Polistes austroccidentalis

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Polistes austroccidentalis
Polistes semenowi 28877131.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Vespidae
Subfamily: Polistinae
Tribe: Polistini
Genus: Polistes
Species:
P. austroccidentalis
Binomial name
Polistes austroccidentalis
Van Achterberg & Neumeyer, 2017

Polistes austroccidentalis is a kleptoparasitic paper wasp that is found in several regions of high altitude in Europe, and until 2017 was universally mistakenly referred to as Polistes semenowi, which is instead the correct name of the species formerly known as "Polistes sulcifer". [1] As one of only four obligate parasites in the subgenus Polistes , it uses the nests of other paper wasps (primarily Polistes dominula ) to rear its young. [2] To evade detection by the host nest, P. austroccidentalis employs mimicry by adjusting its cuticular hydrocarbons to match those of the host. [3] Once the host nest has been infiltrated, the parasitic female physically attacks the host queen to subdue her and become the colony's new queen. P. austroccidentalis displays several morphological adaptations for parasitism such as increased mandible size and an enlarged Van der Vecht's organ. This species is unusual because it does not have the ability to produce workers and is only able to produce individuals who have the capacity to reproduce.

Contents

Taxonomy and phylogeny

Due to its morphological differences from other Polistes species, Polistes austroccidentalis was placed in a separate genus Sulcopolistes by Blüthgen in 1938. [4] However, in 1991 Carpenter established that this species belonged in the subgenus Polistes. [2] P. austroccidentalis is closely related to Polistes atrimandibularis , Polistes maroccanus , and Polistes semenowi . [1] Research using mitochondrial rRNA suggests that these species descended from a common ancestor, and that they are more closely related with Polistes nimpha and Polistes dominula than with Polistes gallicus and Polistes biglumis . [2] In 2017, careful taxonomic research revealed that for over 100 years, the species originally named Polistes semenowi in 1889 had been misclassified, and been recognized instead under the name Polistes sulcifer, while the species that had been called Polistes semenowi had never been given a name, so it was named Polistes austroccidentalis. [1]

Description and identification

P. austroccidentalis is larger than most Polistes species, which initially caused it to be classified in a separate genus (Sulcopolistes). [4] Both the first femur and posterior tibia of this wasp are elongated, and its mandibles are significantly thicker than those of other wasp species. Moreover, the mandibles of this species, similarly to related parasitic species, are marked by a distinct groove. [2] This wasp species also has distinctive black markings on its clypeus, the function of which are currently unclear. [5]

Distribution and habitat

The overall distribution of this species is southwestern and southern central Europe, and northern Africa. [1] P. austroccidentalis populations typically exist near regions of high altitude around the Mediterranean basin. However, on occasion, they may also be found around the Caspian basins. The distribution of P. austroccidentalis is patchy as a result of its altitudinal migration patterns. During the winter, the wasps ascend to a higher altitude; in the spring, however, they descend to the lowlands to find host colonies. [2]

Colony cycle

These wasps migrate to high altitudes to mate and then proceed to overwinter in the same mountainous areas. [3] In the spring, females move down the elevation gradient parasitize P. dominula, a lowland species. Once a P. austroccidentalis female discovers a host nest, it attempts to usurp it. The timing of this usurpation is intimately linked to the emergence of P. dominula workers. If no workers have emerged, the hosts may simply abandon the colony. If most of the workers have already emerged, they may be able to fend off a P. austroccidentalis invasion. [2] Having usurped the dominant female host, the P. austroccidentalis female proceeds to lay her eggs. After a period of several weeks, the parasitic female will abandon the nest. [4] Once her offspring emerge from the host nest, they migrate to high altitudes, continuing the cycle.

Parasitism

P. austroccidentalis are one of only four species of Polistes that are obligate social parasites. This means these wasps take advantage of the social systems of other species. [6] As a social parasite, P. austroccidentalis usurps a host colony in order to take advantage of the entire host colonial cycle. [2] Specifically, this parasitic wasp exploits P. dominula, a lowland wasp species. Although P. austroccidentalis is a specialized parasite of P. dominula, it is also able to parasitize colonies of P. nimpha. Since P. austroccidentalis is unable to create nests and produce worker classes, it is completely dependent on a host colony to fulfill these functions. [6]

Because P. austroccidentalis normally attacks the host's nests just prior to worker emergence, it is surmised that such selection pressure might have impacted the developmental times in P. dominula to be shorter. It would be advantageous for the hosts to make their brood developmental time to be shorter so that they can rapidly generate workers and defend their nests.

