Polistes dominula

The European paper wasp (Polistes dominula, often misspelled as dominulus) is one of the more common and well-known species of social wasps in the genus Polistes. Its diet is more versatile than that of most Polistes species (many genera of insects versus mainly caterpillars in other Polistes), making it superior over many others during the shortage of resources. The dominant females (queens) are the principal egg layers, while the subordinate females ("auxiliaries") primarily forage and do not lay eggs. This hierarchy is not permanent, however; when the queen (alpha-female) is removed from the nest, the second-most dominant female (beta-female) displaces the role of the previous queen.^[1] Dominance in females is determined by the severity of the scattered-ness in the coloration of the clypeus (face), whereas dominance in males is shown by the variation of spots of their abdomens.^[2] Polistes dominula is far from being extinct or even being in danger due to their exceptional survival features such as productive colony cycle, short development time, higher ability to endure predator attacks and many more.^[3]

Polistes dominula wasps have a lek-based mating system. Unlike most social insects, 35% of Polistes dominula wasps in a colony are unrelated. It is considered an invasive species in Canada and the United States.

Taxonomy

Polistes dominula was originally described in 1791 by Johann Ludwig Christ as Vespa dominula. The specific epithet dominula is a noun meaning "little mistress",^[4] and following the International Code of Zoological Nomenclature, species epithets which are nouns do not change when a species is placed in a different genus. Authors who were unaware that dominula was a noun have misspelled the species name as "dominulus" for decades. Another cause of the confusion in the species' name was the ambiguous distinction between masculine and feminine genitive nouns.^[5] Polistes dominula is often referred to as the European Paper Wasp because of its native distribution and its nests, which are constructed from paper and saliva. Polistes dominula is also frequently referred to in older literature as Polistes gallicus, a separate species with which it was often confused.^[6]

Description and Identification

There is little variation among individual P. dominula; the wing length of males range from 9.5 to 13.0 mm, while that of females ranges from 8.5 to 12.0 mm. Its body is colored entirely yellow and black, similar to that of Vespula germanica, one of the most common and aggressive wasps in its native range.^[7] The female mandible is black and sometimes has a yellow spot. Females have a black subantennal mark that rarely has a pair of small, yellow spots. The female vertex sometimes has a pair of small, yellow spots behind the hind ocelli. Females have yellow, comma-shaped scutal spots.^[8]

Variations amongst individual Polistes dominula

Although it is difficult to find conspicuous variations amongst individual Polistes dominula with bare eyes, there are definite features unique to each individual. For example, the abdominal spots on male P. dominula vary in sizes, locations and patterns. They act as sexually selective signals and also are used to determine social hierarchy within the colonies. Male P. dominula with smaller, regular patterns of spots were more aggressive and dominant over those who had larger, irregular patterns. Similarly, morphology of female P. dominula also varies between individuals. The larger and the more scattered the clypeus marks on the foundress are, the higher the chance for her to be dominant over other females.^[9]

Distribution

The native range of Polistes dominula covers much of southern Europe and North Africa, and temperate parts of Asia as far east as China.^[10] It has also been introduced to Australia, New Zealand, South Africa,^[11] and North and South America. Since the mid-1980s, the population of P. dominula has expanded to rather cooler regions, especially towards northern Europe. It is speculated that global warming has raised temperatures of certain areas, allowing P. dominula to expand to originally cooler regions.^[8]

The first North American occurrence of P. dominula was reported in Massachusetts in the late 1970s,^[12] and by 1995 this species had been documented throughout the northeastern USA.^[13] However, there is a large possibility that the species is also present in additional states, but has just not yet been reported. Although detailed mechanisms of the species' dispersal are still unknown, it is likely that some number of individuals, including the foundresses, may have hidden inside transportable items such as shipping crates, trailers, boats, or other human-made structures that were used during international trading between countries.^[8]

Habitat

Polistes dominula generally live in temperate, terrestrial habitats such as chaparral, forest and grassland biomes. They also have the propensity to colonize nearby human civilizations because human-made structures can act as great shelters and also oftentimes located close to the resources such as food.^[14]

