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''Ropalidia marginata'' is an
Old World The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by thei ...
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
of
paper wasp Paper wasps are vespid wasps that gather fibers from dead wood and plant stems, which they mix with saliva, and use to construct nests made of gray or brown papery material. Some types of paper wasps are also sometimes called umbrella wasps, d ...
. It is primitively eusocial, not showing the same bias in brood care seen in other social insects with greater asymmetry in relatedness. The species employs a variety of colony founding strategies, sometimes with single founders and sometimes in groups of variable number. The queen does not use physical dominance to control workers; there is evidence of pheromones being used to suppress other female workers from overtaking queenship.


Taxonomy and phylogeny

''R. marginata'' was originally described by
Johan Christian Fabricius Johan Christian Fabricius (7 January 1745 – 3 March 1808) was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others. He was a student of Carl Linnaeus, and is co ...
in 1793 under the name ''Vespa'''' ferruginea'', but that name was previously applied to a different species, so the oldest available name for the species was given by
Amédée Louis Michel le Peletier Amédée is a French masculine forename. Notable people with the forename include: Persons * Amédée, stage name of Philippe de Chérisey (1923-1985), French writer, radio humorist, surrealist and actor *Amédée Artus (1815-1892), French condu ...
in 1836. One of its
subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. Not all specie ...
, ''R. marginata jocund'' from
New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...
and Australia, was described in 1898, and two others, ''R. marginata rufitarsis'' from
Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...
and ''R. marginata sundaica'' from
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
and the
Malay Peninsula The Malay Peninsula ( Malay: ''Semenanjung Tanah Melayu'') is a peninsula in Mainland Southeast Asia. The landmass runs approximately north–south, and at its terminus, it is the southernmost point of the Asian continental mainland. The ar ...
, were described in 1941. ''R. marginata'' is an insect, having six legs. It is in the order Hymenoptera, containing wasps, ants and bees. It is in the family Vespidae, with wasps, yellow jackets, and hornets. It is in the subfamily Polistinae, containing
eusocial Eusociality (from Greek εὖ ''eu'' "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping gen ...
wasps and it is in the tribe
Ropalidiini Ropalidiini is a tribe of social wasps inhabiting the Afrotropical, Indomalayan and Australasian biogeographical regions. Genera and selected species *'' Belonogaster'' **''Belonogaster juncea ''Belonogaster juncea'' is a typical quasisoc ...
. On the Indian subcontinent, there are 22 recognized species of the genus ''Ropalidia''. The species ''R. travancorica'', once thought separate, was determined synonymous with ''R. marginata'' after intensive specimen comparisons in 1989. ''R. marginata'' is most closely related to ''R. spatulata'' and ''R. brevita''. The male antenna and genitalia are similar between ''R. brevita'' and ''R. marginata.''


Description

''R. marginata'' are a dark reddish color (slightly lighter than '' Ropalidia revolutionalis''), with yellow spots on some joints and a yellow ring around the lower abdomen. Males differ from females by having a weaker mandible and lacking a stinger. The female workers are not morphologically different from the queen and are more distinguishable by behavior.


Females

Females are hard to distinguish morphologically except for their level of ovary development, which generally increases with their age. Females are the default workers of ''R. marginata'', but they may also rise to queenship by taking over a resident queen, founding a new colony, or adopting an abandoned one.


Workers

Female workers forage to feed themselves and non-foragers, such as the queen, larvae, and males. They help to build the nest and care for the larvae. Workers regulate the foraging levels within the colony through aggression, and are a good example of self regulation in insect societies. Workers may mate with males and remain inseminated even if they are never able to attain queenship and produce offspring. Worker-worker relatedness is not asymmetrically higher than relatedness between workers and males or workers and the queen. This is because of overlapping matrilines and patrilines within the colony which decreases relatedness overall between individuals.