Evolutionary basis of parasitism

Like other hymenopterans, Polistes species undergo a complete metamorphosis during development in which the young are completely dependent on workers for all of their food and protection needs. A large energetic investment is necessary for the young to successfully pupate and grow to reproductive age. The amount of resources invested in the young determines which caste they belong to: less food causes the larvae to develop into workers, while more food causes the larvae to develop into reproductives. [2] By manipulating another species into investing a large amount of energetic resources into their own young, P. austroccidentalis would be able to take advantage of host workers and would no longer have a need to produce its own workers. Instead, more resources could be devoted to larvae, causing all of them to develop into reproductives. Over time, P. austroccidentalis has completely lost the ability to create its own worker class and has adopted a strategy of parasitism. [6] [3] The parasitic larvae display rapid growth, which allows P. austroccidentalis to optimize its rate of offspring production. [2]

Establishing dominance over host queen

Approximately two months after a P. dominula female has founded a colony, the female parasite attempts to usurp the nest. [3] Approaching the dominant host female, the parasite aggressively attacks her in an attempt to drive her out of the nest. [7] Behaviors include chasing the queen out of the nest as well as physically confronting her. [4] These behaviors have been demonstrated in the laboratory: in controlled experiments, female parasites introduced to host nests immediately entered the nest and identified the most dominant female, proceeding to aggressively approach her. [3] After initially physically establishing dominance over the queen, the parasitic female coexists with subordinate females and may, in some cases, allow the former dominant female to stay in the nest. [2]

Reproduction within host colony

Once she has entered the colony and subdued the dominant host female, the parasite immediately begins laying eggs. Some time after the initial invasion – approximately thirty days – the hosts chemically recognize the parasites as their own species. [3] Additionally, the parasite attempts to destroy the larvae and eggs of the host queen to ensure that the host colony invests all of its resources into her young. After this initial destruction, however, the P. austroccidentalis female does not attack any emerging host workers, and spends most of her time laying eggs. [4] [2] Unable to differentiate between the parasite and their own species, host workers feed and care for the parasite young as the parasite queen continues to lay eggs.

Morphological adaptations for parasitism

For their parasitic strategy to succeed, P. austroccidentalis must be able to enter and successfully usurp a host nest. However, host colonies are able to mount a defense by mobilizing any emerging workers as well as dominant females. Therefore, P. austroccidentalis must be morphologically adapted to overcome such defensive attacks. The parasitic wasp is significantly larger than its host; in fact, P. austroccidentalis is so much larger than P. dominula that it was initially thought to be in a separate genus. [4] The first femur and posterior tibia of this wasp is enlarged, providing an advantage during attacks. P. austroccidentalis also has thicker and larger mandibles, which are used during attacks to drive off dominant host females. However, since this species does not use its sting during a host colony invasion, its sting is not morphologically distinct from other Polistes species. [2]

Mimicry

Host colonies only mount a defense against parasites if they recognize it as distinct from their own species. Though the parasitic wasp can overcome the physical defenses of a host nest, it must also be able to camouflage itself after usurpation. This aids the wasp from having to continually battle for dominance. For P. austroccidentalis, this is achieved by mimicking the chemical signals of the host colony so that the parasite is recognized as a member of the host species. By successfully mimicking the hydrocarbon patterns of host wasps, P. austroccidentalis wasps are accepted by the colony and can ensure that host workers will raise the parasitic offspring. [6]

Hydrocarbon signals

Like other social insects, wasps recognize each other through chemical signals. Each colony has a specific blend of hydrocarbons that is secreted onto the cuticle of the wasps. [3] [8] This hydrocarbon signature allows individuals to distinguish nest mates from interlopers. An unfamiliar hydrocarbon signature signals that the colony should mount a defense against a potential intruder. As soon as a female P. austroccidentalis wasp enters a host nest, she begins to vigorously rub her abdomen against the comb. [2] This allows the parasitic female to coat herself with the host hydrocarbon pattern, which she immediately begins to mimic. Although its initial hydrocarbon signature is relatively close to that of its host P. dominula, after usurpation, P. austroccidentalis is able to exactly match the hydrocarbons of its host colony. [3]