Spread within North America

Behavioral adaptations of Polistes dominula have allowed it to move past its native range and invade the United States and Canada. While most Polistes species in the United States feed only on caterpillars, P. dominula eats many different types of insects. P. dominula also nests in areas with better protection, and are therefore able to avoid predation that has affected many other Polistes species. Much of North America has a very similar ecology and habitat to that of Europe, and this has allowed a faster and more successful colonization.^[15] P. dominula was also compared to and found to be more productive than Polistes fuscatus, which is indigenous to the United States. P. dominula produces workers about a week earlier and forage earlier in the day than Polistes fuscatus.^[16] It is a concern for cherry and grape growers in British Columbia, Canada, as it injures the fruit by biting off the skin. They also spread yeast and fungi that harm fruit and can be a nuisance to workers and pickers at harvest.^[17]

Displacement of native species by Polistes dominula invasion

Before 1995, Polistes fuscatus was the only species of Polistes in Michigan.^[18] In the spring of 1995, one single foundress colony of P. dominula was discovered nesting in the Polistes nestbox at the Oakland University Preserve in Rochester, Michigan.^[13] In 2002, approximately one third of the P. dominula colonies at the Preserve was removed because of the concern about losing the resident population of Polistes fuscatus. Although the removal of P. dominula population did slow down their expansion, in 2005, it was recorded that 62% of the colonies at the Preserve were P. dominula.^[19] After studying these data, a number of researchers concluded that Polistes dominula was likely replacing Polistes fuscatus through indirect or exploitative competition, which was consistent with their finding that Polistes dominula was significantly more productive than Polistes fuscatus.^[18] (See below for more comparisons of P. dominula and P. fuscatus)

Genetic variations within the Polistes dominula population

Populations of P. dominula contain relatively high levels of genetic variation and these variations are most likely due to different dispersal events.^[20] Through genetic observations of diverse regional P. dominula populations, it was proved that there is an allelic richness and distribution of private alleles in the introduced population, as well as that the oldest population (Massachusetts) had the lowest level of genetic variation. These researches showed that there were various dispersion mechanisms amongst the P. dominula species and suggested that its origin might not only be confined to a single regional area. Furthermore, it was also discovered that the genetics of southern Californian population differed from both the eastern and northern Californians, suggesting that the source of the southern Californian population may be from either an unsampled area with the introduced range or from a different geographic area from within the native range.^[19]

Behaviors influenced by genetic diversity

Colony founding

Typically, a Polistes colony is founded by a single or a small group of females who have just emerged from hibernation during the winter. They generally prefer warmer climates and initiate constructing new nests.^[21] However, a different approach has been observed during the spring colony-founding phase of P. dominula in some areas of North America, where a large group of more than 80 wasps aggregated to reuse and expand an old nest.^[22] Such unusual nesting method is thought to contribute to the extremely extensive spread of the P. dominula species in novel areas where it might otherwise be difficult for new-comer individuals to find conspecifics.^[23]

Life cycle

Overwintering founding queens, or foundresses, spend about a month in the spring constructing a nest and provisioning offspring, the first of which will become daughter workers in the growing colony. One or more foundresses will begin the colonies in the spring. If there are multiple foundresses, the one who lays the most eggs will be the dominant queen. The remaining foundresses will be subordinate and do work to help the colony.^[18]

Males are produced later, and when they start to appear, a few daughters may mate and leave their nest to become foundresses the next season. The switch from production of workers to production of future foundresses (gynes) is not utterly abrupt, as has been considered the case for other species of Polistes.

The colony disperses in the late summer, with only males and future foundresses produced instead of workers, and individuals frequently cluster in groups (called a hibernaculum) to over-winter. Hibernation does not usually take place on former nest sites.

Social hierarchies established within the colony can also influence individual P. dominula's longevity. Queen P. dominula lives longer than the males or the workers because the workers protect the queen from predators. The queen starts laying eggs in late March or early April, immediately after the 'founding phase' of the newly built nest. Then, the colony disperses in the late summer, with only males and future foundresses produced instead of workers. Although individuals frequently cluster in groups (called a hibernaculum) to over-winter, neither most non-reproductive males nor non-reproductive females survives the winter because their lifespans are shorter than a year (around 11 months) and they best survive during warm temperatures. Queens may survive the winter by hibernating. Hibernation does not usually take place on former nest sites.