Potential queens

When a queen is lost, a worker has the ability to take her place. The mechanism by which the next-in-line-queen is chosen is cryptic; neither age nor dominance accurately predicts the successor. The potential queen may or may not be inseminated or have developed ovaries. The only certainty is that after the queen is gone, the worker who is the potential queen will become very aggressive. The aggressiveness subsides after about two days. The potential queen seems to require this heightened aggression in order to boost her own development.


Queens

Primitively eusocial societies are typically headed by behaviourally aggressive queens, who use aggression to suppress worker reproduction. However, the queen in ''R. marginata'' is a "docile sitter" who does ''not'' use physical aggression to maintain her reproductive monopoly in the colony. The queens are suspected to control workers through
pheromones 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 behavio ...
. She uses these pheromones to signal her presence and
fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...
to her workers, who perceive these signals and refrain from reproducing. The tenure length, age, and productivity of a queen vary greatly on a case by case basis. The exact mechanisms by which the queen is recognized by her colony are not fully understood. One possibility is that there are chemicals in the queen's Dufour's glands that signal her queen status and influence workers who are on the nest with those chemicals. A potential queen who is acting aggressively can be experimentally subdued by applying the old queen's Dufour's gland's chemicals to the nest. The queen interacts with her workers primarily through chemical communication; physical interactions between the queen and workers do not serve a communicative function. She does not regulate worker behaviors such as foraging and nest matienance.


Males

Males are produced less frequently and in less quantity than females are produced. After eclosion males remain on the nest for up to a week. Upon leaving, they live nomadically and mate with females of other nests. Males do not assist in any of the colony maintenance activities while they reside in the nest. They are not well suited for foraging or defending the colony because of their weaker mandibles and lack of a stinger. They are dependent on female workers feeding them and are sometimes observed to cannibalize nest larvae. It has been experimentally demonstrated that males of ''R. marginata'' have the ability to feed larvae, but they do not because they lack food access and females do not give them an opportunity to do so in natural populations.


Nests

''R. marginata'' makes gymnodomous nests with up to 500 cells and up to 10 pedicels. The nests are made of paper, which are produced by wasps masticating
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
and mixing it with
saliva Saliva (commonly referred to as spit) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can ...
. The nests are usually found in closed spaces with small openings in natural and man-made structures.


Distribution

The distribution of ''R. marginata'' extends as far west as Pakistan and as far east as New Guinea, Queensland, and some eastern Pacific islands. They are the most common social wasp in India. Although ''R. marginata'' has been studied extensively in India, there is a lack of literature about the animal in other parts of its range.


Colony cycle

In India, ''Ropalidia marginata'' has an aseasonal, indeterminate and perennial
colony In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state' ...
cycle, which means that nest initiation starts throughout the year, and nests are active throughout the year. Colonies are started more frequently from May to July when food is abundant and less frequently from December to February when temperatures are colder. Each colony has one reproductive female, a queen, and that position can be taken by adopting an abandoned nest, taking over queenship at an existing nest, or starting a new nest alone or with other foundresses.


Brood development

The amount of time it takes for a brood to fully develop is highly variable and is complicated by occurrences of nest cannibalism, which is often undetected as replacement eggs appear. Males leave the nest 2–7 days after eclosion. Tenure on the nest for a worker female is more variable. Their residence time ranges from 1–60 days.


Foundress variation

Colonies can be started by as many as 20 foundresses, but most frequently they are started with four or less. Studies on wild and captive populations indicate that it is most common for colonies to start with three or more foundresses, rather than two foundresses; single foundress colonies are the least common. Although the multiple foundress colonies were less likely to fail, all colonies, regardless of number of foundresses, had the same per capita productivity. Only one individual acts as an egg layer in each colony. *Single Foundress colonies :If there is only a single foundress, she will work alone to build the nest and care for larva until they reach adulthood. The adult offspring will help her rear future broods. Single-foundresses produce much less offspring, average of two, than the queen of a multiple-foundress colony, and in many cases a single foundress colony fails before any of the brood reach adulthood. *Multiple Foundress colonies :Of the females in multiple foundress colonies, only one takes the role of queen and is the sole egg layer. The others work on the nest and care for the brood. Multiple foundress colonies do not have a greater per capita production rate but do have greater productivity overall compared to single-foundress colonies. It is suspected that competing interests of taking care of the queen's brood (indirect fitness) and seeking queenship and the chance to reproduce (individual fitness) prevent the efficiency that would lead to higher productivity in multi-foundress groups. Colonies with more than one founder are more likely to survive overall, which may be why individuals migrate into them more frequently than starting single-foundress colonies, even when the chances of taking over the role of queen are lower.