Van der Vecht's organ

The hydrocarbons secreted by Polistes wasps are efficiently spread on to the cuticle by a structure called the Van der Vecht’s organ. This structure is located on the last gastral sternite of the wasp, on the anterior edge. It is composed of a hairy, transparent cuticle. When compared to females of their host species P. dominula, female P. austroccidentalis wasps have a significantly enlarged Van der Vecht’s organ. Since the Van der Vecht’s organ spreads hydrocarbons that enable P. austroccidentalis mimicry, increased size of the structure in this species most likely occurred as a result of selective pressure on the wasp due to the success of its parasitic life strategy. [6]

Related Research Articles

<i>Polistes</i> Genus of insects

Wasps of the cosmopolitan genus Polistes are the most familiar of the polistine wasps, and are the most common type of paper wasp in North America. Walter Ebeling coined the vernacular name "umbrella wasps" for this genus in 1975 to distinguish it from other types of paper wasp, in reference to the form of their nests. It is also the single largest genus within the family Vespidae, with over 300 recognized species and subspecies. Their innate preferences for nest-building sites leads them to commonly build nests on human habitation, where they can be very unwelcome; although generally not aggressive, they can be provoked into defending their nests. All species are predatory, and they may consume large numbers of caterpillars, in which respect they are generally considered beneficial. The European paper wasp, Polistes dominula, was introduced into the US about 1981 and has quickly spread throughout most of the country, in most cases replacing native species within a few years. This species is very commonly mistaken for a yellow jacket, as it is black, strongly marked with yellow, and quite different from the native North American species of Polistes. The cuckoo wasp, Polistes semenowi, is an obligate social parasite, whose only host is P. dominula. Polistes metricus adults malaxate their insect prey by chewing them into a pulp, sucking out and ingesting the body fluids, then feeding the rest of the morsel to their larvae. The most widely distributed South American wasp species, Polistes versicolor, is particularly common in the southeastern Brazilian states. This social wasp is commonly referred to as the yellow paper wasp due to the distinct yellow bands found on its thorax and abdomen. Polistes wasps can be identified by their characteristic flight; their long legs dangle below their bodies, which are also more slender than a yellow jacket.

<span class="mw-page-title-main">Brood parasite</span> Animal that relies on others to raise its young

Brood parasites are animals that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its own, usually using egg mimicry, with eggs that resemble the host's.

An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. This is opposed to a facultative parasite, which can act as a parasite but does not rely on its host to continue its life-cycle. Obligate parasites have evolved a variety of parasitic strategies to exploit their hosts. Holoparasites and some hemiparasites are obligate.

<span class="mw-page-title-main">European paper wasp</span> Species of wasp

The European paper wasp is one of the most common and well-known species of social wasps in the genus Polistes. Its diet is more diverse than those of most Polistes species—many genera of insects versus mainly caterpillars in other Polistes—giving it superior survivability compared to other wasp species during a shortage of resources.

<i>Polistes gallicus</i> Species of wasp

Polistes gallicus is a species of paper wasp found in various parts of Europe, excluding England, Denmark, and Scandinavia, from warmer climates to cooler regions north of the Alps. Nests of these social insects are created in these various conditions. The Polistes species use an oral secretion to construct their nests, which consist of a combination of saliva and chewed plant fibers. This structural mixture physically protects the nest from various harsh elements and from weathering over time.

<i>Bombus bohemicus</i> Species of bee

Bombus bohemicus, also known as the gypsy's cuckoo bumblebee, is a species of socially parasitic cuckoo bumblebee found in most of Europe with the exception of the southern Iberian Peninsula and Iceland. B. bohemicus practices inquilinism, or brood parasitism, of other bumblebee species. B. bohemicus is a generalist parasite, successfully invading several species from genus Bombus. The invading queen mimics the host nest's chemical signals, allowing her to assume a reproductively dominant role as well as manipulation of host worker fertility and behavior.