Biological superiority of Polistes dominula over other Polistes species

There have been many reports of regions where which were originally home for Polistes fuscatus have slowly altered to that of Polistes dominula. There are a couple of possible factors that contribute to the superiority of Polistes dominula over Polistes fuscatus, specifically in settling into a territory. Some of the factors include productive colony cycle, short developmental time, aposematic coloration, a generalist diet, and the ability to colonize new environment.^[18]

Colony cycle

P. dominula colonies are established by females who have left their natal combs to mate and find new settlements. There are three major strategies these “foundresses” use to establish new colonies including (1) building a nest by herself, (2) finding “associate-foundresses” to build the nest together, and (3) 'sitting-and-waiting' for the original foundresses to leave the nest and then displace her. Once the foundresses have settled, the 'founding phase' is over and is followed by the 'worker phase' where the first generation of offsprings are produced and grow as workers.^[24]

Polistes dominula appears to have relatively high colony productivity as compared to other Polistes species.^[18][25] In matched comparisons of filed colonies in Michigan, single foundress colonies of Polistes dominula were 4-5 times as productive at the colony cycle as that of Polistes fuscatus. In North America, it was reported that P. dominula were significantly more productive than comparable colonies of the native Polistes metricus.^[26]

Short development time

The relatively high productivity of P. dominula may be correlated to the timing of its brood development. Compared to that of other Polistes species, P. dominula brood developmental period is much shorter. For instance, there was a laboratory evidence that P. dominula produced its first workers much earlier than the native Polistes metricus, a native North American species.^[26] Similarly when compared to Polistes fuscatus, P. dominula workers were produced approximately 6 days earlier even when their egg-hatching dates were the same. This indicated that the development times for the larvae and pupae, and not eggs, were significantly shorter in P. dominula than in P. fuscatus.^[7]

The precise reasons for P. dominula such shorter brood development timing is unknown but there are a number of conjectures. At the mechanical level, both genetic factors (e.g., smaller adult body size) and environmental influences (e.g., higher provisioning levels) may play a role. In a different aspect, the selection pressure exerted by the European social parasites such as Polistes sulcifer and Polistes semenowi might have impacted the developmental times in P. dominula to be shorter. Because these parasites normally attack the host nests just prior to worker emergence, it would be advantageous for P. dominula to have a shortened brood developmental time.^[19]

Generalist diet

P. dominula has a more generalist diet than many other Polistes species, giving it a more flexible selection of prey.^[15] One study in Europe found that the prey items brought back to nests by Polistes dominula colonies represented three insect orders^[27] while in contrast, North American Polistes primarily only use caterpillars to feed their offsprings.^[28] Some other theories however, suggested that it is not that individual P. dominula have a more general dietary, but rather the response of P. dominula colonies may be more opportunistic relative to resources. For example, P. dominula use more workers to increase the amount of foraging, utilize eggs to feed the offsprings and reduce allocation of protein to nest construction to take advantage of poorer quality prey during periods of low prey availability.^[19]

Strong defense against predation

Another strength of P. dominula in terms of survivorship is their ability to suffer less nest predation than other Polistes. There were studies conducted that showed P. dominula is of a less attractive prey for birds mainly due to their aposematic coloration and also the relatively strong attachment of their comb to the substrate – typically tree branches or human-made structures.^[15] Unlike Polistes fuscatus, which is colored brown with a few faint, thin, yellow stripes, P. dominula is colored bright yellow with alternating black, similar to the warning coloration of Vespula germanica, a common and aggressive yellowjacket.^[15] Additionally to their alerting coloration, P. dominula comb strength also contributes to their higher chance of survivorship. P. dominula might have an advantage over Polistes fuscatus against avian predators because their combs are less likely to be dislodged from their substrate by birds because the side force required to dislodge it is greater for P. dominula than for P. fuscatus' combs.^[29]

Dominance hierarchy

Caste system

Hierarchies in social insects serve two functions: to allow a single reproducing individual to emerge, and to enable the progressive exclusion of non-reproducing individuals from the nest space.^[30]

