Letter box

A letter box, letterbox, letter plate, letter hole, mail slot, or mailbox is a receptacle for receiving incoming mail at a private residence or business...

es. Nests that can be accessed only through very small openings are well protected from the hornets Vespa tropica, which are the prime predators of these wasps. Nest sizes range from 0 to 722 cells (mean ± s.d.: 133.7 ± 119.2), with 1 to 200 females (mean ± s.d.: 21.9 ± 22.3) and 0 to 33 males (mean ± s.d.: 2.4 ± 5.4).

Males are produced aseasonally, and are thus found throughout the year in a subset of nests in the population. There is only a single queen

Eusociality

Eusociality is a term used for the highest level of social organization in a hierarchical classification....

 in any nest of R. marginata, and she is not morphologically

Morphology (biology)

In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

 distinguishable from the workers

Eusociality

Eusociality is a term used for the highest level of social organization in a hierarchical classification....

. The nests are made of paper, which is produced by masticating cellulose

Cellulose

Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....

 (collected usually from plant sources) and mixing it with saliva

Saliva

Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...

.

The queen lays a single egg per cell, and the larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e grow inside the cells, being fed by the workers. The largest larvae spin a cap of silk

Silk

Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...

 on their cells and pupa

Pupa

A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...

te inside. R. marginata nests can be founded either by solitary or multiple foundresses, and nest usurpation, adoption and joining are also quite commonly observed.

A female wasp eclosing on a nest at any time of the year has several options open to her. She can (i) leave her natal nest and start her own single foundress colony; (ii) leave her natal nest and initiate or join other multiple foundress colonies along with her nestmates or with wasps from other nests; (iii) stay in her natal nest as a worker; (iv) stay in the natal nest as a worker for some time and then drive away the queen and take over as the new queen of the colony.

It is clear that this versatility in the options for the workers provides a platform for potential conflict in the R. marginata society, and the fact that the queen is able to maintain complete reproductive monopoly makes this an excellent model for studying the evolution of co-operation in a primitive society.

The queen

Primitively eusocial societies are typically headed by behaviourally aggressive queens, who use aggression to suppress worker reproduction. The queen in R. marginata, however, is a "docile sitter" who does not use physical aggression to maintain her reproductive monopoly in the colony.

The queen is also not responsible for maintaining worker activity in her colony, as in similar species. However, the queen in R. marginata is able to maintain complete reproductive monopoly in the colony. It has been argued for several years that the R. marginata queen uses a pheromone

Pheromone

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 outside the body of the secreting individual to impact the behavior of the receiving individual...

 to signal her presence and fecundity

Fecundity

Fecundity, derived from the word fecund, generally refers to the ability to reproduce. In demography, fecundity is the potential reproductive capacity of an individual or population. In biology, the definition is more equivalent to fertility, or the actual reproductive rate of an organism or...

 to her workers, and this signal is perceived by the workers who refrain from reproducing; however, it has been shown that any such pheromone is non-volatile.
The queen interacts very rarely with her workers, and direct or indirect physical interactions are not used by the workers to perceive their queen. The queen probably uses abdomen-rubbing behaviour to apply her pheromone on the nest material, through which the workers perceive her presence in the colony.

When the queen is removed from the colony, the pheromone decays, and eventually the workers no longer perceive the queen signal. One of the workers then increases her aggression drastically; this individual, the "potential queen" (PQ), develops her ovaries

Ovary

The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...

within a few days and assumes the role of the queen.

The potential queen

Primitive wasp societies are known to have distinguishable succession hierarchies, i.e., the loss of the queen results in her successor becoming the next egg-layer. Typically, such hierarchies are based on dominance rank, age or in some cases, body size.

However, in R. marginata, the potential queen, or the individual who steps up her aggression immediately after queen removal and eventually becomes the queen, seems to be an unspecialized individual in the presence of the queen. She is not unique in her dominance rank, behavioural repertoire, age, body size or ovarian condition. However, within minutes of queen removal, the potential queen becomes obvious to an observer due to her heightened aggression. Interestingly, the potential queen maintains this high aggression for only a few days, and gradually reduces the levels of aggression over a week or so, while she develops her ovaries.

Contrary to popular belief among scientists, the potential queen seems to require this heightened aggression, not to suppress the ovarian development in her nestmates, but to boost her own development.

Typically, this heightened aggression is one-way, and shown by a single individual. She hardly even receives any aggression from the others in the colony. It has now been established that though the identity of the potential queen is cryptic to the observer in the presence of the queen, the wasps "know" who their successor is, and hence she does not face any challenge from her nestmates.

Other sources

• Das, B. P. and Gupta, V. K. (1989). The social wasps of India and the adjacent countries (Hymenoptera: Vespidae). Gainseville, Fla: The Association for the Study of Oriental Insects.
• Gadagkar, R. (1991). Belonogaster, Mischocyttarus, Parapolybia, and Independent founding Ropalidia, In: The Social Biology of Wasps, (ed.) K. G. Ross and R. W. Matthews pp. 149–187. Ithaca and London: Cornell University Press. PDF