<i>Polistes metricus</i> Species of wasp

Polistes metricus is a wasp native to North America. In the United States, it ranges throughout the southern Midwest, the South, and as far northeast as New York, but has recently been spotted in southwest Ontario. A single female specimen has also been reported from Dryden, Maine. Polistes metricus is dark colored, with yellow tarsi and black tibia. Nests of Polistes metricus can be found attached to the sides of buildings, trees, and shrubbery.

<i>Polistes fuscatus</i> Species of insect

Polistes fuscatus, whose common name is the dark or northern paper wasp, is widely found in eastern North America, from southern Canada through the southern United States. It often nests around human development. However, it greatly prefers areas in which wood is readily available for use as nest material, therefore they are also found near and in woodlands and savannas. P. fuscatus is a social wasp that is part of a complex society based around a single dominant foundress along with other cofoundresses and a dominance hierarchy.

<i>Dolichovespula adulterina</i> Species of wasp

Dolichovespula adulterina is a species of parasitic social wasp found in the Palearctic region. D. adulterina feeds on a variety of foods, including insects, spiders, arthropods, meat, molluscs, fruit, nectar, and larval secretions. D. adulterina was formerly considered to be synonymous with D. arctica from the Holarctic region, but more recent research indicates that D. arctica is a separate species.

<i>Polistes exclamans</i> Species of wasp

Polistes exclamans, the Guinea paper wasp, is a social wasp and is part of the family Vespidae of the order Hymenoptera. It is found throughout the United States, Mexico, the Bahamas, Jamaica and parts of Canada. Due to solitary nest founding by queens, P. exclamans has extended its range in the past few decades and now covers the eastern half of the United States, as well as part of the north. This expansion is typically attributed to changing global climate and temperatures. P. exclamans has three specific castes, including males, workers, and queens, but the dominance hierarchy is further distinguished by age. The older the wasp is, the higher it is in ranking within the colony. In most P. exclamans nests, there is one queen who lays all the eggs in the colony. The physiological similarities between the worker and queen castes have led to experiments attempting to distinguish the characteristics of these two castes and how they are determined, though males have easily identifiable physiological characteristics. Since P. exclamans live in relatively small, open combed nests, they are often subject to predators and parasites, such as Chalcoela iphitalis, Elasmus polistis, and birds. P. exclamans have defense and recognition strategies that help protect against these predators and parasites.

Apoica flavissima is a paper wasp found primarily in South America. The species is distinguishable by its light coloring, unique single comb nests, and nocturnal nature. A notable feature of this species is the size dimorphism between queens and workers. Unlike most Vespidae wasps, Apocia flavissima queens are smaller than their worker counterparts which results in unique intraspecies relationships.

<i>Polistes nimpha</i> Species of wasp

Polistes nimpha is a eusocial paper wasp found all over Europe, with particular sightings in Turkey, Finland, Estonia, and Latvia. It is also found in northern Africa, Pakistan, Iran, India, Kazakhstan, Mongolia, and China. The climate in these areas is relatively cold and snowy in the winter, while summers are usually hot and dry, with steppe vegetation. Polistes nimpha colonies are relatively small and easily manipulated.

<i>Polistes bellicosus</i> Species of insect

Polistes bellicosus is a social paper wasp from the order Hymenoptera typically found within Texas, namely the Houston area. Like other paper wasps, Polistes bellicosus build nests by manipulating exposed fibers into paper to create cells. P. bellicosus often rebuild their nests at least once per colony season due to predation.

<i>Polistes atrimandibularis</i> Species of wasp

Polistes atrimandibularis is one of three obligate social parasites among the Polistes wasps found in Europe. Of the four social paper wasp parasite species known, it is the smallest. It parasitizes multiple species such as P. dominula, P. nimpha, P. associus, P. gallicus, and P. biglumis. Females of P. atrimandibularis are unable to build a nest or produce workers, and therefore rely entirely on the host colony.