Morphologically, there are few differences between the foundress and subordinate members of the colony. However, several studies have shown that behavioral differentiation does occur,^[31][32] with the role an individual female takes being determined by social interaction within the colony. Dominant females, also known as the queens, are the principal egg-layers. Queens occupy the nest, oviposition, and rarely forage. In comparison, auxiliaries, or subordinate females, primarily forage and do not lay eggs.^[33] Autumnal helpers display a unique, behavioral phenotype demonstrated by only a small percentage of workers. These individuals leave their natal nest to overwinter in order to found new colonies in the spring. Compared to non-helpers, these helpers exhibit higher overall levels of activity, demonstrating higher frequencies of behaviors.^[34] Specifically they gave more trophallaxis, attacked more, and received more RDB [ritualized dominance behavior]. Non-helpers received more trophallaxis and performed more RDB.^[34] Researchers have also found that the survival rate of helpers is around 14% while the survival rate of non-helpers is around 59%.^[34]

These behavioral divisions are not permanent. For instance, if an alpha female is removed from a nest, then another female, usually the second-most dominant, beta female, assumes the role and behavioral profile of the removed dominant. Indeed, individuals alternate between different profiles of behavior within their own dominance rank position. When larvae were artificially removed, the frequency of worker reproduction increased. Therefore, workers lay eggs when they perceive a decline in queen power, as demonstrated by artificially empty cells.^[35]

The interactions of females in the nest can influence which daughters become workers and which become gynes. Despite some minor physiological differences (primarily in the fat body), gyne-destined females produced late in the colony cycle can be induced to become workers if placed on nests that are at an earlier stage of colony development, and the reverse is also true. This indicates a significant degree of flexibility in the caste system of this species.

Female dominance

Typically, the alpha female dominates all other individuals of a colony, laying the majority of eggs and partaking in differential oophagy. The alpha female devotes much of her time to social interaction, in comparison to subordinates that are much more involved in foraging and brood care.^[36] The clypeus, the yellow region above the mouth, is extremely variable in number, size, and shape of black spots, and this variation correlates to dominance; more dominant individuals have more black spots.^[37] The arrival at the nest correlates with the dominance hierarchy. Therefore, individuals that join the nest later are seldom dominant.^[38]

P. dominula show distinct behavioral differences in response to face marking. Researchers used paint to alter the number of facial spots on two wasps of the same size after killing them. They put these dead wasps as guards in front of food sources and introduced a third wasp to see where this wasp would go. The third wasps chose the food source that was guarded by the wasp with fewer spots 39 out of the 48 times. Therefore, the dominance of wasps of the same size is predicted by facial coloring, with more dominant individuals having more spots.^[39] Researchers experimented to determine whether social costs maintain the honesty of facial signals. They altered the facial coloring of wasps and then put them together to battle. The winner is clearly identified by mounting the loser while the loser lowers its antennae. While the manipulation of coloring did not affect who won the battle for dominance, it did significantly affect the behavior after the battle. Losers who were painted with more spots experienced six times more aggression than controls who had not been painted. The honesty of facial coloring is explained by social costs that are imposed when wasps do not signal honestly.^[40]

Male dominance

Male abdominal spots correlate with dominance. Smaller, elliptically shaped spots reflect a more dominant male who is preferred by females and wins competitions with other males. This is in contrast to males with larger, irregularly shaped abdominal spots who are generally subordinate and less sexually successful.^[41]

Abdomen stroking behavior and its possible functions

Abdomen rubbing of the female P. dominula occurs during the egg stage of the colonies, more in multiple female colonies than in solitary colonies. There are several possible functions of female P. dominula abdominal rubbing, one of them being painting predator-resistant chemicals on the surface of the nest for defense.^[42] Second possible function is to communicate the dominance status of the female P. dominula to the young brood.^[26] Alpha females perform abdomen stroking more than subordinate females. After an alpha female is removed, subordinates increase their abdomen stroking rate. The substances that are secreted during the rubbing has two potential functions; (1) repressing future ovarian development In the brood, (2) informing the brood of which adult female is the dominant individual.^[43]

Relatedness

Polistes dominula is a social insect that lives in colonies. P. dominula are haplodiploid insects, as are other Polistes species including Polistes metricus and Polistes annularis. This means they have haploid males that produce identical haploid sperm, and diploid females that produce haploid eggs through meiosis. In most social insects, colonies are composed of related individuals, and it is usually assumed that social insects help close relatives according to W. D. Hamilton's theory of kin selection. However, in P. dominula 35% of the nest mates are unrelated.^[18][37] In many other species, unrelated individuals only help the queen when no other options are present. In this case, subordinates work for unrelated queens even when other options may be present. No other social insect submits to unrelated queens in this way. This seemingly unfavorable behavior parallels some vertebrate systems. It is thought that this unrelated assistance is evidence of altruism in P. dominula.^[18]