Switching colonies

Individuals may migrate from their birth or founded colony to take up residence in another. This is most common during the pre-emergence phase and when there are around forty to fifty adults on the home nest. Migrant wasps are more likely to be accepted while they are younger, which is generally less than six days old. Age has been shown to be the determining factor for whether the resident wasps react with hostility or tolerance. Age might be an indicator of ovarian development (reproductive threat) or of other important qualities such as plasticity for role specialization. Multiple-foundress colonies are preferentially selected by migrant wasps, despite the fact that individuals are more successful at becoming a queen in a single-foundress colony. Young migrants become fully integrated into the new colony, becoming foragers and sometimes taking over the role of queen.


Colony adoption

In some cases, all adult wasps will be absent from a nest when a migrant finds it. Females sometimes adopt these abandoned nests and take over queenship in variable numbers of foundresses. This has been observed to be more common in predator-protected vespiaries than in the field.


Behavior


Larval feeding

Females feed larvae by masticating acquired solid food for three to four minutes before feeding it to the larvae. She feeds about two larvae the solid food and then grooms herself. Then she feeds six larvae with a liquid of regurgitated food and grooms herself again. Females also engage in behaviors such as fanning wings, antennal drumming, and body jerks which are sometimes synchronous between many females. These behaviors are expected to be related to adult/larval communication. Female feeding behavior is more complicated than that of males, who do not use liquid food or this set of behaviors.


Male feeding behavior

Males have been experimentally shown to be capable of deliberately delivering food to larvae when females are absent and food surplus is available. Males feed the larvae with the same proportion of individuals as females. They are, however much less efficient than females at feeding. They spend over 90% of feeding bouts masticating and end up feeding far fewer larvae. The males also preferentially feed the largest larvae, resulting in the death of many smaller and younger larvae. It was only possible to observe this behavior by removing all females from a nest and hand feeding the males, as the males cannot forage on their own and have no opportunity to care for larvae if females occupy this role. While males are typically not responsible for feeding larvae in naturally occurring populations, they are capable of doing so.


Aggression

Aggression in the form of chasing and sometimes stinging is needed to defend the nests from predators and non-nestmates. Older females from different nests are chased away, as are predators such as ''
Vespa tropica ''Vespa tropica'', the greater banded hornet, is a tropical species of hornet found in Southern Asia, New Guinea and west Africa, and which has recently been discovered to be an invasive species on the Pacific island of Guam. It is a predator of ...
''. Dominance relationships, mediated by aggression, control foraging amidst workers. Aggressive behavior is a crucial part of the transition from worker to queen.


Dominance

Behaviorally dominant queens are standard among other primitively eusocial wasps, but in ''R. marginata'', it is the workers who engage in subordinate-dominant behavior. Among the workers, the dominance hierarchy does not relate to reproductive competition or accurately predict individuals to take over queenship. Worker dominant-subordinate interactions seem to regulate foraging behavior. This is supported by the fact that dominance is received more by foragers and that frequency of received dominance correlates with foraging rate. It has been experimentally shown that dominance frequency is related with hunger of the colony, suggesting that dominance interactions are a system of peer regulation to support the survival of the colony.


Recognition

Nestmates act tolerantly towards their fellow nestmates, which can still be recognized after days of isolation. ''Ropalidia marginata'' can distinguish nestmates from non-nestmates, and react aggressively to non-nestmates that are older, while younger foreigners may be accepted into the colony. Discriminating nestmates from non-nestmates is dependent on acquiring and encountering odors from the nest post-eclosion. Individuals removed from a nest before eclosion will not recognize, or be recognized by, members of that nest. There is no indication that there is any recognition based on genetic relatedness.