<i>Polistes biglumis</i> Species of wasp

Polistes biglumis is a species of social wasp within Polistes, the most common genus of paper wasp. It is distinguished mainly by its tendency to reside in montane climates in meadows or alpine areas. Selection pressure from the wasp's environment has led to several idiosyncrasies of its behavior and lifecycle with respect to its relative species in the genus Polistes. It alone among paper wasps is often polyandrous. In addition, it has a truncated nesting season that gives rise to unique competitive dynamics among females of the species. P. biglumis wasps use an odor-based recognition system that is the basis for all wasp-to-wasp interaction of the species. The wasp's lifecycle is highly intertwined with that of Polistes atrimandibularis, an obligate social parasite wasp that frequently invades the combs of P. biglumis wasps.

<i>Polistes semenowi</i> Species of wasp

Polistes semenowi is a species of paper wasp in the genus Polistes that is found in southeastern and southern central Europe, as well as central Asia, and was until 2017 erroneously known by the name Polistes sulcifer, while a different species was incorrectly believed to represent P. semenowi. It is one of only four known Polistes obligate social parasites, sometimes referred to as "cuckoo paper wasps", and its host is the congeneric species Polistes dominula. As an obligate social parasite, this species has lost the ability to build nests, and relies on the host workers to raise its brood. P. semenowi females use brute force, followed by chemical mimicry in order to successfully usurp a host nest and take over as the queen.

<i>Polistes versicolor</i> Species of wasp

Polistes versicolor, also known as the variegated paper wasp or yellow paper wasp, is a subtropical social wasp within Polistes, the most common genus of paper wasp. It is the most widely distributed of South American wasp species and is particularly common in the Southeastern Brazilian states. This social wasp is commonly referred to as the yellow paper wasp due to the distinct yellow bands found on its thorax and abdomen. The P. versicolor nest, made of chewed vegetable fiber, is typically a single, uncovered comb attached to the substratum by a single petiole. The yellow wasp is frequently found in urban areas. New nests and colonies are usually founded by an association of females, sometimes in human buildings. The P. versicolor colony cycle broadly ranges from 3 to 10 months, although there appears to be no relationship between the colony's development and the season of the year. While yellow paper wasps do have clear annual colony cycles, many young queens have the opportunity to hibernate during the winter, forming optional winter aggregations. Dominance hierarchies within these aggregations are characterized by physical aggression of the dominant female(s) towards the associated females, who tend to be sisters. Wagging movements are also often used as a form of communication within the colony. The yellow paper wasp is generally predatory, capturing a wide range of insects, although it often feeds on pollen and nectar as well. Therefore, P. versicolor can be useful as a pollinator or as effective pest control.

The name cuckoo paper wasp refers to a monophyletic species group of brood-parasitic paper wasps in the genus Polistes. This species group contains only four species; Polistes atrimandibularis, P. austroccidentalis, P. maroccanus, and P. semenowi, all of them obligate social parasites on other Polistes species.

<i>Vespula infernalis</i> Species of wasp

Vespula infernalis is an obligate parasitic wasp, parasitizing the nests of other species in the genus Vespula. Its common host species is V. acadica in North America. It is sometimes called the cuckoo yellowjacket wasp due to its inquiline lifestyle. They differ from other parasitic wasps in their intensely aggressive behaviour during invasion and occupation of the host colony. Several morphological adaptations such as bigger body parts and more curved sting shafts are observed in these wasps to aid their aggressive parasitic behaviour. Once they occupy a host's nest, V. infernalis are known to engage in mauling and chasing of host workers and forced trophallaxis. Female wasps will also force host workers to feed and take care of their brood.

Van der Vecht's gland or Van der Vecht's organ is a gland which is located in an area of modified cuticle on the rearmost gastral sternite of female wasps. This gland secretes chemicals which are important in the determination and maintenance of the hierarchy of groups of eusocial wasps and are used in the defence of the nests in others. In the Asian giant hornet the van der Vecht's gland is used to scent mark hives of honey bees to attract other members of their colony to cooperatively attack the hive; the only known case of the gland's use to scent mark a food source. In the cleptoparasitic paper wasp Polistes semenowi the female usurps the host foundress, usually Polistes dominula and uses an enlarged Van der Vecht's gland to produce large quantities of hydrocarbons and to control the host workers, and even sometimes the host foundress. The gland was discovered by, and named in honour of, the Dutch entomologist Jacobus van der Vecht.

References

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