It was found that the majority of nests had one or more females that were unrelated, especially in the winter before nests are formed and workers born. The nests tend to form from foundresses of different nests from previous years. The foundresses are also found over-wintering with other wasp species, showing why unrelated wasps are found during winter. However, after winter when the nests are starting to be formed, there is an increase in relatedness in the nests, which could result from foundresses searching for more related sisters, instead of unrelated wasps. After winter, as wasps leave their winter areas and return to their nests, there is an increase in relatedness in the early nest phase. In later stages of the nest, there are more unrelated wasps, which could be because new wasps join established nests.^[44]

Recognition

Usage of cutical hydrocarbon (CHC) in recognizing nestmates and non-nestmates

P. dominula females are able to distinguish between nestmates and non-nestmates. Triads of wasps show more discrimination and aggression toward non-nestmates than dyads of wasps. In triads, there is increased aggression because a defense of the nest can be shared with other nestmates, but for an individual the cost of the aggression is greater than the benefit of the defense.^[19] Insect body surface is coated with cuticular hydrocarbons (CHC) for waterproofing. These chemicals also contribute to recognition among individuals, kin, and nest mates.^[45] The same cuticle that the adults have are coated on the nests, allowing the wasps to recognize their home. An analysis of the differences in CHC profiles between dominant and subordinate females found that while differences are not clear at the early stages of nest founding, these differences become prominent upon worker emergence.^[46] The CHC profiles of the dominant female exhibit a greater proportion of distinctive unsaturated alkenes of longer chain length compared to those of subordinates.^[47] When the queen is removed, the replacement queen's CHC profile becomes similar to that of the original queen.^[45] Upon analyzing whether CHC is a signal for fertility or dominance, researchers concluded that it is a signal for dominance because subordinates with developed ovaries still exhibited profiles that differed from those of dominants.^[47]

Sexually selected signals in male Polistes dominula wasps

Male P. dominula utilize their physical features to sexually appeal to the females and copulate. They have a pair of yellow dorsal abdominal spots that act as sexually selected signals. The size, location and coloration of the spots also determine the male P. dominula hierarchy, mating success (being preferred/rejected by females) and victory in male-male competition. Through laboratory experiments, it was discovered that females preferred males with smaller, more regular spots. Similarly, those “preferred” male P. dominula were more likely to be the dominant males in the population by winning more same-sex fights, compared to those with larger, irregularly shaped spots.^[41]

Visual signals of status and rival assessments

The black facial patterns are associated with the male P. dominula dominance and conditions.^[48] There are variations in the facial patterns of the male P. dominula, from being “unbroken” to “scattered” - unbroken black spot represents “low quality” while scattered spots (having several spots) represent “high quality”. Male P. dominula generally avoid combating with “high quality” males and fight for resources that “low quality” males are protecting to reduce the cost of aggressive competition.^[41] Naturally, such behaviors give rise to social hierarchy, placing males with more spots on top of the social class.

Similar to the abdominal spots that imply strong fighting fitness and mating success in male P. dominula, the salient patterns on the female P. dominula clypeus demonstrate strong correlation to its dominance and is used to facilitate rival assessments.

Dufour's Gland Secretion

The usage of cuticular hydro-carbon (CHC) in recognizing nestmates and neighbors is a relatively well-known method for Hymenoptera, especially among Polistes. However, Dufour's gland secretion has also been discovered to contribute in such assessments of invaders and nestmates. Chemical analysis of the Dufour's gland secretion revealed that it has a very similar composition as the cuticular hydrocarbons. However, a big difference was that cuticular hydrocarbons had more linear hydrocarbons than the glands and dimethylalkanes were more prevalent in gland secretions. Significantly different dimethylalkanes were found in foundresses belonging to different colonies, suggesting that these could be used to discriminate species of different origins.^[49]

Roles of Cuticular Hydrocarbons (CHC) in Polistes dominula larvae

Because the chemicals coated on the nests are equivalent to that present in adult P. dominula bodies, young wasps learn this chemical template in the very early state of the adult life to later on be able to distinguish their nestmates from non-nestmates.^[7] The CHC composition of the larvae and adults are very different, that the larvae's relative abundance of low molecular weight CHC is higher and that the larval profiles are more uniform than those of adults.^[50] Not only that, adults are able to distinguish odors of their own colonial larval CHC from foreign colony's.