Foraging

These predatory wasps are solitary foragers (that means each forager finds the prey, kills it and brings that back to the nest all alone). Foragers typically forage within about 300 to 700 m from their nests, though if food is scarce, they can travel up to about 1.5 km from their nest. With experience, they acquire a vivid familiarity with their foraging range; they perhaps remember the sites from where they have collected food previously. Such familiarity with the foraging landscape eventually helps them to reduce their search for food.


Mating system

The
haplodiploid Haplodiploidy is a sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid. Haplodiploidy is sometimes called arrhenotoky. Haplodiploidy determines the sex ...
genetic system creates asymmetry in relatedness of most Hymenoptera species. ''R. marginata,'' however, have increasingly unrelated workers and broods because of "simultaneous production of several different patrilines and matrilines within a colony." Serial polygyny works against the inclusive fitness benefits workers have of caring for broods because of reduced relatedness. Gadagkar devised a unified model that makes predictions about what proportion of the population of ''R. marginata'' "should opt for a selfish solitary nesting strategy and what proportion should opt for an altruistic worker strategy" (853). From this, he was able to predict that 5% should opt for the selfish solitary nesting strategy while 95% should opt for the altruistic worker strategy. Gadagkar et al. genotyped ''R. marginata'' mothers and daughters at a "few non-specific esterase loci" to infer the genotypes of the haploid fathers or estimate the number of fathers needed to produce the daughters observed (850). The researchers ultimately found, "''R. marginata'' queens mate with 1–3 different males and the average relatedness among their daughters thus drops from the theoretically expected 0.75 to about 0.50, thus entirely negating the advantage of
haplodiploidy Haplodiploidy is a sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid. Haplodiploidy is sometimes called arrhenotoky. Haplodiploidy determines the sex ...
for social evolution, as predicted by Hamilton" (851). Gadagkar "found no evidence for intra-colony
kin recognition Kin recognition, also called kin detection, is an organism's ability to distinguish between close genetic kin and non-kin. In evolutionary biology and psychology, such an ability is presumed to have evolved for inbreeding avoidance, though animals d ...
" (851).


Mate choice

To avoid
inbreeding Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders a ...
, most taxa recognize
kin __NOTOC__ Kin usually refers to kinship and family. Kin or KIN may also refer to: Culture and religion *Otherkin, people who identify as not entirely human *Kinism, a white supremacist religious movement * Kinh, the majority ethnic group of V ...
and do not consider them in mate selection. ''R. marginata'' however show no indication of discriminating against nestmates for mate choice in both males and females. Because males disperse and live nomadically after leaving the nest and breeding does not occur on the nest, inbreeding is relatively unlikely in this species even without the anti-incest behavior. Body size is arbitrary in mate choice for both males and females of this species.


Serial polygyny

Colonies of ''R. marginata'' often outlive the queens; workers may serve different queens throughout their lifetimes. This creates overlapping matrilines within the colony where workers end up caring for the brood of different mothers, yet again decreasing the relatedness amidst workers.


Predation

''
Vespa tropica ''Vespa tropica'', the greater banded hornet, is a tropical species of hornet found in Southern Asia, New Guinea and west Africa, and which has recently been discovered to be an invasive species on the Pacific island of Guam. It is a predator of ...
'', a hornet species, is a key predator of ''R. marginata'' brood in Indian populations. As a predator avoidance strategy, nests are often built to only be accessible through small openings, thus, preventing hornets from getting through.


References


Other sources

* Das, B. P. and Gupta, V. K. (1989). "The social wasps of India and the adjacent countries (Hymenoptera: Vespidae)". Gainesville, 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. {{Taxonbar, from=Q3941191 Vespidae Hymenoptera of Asia Hymenoptera of Australia Hymenoptera of Oceania Taxa named by Amédée Louis Michel le Peletier Insects described in 1836