Behavior

Foundress behavior

In the first 12 days of the nesting period, 75% of foundresses leave their original nest, traveling to around three nests before settling permanently. Foundresses visit multiple nests before choosing the nest with the highest reproductive payoff.^[33] Foundresses choose nest sites by weighing the benefit of an expanded colony with the cost of predation risk.^[51] Multiple-foundress nests have a higher chance of survival compared to single-foundress nests, and in general, foundresses found nests with those they hibernate with in the same aggregation.^[38]

Comb arrangement

The nest, consisting of a single comb, is the heart of the colony, where food is stored and the immature brood reared. It is also the central spatial reference where the majority of individuals spend their time.^[52] P. dominula do not occupy the comb in random distribution. Each wasp spends the majority of its time on the comb in a relatively small area, approximately 12% of the comb. This small use of space is the norm regardless of the number of wasps on the nest. However, this area could occasionally cover up to 50% of the comb. Dominant females occupy a smaller area than do subordinate foundresses and workers. Superimposition rates are low, which suggests that wasps limit each other's spaces. Workers prefer to overlap areas with other workers, while foundresses prefer to overlap areas with other foundresses. Around 70% of workers are active and occupy a small area of the comb, while the rest do not have particular fidelity areas and spend most of their time away from the nest or remaining motionless behind the nest. Alpha females are affected by cell content, resting more frequently on capped cells and avoiding empty ones.^[52]

Cooperation

Cooperation provides survival benefits; multiple-foundress groups are more likely to survive to produce offspring than are single-foundress groups, and individual foundresses in multiple-foundress colonies are less likely to disappear before worker emergence than foundresses nesting alone. Therefore, association provides significant productivity and survival advantages for cooperating foundresses.^[53] Cooperation provides survival benefits only if individual foundresses on a multi-foundress nest have a greater chance of survival than individuals who found nests alone or the foundress' contribution to the nest is preserved even after she leaves.^[53]

Queen loss

Queen loss is a crisis for a colony of social insects. This situation may cause increased aggression and work inefficiencies. Also, if the colony can produce a new queen, it could be slow to produce eggs.^[54] After queen loss, replacement queens do not mate in the 12 days following queen removal and few had mature eggs in their ovaries. After a month, most replacement queens develop ovaries and mate.^[54] Nest growth decreases with colonies that lose their queen, which can be expected if increased dominance behavior interfered with other essential behaviors or if the new queen is not competent at egg laying. Among queenless colonies of P. dominula, individuals demonstrated an increased level of chewing and climbing, but not of lunging and biting. These are all dominance behaviors. There is no difference of foraging behaviors between colonies with and without queens. Subordinates are kept reproductively suppressed enough not to be a threat to the existing queen, as indicated by the high cost of queen replacement.^[54]

Nest adoption

Adoption is a result of three situations: when (1) queens lose their nests and 'make the best of a bad situation,' (2) workers leave multiple-foundress nests, and (3) subordinates employ a 'sit-and-wait' strategy, waiting for nests to be orphaned. Nests are orphaned when the adult wasps die while taking care of their nest, leaving an immature brood. Orphaned nests allow a new wasp to gain status as queen without a fight.^[27] Females who adopt nests are less cooperative and expend less energy than those who found nests. Spring foundresses sometimes found colonies alone, form associations with others, take over established conspecific colonies, or even adopt abandoned nests.^[55] Females would adopt an abandoned nest if they lost their nest due to predation or other damage or if they waited to adopt an orphaned nest rather than found their own. Females engaging in the 'sit-and-wait' reproductive strategy adopted the most mature nest rather than the nest with an increased probability of containing kin (from the same population). Females prioritize the quality of the nest over rescuing possible kin from another abandoned nest. Females demonstrate a preference for mature nests and nests with a large proportion of fourth and fifth instar larvae. When a female adopts an orphaned nest, she will destroy the existing eggs and instar larvae, but allow older larvae and pupae to complete development. Adopting a nest maximizes the potential of possessing a mature pre-worker phase colony without expending excessive energy during the nest founding period or cooperating in the construction of the nest.^[55]

Of note, once a nest is established it may be used by multiple generations and in multiple seasons. Nests aboandonded during the hibernation cycle are almost always re-populated the following spring. With each succession, the nest continues to grow in size. A few have been recorded at 8 inches in diameter. It has also been noted that multiple nests may be located in the same area within inches of each other.^[56]

Mating

Polistes dominula wasps have a lek-based mating system. Males compete intensely for dominant positions on the lek, while females are scrupulous when choosing their mate. Males form aggregations on the uppermost portions of structures such as fences, walls, roof peaks, and trees. Males often fight with other males in mid-air or on the structure. Males who lose will fly away from the lek. Females fly through leks or perch near lekking areas to observe males before making choices on mates. Females use the highly conspicuous abdominal spots on males, which are highly variable in size and shape, to aid in mate choice. Males with smaller, more elliptically shaped spots are more dominant over other males and preferred by females compared to males who have larger, more irregularly shaped spots.^[41]

Social insect males are often seen as mating machines, with an undiscriminating eagerness to mate. However, males encounter costs of unsuccessful mating in terms of energy investment. Therefore, P. dominula males are able to recognize female castes and preferentially choose reproductive females to workers, regardless of health or age. Males are able to differentiate castes through perceiving differences in chemical signals and physiological status. While males are able to discriminate between castes, they are not capable of discriminating between health as males showed a strong preference for gynes, both healthy and parasite-castrated, compared to workers. This is because males distinguish females by CHC profiles and CHC profiles of healthy and parasitized gynes are very similar. Therefore, males are not able to evaluate the true reproductive potential of the females they encounter.^[57]

In response to the males being sexually aggressive, there are ways female P. dominula demonstrate to weed out the low quality males. Females are typically larger and more dominant than males, so females exert strong choice by rejecting males.^[21] There are several different ways female P. dominula reject males. One way is to express aggressive behaviors such as biting, darting or stinging to stop the male from copulating with her. Another way is to remain still while the male mounts but move its abdomen to prevent the male's genitalia entering her body.^[15] Female P. dominula are also known to mate with multiple males, especially with non-nestmates.^[23] They fly over to different males' nests to assess the best quality males and generally copulate with the resident males. That males are resident males often implies that they are large, sexually active and aggressive – providing better protection for her and the brood.^[57]

Parasitoidism

Polistes dominula nests, constructed from paper and saliva, and resident brood host parasites and parasitoids, including predacious Lepidoptera larvae, Hymenoptera, Diptera, and Strepsiptera.^[6] P. dominula are also parasitized by Polistes sulcifer, a permanent workerless social parasite. Polistes sulcifer females take over the host colony by eliminating dominant foundresses and matching the host cuticular profiles. Females gain these profiles by intensively grooming and licking the host foundresses and workers or from the nest material, which is covered in hydrocarbons essential for nestmate recognition. This chemical mimicry allows the host colony to accept these foreign females.^[58] The first well documented case of parasitoidism of the North American invasive population was reported in 2010.^[6]

Industrial use of salivary proteins

Salivary proteins harvested from the nest of Polistes dominula have been cloned for use as a waterproof coating used in the manufacture of biodegradable UAVs. The lightweight material used to construct the body of the UAV consists of fungal mycelium covered with bacterial cellulose sheets. The cellulose is then waterproofed with a coating of the cloned protein, which is a component of the saliva used by the wasps to waterproof their paper nests.^[59][60]

References

Further reading

• Karsai, I. & Penzes, Z. (1996). "Intra-specific variation in the comb structure of Polistes dominulus: parameters, maturation, nest size and cell arrangement". Insectes Sociaux 43 (3): 277–296. doi:10.1007/BF01242929. 

External links

Wikimedia Commons has media related to Polistes dominula.

External identifiers for Polistes dominula
Encyclopedia of Life	1032903
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Also found in: Wikispecies

• Paper wasp Polistes dominula reference photographs, biological notes
• Polistes dominula facial markings indicating dominance
• "The European Paper-Wasp: A New Threat to Cavity-nesting Birds Is Coming!
• "Phylogenetic Tree of Polistes dominula "